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Multiple studies in the first decade of the 21 st century have established contrast-enhanced breast MRI as a screening modality for women with a hereditary or familial increased risk for the development of breast cancer. In recent studies, in women with various risk profiles, the sensitivity ranges between 81% and 100%, which is approximately twice as high as the sensitivity of mammography. The specificity increases in follow-up rounds to around 97%, with positive predictive values for biopsy in the same range as for mammography. MRI preferentially detects the more aggressive/invasive types of breast cancer, but has a higher sensitivity than mammography for any type of cancer. This performance implies that in women screened with breast MRI, all other examinations must be regarded as supplemental. Mammography may yield ~5% additional cancers, mostly ductal carcinoma in situ, while slightly decreasing specificity and increasing the costs. Ultrasound has no supplemental value when MRI is used. Evidence is mounting that in other groups of women the performance of MRI is likewise superior to more conventional screening techniques. Particularly in women with a personal history of breast cancer, the gain seems to be high, but also in women with a biopsy history of lobular carcinoma in situ and even women at average risk, similar results are reported. Initial outcome studies show that breast MRI detects cancer earlier, which induces a stage-shift increasing the survival benefit of screening. Cost-effectiveness is still an issue, particularly for women at lower risk. Since costs of the MRI scan itself are a driving factor, efforts to reduce these costs are essential. The use of abbreviated MRI protocols may enable more widespread use of breast MRI for screening. Level of Evidence: 1 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019;50:377-390., (© 2019 The Authors. Journal of Magnetic Resonance Imaging published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.)

Purpose To synthesize two low-molecular-weight iron chelates and compare their T1 contrast effects with those of a commercial gadolinium-based contrast agent for their applicability in dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging. Materials and Methods The animal experiments were approved by the local ethics committee. Two previously described iron (Fe) chelates of pentetic acid (Fe-DTPA) and of trans-cyclohexane diamine tetraacetic acid (Fe-tCDTA) were synthesized with stability constants several orders of magnitude higher than those of gadolinium-based contrast agents. The T1 contrast effects of the two chelates were compared with those of gadopentetate dimeglumine in blood serum phantoms at 1.5 T, 3 T, and 7 T. For in vivo studies, a human breast cancer cell line (MDA-231) was implanted in five mice per group. The dynamic contrast effects of the chelates were compared by performing DCE MR imaging with intravenous application of Fe-DTPA or Fe-tCDTA on day 1 and DCE MR imaging in the same tumors with gadopentetate dimeglumine on day 2. Quantitative DCE maps were generated with software and were compared by means of a one-tailed Pearson correlation test. Results Relaxivities in serum (0.94 T at room temperature) of Fe-tCDTA (r1 = 2.2 mmol -1 · sec -1 , r2 = 2.5 mmol -1 · sec -1 ) and Fe-DTPA (r1 = 0.9 mmol -1 · sec -1 , r2 = 0.9 mmol -1 · sec -1 ) were approximately twofold and fivefold lower, respectively, compared with those of gadopentetate dimeglumine (r1 = 4.1 mmol -1 · sec -1 , r2 = 4.8 mmol -1 · sec -1 ). Used at moderately higher concentrations, however, iron chelates generated similar contrast effects at T1-weighted MR imaging in vitro in serum, in vivo in blood, and for DCE MR imaging of breast cancer xenografts. The volume transfer constant values for Fe-DTPA and Fe-tCDTA in the same tumors correlated well with those observed for gadopentetate dimeglumine (Fe-tCDTA Pearson R, 0.99; P = .0003; Fe-DTPA Pearson R, 0.97; P = .003). Conclusion Iron-based contrast agents are promising as alternatives for contrast enhancement at T1-weighted MR imaging and have the potential to contribute to the safety of MR imaging. © RSNA, 2017 Online supplemental material is available for this article.

