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The aim of this study was to compare the size and shape of the indicated ablation zone using magnetic resonance (MR) imaging with different contrast weightings after MR-guided radiofrequency ablation (RFA) at 1.5 T.Magnetic resonance images of 50 patients treated for hepatic malignancies using MR-guided RFA were retrospectively evaluated. Areas indicating ablation zones in contrast-enhanced images were compared with nonenhanced T1- and T2-weighted images acquired after the intervention and 1 and 7 months after therapy. Corresponding slices were selected and registered to each other. Regions indicating ablation zones were segmented and compared. Areas in cm, positive predictive value, and sensitivity of native T1- and T2-weighted images were calculated with regard to their accordance with the contrast-enhanced images.Directly after the intervention, the ratios between the areas of the ablation zone in the contrast-enhanced and the tested sequences were 1.02 ± 0.12 in the T1-weighted images and 2.03 ± 0.78 in the T2-weighted images. Sensitivity (portion of the coagulation zone that was correctly detected based on the tested sequences) was 0.88 ± 0.08 using the T1-weighted and 0.54 ± 0.20 using the T2-weighted images. The positive predictive values were 0.89 ± 0.06 (T1 weighted) and 0.93 ± 0.06 (T2 weighted). One month after therapy, the ratios between the areas in the contrast-enhanced and the tested sequences were 1.02 ± 0.12 in the T1-weighted images and 1.04 ± 0.25 in the T2-weighted images. Seven months after therapy, the ratios were 1.04 ± 0.16 in the T1-weighted and 1.18 ± 0.22 in the T2-weighted images.In examinations performed directly after the intervention, the T2-weighted images tend to underestimate the ablation zone, whereas T1-weighted images clearly better reflect the ablation zone. T1-weighted images therefore seem more adequate for repetitive monitoring of MR-guided RFA at 1.5 T.

Hybrid whole-body magnetic resonance/positron emission tomography (MR/PET) systems are a new diagnostic tool enabling the simultaneous acquisition of morphologic and multiple functional data and thus allowing for a diversified characterization of oncological diseases.The aim of this study was to investigate the image and alignment quality of MR/PET in patients with pulmonary lesions and to compare the congruency of the 2 functional measurements of diffusion-weighted imaging (DWI) in MR imaging and 2-deoxy-[18F] fluoro-2-D-glucose (FDG) uptake in PET.A total of 15 patients were examined with a routine positron emission tomography/computer tomography (PET/CT) protocol and, subsequently, in a whole-body MR/PET scanner allowing for simultaneous PET and MR data acquisition. The PET and MR image quality was assessed visually using a 4-point score (1, insufficient; 4, excellent). The alignment quality of the rigidly registered PET/CT and MR/PET data sets was investigated on the basis of multiple anatomic landmarks of the lung using a scoring system from 1 (no alignment) to 4 (very good alignment). In addition, the alignment quality of the tumor lesions in PET/CT and MR/PET as well as for retrospective fusion of PET from PET/CT and MR images was assessed quantitatively and was compared between lesions strongly or less influenced by respiratory motion. The correlation of the simultaneously acquired DWI and FDG uptake in the pulmonary masses was analyzed using the minimum and mean apparent diffusion coefficient (ADC min and ADC mean) as well as the maximum and mean standardized uptake value (SUV max and SUV mean), respectively. In addition, the correlation of SUV max from PET/CT data was investigated as well. On lesions 3 cm or greater, a voxelwise analysis of ADC and SUV was performed.The visual evaluation revealed excellent image quality of the PET images (mean [SD] score, 3.6 [0.5]) and overall good image quality of DWI (mean [SD] score of 2.5 [0.5] for ADC maps and 2.7 [0.5] for diffusion-weighted images, respectively). The alignment quality of the data sets was very good in both MR/PET and PET/CT without significant differences (overall mean [SD] score of MR/PET, 3.8 [0.4]; PET/CT 3.6 [0.5]). Also, the alignment quality of the tumor lesions showed no significant differences between PET/CT and MR/PET (mean cumulative misalignment of MR/PET, 7.7 mm; PET/CT, 7.0 mm; P = 0.705) but between both modalities and a retrospective fusion (mean cumulative misalignment, 17.1 mm; P = 0.002 and P = 0.008 for PET/CT and MR/PET, respectively). Also, the comparison of the lesions strongly or less influenced by respiratory motion showed significant differences only for the retrospective fusion (21.3 mm vs 11.5 mm, respectively; P = 0.043). The ADC min and SUV max as measures of the cell density and glucose metabolism showed a significant reverse correlation (r = -0.80; P = 0.0006). No significant correlation was found between ADC mean and SUV mean (r = -0.42; P = 0.1392). Also, SUV max from the PET/CT data showed significant reverse correlation to ADC min (r = -0.62; P = 0.019). The voxelwise analysis of 5 pulmonary lesions each showed weak but significant negative correlation between ADC and SUV.Examinations of pulmonary lesions in a simultaneous whole-body MR/PET system provide diagnostic image quality in both modalities. Although DWI and FDG-PET reflect different tissue properties, there may very well be an association between the measures of both methods most probably because of increased cellularity and glucose metabolism of FDG-avid pulmonary lesions. A voxelwise DWI and FDG-PET correlation might provide a more sophisticated spatial characterization of pulmonary lesions.

Objectives The aim of this study was to evaluate the quantitative and semiquantitative measures of regional pulmonary parenchymal perfusion in patients with chronic obstructive pulmonary disease (COPD) in relationship to global lung perfusion (GLP) and lung diffusing capacity (DLCO). Materials and methods A total of 143 participants in the Multiethnic Study of Atherosclerosis COPD Study were examined by dynamic contrast-enhanced pulmonary perfusion magnetic resonance imaging (MRI) at 1.5 T. Pulmonary microvascular blood flow (PBF) was calculated on a pixel-by-pixel basis by using a dual-bolus technique and the Fermi function model. Semiquantitative parameters for regional pulmonary microvascular perfusion were calculated from signal intensity-time curves in the lung parenchyma. Intraoberserver and interobserver coefficients of variation (CVs) and correlations between quantitative and semiquantitative MRI parameters and with GLP and DLCO were determined. Results Quantitative and semiquantitative parameters of pulmonary microvascular perfusion were reproducible, with CVs for all parameters of less than 10%. Furthermore, these MRI parameters were correlated with GLP and DLCO, and there was good agreement between PBF and GLP. Quantitative and semiquantitative MRI parameters were closely correlated (eg, r = 0.86 for maximum signal increase with PBF). In participants without COPD, the physiological distribution of pulmonary perfusion could be determined by regional MRI measurements. Conclusion Regional pulmonary microvascular perfusion can reliably be quantified from dynamic contrast-enhanced MRI. Magnetic resonance imaging-derived quantitative and semiquantitative perfusion measures correlate with GLP and DLCO.

To evaluate radiation exposure and image quality in thoracic computed tomography (CT) using a new dose-saving algorithm to protect radiosensitive organs.For dose measurements, an Alderson RANDO phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to the International Commission on Radiologic Protection 103. Exposure was performed on a second-generation dual-source CT. The following parameters for thoracic CT were used: 160 effective mAs, 120 kV, scan range of 30 cm, collimation of 128 × 0.6 mm. For the acquisition, the tube current modulation type XCare was used, which reduces the tube current for anterior tube position to minimize direct exposure to anterior located organs. To compare differences, scans with and without XCare were performed. Objective signal-to-noise measurements were evaluated, and the subjective noise perception was rated in a 3-point scale (1: excellent, 3: affecting diagnostic accuracy) in 30 patients with a standard thoracic examination and a follow-up using XCare.A substantial dose reduction in radiosensitive tissues was evident using the dose-saving algorithm XCare. Specifically, reductions of 35.2% for the female breast and 20.1% for the thyroid gland were measured, resulting in a decreasing effective whole-body dose of 8.0% and 14.3% for males and females, respectively. The objective and subjective evaluation of image quality showed no significant differences between both scan protocols (P0.05). Mean signal-to-noise ratio was 1.3 ± 0.2 and 1.2 ± 0.2 in scan protocols without and with XCare, respectively. The subjective scores at the level of the pulmonary trunk were 1.2 ± 0.4 and 1.4 ± 0.5 in standard chest scan and scans with the dose-saving algorithm XCare, respectively.The XCare technique protects radiosensitive organs like the female breast and the thyroid gland without affecting image quality. Therefore, this dose-saving algorithm may be used in thoracic CT examinations in male and female patients.

To develop suitable strategies for quantification of longitudinal relaxation time (T1) by means of ultrashort echo time (UTE) sequences and the variable flip-angle approach in materials and tissues with extremely fast signal decay.: A recently published modified Ernst equation, which correctly accounts for in-pulse relaxation of transverse magnetization, was used to numerically determine optimal flip angles for reliable assessment of T1 in case of extremely short effective transverse relaxation time (T2*). Various ratios of repetition time (TR) to T1 and radiofrequency (RF) pulse duration (TRF) to T2* were evaluated. Theoretical considerations were applied to solid polymeric material (T2* = 0.295 milliseconds), and T1 quantification was performed using various optimized flip-angle approaches at different RF pulse durations (TRF = 0.1-0.4 milliseconds). Furthermore, in vivo measurement of T1 in cortical bone was exemplarily performed in 3 healthy volunteers to test the applicability of the proposed method in vivo. For in vitro and in vivo studies, MR imaging was performed on a 3 T whole-body MR system using a 3D UTE sequence with a rectangular excitation pulse and centric radial readout.: Optimal flip angles were shown to be strongly dependent on TR/T1 and TRF/T2* ratios. Exemplarily, longitudinal relaxation time of the investigated solid polymeric material was determined to T1 = 223.1 ± 3.1 milliseconds with RF pulse duration of TRF = 0.2 milliseconds, and 12 acquired flip angles ranging from 5 to 60 degrees. Using only 2 optimized flip angles (8 degrees, 44 degrees), T1 of the same material was determined to T1 = 223.8 ± 4.2 milliseconds in a markedly less acquisition time. In vivo evaluation of cortical bone was feasible and showed T1 values of 80.4 ± 25.1 milliseconds, exemplarily.: Using the modified Ernst equation, it seems possible to rapidly evaluate 3D distribution of longitudinal relaxation time in materials and tissues with extremely fast signal decay by means of UTE sequences and only 2 measurements with optimized flip angles.

