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For contrast-enhanced imaging techniques relying on strong T1 weighting, 3 T provides increased contrast compared with 1.5 T. The aim of our study was the intraindividual comparison of delayed enhancement MR imaging at 1.5 T and at 3 T. Twenty patients with myocardial infarction were examined at 1.5 T and 3 T. Fifteen minutes after injection of contrast agent (0.1 mmol gadobenate dimeglumine per kg body weight), inversion recovery gradient recalled echo (IR-GRE) sequences were acquired (1.5 T/3 T: TR 11.0/9.9 ms, TE 4.4/4.9 ms, flip 30 degrees /30 degrees , slice thickness 6/6 mm) to assess myocardial viability. Two observers rated image quality (Wilcoxon signed rank test). Quantification of hyperenhanced myocardium and standardized SNR/CNR measurements were performed (Student's t test). There was no significant difference with respect to image quality (1.5 T/3 T: 3.5/3.3, p = 0.34, reader 1; 2.4/2.7, p = 0.12, reader 2) and infarction size (760 +/- 566/828 +/- 677 mm(2) at 1.5 T, 808 +/- 639/826 +/- 726 mm(2) at 3 T, reader 1/reader 2, p0.05). Mean SNR in hyperenhanced/normal myocardium was 19.2/6.2 at 1.5 T and 29.5/8.8 at 3 T (p0.05). Mean CNR was 14.3 at 1.5 T and 26.0 at 3 T (p0.05). Delayed enhancement MR imaging at 3 T is a robust procedure yielding superior tissue contrast at 3 T compared with 1.5 T which is, however, not reflected by increased image quality.

To prospectively compare three-dimensional (3D) contrast material-enhanced abdominal magnetic resonance (MR) angiography at 1.5 and 3.0 T intraindividually in healthy volunteers.After institutional review board approval and informed consent were obtained, 15 healthy male volunteers (age range, 24-41 years) underwent one abdominal 3D contrast-enhanced MR angiographic examination each at 1.5 and 3.0 T in random order. Fast 3D gradient-echo sequence with parallel imaging acceleration factor of three was used for MR angiography; acquired spatial resolutions were 1x0.8x1 mm3 (imaging time, 19 seconds) at 1.5 T and 0.9x0.8x0.9 mm3 (imaging time, 18 seconds) at 3.0 T. With the latter, volume of the 3D slab was 8% larger. At 1.5 T, 20-mL bolus of gadobenate dimeglumine was delivered at 2 mL/sec; at 3.0 T, 15-mL bolus was delivered at 2.5 mL/sec. Two blinded radiologists rated image quality of aorta and proximal renal arteries in consensus with five-point scale (4=very good, 0=nondiagnostic) according to sequence and in direct intraindividual comparison. Visibility of proximal and segmental renal arteries was rated with three-point scale (3=completely visible, 1=nonvisible). Signal-to-noise ratio (SNR) was determined with phantoms. For statistical analysis of the SNRs, t tests were used.All MR angiographic measurements were diagnostic. Median score for image quality at both field strengths was 4. Depiction of proximal renal arteries was rated 3 at both field strengths. The visibility of the distal renal arteries was better at 3.0 T (median score, 3) than at 1.5 T (median score, 2). With direct comparison, 3.0-T MR angiography was better in 14 of 15 cases; no field strength was preferred in the other case. Mean SNR was significantly (P.001) higher at 3.0 T (17.8+/-0.09 [standard deviation]) than at 1.5 T (11.9+/-0.10).MR angiography at 3.0 T provided better vessel visibility and SNR than did that at 1.5 T, although voxel size and imaging time were reduced.