Objectives: To evaluate the effect of contrast medium dose adjustment for body surface area (BSA) compared with a fixed-dose protocol in combined positron emission tomography (PET) and computed tomography (CT) (PET/CT)., Methods: One hundred and twenty patients were prospectively included for (18)F-2-deoxy-fluor-glucose ((18)F-FDG)-PET/CT consisting of a non-enhanced and a venous contrast-enhanced CT, both used for PET attenuation correction. The first 60 consecutive patients received a fixed 148-ml contrast medium dose. The second 60 patients received a dose that was based on their calculated BSA. Mean and maximum standardised FDG uptake (SUVmean and SUVmax) and contrast enhancement (HU) were measured at multiple anatomical sites and PET reconstructions were evaluated visually for image quality., Results: A decrease in the variance of contrast enhancement in the BSA group compared with the fixed-dose group was seen at all anatomical sites. Comparison of tracer uptake SUVmean and SUVmax between the fixed and the BSA group revealed no significant differences at all anatomical sites (all P > 0.05). Comparison of the overall image quality scores between the fixed and the BSA group showed no significant difference (P = 0.753)., Conclusions: BSA adjustment results in increased interpatient homogeneity of contrast enhancement without affecting PET values. In combined PET/CT, a BSA adjusted contrast medium protocol should be used preferably., Key Points: • Intravenous contrast medium is essential for many applications of PET/CT • Body surface area adjustment of contrast medium helps standardise contrast enhancement • Underdosing or overdosing of contrast medium will be reduced • PET image quality is not influenced • BSA adjusted contrast medium protocol should be used preferably in combined PET/CT.

Objectives: To evaluate the influence of intravenous contrast medium and different contrast medium phases on attenuation correction, PET image quality and clinical staging in combined PET/CT in patients with a suspicion of lung cancer., Methods: Sixty patients with a suspicion of lung cancer were prospectively enrolled for combined (18)F-FDG-PET/CT examination. PET images were reconstructed with non-enhanced and arterial and venous phase contrast CT. Maximum and mean standardised uptake values (SUVmax and SUVmean) and contrast enhancement (HU) were determined in the subclavian vein, ascending aorta, abdominal aorta, inferior vena cava, portal vein, liver and kidney and lung tumour. PET data were evaluated visually for clinical staging and image quality., Results: SUVmax was significantly increased between contrast and non-contrast PET/CT at all anatomic sites (all P < 0.001). SUVmax was significantly increased for arterial PET/CT compared to venous PET/CT in the arteries (all P < 0.001). Venous PET/CT resulted in significantly higher SUVmax values compared to arterial PET/CT in the parenchymatous organs (all P < 0.05). Visual clinical evaluation of malignant lesions showed no differences between contrast and non-contrast PET/CT (P = 1.0)., Conclusions: Contrast enhanced CT is suitable for attenuation correction in combined PET/CT in lung cancer; it affects neither the clinical assessment nor image quality of the PET images., Key Points: • Positron emission tomography combined with computed tomography is now a mainstream investigation • There has been debate about whether CT contrast agents affect PET results • Contrast-enhanced CT is satisfactory for attenuation correction in lung cancer PET/CT • Multiphase CT does not affect PET; additional unenhanced CT is unnecessary • For quantitative follow-up PET analysis, an identical PET/CT protocol is required.

Objective: The purpose of this study was to perform an intraindividual comparison of the influences of different iodine contrast media on tracer uptake, contrast enhancement, and image quality in combined positron emission tomography (PET)/computed tomography (CT)., Materials and Methods: Fifty-one patients underwent baseline and follow-up combined PET/CT consisting of low-dose unenhanced and venous contrast-enhanced CT with contrast media containing a high concentration of iodine (iopromide, 370 mg/mL) and a standard iodine concentration (iopromide, 300 mg/mL). The total iodine load (44.4 g) and the iodine delivery rate (1.29 g/s) were identical for the 2 protocols. The mean and maximum standard uptake values, as measures of tracer uptake and contrast enhancement for unenhanced and contrast-enhanced PET/CT, were quantified at 10 different anatomical sites, and images were analyzed for clinically relevant differences., Results: The mean and maximum standard uptake values were significantly increased in contrast-enhanced PET/CT compared with unenhanced PET/CT at each anatomical site (P < 0.05). Comparison of tracer uptake between the 300- and 370-mg iodine contrast media showed no significant differences (all P > 0.05). Comparison of contrast enhancement between the 300- and 370-mg iodine contrast media showed no significant difference at any anatomical site (all P > 0.05). Analysis of image quality revealed no clinically relevant differences between the 2 different iodine contrast media (P = 0.739)., Conclusion: The use of contrast-enhanced CT scans for attenuation correction in PET/CT does not cause clinically relevant artifacts in PET scan reconstruction, regardless of the iodine concentration used. Standard- and high-iodine contrast media can be used equivalently.

