[18F]FDG PET/MR enterography for the assessment of inflammatory activity in Crohn's disease: comparison of different MRI and PET parameters.

PURPOSE: To evaluate the diagnostic performance of integrated whole-body positron emission tomography (PET)/magnetic resonance (MR) enterography in patients with Crohn's disease (CD). METHODS: Fifty patients with known CD and recurrent symptoms underwent ileocolonoscopy (reference standard) as well as PET/MR enterography. Seven ileocolonic segments were endoscopically analysed using the Simplified Endoscopic Activity Score for Crohn's Disease (SES-CD) and additionally classified into three categories of inflammation (none, mild to moderate and severe ulcerative inflammation). A total of 14 PET/MR parameters were applied for the assessment of inflamed segments. Contingency tables and the chi-squared test were used for the analysis of qualitative parameters, and the Mann-Whitney U test and receiver operating characteristic (ROC) curve for the analysis of quantitative parameters. The PET/MR parameters were ranked according to their diagnostic value by random forest classification. Correlations between PET/MR parameters and the severity of inflammation on endoscopy and SES-CD were tested using Spearman's rank correlation test. RESULTS: A total of 309 segments could be analysed. Based on multivariate regression analysis, wall thickness and the comb sign were the most important parameters for predicting segments with active inflammation of any type. SUVmax ratio of the bowel segment (relative to SUVmax of the liver) was the most important parameter for detecting segments with severe ulcerative inflammation. Wall thickness was the only parameter that moderately correlated with inflammation severity on endoscopy as well as with SES-CD (ρ = 0.56 and 0.589, both p < 0.001). CONCLUSION: PET/MR enterography is an excellent noninvasive diagnostic method, and both MR parameters and PET findings provided high accuracy in detecting inflamed segments.

Evaluation of combined Gd-EOB-DTPA and gadobutrol magnetic resonance imaging for the prediction of hepatocellular carcinoma grading.

BACKGROUND: Tumor biopsy is not essential for the diagnosis of hepatocellular carcinoma (HCC); however, grading remains important for the prognosis. PURPOSE: To investigate whether combined Gd-EOB-DTPA and gadobutrol liver magnetic resonance imaging (MRI) can predict HCC grading. MATERIAL AND METHODS: Thirty patients (66.6 ± 7.3 years) with histologically confirmed HCC (grade 1, n = 5; grade 1-2, n = 6; grade 2, n = 13; grade 2-3, n = 2; grade 3, n = 4) underwent two liver MRIs, one with gadobutrol and one with Gd-EOB-DTPA, on consecutive days. Blinded to grading, two radiologists reviewed the gadobutrol and Gd-EOB-DTPA images in consensus with respect to: (i) HCC hyper-/iso-/hypointensity in the arterial, portal-venous/delayed, and Gd-EOB-DTPA hepatocellular phase; and (ii) morphologic tumor features (encapsulated growth, vessel invasion, heterogeneity, liver capsule infiltration, satellite metastases). RESULTS: A significant correlation with grading was not found for either the combined dynamic information of all gadobutrol phases (r = -0.187, P = 0.331) or all the Gd-EOB-DTPA phases (r = 0.052, P = 0.802). No correlation with grading was found for a combination of arterial and hepatocellular phase in Gd-EOB-DTPA MRI (r = 0.209, P = 0.305), a combination of both arterial phases (gadobutrol and Gd-EOB-DTPA) with the Gd-EOB-DTPA hepatocellular phase (r = 0.240, P = 0.248), or a combination of all available gadobutrol and Gd-EOB-DTPA phases (r = 0.086, P = 0.691). For all gadobutrol information (dynamic phases and morphology; r = 0.049, P = 0.801) and for all Gd-EOB-DTPA information (r = 0.040, P = 0.845), no correlation with grading was found. Hepatocellular Gd-EOB-DTPA phase iso-/hyperintensity never occurred in grade 3 HCCs. CONCLUSION: Histological HCC grading cannot be predicted by combined Gd-EOB-DTPA/gadobutrol MRI. However, Gd-EOB-DTPA hepatocellular phase iso-/hyperintensity was never detected in grade 3 HCCs.

Dual-energy computed tomography for evaluation of pulmonary nodules with emphasis on metastatic lesions.