Rationale and Objective: The objective of this study was to compare 0.1 and 0.2 mmol/kg body weight (bw) doses gadobenate dimeglumine (Gd-BOPTA; MultiHance) and gadobutrol (Gd-BT-DO3A; Gadovist) for cerebral perfusion magnetic resonance (MR) imaging at 1.5 T. Methods: Twelve healthy male volunteers enrolled into a randomized intraindividual comparative study underwent 4 perfusion MR imaging examinations with 0.1 and 0.2 mmol/kg bw doses of each contrast agent. The imaging parameters, slice positioning, and contrast agent application were highly standardized. Quantitative determinations based on signal intensity/time (SI/T) curves at regions of interest (ROI) on the gray and white matter were made of the regional cerebral blood volume and flow (rCBV and rCBF, respectively), the percentage signal drop, and the full width half maximum (FWHM) of the SI/T curve. Qualitative evaluation of the quality of the rCBV and rCBF maps was assessed by an independent offsite blinded reader. Results: A single dose of both agents was sufficient to achieve high-quality, diagnostically valid perfusion maps at 1.5 T, and no significant benefit for one agent over the other was noted for quantitative or qualitative determinations. The susceptibility effect, described by percentage of signal loss (gadobutrol: 29.4% vs gadobenate dimeglumine: 28.3%) and the FWHM (gadobutrol: 6.4 seconds vs gadobenate dimeglumine: 7.0 seconds) were similar for 0.1 mmol/kg bw doses of the 2 agents. Double doses of the 2 agents produced better overall image quality but no clinical benefit over the single-dose examinations. Conclusion: Both the 1 molar MR contrast agent gadobutrol and the weak protein-interacting agent gadobenate dimeglumine permit the acquisition of high-quality perfusion maps at doses of 0.1 mmol/kg bw. The susceptibility effect is comparable for both agents and stronger than for conventional MR contrast agents.

To evaluate partially parallel three-dimensional (3D) magnetic resonance (MR) imaging for assessment of regional lung perfusion in healthy volunteers and patients suspected of having lung cancer or metastasis.Seven healthy volunteers and 20 patients suspected of having lung cancer or metastasis were examined with 3D gradient-echo MR imaging with partially parallel image acquisitions (fast low-angle shot 3D imaging; repetition time msec/echo time msec, 1.9/0.8; flip angle, 40 degrees; acceleration factor, two; number of reference k-space lines for calibration, 24; field of view, 500 x 440 mm; matrix, 256 x 123; slab thickness, 160 mm; number of partitions, 32; voxel size, 3.6 x 2.0 x 5.0 mm(3); acquisition time, 1.5 seconds) after administration of 0.1 mmol/kg of gadobenate dimeglumine. In volunteers, 3D MR perfusion data sets were assessed for topographic and temporal distribution of regional lung perfusion. Sensitivity, specificity, accuracy, and positive and negative predictive values for perfusion MR imaging for detecting perfusion abnormalities in patients were calculated, with conventional radionuclide perfusion scintigraphy as the standard of reference. Interobserver and intermodality agreement was determined by using kappa statistics.Topographic analysis of lung perfusion in volunteers revealed a significantly higher signal-to-noise ratio (SNR) of up to 327% in gravity-dependent lung areas. Temporal analysis similarly revealed much shorter lag time to peak enhancement in gravity-dependent lung areas. In patients, perfusion MR imaging achieved high sensitivity (88%-94%), specificity (100%), and accuracy (90%-95%) for detection of perfusion abnormalities. Interobserver agreement (kappa = 0.86) was very good and intermodality agreement (kappa = 0.69-0.83) was good to very good for detection of perfusion defects. A significant difference (P.0001) in SNR was observed between normally perfused lung (14 +/- 7 [SD]) and perfusion defects (7 +/- 4) in patients.Partially parallel MR imaging with high spatial and temporal resolution allows assessment of regional lung perfusion and has high diagnostic accuracy for detecting perfusion abnormalities.