The purpose of the study was to examine if the higher susceptibility at 3.0 Tesla (T) compared to 1.5 T will affect the contrast in MR imaging of the liver after application of superparamagnetic iron oxide particles (SPIO). The study was approved by our institutional review board and informed consent was obtained. Seventeen healthy volunteers were examined in a prospective, intra-individual comparative study within one day on a 1.5 T and a 3.0 T MRI system. T2 weighted TSE sequences were acquired after bolus injection of a SPIO contrast agent. Image contrast and signal to noise ratio (SNR) were compared between the field strengths. Image contrast was calculated between the liver tissue and the kidneys / spleen / muscles and fluids. The students'T-test was used for statistical analysis. No influence of the higher field strength could be observed on image contrast except for the liver / muscle contrast. This was due to a distinct SNR increase of the muscle tissue at 3.0 T as a result of their relaxation properties. The higher susceptibility at 3.0 T compared to 1.5 T does not translate into a stronger signal attenuation of the SPIO enhanced liver parenchyma.

Purpose: To prospectively evaluate adverse events (AEs) in patients who underwent nonionic monomeric or dimeric contrast media-enhanced computed tomography (CT) and to compare these effects with AEs in patients who underwent unenhanced CT., Materials and Methods: Local ethics committee approval and written informed consent were obtained. Patients were randomly assigned to the dimeric group, monomeric group, or concurrent control group. Acute (occurring during or within 1 hour after contrast agent injection) and delayed (occurring between 1 hour and 7 days after contrast agent injection) AEs were evaluated and categorized (mild, not requiring treatment; moderate, self-limiting AE requiring simple treatment; severe, AE requiring extensive treatment or endangering life). The two-sided Fisher exact test and the Mann-Whitney U and Wilcoxon signed rank tests were used for statistical analysis., Results: A total of 895 patients were recruited. Acute AEs were noted significantly (P < .05) more often in the monomeric group (44.8% [133 of 297 patients]) than in the dimeric (23.7% [71 of 300 patients]) or control (9.4% [28 of 298 patients]) groups. Two moderate acute AEs were noted in one patient in each contrast agent group; all other acute AEs were mild. There was no significant difference in the overall incidence of delayed AEs between the dimeric and monomeric groups (53.1% [139 of 262 patients] vs 50.8% [131 of 258 patients]). Delayed cutaneous AEs were noted significantly (P < .05) more often in the dimeric group. A total 16 AEs (2.0%) were moderate; no AE was severe., Conclusion: The dimeric contrast agent caused fewer acute AEs than the monomeric contrast agent; however, the dimeric and monomeric agents caused a similar overall number of delayed AEs. Delayed cutaneous symptoms were noted more often with the dimeric contrast agent. Both contrast agents were safe in that no severe AEs and only a few moderate AEs were observed., (RSNA, 2006)