The objective of this study was to evaluate effects of 6 commercially available magnetic resonance contrast media (CM) on human umbilical vein endothelial cells (HUVEC) and the induction of transforming growth factor-beta (TGF-β) in dermal fibroblasts (HSF) as a possible model for the pathogenesis of nephrogenic systemic fibrosis.HUVECs were incubated with 10× and 20× of the molar standard blood concentration achieved with CM applications for magnetic resonance imaging examinations (10× and 20× concentration) for 24 hours using gadolinium-based CM Gadovist, Magnevist, Multihance, and Omniscan, as well as Teslascan (Manganese-based), and Resovist (Iron-based). Proliferation kinetics (PK), colony formation, and viability assays were performed. Additionally, human dermal fibroblasts (HSF) were incubated for 24 hours with 1× and 20× concentration in all 6 CM, and TGF-β levels were assessed directly after the incubation period as well as on days 3 and 8 postincubation.HUVEC PK data show similar gains in cell numbers for all 6 CM in both concentration groups over the 17-day assessment period. Only cells incubated with Omniscan and Teslascan differed from the other groups on days 3 and 7 postincubation (P0.05). After day 7, a cell regain occurred in the Omniscan and Teslascan groups reaching the numbers of the other groups in sequel. Differences in colony formation were consistent with PK results with a statistically significant reduction in clonogenic activity for Teslascan and Omniscan in HUVEC cells, P0.05. No reduction in viability was seen for all groups and conditions. TGF-β expression of HSF cells incubated with 1× concentration and all CM did not differ significantly from control cells for any point in time investigated. At 20× concentration directly after incubation, TGF-β was significantly reduced for the Teslascan and Resovist group as 3 compared with control and all other CM groups, P0.05. On day 3 postincubation, only Resovist-incubated HSF cells showed a significant reduction of TGF-β (1.614, standard deviations: 89) as compared with the control group (2.883, standard deviations: 30) and the other CM. TGF-β was slightly reduced for all CM groups 8 days after incubation (not statistically significant, P0.05).After 24 hours of incubation with Omniscan and Teslascan (10× and 20× concentration), considerable short-term antiproliferative effects in HUVECs were observed. HSF cells (20× concentration) showed a reduction of TGF-β for Resovist and Teslascan directly after incubation, whereas TGF-β levels in HSF cells were slightly reduced for all CM 8 days after incubation. Therefore, TGF-β-mediated proliferative effects on fibroblasts or on collagen synthesis potentially leading to nephrogenic systemic fibrosis may mainly be triggered by tissue monocytes and macrophages in the peripheral blood instead of dermal fibroblasts.

Aim of the study was to assess the potential value of cross-sectional adipose tissue evaluation in well defined single transverse slices for estimation of volumes of metabolically important adipose tissue compartments as visceral adipose tissue (VAT), nonvisceral adipose tissue (NVAT), and total body adipose tissue (TAT). In addition, validity of easily accessible anthropometric indices (waist-to-hip-ratio [WHR] and body mass index [BMI]) for prediction of volumes of those adipose tissue compartments were validated and compared.True volumes of main adipose tissue compartments VAT, TAT, and NVAT were carefully assessed based on whole-body magnetic resonance (MR) examinations in 367 volunteers (227 females, 140 males, age 18-69 years) at increased risk for type 2 diabetes. Volumes of VAT, NVAT, and TAT were compared with cross-sectional areas of adipose tissue in single transverse slices recorded on the level of (1) umbilicus (u), (2) head of humerus (h), (3) head of femur (f), and anthropometric data such as BMI and WHR. Separate analyses were performed in males and females.In both genders, strong correlations were found between TAT and the cross-sectional areas: subcutaneous adipose tissue (u) with r = 0.88 in females and r = 0.92 in males, TAT(h) with r = 0.80 in females and r = 0.82 in males, and TAT(f) with r = 0.90 in females and r = 0.90 in males. VAT assessed by MR single slice evaluation at the umbilical level (VAT(u)) showed a strong correlation with total VAT in both genders (r = 0.93 in females, r = 0.87 in males). Suitable algorithms for predicting VAT in liter from fat planimetry in a slice recorded at the umbilical level were derived: VAT = 0.16 x (VAT(u) x body height) + 0.3 in women and VAT = 0.15 x (VAT(u) x body height) + 1.2 in men. Disregarding the body height, the best equations were as follows: VAT = 0.03 x VAT(u) + 0.3 in women and VAT = 0.02 x VAT(u) + 1.4 in men. In contrast, BMI versus VAT showed a lower correlation in both genders: r = 0.71 in females, r = 0.56 in males, and WHR versus VAT was only weakly correlated in females and in males (r = 0.49 and r = 0.55, respectively). For WHR versus TAT, significant results were only found in males (r = 0.44).Axial MRI at the umbilical level allowed for a fast and reliable estimation, especially for VAT and TAT in a collective at risk for type 2 diabetes. WHR and BMI were found clearly worse in prediction of VAT volumes compared with single slice evaluation at the umbilical level.

Objectives In dual energy (DE) computed tomography (CT), spectral shaping by additional filtration of the high energy spectrum can theoretically improve dual energy contrast. The aim of this in vitro study was to examine the influence of an additional tin filter for the differentiation of human urinary calculi by dual energy CT. Materials and methods A total of 36 pure human urinary calculi (uric acid, cystine, calciumoxalate monohydrate, calciumoxalate dihydrate, carbonatapatite, brushite, average diameter 10.5 mm) were placed in a phantom and imaged with 2 dual source CT scanners. One scanner was equipped with an additional tin (Sn) filter. Different combinations of tube voltages (140/80 kV, 140/100 kV, Sn140/100 kV, Sn140/80 kV, with Sn140 referring to 140 kV with the tin filter) were applied. Tube currents were adapted to yield comparable dose indices. Low- and high energy images were reconstructed. The calculi were segmented semiautomatically in the datasets and DE ratios (attenuation@low_kV/attenuation@high_kV) and were calculated for each calculus. DE contrasts (DE-ratio_material1/DE-ratio_material2) were computed for uric acid, cystine and calcified calculi and compared between the combinations of tube voltages. Results Using exclusively DE ratios, all uric acid, cystine and calcified calculi (as a group) could be differentiated in all protocols; the calcified calculi could not be differentiated among each other in any examination protocol. The highest DE ratios and DE contrasts were measured for the Sn140/80 protocol (53%-62% higher DE contrast than in the 140/80 kV protocol without additional filtration). The DE ratios and DE contrasts of the 80/140 kV and 100/Sn140 kV protocols were comparable. Conclusion Uric acid, cystine and calcified calculi could be reliably differentiated by any of the protocols. A dose-neutral gain of DE contrast was found in the Sn-filter protocols, which might improve the differentiation of smaller calculi (Sn140/80 kV) and improve image quality and calculi differentiation in larger patients (Sn140/100 kV). However, even with the improved spectral separation of the Sn-filter protocols, the DE ratios of calcified calculi are not sufficiently distinct to allow a differentiation within this group.

Purpose: The aim of this study was to test and demonstrate the feasibility of diffusion tensor imaging (DTI) with a hybrid positron emission tomography (PET)/magnetic resonance imaging system for simultaneous PET and magnetic resonance (MR) data acquisition. Materials and Methods: All measurements were performed with a prototype hybrid PET/MR scanner dedicated for brain and head imaging. The PET scanner, which is inserted into a conventional 3.0-Tesla high field MR imager equipped with a transmit/receive birdcage head coil, consists of 192 block detectors with a matrix of 12 × 12 lutetium oxyorthosilicate scintillation crystals combined with MR-compatible 3 × 3 avalanche photodiode arrays. In 7 volunteers and 4 patients with brain tumors, DTI was performed during simultaneous PET data readout applying a diffusion weighted echo planar sequence (12 noncollinear directions, echo time (TE)/repetition time (TR) 98 ms/5300 ms, b-value 800 s/mm2). Image quality and accuracy of DTI were assessed in comparison with DTI images acquired after removal of the PET insert. Results: The diffusion images showed good image quality in all volunteers regardless of simultaneous PET data readout or after removal of the PET scanner; however, significantly (P < 0.01) stronger rim artifacts were found in fractional anisotropy images computed from DTI images recorded during simultaneous PET acquisition, demonstrating higher eddy-current effects. In region of interest analysis, no notable differences were found in the computation of the direction of the principal eigenvector (P > 0.05) and fractional anisotropy values (P > 0.05). In the assessment of pathologies, in all 4 patients PET and DTI provided important clinical information in addition to conventional magnetic resonance imaging. Conclusion: Diffusion tensor imaging may be combined with simultaneous PET data acquisition, offering additional important morphologic and functional information for treatment planning in patients with brain tumors.

To test the feasibility of a single MR-based examination allowing for the comprehensive assessment of renal anatomy, function, and vascular status in candidates for kidney transplantation.Twelve healthy potential kidney donors (mean age: 47 +/- 14 [standard deviation] years, 3 men and 9 women) participated in the study, which was approved by the local ethics committee. MR-nephrography was performed using a navigator-gated T1-weighted saturation-recovery sequence (TrueFISP: TR/TE = 621.31 milliseconds/1.27 milliseconds, Flip angle = 70 degrees, TI = 300 milliseconds, BW = 977 Hz/Px, or TurboFLASH: TR/TE = 528 milliseconds/1.15 milliseconds, Flip angle = 8 degrees, TI = 300 milliseconds, BW = 600 Hz/Px). Images were acquired up to 60 minutes after the injection of 4 mL of gadobutrol. The glomerular filtration rate (GFR) was evaluated from the renal clearance of gadobutrol within the extra cellular fluid volume by exponential fitting of time-signal curves measured over the liver. MR-angiography was performed using a T1-weighted 3D-Flash sequence. The overall measuring time was 70 to 80 minutes. For each subject, GFR data were compared with the results of renal scintigraphy with Tc-labeled DTPA from the same day.Kidney anatomy and vascular status were successfully assessed in all subjects. The results of MR-angiography were in excellent accordance with the surgical findings. MR-nephrography presented a good agreement to the scintigraphy (mean GFR from MR-nephrography = 117 +/- 24 mL/min per 1.73 m; mean GFR from scintigraphy = 116 +/- 26 mL/min per 1.73 m). The Bland-Altman-plot showed a mean difference in measurements pairs of -1 +/- 12 mL/min per 1.73 m. The absolute paired difference ranged between 0 and 22 mL/min per 1.73 m.The study showed the feasibility of the comprehensive assessment of renal anatomy, function, and vascular morphology, using 1 single MR examination. The proposed protocol may find immediate clinical application in the preoperative assessment of potential kidney donors.