To evaluate the safety of and compare the enhancement characteristics of gadobenate dimeglumine (MultiHance; Bracco Imaging, Milan, Italy) with those of a standard gadolinium chelate (gadopentetate dimeglumine, Magnevist; Schering, Berlin, Germany) in primary and secondary brain tumors on the basis of qualitative and quantitative parameters, on an intraindiviual basis.Twenty-seven patients with either high-grade glioma or metastases were enrolled in a bicentric intraindividual crossover study to compare lesion enhancement with doses of 0.1 mmol per kilogram of body weight of 0.5 mol/L gadopentetate dimeglumine and 0.5 mol/L gadobenate dimeglumine. MR imaging was performed before injection (T1-weighted spin-echo [SE] and T2-weighted fast SE acquisitions) and at 1, 3, 5, 7, 9, and 16 minutes after injection (T1-weighted SE acquisitions). Qualitative assessment was performed by blinded off-site readers (for 22 patients) and on-site investigators (for 24 patients) in terms of global contrast enhancement, lesion-to-brain contrast, lesion delineation, internal lesion morphology and structure, tumor vascularization, and global image preference. Additional quantitative assessment with region-of-interest analysis was performed by off-site readers alone. Statistical analysis of qualitative data was performed with the Wilcoxon signed rank test, whereas a nonparametric approach was adopted for analysis of quantitative data.Significant (P.05) preference for gadobenate dimeglumine over gadopentetate dimeglumine was noted both off-site and on-site for the global assessment of contrast enhancement. For off-site readers 1 and 2 and the on-site investigators, respectively, gadobenate dimeglumine was preferred in 13, 17, and 16 patients; gadopentetate dimeglumine was preferred in four, four, and four patients; and equality was found in five, one, and four patients). Similar preference for gadobenate dimeglumine was noted by off-site readers and on-site investigators for lesion-to-brain contrast and all other qualitative parameters. Off-site quantitative evaluation revealed significantly (P.05) superior enhancement for gadobenate dimeglumine compared with that for gadopentetate dimeglumine at all time points from 3 minutes after injection.Significantly superior contrast enhancement of intraaxial enhancing brain tumors was achieved with 0.1 mmol/kg gadobenate dimeglumine compared with that with 0.1 mmol/kg gadopentetate dimeglumine.

To investigate the diagnostic value of a half dose compared with a full dose of gadobenate dimeglumine in the assessment of synovitis or tenosynovitis in the wrist and finger joints in patients with early rheumatoid arthritis (RA) and a disease activity score greater than 3.2.With institutional review board approval and informed consent, 57 patients with early RA underwent 3-T magnetic resonance (MR) imaging with two different doses of contrast media. The contrast enhancement was measured in inflamed synovial tissue at half dose (0.05 mmol per kilogram of body weight) and at full dose (0.1 mmol/kg) by using T1-weighted sequences with fat saturation. The differences and the correlation of signal intensities (SIs) at half- and full-dose sequences were compared by using the paired t test and Pearson correlations. Image quality, Rheumatoid Arthritis MRI Score (RAMRIS), and tenosynovitis score on half- and full-dose images were compared by two observers using the Wilcoxon test. Interrater agreement was assessed by using κ statistics.A significant difference in SI was found between half-dose and full-dose gadobenate dimeglumine-enhanced synovial tissue (mean: 914.35 ± 251.1 vs 1022 ± 244.5, P.001). Because the SI showed high correlation between the ratio at half dose and full dose (r = 0.875), the formula, ratio of synovial enhancement to saline syringe at full dose = 0.337 + 1.070 × ratio of synovial enhancement to saline syringe at half dose, can be used to convert the normalized value of half dose to full dose. However, no difference in RAMRIS (score 0 in 490 of 1026 joints; score 1 in 344; score 2 in 158; and score 3 in 34) or tenosynovitis scores in grading synovitis or tenosynovitis in image quality and in assessment of synovial enhancement was detected between half-dose and full-dose images (P = 1).Postcontrast synovial SIs showed high correlation between half dose and full dose, and image quality was rated identically. Therefore, half-dose gadobenate dimeglumine at 3-T MR imaging may be sufficient for assessing synovitis or tenosynovitis in early RA.