BACKGROUND: The contrast enhancement of pulmonary nodules is a differential diagnostic criterion which can be helpful in staging investigations. PURPOSE: To investigate the impact of dual-energy computed tomography (DECT) with regards to the evaluation of pulmonary nodules with emphasis on metastatic lesions. MATERIAL AND METHODS: DECT scans of the thorax were performed in 70 consecutive patients. Data of the lung were acquired in the arterial and in delayed venous phase. The virtual native and overlay image data based on arterial and delayed venous phase of these lesions were compared using CT density values (HU) within the nodule tested for statistical significance. RESULTS: A total of 156 pulmonary lesions ≥5 mm were identified on 70 DECT scans. There were no significant differences between the CT-value measurements in the virtual native images based on the arterial and delayed venous phase (27.9+/-3.9 HU vs.28.1+/-4.2 HU, P = 0.89) and between the CT-value measurements in the overlay images based on the arterial und delayed venous phase (35.5+/-6.8 HU vs. 36.6+/-5.0 HU, P = 0.75). Metastases of colorectal carcinoma (51.4+/-9.4 HU vs. 32.5+/-8.9 HU, P = 0.0001), malignant melanoma (56.1+/-6.4 HU vs. 34.2+/-1.6 HU, P = 0.0045), and thyroid cancer (53.5+/-15.5 HU vs. 15.7+/-4.2 HU, P = 0.001) showed a distinct wash-out, whereas metastases of lung cancer (23.1+/-6.3 HU vs. 58.6+/-4.8 HU, P = 0.001), salivary gland cancer (41.4+/-20.3 HU vs. 65.7+/-15.7 HU, P = 0.023), and sarcoma (56.2+/-7.4 HU vs. 90.2+/-3.4 HU, P = 0.001) had an increased enhancement in the delayed venous phase. CONCLUSION: The contrast enhancement behavior of pulmonary metastases can be evaluated with DECT and depends on the type of the primary malignant tumor.

[(18)F]FDG PET/MRI vs. PET/CT for whole-body staging in patients with recurrent malignancies of the female pelvis: initial results.

PURPOSE: To evaluate the diagnostic potential of PET/MRI with [(18)F]FDG in recurrent ovarian and cervical cancer in comparison to PET/CT. METHODS: A group of 19 patients with suspected recurrence of pelvic malignancies (ovarian cancer, 11 patients; cervical cancer, 8 patients) scheduled for an [(18)F]FDG PET/CT were subsequently enrolled for a PET/MRI. The scan protocol comprised: (1) a T1-W axial VIBE after contrast agent adminstration, (2) an axial T2-W HASTE, (3) a coronal TIRM, (4) an axial DWI, and dedicated MR sequences of the female pelvis including (5) a T1-W VIBE before contrast agent adminstration, (6) a sagittal T2-W TSE, and (7) a sagittal T1-W dynamic VIBE. The datasets (PET/CT, PET/MRI) were rated separately by two readers regarding lesion count, lesion localization, lesion conspicuity (four-point scale), lesion characterization (benign/malignant/indeterminate) and diagnostic confidence (three-point scale). All available data (histology, prior examinations, PET/CT, PET/MRI, follow-up examinations) served as standard of reference. Median values were compared using the Wilcoxon rank sum test. RESULTS: Metastatic lesions were present in 16 of the 19 patients. A total of 78 lesions (malignant, 58; benign, 20) were described. Both PET/CT and PET/MRI allowed correct identification of all malignant lesions and provided equivalent conspicuity (3.86 ± 0.35 for PET/CT, 3.91 ± 0.28 for PET/MRI; p > 0.05). Diagnostic confidence was significantly higher for PET/MRI in malignant (p < 0.01) and benign lesions (p < 0.05). CONCLUSION: Both PET/CT and PET/MRI offer an equivalently high diagnostic value for recurrent pelvic malignancies. PET/MRI offers higher diagnostic confidence in the discrimination of benign and malignant lesions. Considering the reduced radiation dose and superior lesion discrimination, PET/MRI may serve as a powerful alternative to PET/CT in the future.

Integrated PET/MRI for whole-body staging of patients with primary cervical cancer: preliminary results.