Objectives: With the introduction of ultrashort echo time (UTE) sequences solid polymeric materials might become visible on clinical whole-body magnetic resonance (MR) scanners. The aim of this study was to characterize solid polymeric materials typically used for instruments in magnetic resonance guided interventions and implants. Relaxation behavior and signal yield were evaluated on a 3-Tesla whole-body MR unit. Materials and Methods: Nine different commonly used solid polymeric materials were investigated by means of a 3-dimensional (3D) UTE sequence with radial k-space sampling. The investigated polymeric samples with cylindrical shape (length, 150 mm; diameter, 30 mm) were placed in a commercial 8-channel knee coil. For assessment of transverse signal decay (T 2 *) images with variable echo times (TE) ranging from 0.07 milliseconds to 4.87 milliseconds were recorded. Spin-lattice relaxation time (T 1 ) was calculated for all MR visible polymers with transverse relaxation times higher than T 2 * = 300 μs using an adapted method applying variable flip angles. Signal-to-noise ratio (SNR) was calculated at the shortest achievable echo time (TE = 0.07 milliseconds) for standardized sequence parameters. All relaxation times and SNR data are given as arithmetic mean values with standard deviations derived from 5 axially oriented slices placed around the isocenter of the coil and magnet. Results: Six of the 9 investigated solid polymers were visible at TE = 0.07 milliseconds. Visible solid polymers showed markedly different SNR values, ie, polyethylene SNR = 1146 ± 41, polypropylene SNR = 60 ± 6. Nearly mono-exponential echo time dependent signal decay was observed: Transverse relaxation times differed from T 2 * = 36 ± 5 μs for polycarbonate to T 2 * = 792 ± 7 μs for polyvinylchloride (PVC). Two of the investigated solid polymers were applicable to T 1 relaxation time calculation. Polyurethane had a spin-lattice relaxation time of T 1 = 172 ± 1 milliseconds, whereas PVC had T 1 = 262 ± 7 milliseconds, respectively. Conclusions: A variety of solid polymers can be visualized by means of clinical whole-body MR scanners and 3D ultrashort echo time (UTE) sequences. The investigated polymers differ substantially in signal yield, signal-decay, and spin-lattice relaxation time. The knowledge of the signal behavior of solid polymers on whole-body clinical MR scanners may help to select suitable polymeric materials for instruments and implants which are visible using UTE sequences.

PURPOSE To assess susceptibility related signal decay in lung tissue and to measure the influence of body positioning, together with inspiration and expiration, as well as oxygen inhalation. T2* maps and line shape maps of lung parenchyma were derived from datasets acquired at 0.2 T and compared with findings at 1.5 T. The line shape maps allow for a visualization of the intravoxel frequency distribution of lung parenchyma. MATERIALS AND METHODS A multiecho spoiled gradient-echo sequence with 16 echoes was implemented both on a 0.2 T [repetition time (TR) = 100 milliseconds, echo time (TE)1 = 2.15 milliseconds, DeltaTE = 2.94 milliseconds, flip angle 30 degrees] and on a 1.5 T magnetic resonance scanner (TR = 100 milliseconds, TE1 = 1.25 milliseconds, DeltaTE = 1.65 milliseconds, flip angle 30 degrees). Sagittal datasets were recorded in 8 healthy volunteers at 0.2 T in supine position under maximal expiration and inspiration and during oxygen breathing. Additional measurements were performed after 20 minutes inside the scanner in supine position and after prone repositioning. In 2 volunteers, further datasets were acquired at 1.5 T. Color-encoded T2* maps and full-width-at-half-maximum (FWHM) maps of the frequency distribution were computed on a pixel-by-pixel basis. T2* maps were generated by mono-exponential fitting and, additionally, with an extended nonexponential fitting approach. The FWHM maps were calculated with a model-free approach using a discrete Fast Fourier Transformation. RESULTS A notably slower T2* decay was found at 0.2 T (T2*: 5.9-11.8 milliseconds) when compared with 1.5 T (T2*: 1.0-1.4 milliseconds), allowing for the measurement of up to 6 to 8 gradient echoes above the noise level. The T2* maps and the FWHM maps computed from the datasets acquired at 0.2 T allowed regional comparison of the derived parameters. If volunteers were positioned in supine position, expiration resulted in a T2* of 10.9 +/- 1.0 milliseconds and a FWHM of 47.1 +/- 4.0 Hz in the dorsal lung. Significant changes (P < 0.05) were found, eg, in the ventral lung in expiration (T2*: 7.5 +/- 0.8, FWHM: 76.7 +/- 11.2) versus dorsal lung in expiration, in the dorsal lung in inspiration (T2*: 8.4 +/- 1.0, FWHM: 67.8 +/- 12.5) versus dorsal lung in expiration, in the dorsal lung during oxygen breathing (T2*: 8.7 +/- 1.1, FWHM: 52.2 +/- 5.2) versus dorsal lung while breathing room air, and in the dorsal lung in prone position (T2*: 8.5 +/- 0.6, FWHM: 67.0 +/- 9.2) versus dorsal lung in supine position. CONCLUSION The proposed method allows for the computation of color-encoded T2* maps and FWHM maps of lung parenchyma in good image quality using datasets acquired at 0.2 T. The technique is robust and sensitive to physiological changes of lung magnetic resonance properties, eg, due to the type of body positioning or oxygen breathing.

OBJECTIVES The goal of the present study was the assessment of pancreatic and hepatic fat content applying 2 established magnetic resonance (MR) imaging techniques: in-phase/opposed-phase gradient-echo MR imaging and fat-selective spectral-spatial gradient-echo imaging. Results of both approaches were compared, and influences of T1- and T2*-related corrections were assessed. The possibility of a correlation between pancreatic lipomatosis and liver steatosis was investigated. MATERIALS AND METHODS Seventeen volunteers at risk for type 2 diabetes (6 male, 11 female; age, 26-70 years; body mass index, 19.4-41.3 kg/m2; mean, 31.7 kg/m2) were examined. Liver and pancreas fat content were quantified with 2 different gradient-echo techniques: one uses a spectral-spatial excitation technique with 6 binomial radio frequency pulses, which combines chemical shift selectivity with simultaneous slice-selective excitation. The other technique based on double-echo chemical shift gradient-echo MR provides in- and opposed-phase images simultaneously. Influences of T1 and individual T2* effects on results using in-phase/opposed-phase imaging were estimated and corrected for, based on additional T2* measurements. RESULTS The fat content calculated from images recorded with the fat-selective spectral-spatial gradient-echo sequence correlated well with the fat fraction determined with in-phase/opposed-phase imaging and following correction for T1/T2* effects: pancreas r = 0.93 (P < 0.0001) and liver r = 0.96 (P < 0.0001). In-phase/opposed-phase imaging revealed a pancreatic fat content between 1.6% and 22.2% (mean, 8.8% +/- 5.7%) and a hepatic fat fraction between 0.6% and 33.3% (mean, 7.9% +/- 9.1%). The fat-selective spectral-spatial gradient-echo sequence revealed a pancreatic lipid content between 3.4% and 16.1% (mean, 9.8% +/- 4.0%) and a hepatic fat content between 0% and 28.5% (mean, 8.8% +/- 8.3%). With neither technique was a substantial correlation between pancreatic and hepatic fat content found. CONCLUSION The presented results suggest that both methods are reliable tools for pancreatic and hepatic fat quantification. However, for reliable assessment of quantitative fat by the in-phase/opposed-phase technique, an additional measurement of T2* seems crucial.

Objective: To evaluate and compare positron emission tomography/ computed tomography (PET/CT) with whole-body magnetic resonance imaging (wbMRI) in the correct staging of patients with advanced nonsmall cell lung cancer (NSCLC). Materials and Methods: Fifty-two patients with an NSCLC stage IIIa or IIIb (36 males and 16 females) were included in this study. Patients were referred to our department for restaging. Within 1 week PET/CT and wbMRI were performed in all patients. Images were examined independently by 2 experienced physicians from the Department of Nuclear Medicine and Radiology. Afterward, consensus reading was performed. In 22 patients, surgery served as gold standard, whereas in 30 patients, follow-up controls (after 2 months) were performed. Results: The use of wbMRI correctly T-staged all patients. Especially volume interpolated breathhold examination sequence correctly T-staged all tumors. PET/CT did not correctly stage chest wall infiltration in 4 cases [sensitivity 92.3% (P < 0.05 to wbMRI)/ specificity 100%], verified by surgery. PET/CT correctly N-staged 51 patients (sensitivity 96.1%/specificity 100%). WbMRI showed a significant tendency to understage N-status [sensitivity 88.5% (P < 0.05)/specificity 96.1%]. Different N-status by PET/CT changed operability in 4 patients. In 2 patients, distant metastases were detected by both techniques. Conclusion: In the correct staging of advanced NSCLC, PET/CT has advantages in N-staging. This is of high relevance for therapy planning. WbMRI especially using volume interpolated breathhold examination sequences, has certain advantages in T-staging.

PURPOSE In this volunteer study, 2 navigator-gated strongly T1-weighted saturation-recovery (SR) sequences, a turbo fast low angle shot (TurboFLASH) and a new true fast imaging in steady precession (TrueFISP) readout technique, were compared for suitability in dynamic magnetic resonance nephrography. MATERIALS AND METHODS Ten healthy volunteers (mean age 26.1 +/- 3.6) were equally divided into 2 subgroups. After bolus-injection of 3.75 mL of gadobutrol (approximately 0.05 mmol/kg body weight), slightly obliqued coronal single-slice images of the kidneys were recorded every 4-5 seconds during free breathing using 1 of the 2 sequences. Time-intensity curves were determined from manually drawn regions-of-interest over the kidney parenchyma. Both sequences were subsequently evaluated with regard to linearity of signal, signal to noise ratio (SNR), and time-dependent behavior of signal intensity curves. RESULTS : The TurboFLASH readout showed better linearity of the signal behavior as compared with the TrueFISP technique (TurboFLASH: no deviation from linearity down to T1 = 400 milliseconds; TrueFISP at T1 = 700 milliseconds: 12% deviation, at T1 = 400 milliseconds: 19%). The time-intensity curves of the TrueFISP sequence exhibited distinctly lower variability than the TurboFLASH approach. The SNR increased with TrueFISP by 3.4 +/- 0.5-fold for native renal parenchyma and by 3.3 +/- 0.9 for contrast-enhanced renal parenchyma. For split renal function evaluation, the linear regression to the signal increase in the first minutes after the first pass could be performed with higher reliability using the TrueFISP technique (increase of correlation coefficient by 17.1%). CONCLUSION A SR navigator-gated TrueFISP sequence seems most favorable for dynamic magnetic resonance nephrography due to the high signal yield and low curve variability.