Purpose To investigate the dependence of semiquantitative renal perfusion parameters on the acquisition technique and field strength used. Materials and Methods After intravenous injection of 7-mL Gd-chelates, high-temporal-resolution turbo fast low-angle shot (TurboFLASH) renal perfusion measurements were performed on eight healthy volunteers at 1.5T and another eight healthy volunteers at 3.0T. Another eight healthy volunteers were examined at 3.0T using time-resolved echo-shared angiographic technique (TREAT) after bolus administration of 7-mL Gd-chelates with a temporal resolution of 1.4 seconds. Analysis of the first-pass perfusion data yielded the following semiquantitative renal perfusion indices: mean transit time (MTT), time to peak (TTP), maximal upslope (MUS), and maximal signal intensity (MSI). Results MTT and TTP did not show significant differences between the different techniques. MSI and MUS were significantly (P ≤ 0.002) higher with TREAT (591.1 a.u./second and 103.5 a.u./second) than with TurboFLASH at both field strengths (1.5T: 400.5 a.u./second and 65.4 a.u./second; 3.0T: 362.2 a.u./second and 68.7 a.u./second). Conclusion Semiquantitative renal perfusion measurements are feasible with time-resolved echo-shared sequences and TurboFLASH techniques. While MTT and TTP appear to be independent of the technique and field strength applied, MUS and MSI are higher with TREAT. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc.

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.

Rationale and Objectives Pancreatic and hepatic contrast enhancement after different modes of administration of Mn-bis pyridoxal ethylene diamine diacetic acid (Mn-DPDP) and the influence of the hormones secretin and cholecystokinin on the uptake of this new contrast agent were studied by using magnetic resonance (MR) imaging and atomic absorption spectroscopy (AAS) examinations carried out on 13 young domestic pigs. Methods Mn-DPDP was administered either as bolus injection or 30-min infusion. The course of contrast enhancement was noted. MR imaging was carried out with or without pancreatic stimulation. The Mn content in pancreatic and hepatic tissue was analyzed by using AAS. Results Mn-DPDP caused a significant increase (66±40.1%) in pancreatic signal intensity, an increase in hepatic signal intensity (78±23.0%), and a significantly higher Mn content on tissue samples of both organs. The results showed a wide individual range. With infusion of Mn-DPDP, pancreatic enhancement was slower, with a peak at 82±34 min compared with 54±51 min following bolus injection. The Mn content of both hepatic and pancreatic tissue determined by AAS seemed to be higher after infusion. An incomplete washout of Mn after 24 hr was demonstrated. Hormonal stimulation of the pancreas further increased pancreatic signal intensity but did not influence hepatic contrast enhancement. Conclusion Infusion is the method of choice for administering Mn-DPDP because it causes an increase in hepatic signal intensity but does not change pancreatic enhancement. Although pancreatic hormonal stimulation intensifies enhancement, the increase is not statistically significant, and this practice will not contribute to day-to-day clinical practice.

To assess both the effect of Mn-DPDP as a hepatobiliary-specific contrast agent in bile duct obstruction and the relative role of liver and kidney in the elimination of this agent from the body, an animal experiment was set up. Twelve rats were used and divided into three groups. In group 1 the common bile duct was ligated, in group 2 bile duct ligation was limited to one lobe, and group 3 served as control. Magnetic resonance T1-weighted SE images were obtained before and after the injection of 25 μmol/kg of Mn-DPDP during the first 2 h and at day 1, 2, 3, 4, and, in some animals, up to 21 days. In normal rats the absolute enhancement signal-to-noise ratio (S/N) versus time plots obtained from the liver after Mn-DPDP injection returned to precontrast values within 24 h. In the group with common bile duct ligation, important liver enhancement persisted up to 21 days. In the group with selective obstruction, liver intensity normalized after 3 days. The S/N plots from spleen, renal cortex, and obstructed liver lobe showed similarities in time course. The present data indicate that Mn elimination is strongly impaired in the presence of bile duct obstruction. Renal glomerular filtration is ineffective in eliminating Mn from the body. The persisting splenic and renal cortical enhancement suggests that free Mn or some Mn-DPDP metabolite either is strongly bound to plasma proteins and acts as a blood pooling agent and/or is uptaken by the splenic or renal parenchyma.