Ultrasound-Derived Fat Fraction for Hepatic Steatosis Assessment: Prospective Study of Agreement With MRI PDFF and Sources of Variability in a Heterogeneous Population.

BACKGROUND. Metabolic dysfunction-associated steatotic liver disease is a growing global public health concern. Quantitative ultrasound measurements, such as ultrasound-derived fat fraction (UDFF), could provide noninvasive, cost-effective, and portable steatosis evaluation. OBJECTIVE. The purpose of this article was to evaluate utility of UDFF for steatosis assessment using proton density fat fraction (PDFF) as reference in patients undergoing liver MRI for heterogeneous indications and to assess UDFF variability. METHODS. This prospective study included a primary analysis of 187 patients (mean age, 53.8 years; 112 men, 75 women) who underwent 3-T liver MRI for any clinical indication from December 2020 to July 2021. Patients underwent investigational PDFF measurement, including determination of PDFFwhole-liver (mean PDFF of entire liver), and PDFFvoxel (PDFF in single voxel within right lobe, measured by MR spectroscopy), as well as investigational ultrasound with UDFF calculation (mean of five inter-costal measurements) within 1 hour after MRI. In a subanalysis, 21 of these patients underwent additional UDFF measurements 1, 3, and 5 hours after meal consumption. The study also included repeatability and reproducibility analysis of 30 patients (mean age, 26.3 years; 10 men, 20 women) who underwent clinical abdominal ultrasound between November 2022 and January 2023; in these patients, three operators sequentially performed UDFF measurements. RESULTS. In primary analysis, UDFF and PDFFwhole-liver measurements showed intra-class correlation coefficient (ICC) of 0.79. In Bland-Altman analysis, UDFF and PDFFvoxel measurements showed mean difference of 1.5% (95% CI, 0.6-2.4%), with 95% limits of agreement from -11.0% to 14.0%. UDFF measurements exhibited AUC for detecting PDFFvoxel at historic thresholds of 6.5% and greater, 17.4% and greater, and 22.1% and greater of 0.90, 0.95, and 0.95, respectively. In subanalysis, mean UDFF was not significantly different across time points with respect to meal consumption (p = .21). In repeatability and reproducibility analysis, ICC for intraoperator repeatability ranged from 0.98 to 0.99 and for interoperator reproducibility from 0.90 to 0.96. Visual assessment of patient-level data plots indicated increasing variability of mean UDFF measurements across operators and of intercostal measurements within individual patients with increasing steatosis. CONCLUSION. UDFF showed robust agreement with PDFF, diagnostic performance for steatosis grades, and intraoperator repeatability and interoperator reproducibility. Nonetheless, UDFF exhibited bias toward slightly larger values versus PDFF; intraoperator and interoperator variation increased with increasing steatosis. CLINICAL IMPACT. UDFF shows promise for steatosis assessment across diverse populations, although continued optimization remains warranted.

Efficacy of Whole-Blood Model of Gadolinium-Based Contrast Agent Relaxivity in Predicting Vascular MR Signal Intensity In Vivo.

BACKGROUND: Previous in vitro studies have described sub-linear longitudinal and heightened transverse H2 O relaxivities of gadolinium-based contrast agents (GBCAs) in blood due to their extracellular nature. However, in vivo validation is lacking. PURPOSE: Validate theory describing blood behavior of R1 and R2 * in an animal model. STUDY TYPE: Prospective, animal. ANIMAL MODEL: Seven swine (54-65 kg). FIELD STRENGTH/SEQUENCE: 1.5 T; time-resolved 3D spoiled gradient-recalled echo (SPGR) and quantitative Look-Locker and multi-echo fast field echo sequences. ASSESSMENT: Seven swine were each injected three times with 0.1 mmol/kg intravenous doses of one of three GBCAs: gadoteridol, gadobutrol, and gadobenate dimeglumine. Injections were randomized for rate (1, 2, and 3 mL/s) and order, during which time-resolved aortic 3D SPGR imaging was performed concurrently with aortic blood sampling via an indwelling catheter. Time-varying [GBCA] was measured by mass spectrometry of sampled blood. Predicted signal intensity (SI) was determined from a model incorporating sub-linear R1 and R2 * effects (whole-blood model) and simpler models incorporating linear R1 , with and without R2 * effects. Predicted SIs were compared to measured aortic SI. STATISTICAL TESTS: Linear correlation (coefficient of determination, R2 ) and mean errors were compared across the SI prediction models. RESULTS: There was an excellent correlation between predicted and measured SI across all injections and swine when accounting for the non-linear dependence of R1 and high blood R2 * (regression slopes 0.91-1.04, R2 ≥ 0.91). Simplified models (linear R1 with and without R2 * effects) showed poorer correlation (slopes 0.67-0.85 and 0.54-0.64 respectively, both R2 ≥ 0.89) and higher averaged mean absolute and mean square errors (128.4 and 177.4 vs. 42.0, respectively, and 5506 and 11,419 vs. 699, respectively). DATA CONCLUSION: Incorporating sub-linear R1 and high first-pass R2 * effects in arterial blood models allows accurate SPGR SI prediction in an in vivo animal model, and might be utilized when modeling MR blood SI. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 1.