Purpose: To establish a pulse sequence for dynamic contrast material-enhanced magnetic resonance (MR) imaging of the breast at 3.0 T and to prospectively compare MR imaging at 3.0 T with MR imaging at 1.5 T in the same patients., Materials and Methods: A prospective intraindividual internal review board-approved study was performed in 37 women with 53 lesions (25 breast cancers, 28 benign focal lesions) who underwent contrast-enhanced dynamic bilateral subtraction MR imaging twice, once at 1.5 T with a standard technique (voxel size, 1.44 mm3) and once at 3.0 T (voxel size, 0.45-0.72 mm3) with variable repetition time and flip angle settings. Written informed consent was obtained. Sagittal single breast high-spatial-resolution MR imaging was performed with active fat suppression. Image quality, number and features of enhancing lesions, and Breast Imaging Reporting and Data System categories were compared by using the Wilcoxon matched-pairs signed rank test and Student t test for matched pairs. Diagnostic confidence was compared by using a receiver operating characteristic (ROC) analysis., Results: With repetition time prolonged to account for longer T1 relaxation times at 3.0 T and a flip angle of 60 degrees, enhancement rates at 3.0 T were substantially below those at 1.5 T. In two patients with benign lesions, enhancement was rated as insufficient to establish diagnosis. When parameter settings were kept equivalent, equivalent enhancement rates were observed with both systems. With these settings, 3.0-T MR imaging yielded homogeneous signal intensity over the entire field of view. No dielectric resonance effects were observed. Overall image quality scores for the dynamic series were slightly higher at 3.0 T (P<.01). A total of 49 lesions were prospectively identified with both systems. Owing to substantial patient motion at 1.5 T, two malignant lesions in one patient were visualized at 3.0 T only. At 3.0 T, differential diagnosis of enhancing lesions was possible with higher diagnostic confidence, as reflected by a larger area under the ROC curve (P<.05)., Conclusion: Initial experiences indicate that contrast-enhanced MR imaging at 3.0 T is nearing readiness for clinical use., (Copyright (c) RSNA, 2006.)

Purpose: To prospectively evaluate whether the descriptors of lesion features and the diagnostic criteria that have been established for breast magnetic resonance (MR) imaging in female patients may be used for differential diagnosis with breast MR imaging in male patients as well., Materials and Methods: The study design was approved by the institutional review board; all patients gave informed consent. The Institutional Review Board and informed consent information applied to the prospective and any retrospective component of the study. Seventeen consecutive male patients (mean age, 53 years +/- 14) were referred for imaging of a palpable breast mass. In addition to mammography and high-frequency breast ultrasonography, patients underwent dynamic breast MR imaging in a prone position with a dedicated double-breast surface coil. The standardized protocol consisted of a T2-weighted turbo spin-echo sequence followed by a dynamic series. Findings were recorded by using the terminology and descriptors and by evaluating the diagnostic criteria (related to morphology and enhancement kinetics) that have been developed for breast MR imaging in female patients. Validation was achieved at biopsy (nine patients) or follow-up with clinical examination and conventional imaging (eight patients). Because of the small size of the patient cohort, statistical significance was not tested., Results: A total of 24 breast abnormalities were diagnosed. Three patients had invasive breast cancer (five tumors), 11 had gynecomastia (six unilateral, five bilateral), two had pseudogynecomastia, and one had a benign solid tumor (angiolipoma). All malignant tumors appeared as irregular masses with heterogeneous internal architecture or rim enhancement and showed rapid initial enhancement (mean value, 137% +/- 23) followed by a washout time course (Breast Imaging Reporting and Data System [BI-RADS] category 5). Diffuse and nodular gynecomastia showed slow initial and persistent enhancement with normal-appearing parenchymal architecture (BI-RADS category 2; 15 of 16 breasts in 10 of 11 patients). In one patient with biopsy-proved bilateral gynecomastia, an area with segmental enhancement was classified as suspicious for ductal carcinoma in situ. Pseudogynecomastia did not enhance at all. The angiolipoma showed benign morphologic features and slow initial and persistent enhancement (BI-RADS category 2)., Conclusion: In the small study cohort, the MR imaging features of benign breast diseases and breast cancers in male patients seemed to be comparable to those seen in female patients., ((c) RSNA, 2005)