PURPOSE: To assess the diagnostic value of integrated PET/MRI for whole-body staging of cervical cancer patients, as well as to investigate a potential association between PET/MRI derived functional parameters and prognostic factors of cervical cancer. METHODS: The present study was approved by the local institutional review board. Twenty-seven patients with histopathologically confirmed cervical cancer were prospectively enrolled in our study. All patients underwent a whole-body PET/MRI examination after written informed consent was obtained. Two radiologists separately evaluated the PET/MRI data sets regarding the determination of local tumor extent of primary cervical cancer lesions, as well as detection of nodal and distant metastases. Furthermore, SUV and ADC values of primary tumor lesions were analyzed and correlated with dedicated prognostic factors of cervical cancer. Results based on histopathology and cross-sectional imaging follow-up served as the reference standard. RESULTS: PET/MRI enabled the detection of all 27 primary tumor lesions of the uterine cervix and allowed for the correct determination of the T-stage in 23 (85 %) out of the 27 patients. Furthermore, the calculated sensitivity, specificity and diagnostic accuracy for the detection of nodal positive patients (n = 11) were 91 %, 94 % and 93 %, respectively. PET/MRI correctly identified regional metastatic disease (N1-stage) in 8/10 (80 %) patients and non-regional lymph node metastases in 5/5 (100 %) patients. In addition, quantitative analysis of PET and MRI derived functional parameters (SUV; ADC values) revealed a significant correlation with pathological grade and tumor size (p < 0.05). CONCLUSIONS: The present study demonstrates the high potential of integrated PET/MRI for the assessment of primary tumor and the detection of lymph node metastases in patients with cervical cancer. Providing additional prognostic information, PET/MRI may serve as a valuable diagnostic tool for cervical cancer patients in a pretreatment setting.

Motility mapping as evaluation tool for bowel motility: initial results on the development of an automated color-coding algorithm in cine MRI.

PURPOSE: To develop and implement an automated algorithm for visualizing and quantifying bowel motility using cine magnetic resonance imaging (MRI). MATERIALS AND METHODS: Four healthy volunteers as well as eight patients with suspected or diagnosed inflammatory bowel disease (IBD) underwent MR examinations on a 1.5T scanner. Coronal T2-weighted cine MR images were acquired in healthy volunteers without and with intravenous (i.v.) administration of butylscopolamine. In patients with IBD, cine MRI sequences were collected prior to standard bowel MRI. Bowel motility was assessed using an optical flow algorithm. The resulting motion vector magnitudes were presented as bowel motility maps. Motility changes after i.v. administration of butylscopolamine were measured in healthy volunteers. Inflamed bowel segments in patients were correlated with motility map findings. RESULTS: The acquisition of bowel motility maps was feasible in all subjects examined. In healthy volunteers butylscopolamine led to quantitatively measurable decrease in bowel motility (mean decrease of 59%; P = 0.171). In patients with IBD, visualization of bowel movement by color-coded motility mapping allowed for the detection of segments with abnormal bowel motility. Inflamed bowel segments could be identified by exhibiting a decreased motility. CONCLUSION: Our method is a feasible and promising approach for the assessment of bowel motility disorders.

3 Tesla high-resolution and delayed gadolinium enhanced MR imaging of cartilage (dGEMRIC) after autologous chondrocyte transplantation in the hip.

BACKGROUND: To evaluate the feasibility of 3 Tesla (T) high-resolution and gadolinium enhanced MRI of cartilage (dGEMRIC) in the thin and rounded hip cartilage of patients after acetabular matrix-based autologous chondrocyte transplantation (MACT). METHODS: Under general ethics approval, 24 patients were prospectively examined 6-31 months after acetabular MACT at 3T using high-resolution proton-density weighted (PDw) images (bilateral PD SPACE, 0.8 mm isotropic; unilateral PD-TSE coronal/sagittal, 0.8 × 0.8 resp. 0.5 × 0.5 × 2.5 mm) as well as T1 mapping (3D-FLASH, 0.78 mm isotropic) in dGEMRIC technique, and clinically scored. The cartilage transplant was evaluated using an adapted MOCART score (maximum 85 points). T1 relaxation times were measured independently by two radiologists. Here, regions of interest were placed manually in automatically calculated relaxation-maps, both in the transplant and adjacent healthy cartilage regions. Interobserver reliability was estimated by means of intraclass-correlation (ICC). RESULTS: The transplant was morphologically definable in the PDw images of 23 patients with a mean MOCART score of 69 points (60-80 points, SD 6.5). T1 maps showed a clear differentiation between acetabular and femoral cartilage, but correlation with PDw images was necessary to identify the transplant. Mean T1 relaxation times of the transplant were 616.3 ms (observer 1) resp. 610.1 ms (observer 2), and of adjacent healthy acetabular cartilage 574.5 ms (observer 1) resp. 604.9 ms (observer 2). Interobserver reliability of the relaxation times in the transplant was excellent (ICC-coefficient 0.88) and in adjacent healthy regions good (0.77). CONCLUSION: High-resolution PDw imaging with adapted MOCART scoring and dGEMRIC is feasible after MACT in the thin and rounded hip cartilage.

Does diffusion-weighted imaging improve therapy response evaluation in patients with hepatocellular carcinoma after radioembolization? comparison of MRI using Gd-EOB-DTPA with and without DWI.