Noninferiority of Monoparametric MRI Versus Multiparametric MRI for the Detection of Prostate Cancer: Diagnostic Accuracy of ADC Ratios Based on Advanced "Zoomed" Diffusion-Weighted Imaging.

OBJECTIVES: The aim of this study was to compare the diagnostic accuracy of apparent diffusion coefficient (ADC) ratios as a monoparametric magnetic resonance imaging (MRI) protocol for the detection of prostate cancer (PCa) with the established multiparametric (mp) MRI at 3.0 T. MATERIALS AND METHODS: According to power analysis, 52 male patients were included in this monocenter study with prospective data collection and retrospective, blinded multireader image analysis. The study was approved by the local ethics committee. Patients were recruited from January to December 2020. Based on mpMRI findings, patients underwent in-bore MR biopsy or prostatectomy for histopathologic correlation of suspicious lesions. Three readers, blinded to the histopathologic results and images of mpMRI, independently evaluated ADC maps for the detection of PCa. The ADC ratio was defined as the lowest signal intensity (SI) of lesions divided by the SI of normal tissue in the zone of origin. Predictive accuracy of multiparametric and monoparametric MRI were compared using logistic regression analysis. Moreover, both protocols were compared applying goodness-of-fit analysis with the Hosmer-Lemeshow test for continuous ADC ratios and Pearson χ2 test for binary decision calls, correlation analysis with Spearman ρ and intraclass correlation coefficients, as well as noninferiority assessment with a TOST ("two one-sided test"). RESULTS: Eighty-one histopathologically proven, unique PCa lesions (Gleason score [GS] ≥ 3 + 3) in 52 patients could be unequivocally correlated, with 57 clinically significant (cs) PCa lesions (GS ≥ 3 + 4). Multiparametric MRI detected 95%, and monoparametric ADC detected ratios 91% to 93% of csPCa. Noninferiority of monoparametric MRI was confirmed by TOST (P < 0.05 for all comparisons). Logistic regression analysis revealed comparable predictive diagnostic accuracy of ADC ratios (73.7%-87.8%) versus mpMRI (72.2%-84.7%). Spearman rank correlation coefficient for PCa aggressiveness revealed satisfactory correlation of ADC ratios (P < 0.013 for all correlations). The Hosmer-Lemeshow test for the logistic regression analysis for continuous ADC ratios indicated adequate predictive accuracy (P = 0.55-0.87), and the Pearson χ2 test showed satisfactory goodness of fit (P = 0.35-0.69, χ2 = 0.16-0.87). CONCLUSIONS: Normalized ADC ratios based on advanced DWI are noninferior to mpMRI at 3.0 T for the detection of csPCa in a preselected patient cohort and proved a fast and accurate assessment tool, thus showing a potential prospect of easing the development of future screening methods for PCa.

Diagnostic Performance of a Lower-dose Contrast-Enhanced 4D Dynamic MR Angiography of the Lower Extremities at 3 T Using Multisegmental Time-Resolved Maximum Intensity Projections.

BACKGROUND: For peripheral artery disease (PAD), MR angiography (MRA) is a well-established diagnostic modality providing morphologic and dynamic information comparable to digital subtraction angiography (DSA). However, relatively large amounts of contrast agents are necessary to achieve this. PURPOSE: To evaluate the diagnostic accuracy of time-resolved 4D MR-angiography with interleaved stochastic trajectories (TWIST-MRA) by using maximum intensity projections (MIPs) of dynamic images acquired with reduced doses of contrast agent. STUDY TYPE: Retrospective. POPULATION: Forty adult PAD patients yielding 1088 artery segments. FIELD STRENGTH/SEQUENCE: A 3.0 T, time-resolved 4D MR-angiography with TWIST-MRA and MIP of dynamic images. ASSESSMENT: DSA was available in 14 patients (256 artery segments) and used as reference standard. Three-segmental MIP reconstructions of TWIST-images after administration of 3 mL of gadolinium-based contrast agent (Gadoteridol/Prohance®, 0.5 M) per anatomical level (pelvis, thighs, and lower legs) yielded 256 artery segments for correlation between MRA and DSA. Three independent observers rated image quality (scale: 1 [nondiagnostic] to 4 [excellent]) and the degree of venous overlay (scale: 0 [none] to 2 [significant]) for all segments. Diagnostic accuracy for the detection of >50% stenosis and artery occlusion was calculated for all observers. STATISTICAL TESTS: Binary classification test (sensitivity, specificity, positive/negative predictive values, diagnostic accuracy). Intraclass correlation coefficients (ICCs), logistic regression analysis with comparison of areas under the receiver-operating-characteristics (ROC) curves (AUCs) with the DeLong method. Bland-Altman-comparison. RESULTS: High diagnostic performance was achieved for the detection of >50% stenosis (sensitivity 92.9% [84.3-99.9% (95%-CI)] and specificity 98.5% [95.7-99.8% (95%-CI)]) and artery occlusion (sensitivity 93.1% [77.2-99.2% (95%-CI)] and specificity 99.1% [96.9-99.9% (95%-CI)]). Inter-reader agreement was excellent with ICC values ranging from 0.95 to 1.0 for >50% artery stenosis and occlusion. Image quality was good to excellent for both readers (3.41 ± 0.72, 3.33 ± 0.65, and 3.38 ± 0.61 [mean ± SD]) with good correlation between observer ratings (ICC 0.71-0.81). No significant venous overlay was observed (0.06 ± 0.24, 0.23 ± 0.43 and 0.11 ± 0.45 [mean ± SD]). DATA CONCLUSION: MIPs of dynamic TWIST-MRA offer a promising diagnostic alternative necessitating only reduced amounts (50%) of gadolinium-based contrast agents for the entire runoff vasculature. EVIDENCE LEVEL: 3 TECHNICAL EFFICACY: Stage 2.