Purpose: To prospectively and intraindividually compare the effect of magnetic resonance (MR) imaging at a higher magnetic field strength (3.0 T) on contrast-to-noise ratio (CNR) at different doses of a T1-shortening contrast agent in patients with contrast-enhancing brain lesions, with 1.5-T MR imaging as a reference standard., Materials and Methods: Institutional review board approval and informed consent were obtained for all patient and volunteer studies. Twelve patients (six women, six men; mean age, 58 years; range, 29-76 years) with 12 enhancing brain lesions (11 patients with primary brain tumors and one with a solitary cerebral metastasis) underwent contrast material-enhanced MR imaging three times, on three separate days: once at 1.5 T with a full dose of 0.10 mmol/kg gadopentetate dimeglumine, once at 3.0 T with a full dose, and once at 3.0 T with half that dose, 0.05 mmol/kg. The same contrast-enhanced T1-weighted spin-echo images (repetition time msec/echo time msec, 500/12; section thickness, 5 mm; matrix, 256 x 205) were obtained at both 3.0 T and 1.5 T after prior optimization of parameters at 3.0 T. The number and conspicuity of enhancing brain lesions were assessed with blinded clinical image reading. Signal-to-noise ratio and CNR were determined with region of interest analysis of enhancing lesions and normal contralateral white matter. For 3.0 T with half the standard dose and with the full dose, CNR of lesions was intraindividually compared with CNR at 1.5 T with the full dose by using the Wilcoxon matched-pairs signed rank test., Results: At 3.0 T and full dose, CNR was 2.8-fold higher than that at 1.5 T and full dose (P < .001). At the same time, higher lesion conspicuity at clinical image reading was observed. With only half the standard dose, MR imaging at 3.0 T still yielded higher CNR (1.3-fold higher) than that with full dose at 1.5 T (P < .01)., Conclusion: With the same amount of contrast agent, MR imaging at 3.0 T offered a significantly higher CNR of enhancing cerebral lesions, compared with that at 1.5 T; even with the dose reduced by half, CNR was still higher at 3.0 T., (RSNA, 2005)

Purpose: To assess sensitivity encoding (SENSE) for contrast-enhanced MR angiography (CE-MRA) of the abdominal arteries in comparison with standard MRA protocols., Materials and Methods: In 22 patients MRA of the abdominal arteries was performed twice (once using a standard protocol, and once with the additional use of SENSE). In 10 patients all examination parameters were kept constant (TR/TE/FA = 3.8 msec/1.3 msec/30 degrees ), and a reduction in scan time from 22 to 11 seconds was realized with the use of SENSE. In 12 patients, using SENSE the acquisition matrix was increased from 208 to 416, keeping the scan time constant. Image quality was scored on a five-point scale by three radiologists. Additionally, ROI-based measurements of CNR were performed., Results: For both protocols, image quality was significantly improved using SENSE. The time-reducing SENSE protocol yielded an average score of 4.2 points vs. 3.1 for the standard protocol. Using SENSE to increase the acquisition matrix, an average score of 4.3 was reached vs. 3.2 for the standard protocol (P < 0.05). The number of depictable small vessels and their bifurcations was significantly increased by either of the two SENSE protocols as compared to the standard imaging procedure., Conclusion: SENSE for MRA of the abdominal arteries significantly increases image quality and permits a substantial reduction in breath-hold time or a significantly improved spatial resolution., ((c) 2005 Wiley-Liss, Inc.)