PURPOSE: To investigate whether additional diffusion-weighted imaging (DWI) improves therapy response evaluation by Gd-EOB magnetic resonance imaging (MRI) in hepatocellular carcinoma (HCC) after radioembolization. MATERIALS AND METHODS: Fifty patients with radioembolization for HCC underwent gadobutrol and Gd-EOB MRI with DWI prior to and 30, 90, and 180 days after radioembolization. A combination of gadobutrol MRI, alpha-fetoprotein, and imaging follow-up served as the reference standard. Two radiologists reviewed Gd-EOB alone (Gd-EOB), DWI alone (DWI), and the combination of both (Gd-EOB+DWI) separately and in consensus using a 4-point-scale: 1 = definitely no tumor progression (TP), 2 = probably no TP, 3 = probably TP, 4 = definitely TP. Receiver operating characteristic (ROC) and kappa analysis were performed. RESULTS: Kappa values for Gd-EOB, DWI, and Gd-EOB+DWI ranged between 0.712 and 0.892 (P < 0.001). 30 days after radioembolization three out of 38 patients showed TP, which was missed by DWI in one case. No significant area under the curve (AUC) difference between Gd-EOB (1.0, P = 0.004), DWI (0.881, P = 0.030), and Gd-EOB+DWI (1.0, P = 0.004) was found (P = 0.320). 90 days after radioembolization six out of 28 patients showed TP, which was detected in one patient only by DWI and Gd-EOB+DWI. The AUC did not differ significantly (P = 0.319) between Gd-EOB (0.890, P = 0.004), DWI (1.0, P < 0.001), and Gd-EOB+DWI (1.0, P < 0.001). 180 days after radioembolization five patients showed TP, which in one case was missed by DWI. The AUC did not differ significantly (P1 = 0.322, P2 = 0.369, P3 = 0.350) between Gd-EOB (1.0, P = 0.003), DWI (0.913, P = 0.016), and Gd-EOB+DWI (0.963, P = 0.007). CONCLUSION: Additional DWI does not substantially improve therapy response evaluation by Gd-EOB MRI in HCC after radioembolization but proved helpful in single cases.

In intermediate stage hepatocellular carcinoma: radioembolization with yttrium 90 or chemoembolization?

BACKGROUND & AIMS: Transarterial chemoembolization (TACE) is one of the standard treatments recommended for intermediate stage hepatocellular carcinoma (HCC). At the same time, only little is known about the use of radioembolization with Yttrium-90 microspheres (TARE Y-90) for this subset of patients. To perform comparative analysis between both locoregional therapies in intermediate HCCs. Primary endpoint was overall survival (OS), while safety, response rate and time-to-progression (TTP) were considered as secondary endpoints. METHODS: We collected data of 86 HCC patients in two university hospitals at which conventional TACE with doxorubicin or TARE Y-90 using glass microspheres were performed. The median observation period was 10 months. Patients were followed up for signs of toxicity and response. They underwent imaging analysis at baseline and follow-up at regular time intervals. RESULTS: Eighty-six HCC patients with intermediate stage B (BCLC) were treated with either TACE (n = 42) or TARE Y-90 (n = 44). Despite a higher tumour burden in the TARE Y-90 group, the median OS (TACE: 18 months vs. TARE Y-90: 16.4 months) and the median TTP (TACE: 6.8 months vs. TARE Y-90: 13.3 months) were not statistically different. The number of treatment sessions, the average rate of treatment sessions per patient, total hospitalization time and rate of adverse events were significantly higher in the TACE cohort. CONCLUSION: In intermediate HCC stage patients, both treatments resulted in similar survival probabilities despite more advanced disease in the TARE Y-90 group. Still, TARE Y-90 was better tolerated and associated with less hospitalization and treatment sessions.

Therapy response assessment after radioembolization of patients with hepatocellular carcinoma--comparison of MR imaging with gadolinium ethoxybenzyl diethylenetriamine penta-acetic acid and gadobutrol.