We investigated the influence of magnetic resonance (MR) at 3.0 T on clonogenic ability, proliferation, and cell cycle in an embryonic human cell line.Cells (human lung fibroblasts Hel 299) were exposed to the static magnetic field (3.0 T) of a magnetic resonance imager (MRI) and to a turbo spin echo sequence at 3.0 T within clinical limitations (specific absorption rate 0.92 W/kg). A special MR-compatible incubation system was used. A control group (sham-exposed) and a MRI group (exposed) were set up. We investigated 3 biologic endpoints: colony forming, cell cycle, and proliferation ability. The exposure time was 2 hours in each experiment.In the statistical analysis, none of these tests showed relevant differences between the exposed and sham-exposed group.No influences of the static field alone as well as a turbo spin echo sequence at 3.0 T on clonogenic ability, proliferation, or cell cycle in eugenic human lung fibroblasts were found.

Multislice detector computed tomography (MSCT) is an accurate noninvasive modality to detect and classify different stages of atherosclerosis. The aim of the New Age II Study was to detect coronary lesions in men without established coronary artery disease (CAD) but with a distinct cardiovascular risk profile. We also sought to assess the effect after 1 year of a lipid-lowering therapy (LLT) using 20 mg of atorvastatin.Forty-sixe male patients (mean, 61 +/- 10 years) with an elevated risk for CAD (PROCAM score3 quintile) without LLT were included. Native and contrast-enhanced scans were performed in all patients. A total of 27 of 46 patients received a follow-up scan (after 488 +/- 138 days). Coronary plaque burden (CPB) was assessed volumetrically.The prevalence of CAD was 83% (38/46 patients), and 11% (5/46) without coronary calcifications still had noncalcified plaques. Total cholesterol and low-density lipoprotein cholesterol levels decreased significantly under LLT (225 +/- 41 mg/dL vs. 162 +/- 37 mg/dL, P0.0001 and 148 +/- 7 mg/dL vs. 88 +/- 5 mg/dL, P0.001, respectively). On follow-up, calcium score and CPB remained unchanged (Agatston score: 261 +/- 301 vs. 282 +/- 360; CPB: 0.149 +/- 0.108 vs. 0.128 +/- 0.075 mL, P0.05), whereas mean plaque volume of noncalcified plaques decreased significantly from 0.042 +/- 0.029 mL versus 0.030 +/- 0.014 mL (P0.05, mean reduction 0.012 +/- 0.017 mL or 24 +/- 13%).Statin therapy led to a significant reduction of noncalcified plaque burden that was not reflected in calcium scoring or total plaque burden. This finding might explain the risk reduction after the initiation of statin therapy. Using multislice detector computed tomography, physicians have the potential to monitor medical treatment in patients with coronary atherosclerosis.

To monitor lung motion in patients with malignant pleural mesothelioma (MPM) before and after chemotherapy (CHT) using 2-dimensional (2D) and 3-dimensional (3D) dynamic MRI (dMRI) in comparison with spirometry.Twenty-two patients with MPM were examined before CHT, as well as after 3 and 6 CHT cycles (3 months and 6 months) using 2D dMRI (trueFISP; 3 images/s) and 3D dMRI (FLASH 3D, 1 slab (52 slices)/s) using parallel imaging in combination with view-sharing technique. Maximum craniocaudal lung dimensions (2D) and lung volumes (3D) were monitored, separated into the tumor-bearing and nontumor-bearing hemithorax. Vital capacity (VC) was measured for comparison using spirometry.Using 2D technique, there was a significant difference between the tumor-bearing and the nontumor-bearing hemithorax before CHT (P0.01) and after 3 CHT cycles (P0.05), whereas difference was not significant in the second control. In the tumor-bearing hemithorax, mobility increased significantly from the status before versus after 3 CHT cycles (4.1 +/- 1.1 cm vs. 4.8 +/- 1.4 cm, P0.05). Using 3D technique, at maximum inspiration, the volume of the tumor-bearing hemithorax was 0.6 +/- 0.4 L and of the nontumor-bearing hemithorax 1.25 +/- 0.4 L before CHT. In the follow-up exams, these volumes changed to 1.05 +/- 0.4 L (P0.05) and 1.4 +/- 0.5 L, respectively. Using spirometry, there was no significant change in VC (1.9 +/- 0.4 L vs. 2.2 +/- 0.7 L vs. 2.2 +/- 0.9 L).dMRI is capable of monitoring changes in lung motion and volumetry in patients with MPM not detected by global spirometry. Thus, dMRI is proposed for use as a further measure of therapy response.

Objective The purpose of this prospective study was to investigate the feasibility of high-resolution magnetic resonance angiography (MRA) of the kidneys at 3.0 T using parallel data acquisition. Material and methods Contrast-enhanced MRA of the renal arteries (RA) was performed in 12 volunteers and 12 consecutive patients (mean age 47.1 +/- 16.3 years) on a 3.0 T MR scanner. For CEMRA, a high-resolution 3-dimensional GRE FLASH sequence was implemented. Images were assessed subjectively on a 0 to 5 scoring scale by 2 reviewers. Quantitative evaluation was done by measuring the contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR). Results Diagnostic image quality was acquired in all individuals. In total, 62 RA were found, consisting of 48 main and 14 accessory RA. Overall visibility score for main RA was 4.82 +/- 0.38. RA were identified up to the third-order branches in 88%. In 3 of 12 patients, a hemodynamic relevant stenosis was found and proven by conventional angiogram. Conclusion CEMRA at 3.0 T is advantageous in terms of better SNR and T1 weighting; therefore, measurement time can be reduced and spatial resolution can be increased without corruption of signal yield. Consequently, high-field MRA may be preferred for the evaluation of renal vascular anatomy in potential kidney donors or for the detection of renal artery stenosis.

Purpose: We sought to evaluate the growth-modulating potential of paclitaxel on cultured human arterial smooth muscle cells depending on the administered dose Material and Methods: For all experiments human arterial smooth muscle cells (SMCs) were used. SMCs were either cultured for 5 days or for 20 days with paclitaxel (doses: 10 - 7 M, 10 - 8 M, 10 - 9 M). For a total period of 20 days, proliferation kinetics of the SMC were analyzed. To assess the clonogenic activity of the SMC colony-forming assays were performed. Drug- and dose-dependent cell cycle changes were analyzed by flow cytometry. The effect on cell migration was examined in a 2-chamber migration system. The effects of paclitaxel on the synthesis of tenascin were examined via immunofluorescence. Results: Depending on the dose administered, paclitaxel proved to inhibit SMC proliferation effectively when administered during the total period of 20 days. When incubated for 5 days with doses of paclitaxel ranging between 10 - 8 M and 10 - 9 M, SMCs showed clear signs of regeneration. When being incubated with 10 - 7 M of paclitaxel, however, SMCs reacted with a reduction in cell proliferation, a reduced clonogenic activity, and a drug-induced G2/M phase block. SMC migration was inhibited effectively as well as extracellular matrix formation. Conclusion: Paclitaxel is a potent inhibitor of SMC proliferation, SMC migration, and extracellular matrix formation in vitro, with all three phases of the restenosis process inhibited effectively.

RATIONALE AND OBJECTIVES The purpose of the study was to test the capability of the endothelin A receptor antagonist LU 135252 to reduce neointimal formation in rabbits after balloon denudation with and without the presence of hypercholesterolemia. METHODS Twenty-eight male New Zealand White rabbits underwent balloon denudation of the infrarenal aorta. The animals were randomly assigned to 1 of the 4 groups. After balloon denudation, group 1 (n = 6) and 2 (n = 7) received a standard diet, and group 3 (n = 8) and 4 (n = 7) were fed a 0.5% cholesterol diet. All interventional procedures were performed while the rabbits were under general anesthesia. One week prior to intervention treatment with LU 135252 was started in group 2 and 4. After 6 weeks the animals were killed for morphometric and histological analysis. RESULTS Rabbits in all treatment groups developed neointimal hyperplasia. By additional systemic treatment with LU 135252, the mean neointima to media ratio was significantly reduced only in the hypercholesterolemic animals of group 4 (neointimal to media ratio area of group 3 vs group 4: 2.07 +/- 0.62 vs 1.41 +/- 0.45, P < 0.05). ET receptor blockade in group 2 and 4 did not have an effect on plasma levels of cholesterol, very low-density lipoprotein-, high-density lipoprotein-, and low-density lipoprotein-cholesterol. CONCLUSION LU 135252 was efficient in reducing lipid induced atherosclerotic changes but was ineffective in inhibiting restenosis induced by balloon denudation.

objectives and rationale. To evaluate the hoop strength, the pushability, and the radiopacity of endovascular stents depending on their design. material and methods. The Palmaz Medium (rectangular stent struts, no articulation = RE-NA), the Palmaz-Schatz Long-Medium (rectangular stent struts, central articulations = RE-CA), and the 39 mm and 29 mm version of the Palmaz Corinthian Stent (arch-like stent struts, omega hinges = AR-OH 1 and AR-OH 2) were included in the study. Hoop strength, pushability, and radiopacity were assessed in-vitro. A radiopacity score (RS)—ranging from 0 = invisible, 1 = poor, 2 = average, 3 = good, and 4 = very good—was used. results. Mass adjusted hoop strength was nearly the same for the AR-OH 1 and the AR-OH 2 (AR-OH 1: 159.2 N/g*cm; AR-OH 2: 156.5 N/g*cm). Their hoop strengths per unit mass significantly exceeded that of a RE-NA (125 N/g*cm) and that of a RE-CA (75.3 N/g*cm). The most pushable stent was the AR-OH 2 (0.54 1/N) followed by the AR-OH 1 (0.47 1/N) and the RE-CA (0.169 1/N). Because of multiple stent dislocations, the RE-NA was considered nonflexible. At spotfilm mode the RE-NA was the most visible stent (RS 3.5) followed by the AR-OH 1 (RS 3.25), the RE-CA (RS 3.12), and the AR-OH 2 (RS 1.9). At continuous fluoroscopy the AR-OH 1 (RS 1.8) was better than the RE-CA (RS 1.125), the RE-NA (RS 1.0), and the AR-OH 2 (RS 0.6). At 7.5 pulses per second the RE-NA (RS 1.3) performed slightly better than the AR-OH 1 (RS 1.25), and clearly better than the RE-CA (RS 0.8), and the AR-OH 2 (RS 0.3). conclusion. Overall, the ideal stent—having high hoop strength, a low profile, a good pushability, and a good radiopacity—still does not exist. However, by changing strut design (from rectangular to arch-like struts) and by inserting articulations, hoop strength and pushability can be improved without reducing radiopacity.