Purpose: To prospectively investigate if T2*-weighted dynamic susceptibility-weighted first-pass perfusion magnetic resonance (MR) imaging is feasible at 3.0 T and which dose of contrast agent is suitable for high-field-strength imaging., Materials and Methods: Informed consent was obtained from all participants; study protocol was approved by the institutional review board. Study included three volunteers (two men, one woman aged 35, 39, and 52 years) and 26 patients (mean age, 49 years +/- 12.8 [standard deviation]; range, 19-76 years). Volunteers underwent 3.0-T perfusion MR imaging with 0.20, 0.10, and 0.05 mmol per kilogram body weight of gadopentetate dimeglumine; patients underwent imaging with 0.10- and 0.05-mmol doses. Perfusion MR imaging was performed with three-dimensional echo-shifted echo-planar imaging (repetition time msec/echo time msec, 14/21; isotropic 4 mm3 voxels; 50 dynamic volumes with 30 sections each, covering entire brain at temporal resolution of 1.5 seconds per MR image). Quality of source echo-planar images and perfusion maps was assessed; perfusion maps obtained at studies with different contrast media doses were compared. Quantitative perfusion values and diagnostic sensitivity of perfusion studies with 0.10-mmol dose were compared with results with 0.05-mmol dose. Image quality scores were compared with marginal homogeneity test for multinomial variables (Mantel-Haenszel statistics for ordered categorized values). Signal-to-noise ratio and baseline signal intensity in perfusion studies were tested (Student t test for paired samples). Mean transit time (MTT), negative integral (NI), and maximum T2* effect from region-of-interest analysis were compared (one-tailed Student t test for paired samples). Quantitative data on number of gamma-fitted pixels were compared (t test for paired samples). Difference with P=.05 (t test for paired samples) was considered significant., Results: Perfusion image quality was satisfactory even in areas close to skull base (47 of 52 images, minor distortions; remaining images, marked distortions). Perfusion imaging with 0.20-mmol dose caused almost complete signal cancellation during first pass, particularly in cortical gray matter, since mean maximum T2* effect of 98%, 99%, and 98% for gray matter was reached such that the accurate calculation of perfusion maps was impossible. With 0.10-mmol dose, the NI and maximum T2* effect were comparable to published data for 1.5-T perfusion imaging with 0.20- and 0.05-mmol doses; perfusion maps of sufficient diagnostic quality were obtained. For gray matter, mean maximum T2* effect was 25.4% +/- 9.8 with 0.10-mmol dose and 17.5% +/- 9.0 with 0.05-mmol dose. For white matter, mean maximum T2* effect was 15.2% +/- 4.5 with 0.10-mmol dose and 7.7% +/- 2.9 with 0.05-mmol dose. Difference in maximum signal intensity decrease was significant (P <.01). For NI, the difference between 0.10- and 0.05-mmol doses was significant: For gray matter, mean NI was 3.1 +/- 1.60 for 0.10-mmol dose and 1.56 +/- 1.16 for 0.05-mmol dose. For white matter, mean NI was 1.35 +/- 0.59 with 0.1-mmol dose and 0.59 +/- 0.30 with 0.05-mmol dose., Conclusion: With echo-shifted multishot echo-planar imaging, dynamic susceptibility-weighted perfusion MR imaging at high field strength is feasible without relevant image distortions. Compared with contrast agent dose for 1.5 T imaging, the dose for 3.0 T can be reduced to 0.10 mmol.

Objectives: The aim of this study was to compare success, technical complexity, and complication rates of percutaneous transhepatic biliary drainage (PTBD) in patients with dilated vs. nondilated bile ducts. Methods: In a retrospective analysis, we evaluated all consecutive PTBD performed in our department over a period of 5 years. Technical success, technical data (side, fluoroscopy time, radiation dose, amount of contrast media, use of disposable equipment), procedure-related complications and peri-interventional mortality were compared for patients with dilated vs. non-dilated bile ducts. Independent t test and χ2 test were used to evaluate the statistical significance. Results: A total of 253 procedures were performed on 187 patients, of whom 101/253 had dilated bile ducts and 152/253 not. In total, 243/253 procedures were successful. PTBD was significantly more often successful in patients with dilated vs. nondilated bile ducts (150/153 vs. 93/101; p 0.02). Overall complication rate (13%) did not differ significantly between patients with dilated vs. nondilated bile ducts. Procedures in patients with normal, nondilated bile ducts were associated with a significantly higher rate of post-interventional bleeding (5/101 vs. 0/152). Mean fluoroscopy time (42:36 ± 35:39 h vs. 30:28 ± 25:10 h; p 0.002) and amount of contrast media (66 ± 40 ml vs. 52 ± 24 ml; p 0.07) or use of disposables were significantly higher in patients with nondilated ducts. A significantly lower fluoroscopy time and amount of contrast medium were used in left hepatic PTBD. Conclusion: Despite the higher technical complexity, PTBD with nondilated bile ducts was associated with similar overall complication rates but higher bleeding complications compared with PTBD with dilated bile ducts. Key Points: • PTBD was associated with similar overall complication rates in patients with dilated vs. nondilated bile ducts. • Although overall complication rates were low, PTBD in patients with nondilated bile ducts was associated with a higher incidence of post-interventional bleeding. • PTBD in patients with nondilated bile ducts is technically more complex. [ABSTRACT FROM AUTHOR]