PURPOSE: To compare the utility of gadolinium ethoxybenzyl diethylenetriamine penta-acetic acid (Gd-EOB-DTPA), a liver-specific magnetic resonance (MR) imaging contrast agent, versus gadobutrol for treatment response evaluation of hepatocellular carcinoma (HCC) after radioembolization. MATERIALS AND METHODS: This prospective study included 50 patients with HCC undergoing radioembolization. All patients underwent contrast-enhanced computed tomography (CT) and MR imaging with gadobutrol and Gd-EOB-DTPA on 2 consecutive days before radioembolization and 30 days, 90 days, 180 days, and 270 days after radioembolization. The standard of reference indicating tumor progression was CT combined with either α-fetoprotein or γ-glutamyltransferase. Gadobutrol-enhanced MR imaging, Gd-EOB-DTPA-enhanced MR imaging without late phase imaging (Gd-EOB-DTPA-), and Gd-EOB-DTPA-enhanced MR imaging with late phase imaging (Gd-EOB-DTPA+) were evaluated by 2 radiologists in consensus using a 4-point scale: 1 = definitely no tumor progression; 2 = probably no tumor progression; 3 = probably tumor progression; 4 = definitely tumor progression. Diagnostic accuracy was assessed with receiver operating characteristic analysis. RESULTS: Tumor progression was detected in 14 of 82 study visits according to the reference standard. Pairwise comparison of the area under the curve showed a tendency toward a larger area under the curve for Gd-EOB-DTPA+ compared with gadobutrol (P = .056). Sensitivity and specificity were higher in Gd-EOB-DTPA+ (0.929 and 0.971) than in Gd-EOB-DTPA- (0.786 and 0.941) or gadobutrol (0.643 and 0.956). In 2 cases, tumor progression was detected by Gd-EOB-DTPA+ and by an increase in α-fetoprotein, but not by CT, gadobutrol, or Gd-EOB-DTPA-. CONCLUSIONS: Gd-EOB-DTPA+ MR imaging was not inferior to gadobutrol-enhanced MR imaging in therapy response evaluation after radioembolization and may allow a more accurate detection of early HCC recurrence in single cases.

Impact of dual-energy CT prior to radioembolization (RE).

BACKGROUND: Depiction of the exact arterial liver anatomy as well as identifying potential extrahepatic non-target vessels is crucial for a successful preparation of radioembolization (RE). PURPOSE: To compare the diagnostic impact of dual-energy computed tomography (DECT) to digital subtraction angiography prior to RE. MATERIAL AND METHODS: DECT was applied in 46 patients with hepatocellular carcinoma (HCC) prior to RE. Eighty kV DE as well as reconstructed 120 kV equivalent DE datasets were evaluated in comparison to correlating digital subtraction angiography (DSA) datasets. Two radiologists evaluated in consensus the delineation of liver arteries and extrahepatic non-target vessels utilizing a 4-point scale (4 = excellent delineation; 1 = non-diagnostic). In addition, the arterial vascularization of liver segment IV was evaluated and classified: signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR; liver arteries to adjacent liver tissue) were obtained via ROI analysis. RESULTS: Both imaging techniques (DECT, DSA) enabled high-quality assessment of all analyzed liver arteries. Out of the two CT datasets, 80 kVp-DE datasets offered superior delineation of the right gastric artery (3.5 ± 0.7 vs. 2.5 ± 0.5), the vascularization of segment IV (3.9 ± 0.2 vs. 3.3 ± 0.5) as well as potential extrahepatic non-target vessels (3.9 ± 0.1 vs. 3.3 ± 0.5). In accordance to the results of the qualitative analysis, 80 kVp-DE datasets also yielded higher SNR (34.84 vs. 29.31) and CNR (28.29 vs. 21.8) values in comparison to the 120 kVp datasets. CONCLUSION: Eighty kVp DECT enables a significantly better assessment of the arteries of the upper abdomen for therapy planning in comparison to correlating 120 kVp datasets. This may allow for identification of potential extrahepatic non-target vessels and assessment of target volume for therapy planning prior to DSA.

High and ultra-high b-value diffusion-weighted imaging in prostate cancer: a quantitative analysis.

BACKGROUND: Diffusion-weighted imaging (DWI) is routinely used in magnetic resonance imaging (MRI) of prostate cancer. However, the routine use of b values higher than 1000 s/mm(2) is not clear up to present. Moreover, the complex diffusion behavior of malignant and benign prostate tissues hampers precise predictions of contrast in DWI images and apparent diffusion coefficient (ADC) maps. PURPOSE: To quantitatively analyze DWI with different b values in prostate cancer and to identify b values best suitable for cancer detection. MATERIAL AND METHODS: Forty-one patients with histologically proven prostate cancer were examined with high resolution T2-weighted imaging and DWI at 3 Tesla. Five different b values (0, 800, 1000, 1500, 2000 s/mm(2)) were applied. ADC values of tumors and reference areas were measured on ADC maps derived from different pairs of b values. Furthermore, signal intensities of DW images of tumors and reference areas were measured. For analysis, contrast ratios of ADC values and signal intensities of DW images were calculated and compared. RESULTS: No significant differences were found between contrast ratios measured on ADC maps of all analyzed b value pairs (P = 0.43). Contrast ratios calculated from signal intensities of DW images were highest at b values of 1500 and 2000 s/mm(2) and differed significantly from contrast ratios at b values of 800 and 1000 s/mm(2) (P < 0.01). CONCLUSION: Whereas contrast in ADC maps does not significantly change with different b values, contrast ratios of DW images are significantly higher at b-values of 1500 and 2000 s/mm(2) in comparison to b values of 800 and 1000 s/mm(2). Therefore, diagnostic performance of DWI in prostate cancer might be increased by application of b values higher than 1000 s/mm(2).