To evaluate the potential of targeted electrical impedance scanning (EIS) for classifying suspicious breast lesions.EIS was performed in full knowledge of mammographic findings and findings of clinical breast examination. One hundred seventeen patients with a total of 129 breast lesions were examined with EIS before breast biopsy (surgical excision or vacuum core biopsy). Diagnostic indexes of targeted EIS were calculated depending on major lesion characteristics. Capacitance and conductivity of all positive spots (S) and the surrounding normal breast tissue (NBT) were quantified using ROI measurements. The ratio S/NBT was calculated to compare true positive (n = 44) and false positive (n = 18) spots.With respect to histology, of the 129 lesions 71 were malignant and 58 lesions were benign. Overall sensitivity of targeted EIS was 62%, specificity 69%, PPV 71%, and NPV 60%. Sensitivity of EIS varied depending on the tumor size, which was between 48% (20 mm) and 71% (11-20 mm). Highest specificity (86%) was observed for large lesions (20 mm); however, the NPV was only 35% for lesions of that size. NPV was higher for nonpalpable lesions (74%) and clusters of microcalcifications (85.7%) compared with palpable lesions (39%) and solid lesions (44%). There was no statistical difference of S/NBT ratio neither for conductivity nor capacitance of true and false positive spots. Compared with true positive spots a trend of a higher conductivity ratio at 100 Hz and 200 Hz was seen for false positive spots.EIS showed mediocre overall diagnostic accuracy for classifying suspicious breast lesions. Quantitative analysis of positive EIS findings did not help to differentiate between false and true positive spots.

rationale and objectives. Several radiopharmaceuticals were administered through a porous balloon catheter to compare the absolute amount deposited and the retention in the vessel wall. The reported efficiency of local drug delivery ranges from 0.001% to 0.1%, with poor retention after 24 hours. methods. An endothelin derivative (n = 6), pertechnetate (n = 6), hexamethylpropylene amineoxime (HMPAO) (n = 5), ethyl cysteinate dimer (ECD) (n = 5), and tin colloid (n = 5) were labeled with 185 MBq/mL 99m-technetium. After balloon denudation of the infrarenal aorta in 27 New Zealand White rabbits, 100 μL of each agent was administered through a porous balloon at a pressure of 4 bar. Dynamic and static whole-body scintigrams were obtained for 24 hours. The infrarenal aorta was excised and the activity calculated in a gamma counter. results. Apart from their retention in the region of local administration, the radiopharmaceuticals showed different distribution patterns. The highest regional tracer retention was observed with HMPAO. After administration of HMPAO, a significant difference between regional (vessel wall plus surrounding tissue: 14.5% of injected dose [ID]/24 hours) and local (vessel wall: 1.8% ID/24 hours) delivery was found. In contrast, ECD was eliminated quickly (local retention after 24 hours = 0% ID). The retention efficiencies were HMPAO > endothelin derivative > tin colloid > pertechnetate > ECD. conclusions. The different physicochemical and pharmacokinetic properties of radiopharmaceuticals resulted in different delivery efficiencies after local application.

The purpose of this study was to develop and implement MR sequences for chemical shift-selective breath-hold cine imaging of the heart. Fibroadipose conversion of myocardium in cases suspected of right ventricular dysplasia should be revealed in fat- and water-selective MR images of high quality.Frequency-selective saturation of one chemical shift component was applied in modified k-space-segmented, electrocardiography-gated sequences, allowing high-quality cine imaging of the human heart in a single breath-hold. Phantom studies and human examinations in eight normal subjects (aged 24-62 years) and in seven patients (aged 31-47 years) with suspected right ventricular dysplasia were performed. The patients showed suspicious findings, such as a dyskinetic and dilated right ventricle combined with ventricular arrhythmia, and underwent MR imaging after exclusion of other possible reasons (eg, coronary artery disease or pulmonary hypertension).High selectivity to the desired chemical shift component was confirmed by test measurements in a phantom containing water and lipids. In the human subjects, minor problems with magnetic field inhomogeneities appeared in the thoracic walls only. Four patients with suspected right ventricular dysplasia showed clearly abnormal signal behavior of the right myocardial wall in both fat- and water-selective cine images. Bright transmural structures were exhibited in fat-selective images, but the origin of the fat (epicardium or infiltrated myocardium) was often difficult to assess.Right ventricular areas with fibrosis and fatty degeneration often show normal signal intensity in standard T1-weighted images but can be differentiated from normal tissue by the new chemical shift-selective breath-hold cine techniques.

RATIONALE AND OBJECTIVES In functional cardiac magnetic resonance imaging, reduction of measuring time is very important for many patients who are not able to rest motionless for long-lasting examinations. In this study, the image quality of sequences with k-space segmented data recording was compared with conventional gradient-echo sequences for cine imaging with flow compensation in applications on patients with normal and reduced ejection fractions. METHODS Thirty-one subjects (4 volunteers and 27 patients with cardiac diseases) were examined using different techniques for cine imaging of the left and right ventricles. The ejection fraction in the patients was calculated based on images of a conventional two-dimensional gradient-echo technique using a biplane ellipsoid model. The results from k-space segmented methods (3 to 9 Fourier lines per cardiac cycle for each phase image) were compared with the conventional images of the same short-axis view separately for groups of subjects with normal and reduced ejection fraction. The contrast between blood and myocardium at several sites of the heart and the homogeneity of the blood signal in the ventricle were evaluated for several phases of the heart cycle. RESULTS The segmentation in the acquisition of raw data allows reduction of measuring time to approximately 20% to 40% of the time required for conventional sequences in cine imaging of the heart. In patients with normal or only slightly reduced heart function (ejection fraction > or = 60%) the image quality of k-space segmented sequences was not significantly different from the conventionally recorded images. In contrast, patients with markedly lowered ejection fraction (< 60%) showed degraded results of the k-space segmented sequences compared with the conventional sequence (P < 0.001). The anterolateral border and the right ventricle especially were not sufficiently delineated by the k-space segmented sequences in these patients. CONCLUSION The k-space segmentation for the reduction of examination time is suitable for measuring heart volumes and functional parameters of patients expected to have a nearly normal ejection fraction, whereas for patients with markedly reduced cardiac function further technical improvements of segmented techniques are necessary.

RATIONALE AND OBJECTIVES: Different magnetic resonance imaging techniques were compared with respect to available anatomic information regarding abdominal aortic aneurysms (AAA) and regions involved in thrombosis. METHODS: Twenty patients with AAA were examined by turbo spin-echo (TSE) imaging of coronal and transverse slices, resulting in black blood images. Bright blood imaging was performed using a spoiled gradient-echo sequence with gradient moment nulling. Sets of 25 to 50 thin slices were recorded sequentially in a single slice mode using coronal and transverse orientation. Both sets of bright blood images were reconstructed by maximum intensity projection. RESULTS: In all patients, the size and shape of the AAA could better be assessed by the TSE images than by the gradient-echo images. In contrast, reliable differentiation of thrombotic areas and of the perfused lumen was possible in only 56% of the slices recorded by TSE imaging but in 94% of the gradient-echo images. The two-dimensional inflow technique provided clearly higher sensitivity even to slow blood flow than TSE imaging. Maximum intensity projection reconstructions from sets of coronal two-dimensional inflow images often did not depict the lower part of the AAA because of saturation effects, whereas sets of transverse slices provided complete angiograms of the aortoiliac vascular tree. DISCUSSION: At this time, no single magnetic resonance method can provide all essential information. A comprehensive examination should include TSE imaging for topographic assessment and transverse two-dimensional inflow imaging for analysis of thrombotic areas.

To prospectively evaluate the cardiac magnetic resonance (MR) imaging-derived measurement of right ventricular (RV) septomarginal trabeculation (SMT) mass as a noninvasive marker for pulmonary hypertension (PH), compared with the ventricular mass index (VMI = RV mass/left ventricular mass) and RV mass.: A total of 49 patients (60 ± 12 years; 35 female) with suspected PH underwent cardiac MR and right heart catheterization on the same day. Eighteen normal volunteers were also included. The performance of SMT mass, VMI and RV mass measurement, with regard to PH detection, was analyzed using receiver operating characteristic curves. Logistic regression analysis was used to assess the association between SMT mass, RV mass, VMI, and PH.: The area under the receiver operating characteristic curve for SMT mass/body surface area (BSA), VMI, and RV mass/BSA in diagnosing the presence or absence of PH was 0.88, 0.87, and 0.73 respectively. In multivariable models, both SMT mass/BSA (P = 0.005, odds ratio: 8.6) and VMI (P = 0. 012, odds ratio: 1.1) were found to be significant, independent predictors of PH.: Compared with right heart catheterization measurement, SMT mass and VMI are reproducible and noninvasive MR imaging markers for the diagnosis of PH.