Objectives: Most existing models that are in use to model hepatic function through assessment of hepatic gadoxetic acid enhancement kinetics do not consider quantitative measures of gadoxetic excretion. We developed a model that allows a simultaneous quantitation of uptake and excretion of liver specific contrast agents. The aim was to improve the assessment of hepatic synthetic function, and provide quantitative measures of hepatic excretion function.Methods: Sixteen patients underwent dynamic T1-weighted turbo gradient echo imaging at 1.5 T prior and after bolus injection of gadoxetic acid at 0.1 ml/kg. DCE-images were obtained for 30 min after injection. A dual-inlet two-compartment model was then used to fit the measured liver signal values. Four tissue parameters (extracellular volume fraction, arterial flow fraction, uptake rate and excretion half-time) were extracted for each liver segment.Results: The proposed model provided a good fit to acquired data. Mean values for arterial flow fraction (0.08+-0.04), extracellular volume (0.20±0.08) and uptake rate (4.02 ±1.32 /100 ml/min) were comparable to those obtained with the conventional model (0.08±0.05, 0.21±0.12, and 4.93±1.74), but exhibited significantly less variation and improved fit quality.Conclusions: The proposed model is more accurate than existing conventional models and provides an additional excretion parameter.Key Points: • Models of hepatic contrast agent uptake can be extended to include excretion. • Including an additional excretion parameter improves accuracy of the model. • Standard diagnostic sequences can be extended to incorporate the model. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: To compare the effects of two different contrast medium concentrations for use in computed X-ray tomography (CT) employing two different injection protocols on positron emission tomography (PET) reconstruction in combined 2-18F-desoxyglucose (FDG) PET/CT in patients with a suspicion of lung cancer. Methods: 120 patients with a suspicion of lung cancer were enrolled prospectively. PET images were reconstructed with the non-enhanced and venous phase contrast CT obtained after injection of iopromide 300mg/ml or 370mg/ml using either a fixed-dose or a body surface area adapted injection protocol. Maximum and mean standardized uptake values (SUVmax and SUVmean) and contrast enhancement (HU) were determined in the subclavian vein, ascending aorta, abdominal aorta, inferior vena cava, portal vein, liver and kidney and in the suspicious lung lesion. PET data were evaluated visually for the presence of malignancy and image quality. Results: At none of the sites a significant difference in the extent of the contrast enhancement between the four different protocols was found. However, the variability of the contrast enhancement at several anatomical sites was significantly greater in the fixed dose groups than in the BSA groups for both contrast medium concentrations. At none of the sites a significant difference was found in the extent of the SUVmax and SUVmean increase as a result of the use of the venous phase contrast enhanced CT for attenuation. Visual clinical evaluation of lesions showed no differences between contrast and non-contrast PET/CT (P =0.32). Conclusions: Contrast enhanced CT for attenuation correction in combined PET/CT in lung cancer affects neither the clinical assessment nor image quality of the PET-images. A body surface adapted contrast medium protocol reduces the interpatient variability in contrast enhancement. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: To evaluate the influence of multiphase CT scanning and different intravenous contrast media on contrast enhancement, attenuation correction and image quality in combined PET/CT. Material and methods: 140 patients were prospectively enrolled for F-18-FDG-PET/CT including a low-dose unenhanced, arterial and venous contrast enhanced CT. The first (second) 70 patients, received contrast medium with 370 (300) mg iodine/ml. The iodine delivery rate (1.3mg/s) and total iodine load (44.4g) were identical for both groups. Contrast enhancement and maximum and mean standardized FDG uptake values (SUVmax and SUVmean) were determined for the un-enhanced, arterial and venous PET/CT at multiple anatomic sites and PET reconstructions were visually evaluated. Results: Arterial contrast enhancement was significantly higher for the 300mg/ml contrast medium compared to 370mgI/ml at all anatomic sites. Venous enhancement was not different between the two contrast media. SUVmean and SUVmax were significantly higher for the contrast enhanced compared to the non-enhanced PET/CT at all anatomic sites (all P <0.001). Tracer uptake was significantly higher in the arterial than in the venous PET/CT in the arteries using both contrast media (all P <0.001). No differences in tracer uptake were found between the contrast media (all P >0.05). Visual assessment revealed no relevant differences between the different PET reconstructions. Conclusions: There is no relevant qualitative influence on the PET scan from the use of different intravenous contrast media in its various phases in combined multiphase PET/CT. For quantitative analysis of tracer uptake it is required to use an identical PET/CT protocol. [Copyright &y& Elsevier]