Aspects of postoperative magnetic resonance imaging of patients with avascular necrosis of the femoral head, treated by advanced core decompression.

OBJECTIVE: To analyze remodeling processes after advanced core decompression (ACD) in patients with avascular femoral head necrosis by means of 3T MRI and to identify indicators for clinical outcome considering the defect size and characteristics of the bone graft and of the neighboring regeneration tissue. MATERIALS AND METHODS: Thirty-four hips, with preexisting preoperative MRIs in 21 cases, were examined 1-34 months (mean 12.7) postoperatively by 3T MRI. The volume of necrosis was measured manually pre- and postoperatively to calculate absolute as well as percentage necrosis reduction. The signal intensity of the bone graft was quantified using a 4-point scale. Border phenomena between the bone graft and bone were described and classified into groups. Wilcoxon sign-rank test was used to identify correlations between the analyzed items and clinical signs of femoral head collapse after a mean follow-up time of 28.6 months (10.4-46.8). RESULTS: Mean percentage reduction of necrosis was significantly higher in asymptomatic patients (59.36%) compared to patients with signs of femoral head collapse (28.78%, p = 0.008). Signal intensity of the bone graft increased in T1w and T2w TIRM sequences over time after surgery and was significantly higher in asymptomatic patients. Five border phenomena between the bone graft and healthy bone were identified. Among them, the so-called "rail sign" representing three layers of remodeling tissue correlated with the histological observations. CONCLUSION: A variety of border phenomena representing remodeling processes have been described using 3T MRI. Beneath the percentage amount of necrosis reduction, we identified the signal intensity of the bone graft as an indicator for clinical outcome.

Usefulness of metal artifact reduction with WARP technique at 1.5 and 3T MRI in imaging metal-on-metal hip resurfacings.

OBJECTIVE: To evaluate the usefulness of the metal artifact reduction technique "WARP" in the assessment of metal-on-metal hip resurfacings at 1.5 and 3T in the context of image quality and imaging speed. MATERIALS AND METHODS: Nineteen patients (25 hip resurfacings) were randomized for 1.5 and 3T MRI, both including T1 and T2 turbo spin-echo as well as turbo inversion recovery magnitude sequences with and without view angle tilting and high bandwidth. Additional 3T sequences were acquired with a reduced number of averages and using the parallel acquisition technique for accelerating imaging speed. Artifact size (diameter, area), image quality (5-point scale) and delineation of anatomical structures were compared among the techniques, sequences and field strengths using the Wilcoxon sign-rank and paired t-test with Bonferroni correction. RESULTS: At both field strengths, WARP showed significant superiority over standard sequences regarding image quality, artifact size and delineation of anatomical structures. At 3T, artifacts were larger compared to 1.5T without affecting diagnostic quality, and scanning time could be reduced by up to 64 % without quality degradation. CONCLUSION: WARP proved useful in imaging metal-on-metal hip resurfacings at 1.5T as well as 3T with better image quality surrounding the implants. At 3T imaging could be considerably accelerated without losing diagnostic quality.

Evaluation of the PET component of simultaneous [(18)F]choline PET/MRI in prostate cancer: comparison with [(18)F]choline PET/CT.