Rationale and Objectives: The objective of this investigation was to evaluate 6 magnetic resonance contrast media (CM) with regard to their different effects on human embryonic lung fibroblasts (HEL-299). Methods: Human embryonic fibroblasts (HEL-299) were incubated with 1×, 5×, 10×, and 20× of the normal molar blood concentration (1×, 5×, 10×, 20× conc.) reached through routine contrast media applications for MRI examinations. Four gadolinium-based CM, ie, Gadovist, Magnevist, Multihance, Omniscan, Teslascan (Manganese-based), and Resovist (Iron-based), with incubation periods over 4 hours and 24 hours were investigated. Proliferation kinetics, colony formation, and viability assays were performed after 4 and 24 hours of treatment. Apoptotic cells were quantified after tetramethylrhodamine ethyl ester staining following 24 hours of CM media incubation (20× conc.) by fluorescence activated cell sorting cytometry. Furthermore, immunofluorescence images with vimentin staining were obtained (20× conc., 24 hours treatment). Cell cycle analysis was performed after 24 hours of incubation and 20× conc. directly after incubation and 24 hours later (fluorescence activated cell sorting cytometry). Results: The proliferation kinetics performed with 20× conc. revealed a persistent increase in cell numbers until day 11 for all CM without significant differences after 4 hours of incubation. A significant reduction in initial cell numbers was recorded in the 24-hours-group after 4 days of CM incubation with Magnevist, Multihance, Omniscan, and Teslascan. Solely cells incubated with Resovist and Gadovist failed to show decreased cell numbers when compared with the control group. However, a considerable cell regain occurred afterward reaching control-group levels on day 21. Colony numbers were significantly reduced (about 20%, respectively) with Magnevist at 10× and 20× conc., as well as Omniscan and Multihance at 20× conc. when compared with all other groups, P < 0.05. Cell-cycle distribution showed a reduction of S-phase cells for Magnevist, Omniscan, and Multihance (2.9%-10.5%) when compared with Gadovist, Resovist and Teslascan (16.7%-21.0%). Twenty-four hours after incubation, the percentiles of cells in S-phase were significantly increased for Magnevist, Omniscan, and Multihance (31.4%-38.5%) when compared with Gadovist, Resovist, and Teslascan (18.6%-26.8%), P < 0.05. Viability was not impaired by administration of any CM and no apoptosis was seen after tetramethylrhodamine ethyl ester staining at 24 hours of incubation. Cell morphology remained unchanged in vimentin-staining for all CM and conditioning regimens. Conclusions: No toxic effects on embryonic fetal lung fibroblasts were detectable after 4 and 24 hours of incubation in 6 MRI CM and 10× to 20× conc. in our setting. Antiproliferative effects, initially detected with Magnevist, Omniscan and Multihance, were rapidly compensated for.

The aim of this study was to evaluate the feasibility of 2 established magnetic resonance imaging based techniques to quantify intrahepatic lipids (IHL) within a study population of extremely obese patients by means of a short, wide-bore MR scanner. Fat-selective imaging using a spectral-spatial excitation technique and in-phase/opposed-phase (IN/OP) gradient echo imaging were applied and results were compared. Results for IN/OP technique were corrected for T1- and T2*- relaxation effects. Furthermore, image quality was assessed for both techniques. Differences in regional fat distribution were assessed using parameter maps of voxel-wise calculated IHL.MR examinations of 20 extremely obese patients were included in the study (7 males, 13 females; mean age 40.4 +/- 12.6 years; mean body mass index 46.3 +/- 6.6 kg/m2). IHL, in terms of fat signal fractions, was calculated from simultaneously acquired IN/OP-images using a double-echo gradient echo technique. For correction of transverse relaxation effects an additional multiecho gradient echo sequence was applied in each subject, whereas correction of longitudinal relaxation was performed using literature values for T1 of water and lipid protons in the liver parenchyma. A highly selective spectral-spatial excitation technique with 6 binomial radiofrequency pulses was used for fat-selective imaging. In this case, signal intensity of adjacent subcutaneous adipose (approximately 100% fat) was used as an internal reference for IHL quantification.IN/OP-imaging provided sufficient image quality in all subjects, whereas fat-selective imaging was hampered by insufficient homogeneity of the static magnetic field in 1 of 20 subjects. Hepatic T2* values ranged from 20.1 milliseconds to 42.2 milliseconds. Results for IHL from both techniques were highly correlated with r(s) = 0.915 (P0.0001). Mean values for IHL were 16.5% +/- 9.2% and 10.6% +/- 7.3%, for IN/OP and spectral-spatial excitation technique, respectively, showing a slightly lower estimation of IHL by the spectral-spatial excitation method. In the examined cohort of extremely obese subjects a relatively high number of 4 out of 20 cases (20%) were found with uneven distribution of IHLs.The presented data confirm that both methods are reliable tools for quantification of IHL, if inherent drawbacks and limitations are taken into account. Inhomogeneity of the static magnetic field observed in examinations of extremely obese patients limits the use of spectral-spatial excitation, if performed without time-consuming shimming procedures. Necessity to correct for transverse and longitudinal relaxation effects using the IN/OP method requires additional measurements and postprocessing procedures, which might hamper the clinical applicability. Moreover, significant regional differences in IHL may exist in some patients especially if pronounced hepatic steatosis is present.

Obesity is a commonly known risk for many diseases such as metabolic syndrome and cardiovascular disease. Especially important is the discrimination of the adipose tissue inside the abdomen and the subcutaneous adipose tissue. Aim of this study was to compare the whole body fat distribution, and the volume of different adipose tissue compartments respectively, with anthropometric data.: Sixty-eight volunteers (20 males, 48 females, 42.3 +/- 15.4 years) were investigated in the context of 2 whole body magnetic resonance imaging (MRI) studies which compared the body fat distribution of depressive and bulimic patients with healthy controls. Unpublished data acquired in these studies were analyzed retrospectively.The sample consisted of 38 healthy volunteers, 17 patients with a depressive syndrome and 13 women suffering from bulimia nervosa. Individual body volume, total adipose tissue (TAT) volume, subcutaneous adipose tissue (SCAT) volume at the trunk, and visceral adipose tissue (VAT) volume were determined, using whole body MRI. Additionally, body fat profiles were standardized and a mean body distribution was calculated. Other modalities to acquire body fat content were: skin fold caliper, body impedance (3 different devices) and simple anthropometric data (Waist to Hip Ratio [WHR], Body Mass Index [BMI], distance of the aponeurosis of the rectus abdominis muscle to the ventral rim of the abdominal aorta (measured in MRI images on umbilical level) (AD) and subcutaneous adipose tissue thickness at the same level). The different modalities were correlated with the MRI data.: There were highly significant correlations between the skin fold data and TAT (Spearman coefficient 0.668, P/= 0.0004) and SCAT (0.662, P/= 0.0004). But there was no correlation with VAT. Impedance data revealed significant correlations of TAT and SCAT (Spearman 0.7, P/= 0.0004).Simple anthropometric data like waist and hip circumference, WHR, and BMI revealed significant correlations (Spearman coefficient around 0.7-0.4, P0.05) with the fat compartments TAT, VAT, and SCAT.The standardized body fat slices and the VAT slices were correlated with the anthropometric data and impedance data to explore specific areas along the body axis where the correlations were higher or weaker. Skinfold data, BMI, and body impedance data yielded significant correlations with TAT along the whole body axis, as well as with VAT in almost the whole analyzed area. However, there was no special body region with locally higher correlations. WHR depicted high correlations with whole VAT, and regional TAT at the abdomen (and not with the other body regions) especially in women. Therefore, it seems to be the best marker for abdominal fat and VAT in this study.: We compared different body measures and body fat devices with the whole body fat distribution acquired by MRI. Generally, there were significant correlations of all modalities with body fat content (TAT) and mainly with SCAT. Correlations with VAT compartment were much weaker and an adequate estimation of VAT is, therefore, not possible. Only WHR revealed significant correlations with the fat in the body center, but only in women. If it is important to investigate especially the VAT which is responsible for a higher cardiovascular risk, risk for a metabolic syndrome and that is correlated with the course of different psychiatric diseases, cross sectional techniques such as MRI can not be substituted by simpler methods.

To assess T2* values of liver, pancreas, and spleen in a healthy cohort and to compare the gained values with serum ferritin levels and anthropometric data. In addition, the relationship of T2* between the 3 organs was investigated.One hundred twenty-nine healthy subjects (85 women, 44 men) were examined on a 1.5-T magnetic resonance whole-body unit. Age ranged from 20 to 70 years (mean age, 47.9 +/- 11.4 years). A multislice fat-saturated breath-hold 2D multiecho gradient-echo sequence was applied for T2* measurement. To assess T2* values of the liver, pancreas, and spleen, T2* maps were calculated. The correlation of organ T2* with serum ferritin and anthropometric data (age, gender, body mass index) was investigated.Measurement of T2* was feasible in all volunteers. A gender-related analysis revealed significant higher hepatic and splenic T2* values for women than for men (P0.01). For the pancreas, these differences could not be found. A significant negative correlation was found between hepatic T2*, splenic T2*, and serum ferritin (r = -0.62 liver, r = -0.64 spleen; P0.0001). In contrast, no such relationship was found for pancreatic T2* (r = -0.15). For women, a statistically significant age-dependent increase was found for splenic T2* values.Using a fast quantitative T2* magnetic resonance imaging technique, it was possible to gain insights into the iron metabolism of a healthy cohort. Gender- and age-related differences concerning T2* and serum ferritin levels were found in the liver and spleen, but not in the pancreas.

Objective: The aim of our study was to assess the impact of body mass index (BMI) on image quality and diagnostic accuracy using dual-source computed tomography. Subjects and Methods: Dual-source computed tomography and invasive coronary angiography were performed in 125 consecutive patients. Coronary segments were assessed for both image quality (1: excellent; 4: poor) and presence of significant vessel stenosis (≥50%). Accuracy of lesion detection was calculated using invasive coronary angiography as the standard of reference. The impact of BMI on image quality and accuracy was assessed by multivariate regression and between subgroups of BMI. Results: Mean BMI in our study was 28.4 ± 4.1 kg/m 2 . In multivariate regression, BMI was proved to have a significant and independent impact on image quality (P = 0.009). Similarly, the latter was significantly degraded in a subgroup of patients with BMI ≥30 kg/m 2 (P < 0.05). Although the proportion of segments with diagnostic image quality was equal in all BMI subgroups, linear regression suggested 25 kg/m 2 as the cut-off until which excellent or good image quality can be achieved. Sensitivity, specificity, positive, and negative predictive values were 91.6%, 93%, 75.2%, and 97.9% on a per-segment and 100%, 77.5%, 90.4%, and 100% on a per-patient level. In both multivariate analysis and comparison of subgroups, there was no significant effect of BMI on the per-segment diagnostic accuracy. Conclusion: Although in an unselected population, obesity turns out to have an independent impact on image quality, there is no translation of this effect into a deterioration of diagnostic accuracy.

The aim of the presented study was to evaluate pulsed magnetization transfer contrast (MTC) effects using saturation pulses of variable off-resonance frequency and radio frequency (RF) amplitude for a variety of tissue types (white and gray matter, liver, kidney, spleen, muscle, and articular cartilage) in human subjects at field strengths of 0.2, 1.5, and 3.0 Tesla.MTC imaging studies of the head, knee, and abdomen were performed using an adapted multiple MTC (mMTC) module in 3 healthy volunteers for all field strengths. This mMTC pulse module applies a variable Gaussian shaped magnetization transfer (MT) saturation pulse in a proton-density weighted RF-spoiled gradient echo sequence. It allows for both a flexible MT pulse design and performance of consecutive measurements with variation of amplitude and off-resonance frequency, whereas keeping other MT pulse parameters unchanged. Magnetization transfer signal ratio (MTR) maps were calculated on a pixel-by-pixel basis. Additional mMTC imaging measurements were performed using an agar-water phantom. For assessment of undesired direct saturation effects of the MT pulse on the water pool, numerical simulations based on Bloch's equations were performed and analyzed.The results indicate that MTR values for given MT pulses (pulse shape, off-resonance frequency and flip angle) are larger at higher magnetic field strengths. For white matter, gray matter, cartilage, and muscle, an increase of 10% to 30% was found at 3.0 T when compared with 1.5 T. Low magnetic field strength of 0.2 T led to MTR values of one third to half the values at 1.5 T. MTR values for abdominal tissues were partly lower at 3.0 T compared with 1.5 T, which might be related to reduced B1 field strengths at 3.0 T due to dielectric effects.The increased MT effect at a higher field strength can partly compensate the specific absorption rate related problems in MTC applications. It is shown that for flip angles of 700 degrees to 900 degrees and offset frequencies of 1000 Hz to 1500 Hz, high quality MTR maps could be obtained at an acceptable level of direct saturation for all field strengths. Furthermore, if the better signal-to-noise ratio at higher magnetic fields is taken into account, quality of MTR maps of the head and the knee at 3.0 T was clearly improved compared with lower fields under optimized and comparable conditions.

PURPOSE The purpose of this prospective study was to determine the feasibility and accuracy of high-spatial-resolution MR imaging at 3 Tesla (T) in the preoperative evaluation of potential living related kidney donors. MATERIALS AND METHODS Eighteen potential donors (8 men, 10 women; mean age, 50.1 +/- 14.2 years) for renal transplantation were evaluated with 3 T MR imaging. A high-spatial-resolution 3-dimensional (3D) gradient-echo MR angiography (repetition time/echo time, 3.0/1.14 ms; flip, 19-23 degrees; matrix, 512; slice thickness, 1.0 mm) using parallel acquisition technique (GRAPPA) with an acceleration factor of 3 was performed on a whole body scanner. Images were evaluated in a prospective and blinded fashion by 2 MR radiologists. The number of renal arteries, presence of early branches (defined as a branch arising within 2 cm of the main renal ostium), and renal artery stenosis were analyzed. The renal parenchyma, collecting system and ureters, were evaluated on the MR urograms. Interpretation of MR images were compared with surgical findings. RESULTS Based on MR angiography data sets, a total of 36 main and 9 accessory renal arteries was found. There were 5 renal arteries presenting an early branching (

We sought to evaluate the relationship between parameters of bipolar radiofrequency (RF) ablation using internally cooled electrodes.Bipolar RF ablations (n = 24) were performed in ex vivo bovine liver using an internally cooled applicator with 2 electrodes located on the same shaft. The power-output was systematically varied (20-75 W). On the basis of our experimental data, mathematical functions were fitted and the goodness-of-fit was assessed by the parameter R.The duration to induce an increase of tissue resistance and the amount of applied energy increased with a decreased power-output. The maximum short-axis was 4.5 cm (20 W) and required an application of 64 kilojoules (kJ). The volume of coagulation can be determined as a function of the duration of energy application (R = 0.954) and the amount of applied energy (R = 0.945).The amount of applied energy and the duration of energy application can predict the volume of induced coagulation and may be useful to control internally cooled bipolar RF ablation.

OBJECTIVE Cardiac magnetic resonance imaging (MRI) at 3.0 T has recently become available and potentially provides a significant improvement of tissue contrast in T1-weighted imaging techniques relying on Gd-based contrast enhancement. Imaging at high-field strength may be especially advantageous for methods relying on strong T1-weighting and imaging after contrast material administration. The aim of this study was to compare cardiac delayed enhancement (DE) MRI at 3.0 T and 1.5 T with respect to image quality, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) between infarcted and normal myocardium. MATERIALS AND METHODS Forty consecutive patients with history of myocardial infarction were examined at 3.0 T (n = 20) or at 1.5 T (n = 20). Myocardial function was assessed using cine steady-state-free-precession (SSFP) sequences (TR 3.1 milliseconds, TE 1.6 milliseconds, flip angle 70 degrees , and a matrix of 168 x 256 at 1.5 T and TR 3.4 milliseconds, TE 1.7 milliseconds, flip angle 50 degrees and a matrix of 168 x 256 at 3.0 T), acquired in long- and short-axes views. DE images were obtained 15 minutes after the administration of 0.15 mmol of Gd-DTPA/kg body weight using a segmented inversion recovery prepared gradient echo sequence at 1.5 T (TR 9.6 milliseconds, TE 4.4 milliseconds, flip angle 25 degrees , matrix 160 x 256, bandwidth 140 Hertz/pixel) and at 3.0 T (TR 9.8 milliseconds, TE 4.3 milliseconds, flip angle 30 degrees , matrix 150 x 256, bandwidth 140 Hertz/pixel). For image analysis, standardized SNR and CNR measurements were performed in infarcted and remote myocardial regions. Two independent observers rated image quality on a 4-point scale (0 = poor image quality, 1 = sufficient image quality, 2 = good image quality, 3 = excellent image quality). RESULTS High diagnostic image quality was obtained in all patients. Rating of mean image quality was 2.2 +/- 0.8 at 1.5 T and 2.5 +/- 0.6 at 3.0 T (P = 0.012) for observer 1 and 2.2 +/- 0.7 at 1.5 T and 2.6 +/- 0.6 at 3.0 T (P = 0.003) for observer 2, respectively. Interobserver agreement was good (kappa = 0.68 at 1.5 T and 0.78 at 3.0 T). SNR measurements yielded a mean SNR of 37.8 +/- 13.9/22.9 +/- 6.0 in infarcted myocardium (P < 0.001) and 5.6 +/- 2.2/5.9 +/- 2.4 in normal myocardium (P = 0.45) at 3.0 T/1.5 T, respectively. CNR measurements revealed mean values of 32.4 +/- 13.0/16.7 +/- 5.4 (P< 0.001) at 3.0 T/1.5 T, respectively. CONCLUSIONS Delayed enhancement MRI at 3.0 T is feasible and provides superior image quality compared with 1.5 T. Furthermore, using identical contrast doses, increased SNR and CNR values were recorded at 3.0 T.

Objectives We sought to compare signal changes using Ferucarbotran and gadobenate dimeglumine (Gd-BOPTA) in dynamic 3D T1-weighted (T1w) GRE imaging of the liver. Material and methods Thirty patients were prospectively included in the study. All patients underwent 2 high-field magnetic resonance (MR) examinations: first with Gd-BOPTA (Gd) and then after a mean interval of 4 days with ferucarbotran (Feru). Dynamic MRI was obtained with a 3D T1w GRE sequence (TR 6.33, TE 2.31, flip angle 20 degrees ). Contrast enhanced scans were assessed before intravenous injection of the contrast agent (precontrast), and postcontrast during the arterial phase (30 seconds), portal venous phase (60 seconds), and equilibrium phase (120 seconds). The signal intensities (SIs) of liver, spleen, aorta, and portal vein were defined by region of interest measurements. Signal intensity changes (SICs) and percentage signal intensity change (PSIC) were calculated using the formulas SIC=(SI pre - SI post)/SI pre and PSIC=SIC x 100%. Results Positive signal enhancement was observed after intravenous injection of Feru during all dynamic measurements, whereas the mean SI values were lower compared with Gd. During the portal venous phase the mean SI of Gd was up to a factor of 2.1 higher (portal vein). The widest difference of SIC was observed during the equilibrium phase for liver parenchyma (Gd, 1.03; Feru, 0.24). The dynamic signal courses were similar for liver, portal vein and aorta. Different signal courses were obtained for the spleen. Conclusions Feru-enhanced T1w dynamic images demonstrated significant signal increases for liver, vessels, and spleen but overall lower signal intensities than Gd-BOPTA. The dynamic signal courses of ferucarbotran were similar to that of Gd-BOPTA during ll perfusion phases except in the spleen. Thus, it may be possible to detect typical enhancement pattern of focal liver lesions with Feru-enhanced dynamic T1w MRI.

We sought to determine the relaxivity and accurate relaxation rates of Gd-DTPA, Gd-BT-DO3A, and Gd-BOPTA at 0.2, 1.5, and 3 T in human blood plasma.Contrast media concentrations between 0.01 and 16 mM in human plasma were used for relaxation measurements. The R1 and R2 relaxation rates and r1 and r2 relaxivities were determined.Gd-BOPTA produced the highest relaxation rates and relaxivities at all field strengths. The r1 and r2 values for Gd-BOPTA were 107-131% and 91-244% higher than for Gd-DTPA, respectively, and 72-98% and 82-166% higher than for Gd-BT-DO3A. Higher field strengths resulted in lower values of R1, R2, and r1 for all contrast agents tested and of r2 for Gd-DTPA and Gd-BT-DO3A. A linear dependence of R1 and R2 on concentration was found for Gd-DTPA and Gd-BT-DO3A and a nonlinear dependence for Gd-BOPTA for concentrations larger than 1 mM. The r1 and r2 relaxivity of Gd-BOPTA increased with decreasing concentration.Gd-BOPTA demonstrates the highest longitudinal r1 at all field strengths, which is ascribable to weak protein interaction. The R2/R1 ratio increases at higher field strength only for Gd-BOPTA, hence very short echo times are required for Gd-BOPTA to benefit from the higher longitudinal relaxivity.