PURPOSE: The aim of this study was to evaluate the positron emission tomography (PET) component of [(18)F]choline PET/MRI and compare it with the PET component of [(18)F]choline PET/CT in patients with histologically proven prostate cancer and suspected recurrent prostate cancer. METHODS: Thirty-six patients were examined with simultaneous [(18)F]choline PET/MRI following combined [(18)F]choline PET/CT. Fifty-eight PET-positive lesions in PET/CT and PET/MRI were evaluated by measuring the maximum and mean standardized uptake values (SUVmax and SUVmean) using volume of interest (VOI) analysis. A scoring system was applied to determine the quality of the PET images of both PET/CT and PET/MRI. Agreement between PET/CT and PET/MRI regarding SUVmax and SUVmean was tested using Pearson's product-moment correlation and Bland-Altman analysis. RESULTS: All PET-positive lesions that were visible on PET/CT were also detectable on PET/MRI. The quality of the PET images was comparable in both groups. Median SUVmax and SUVmean of all lesions were significantly lower in PET/MRI than in PET/CT (5.2 vs 6.1, p<0.05 and 2.0 vs 2.6, p<0.001, respectively). Pearson's product-moment correlation indicated highly significant correlations between SUVmax of PET/CT and PET/MRI (R=0.86, p<0.001) as well as between SUVmean of PET/CT and PET/MRI (R=0.81, p<0.001). Bland-Altman analysis revealed lower and upper limits of agreement of -2.77 to 3.64 between SUVmax of PET/CT vs PET/MRI and -1.12 to +2.23 between SUVmean of PET/CT vs PET/MRI. CONCLUSION: PET image quality of PET/MRI was comparable to that of PET/CT. A highly significant correlation between SUVmax and SUVmean was found. Both SUVmax and SUVmean were significantly lower in [(18)F]choline PET/MRI than in [(18)F]choline PET/CT. Differences of SUVmax and SUVmean might be caused by different techniques of attenuation correction. Furthermore, differences in biodistribution and biokinetics of [(18)F]choline between the subsequent examinations and in the respective organ systems have to be taken into account.

Whole-body [¹8F]FDG PET/MRI vs. PET/CT in the assessment of bone lesions in oncological patients: initial results.

OBJECTIVES: To compare [(18)F]FDG PET/MRI with PET/CT for the assessment of bone lesions in oncologic patients. METHODS: This prospective study included 67 patients with solid tumours scheduled for PET/CT with [(18)F]FDG who also underwent a whole-body PET/MRI scan. The datasets (PET/CT, PET/MRI) were rated by two readers regarding lesion conspicuity (four-point scale) and diagnostic confidence (five-point scale). Median scores were compared using the Wilcoxon test. RESULTS: Bone metastases were present in ten patients (15%), and benign bone lesions in 15 patients (22%). Bone metastases were predominantly localized in the pelvis (18 lesions, 38%) and the spine (14 lesions, 29%). Benign bone lesions were exclusively osteosclerotic and smaller than the metastases (mean size 6 mm vs. 23 mm). While PET/CT allowed identification of 45 of 48 bone metastases (94%), PET/MRI allowed identification of all bone metastases (100%). Conspicuity of metastases was high for both modalities with significantly better results using PET/MRI (p < 0.05). Diagnostic confidence in lesion detection was high for both modalities without a significant difference. In benign lesions, conspicuity and diagnostic confidence were significantly higher with PET/CT (p < 0.05). CONCLUSIONS: [(18)F]FDG PET/MRI shows high potential for the assessment of bone metastases by offering superior lesion conspicuity when compared to PET/CT. In hypersclerotic, benign bone lesions PET/CT still sets the reference. KEY POINTS: • PET/MRI and PET/CT are of equal value for the identification of disease-positive patients • PET/MRI offers higher lesion conspicuity as well as diagnostic confidence • PET/MRI is an attractive new alternative for the assessment of bone metastases.

Seven-Tesla MRI of the female pelvis.

OBJECTIVES: The aim of this study was to investigate the feasibility of 7-T contrast-enhanced MR imaging of the female pelvis. METHODS: Ten healthy female volunteers were examined on a 7-T whole-body MR system utilising a custom-built eight-channel transmit/receive radiofrequency body coil. The examination protocol included (1) T1-weighted fat-saturated 2D spoiled gradient echo (FLASH), (2) dynamic T1-weighted fat-saturated 3D FLASH, and (3) T2-weighted TSE sequences. For qualitative image analysis pelvic anatomy, uterine zonal anatomy and image impairment due to artefacts was assessed using a five-point scale. For quantitative analysis contrast ratios between the junctional zone and myometrium were obtained for T2-weighted MRI. RESULTS: Two-dimensional FLASH MRI offered the best overall image quality (meancontrast-enhanced 4.9) and highest tissue contrast (meancontrast-enhanced 4.7). T2-weighted TSE imaging provided a moderate to high conspicuity of the uterine zonal anatomy with mean scores ranging from 3.5 for endometrium to 4.65 for myometrium. Overall image impairment was rated strongest for T2-weighted MRI (2.9) and least for 2D FLASH MRI (mean 4.2). CONCLUSION: This study demonstrated the feasibility of 7-T T1-weighted MRI of the female pelvis and current constraints associated with T2-weighted MRI. KEY POINTS: • Dynamic contrast-enhanced female pelvis MR imaging at 7 T is feasible. • Unenhanced T1-weighted MRI offers inherent hyperintense delineation of pelvic arterial vasculature. • Two-dimensional FLASH MRI provided best overall image quality and least artefact impairment.

Intestinal MRI in Inflammatory Bowel Disease - Literature and Survey-Based Recommendations regarding Reporting by the German Radiological Society (DRG) and the German Competence Network for Inflammatory Bowel Diseases. / Intestinale MRT bei chronisch-entzündlichen Darmerkrankungen ­ Literatur- und umfragebasierte Empfehlungen zur Befundung durch die AG Gastrointestinal-/Abdominaldiagnostik der DRG und der AG Bildgebung des Kompetenznetz Darmerkrankungen.

BACKGROUND: MR-enterography/enteroclysis (MRE) is increasingly used for primary diagnosis, detection of complications, and monitoring of patients with inflammatory bowel disease (IBD). Standardization of reporting is relevant to ensure quality of the methodology and to improve communication between different faculties. The current manuscript describes the features that are required for optimized reporting of MRE in IBD. METHODS: An expert consensus panel of radiologists and gastroenterologists conducted a systematic search of the literature. In a Delphi process, members of the German Radiological Society (DRG) and members of the Competence Network for Inflammatory Bowel Diseases voted on relevant criteria for the reporting of findings in MRE. Based on the voting results, statements were developed by the expert consensus panel. RESULTS: Clinically relevant aspects of MRE findings have been defined to optimize reporting and to standardize terminology. Minimal requirements for standardized reporting are suggested. The statements focus on the description of disease activity as well as on complications of IBD. Attributes of intestinal inflammation are described and illustrated by exemplary images. CONCLUSION: The current manuscript provides standardized parameters and gives practical recommendations on how to report and how to characterize MRE findings in patients with IBD. KEY POINTS: · Systematic overview provides practice-oriented recommendations and names and evaluates the decisive criteria for reporting and interpretation of MRI in inflammatory bowel disease.. · Standardized terminology and reporting criteria for MRI in IBD improves interdisciplinary communication.. · Standardized collection and documentation of MRI findings in IBD helps to further establish the method and to improve care for IBD patients.. CITATION FORMAT: · Wessling J, Kucharzik T, Bettenworth D et al. Intestinal MRI in Inflammatory Bowel Disease - Literature and Survey-Based Recommendations regarding Reporting by the German Radiological Society (DRG) and the German Competence Network for Inflammatory Bowel Diseases. Fortschr Röntgenstr 2023; 195: 675 - 690.

Biliary complications after liver transplantation: addition of T1-weighted images to MR cholangiopancreatography facilitates detection of cast in biliary cast syndrome.

PURPOSE: To evaluate the diagnostic performance of T2-weighted magnetic resonance (MR) cholangiopancreatography pulse sequences in comparison with MR cholangiopancreatography sequences combined with nonenhanced T1-weighted images in the detection of biliary cast syndrome in liver transplant recipients. MATERIALS AND METHODS: This retrospective study was conducted in accordance with the declaration of Helsinki. Institutional review board approval was obtained. MR images in 95 patients who were examined after liver transplantation and who presented with symptoms of biliary obstruction were examined. Two separate sets of images, MR cholangiopancreatograms and MR cholangiopancreatograms plus T1-weighted images, were evaluated independently by three readers. Sensitivities, specificities, and positive and negative predictive values for biliary cast syndrome were calculated, and receiver operating characteristic curves were generated. The results of endoscopic retrograde cholangiopancreatography served as the reference standard. To determine interobserver agreement, κ values were calculated. RESULTS: Cast appeared hyperintense on nonenhanced T1-weighted images. Sensitivities for T2-weighted MR cholangiopancreatography data alone were 0.65, 0.70, and 0.55 for the three readers. Adding unenhanced T1-weighted images resulted in sensitivities of 0.95, 0.90, and 0.90, respectively. Specificities for MR cholangiopancreatography alone and for MR cholangiopancreatography plus T1-weighted images were high on average (0.98, 0.97, and 0.97 vs 1.0 for all readers, respectively). Interobserver agreement was good for T2-weighted MR cholangiopancreatography (κ for readers 1 and 2 = 0.589, κ for readers 2 and 3 = 0.593, κ for readers 1 and 3 = 0.734) and was excellent for MR cholangiopancreatography plus T1-weighted images (κ for readers 1 and 2 = 0.806, κ for readers 2 and 3 = 0.881, κ for readers 1 and 3 = 0.848). CONCLUSION: The combination of T2-weighted MR cholangiopancreatography and T1-weighted imaging yields higher diagnostic performance than MR cholangiopancreatography alone. Therefore, readers evaluating liver MR images with regard to biliary complications after liver transplantation should also look at the bile ducts on unenhanced T1-weighted images, as biliary cast might be more easily depicted on these images.