Purpose: The authors conducted a clinical evaluation of single-slab, 3-dimensional, T2-weighted turbo-spin-echo (TSE) with high sampling efficiency (SPACE) for high isotropic body imaging with large field-of-view (FoV). Materials and Methods: Fifty patients were examined in clinical routine with SPACE (regions of interest: pelvis n = 30, lower spine n = 12, upper spine n = 6, extremities n = 4) at 1.5 T. For achieving a high sampling efficiency, parallel imaging, high turbofactor, and magnetization restore pulses were used. In contrast to a conventional TSE imaging technique with constant flip angle refocusing, the refocusing pulse train of the SPACE sequence consists of variable flip angle radiofrequency pulses along the echo train. Results: Signal-to-noise ratio and contrast-to-noise ratio of SPACE images were of sufficient diagnostic value. The possibility of image reconstruction in multiple planes was of clinical relevance in all cases and simplified data analysis. Conclusion: The achievement of 3-dimensional, T2-weighted TSE magnetic resonance imaging with isotropic and high spatial resolution and interactive 3-dimensional visualization essentially improve the diagnostic potential of magnetic resonance imaging.

We sought to examine high-intensity focused ultrasound (HIFU)-induced hyperthermia in the liver of a rat model to focally induce green-fluorescent protein (GFP).A total of 25 Copenhagen rats were included in this study. Rats were divided into groups treated with an adenovirus coding for green fluorescent protein (GFP) under the control of a hsp70B promoter and a CMV promoter. Ad-CMV-GFP-treated rats served as positive control. Untreated controls only subjected to MRI +/- HIFU-treatment served to find out optimal power of HIFU in the target area of the liver. Temperature was noninvasively monitored by temperature sensitive magnetic resonance imaging (MRI).Rats treated with Ad-hsp70B-GFP demonstrated localized gene induction within the liver parenchyma, in good correlation with MRI and histology. Applying an acoustic power of 1.92 W a relatively uniform focal temperature up to 42 +/- 5 degrees C within the liver parenchyma could be documented. 3 x 10(9) plaque-forming units proved to account for a very homogeneous liver infection. Number of fluorescent cells in the region of hyperthermia was similar to the control group treated with Ad-CMV-GFP.Using the introduced parameters spatially controlled gene induction within a parenchymal organ such as the liver in rats using HIFU under control of MRI is feasible.

The objective of this study was to assess the feasibility and efficacy of magnetic resonance imaging-(MRI) guided percutaneous radiofrequency (RF) ablation of renal cell carcinomas (RCC).Twelve patients with RCC (63 to 82 years old) were treated with RF ablation in an interventional 0.2-Tesla open MR unit. Tumor sizes varied from 1.6 cm to 3.9 cm in maximum diameter (tumor volumes 1.9 cm3 to 28.7 cm3). RF procedures were entirely performed in the MR suite. For positioning of the MR-compatible RF-electrode, near real-time MR fluoroscopy by means of rapid gradient echo sequences (acquisition time approximately 2 seconds) was used. Monitoring of ablation was obtained by intermittent imaging with T1- and T2-weighted spin echo sequences.Accurate placement of the RF electrodes was possible in all cases using near real-time MR fluoroscopy. Eleven of 12 patients were successfully treated within 1 single session; 1 patient had to be retreated for tumor relapse at 13 months follow up. Mean number of electrode repositionings under MR guidance during 1 session was 1.7; ablation time ranged between 12 and 28 minutes. Mean duration of 1 treatment session was 5 hours. Coagulation volumes ranged from 7.3 cm3 up to 30.2 cm3. All patients now appear to be disease-free with a mean follow up of 10.3 months (range, 3-23 months).MRI-guided RF ablation of RCC in an interventional MR unit is safe and feasible. Fast MR imaging is a convenient method for rapid positioning of MR-compatible RF electrodes. MR monitoring of ablation procedure with T2-weighted imaging allows for immediate assessment of coagulation extent.

Objectives: We sought to investigate the potential value of magnetic resonance (MR) elastography to improve the differentiation between benign and malignant tumors. Material and Methods: Measurements of 5 patients with 6 malignant lesions, 11 patients with benign lesions, and 4 patients with no lesions at all were performed at 1.5 Tesla. After breast MR imaging, MR elastography was performed as a targeted measurement. Lowfrequency mechanical waves (65 Hz) were transmitted into the breast tissue using an oscillator and were displayed by means of a MR sequence within the phase of the MR image. After reconstruction, the viscoelastic information was correlated with the signal intensity and morphology data. Results: All examinations were technically successful realized in approximately 25 minutes. Malignant tumors documented higher values of elasticity than benign corresponding with signal intensity and morphologic data. Conclusion: A good separation exists between benign and malignant lesions in elasticity, corresponding with specific signal intensity and morphologic data. Further clinical studies with a larger number of patients are needed for extended validation.

The objective of this study was to evaluate the changes in oxygenation of prostate cancer induced by carbogen breathing using blood oxygen level-dependent (BOLD) magnetic resonance image (MRI) with an endorectal coil (eMRI).In 32 patients with biopsy-proven prostate cancer, endorectal MRI was performed at 1.5 Tesla using the BOLD method. Images were acquired during 4 x 4-minute episodes alternating between room air and carbogen (95% O2/5% CO2) breathing. In each episode, 40 images were acquired (T2*-weighted EPI sequence, 12-14 slices, 3-mm thickness). All patients underwent radical prostatectomy; BOLD-MRI findings were correlated with the histopathologic results.BOLD-MRI could be evaluated in 29 patients, and revealed heterogeneous signal changes of normal prostate and cancer tissue similar to the heterogeneity of prostate tissue in anatomic/pathologic preparation. A significant signal intensity increase (P = 0.004) was found in normal central gland and peripheral zone during carbogen breathing. Signal enhancement in carcinoma was significantly lower (P = 0.004) compared with the contralateral normal side.Intrinsic blood-tissue contrast-functional MRI during carbogen breathing may help detect and characterize prostate carcinoma from normal tissue, particularly in small 1-sided carcinomas. This may be useful for identifying candidates for radiotherapy and monitoring noninvasive therapeutic approaches.

Objective: The objective of this study was to investigate the clinical use of a novel whole-body magnetic resonance imaging (MRI) system for comprehensive assessment of tumor spread in clinical routine. Material and Methods: Sixty-five patients with different tumors with known metastatic disease and 6 healthy volunteers were included. High-resolution MRI from head to toe was performed using multiple phased-array surface coil elements, 24 independent receiver channels, and an integrated parallel acquisition technique (iPAT). A total room time of less than 60 minutes was required. Whole-body MRI and conventional spiral computed tomography (CT) were independently evaluated and compared in terms of feasibility, location/number of detected metastases, and therapeutic relevance. Results: Whole-body MRI was successfully performed in 68 of 71 subjects. Compared with CT, more metastases were detected by MRI in 11 of 63 patients (17%), particularly in brain, liver, spleen, lymph nodes, bone marrow, muscle, and subcutaneous fat tissue. According to these findings, therapy had to be modified in 6 of 63 patients (10%). Conclusions: High-resolution whole-body MRI is feasible in clinical routine within 1 single examination and offers great potential for fast assessment of individual tumor spread and total tumor burden.

Rationale and Objectives: The aim of the study was to determine optimal thresholds for semiquantitative perfusion parameters and to evaluate the influence of different segmentation models in detecting malperfused regions.Material and Methods: In 6 healthy subjects and 13 patients with coronary artery disease, contrast-enhanced first-pass perfusion imaging was performed using a SR-TrueFISP-sequence. Thresholds for semiquantitative parameters were established, and different segmentation models of the left ventricular myocardium were tested. The standard of reference for patient studies was single photon emission computed tomography. Results: Optimal thresholds were determined in healthy subjects for the perfusion parameters upslope, AUC, and peak SI of mv-0.5*std, mv-1.5*std, and mv-1.0*std, respectively. Using the optimal threshold for each parameter/segmentation combination sensitivities and specificities of stress studies were between 66% and 93% and 77% and 92%, respectively. Subdivision of radial segments into subendo/subepicardial segments increased sensitivities for perfusion deficits. Conclusions: Subdivision of radial myocardial segments is essential in analysis of magnetic resonance first-pass perfusion series. Semiquantitative perfusion parameters possess different sensitivities for the detection of perfusion deficits.

Rationale and Objectives: To evaluate the efficiency of 4 radiofrequency (RF) systems by assessing the amount of delivered energy for each thermal induced lesion after perfusion mediated RF ablation and to compare the influence of perfusion mediation types on the energy efficiency. Methods: A total of 43 ablations in 16 male landrace pigs with 4 RF devices were performed strictly according to the manufacturers’ instructions. Total absorbed energy was computed and then related to 3D volumetry obtained after histopathological evaluation. Sixteen ablations were performed under physiological liver perfusion and 27 ablations with occlusion of portal vein, hepatic artery, or both vessels. Energy efficiency values of the RF systems for different vascular occlusion techniques were compared and analyzed by a nonparametrical rank sum test. Results: Under physiological perfusion, the average energy delivered to produce 1-cm3 lesion size was calculated to 1650 ± 929, 3097 ± 389, 8312 ± 2068, and 5493 ± 2306 Watt · s/cm3 for the Berchtold®, RadionicsTM, RadiotherapeuticsTM, and RITA® system, respectively. After perfusion-mediated RF ablation, artery occlusion was not as effective as portal vein occlusion, which reduced the energy to 587 ± 148, 869 ± 276, and 903 ± 394 Watt · s/cm3 for the Berchtold®, RadionicsTM, and RadiotherapeuticsTM system, respectively. The occlusion of vessels, portal vein, and artery or portal vein alone increased the energy efficiency compared with physiological liver perfusion or occlusion of the artery (P = 0,003). Conclusions: Under physiological liver perfusion the open perfused system and the internally cooled system provided the best efficiency values with lowest standard deviations. The energy efficiency was increased markedly for all systems after occlusion of the portal vein either alone or in combination with arterial occlusion. Occlusion of the hepatic artery did not improve the efficiency.