Safety of Catheter Embolization of Pulmonary Arteriovenous Malformations-Evaluation of Possible Cerebrovascular Embolism after Catheter Embolization of Pulmonary Arteriovenous Malformations in Patients with Hereditary Hemorrhagic Telangiectasia/Osler Disease by Pre- and Post-Interventional DWI.

BACKGROUND: This paper aimed to prospectively evaluate the safety of embolization therapy of pulmonary arteriovenous malformations (PAVMs) for the detection of cerebral infarctions by pre- and post-interventional MRI. Method One hundred and five patients (male/female = 44/61; mean age 48.6+/-15.8; range 5-86) with pre-diagnosed PAVMs on contrast-enhanced MRA underwent embolization therapy. The number of PAVMs treated in each patient ranged from 1-8 PAVMs. Depending on the size and localization of the feeding arteries, either Nester-Coils or Amplatzer vascular plugs were used for embolization therapy. cMRI was performed immediately before, and at the 4 h and 3-month post-embolization therapy. Detection of peri-interventional cerebral emboli was performed via T2w and DWI sequences using three different b-values, with calculation of ADC maps. Results Embolization did not show any post-/peri-interventional, newly developed ischemic lesions in the brain. Only one patient who underwent re-embolization and was previously treated with tungsten coils that corroded over time showed newly developed, small, diffuse emboli in the post-interventional DWI sequence. This patient already had several episodes of brain emboli before re-treatment due to the corroded coils, and during treatment, when passing the corroded coils, experienced additional small, clinically inconspicuous brain emboli. However, this complication was anticipated but accepted, since the vessel had to be occluded distally. Conclusion Catheter-based embolization of PAVMs is a safe method for treatment and does not result in clinically inconspicuous cerebral ischemia, which was not demonstrated previously.

Outcomes and Tendon Integrity After Arthroscopic Treatment for Articular-Sided Partial-Thickness Tears of the Supraspinatus Tendon: Results at Minimum 2-Year Follow-Up.

BACKGROUND: The best surgical treatment option for symptomatic moderate- to high-grade articular-sided partial-thickness rotator cuff tears (PTRCTs) is still controversial. PURPOSE/HYPOTHESIS: The purpose of this study was to evaluate patient-reported and clinical outcomes and tendon integrity after arthroscopic debridement or repair for PTRCTs at a minimum of 2 years postoperatively. We hypothesized that the overall outcomes would be positive, showing pain relief, good shoulder function, and high tendon integrity. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: We evaluated 30 patients (16 men, 14 women; mean age, 51 years) who underwent arthroscopic treatment for symptomatic PTRCTs (Ellman grades 2 and 3). Debridement was performed in 15 patients, and arthroscopic tendon repair was performed in the remaining 15 patients. Patients completed the Constant score; American Shoulder and Elbow Surgeons (ASES) shoulder score; Western Ontario Rotator Cuff Index; Simple Shoulder Test; and visual analog scale (VAS) for pain, function, and satisfaction. In addition, patients were examined clinically (range of motion, impingement tests, rotator cuff tests, and tests for the long head of the biceps tendon), and morphologic assessment of rotator cuff integrity was performed using direct magnetic resonance arthrography and was classified according to Sugaya. RESULTS: The mean follow-up period was 55 months. The patient-reported outcome measures showed high patient satisfaction, reduction in persistent pain, and good shoulder function. Linear regression analysis showed that the debridement group had significantly better results on the Constant (bias-corrected and accelerated [BCa] 95% CI, 4.20-26.30), ASES (BCa 95% CI, 5.24-39.26), and VAS (pain: BCa 95% CI, 0.13-3.62; function: BCa 95% CI, 1.04-4.84; satisfaction: BCa 95% CI, 0.14-6.28) scores than did the repair group. At follow-up, there was no significant difference between the groups in clinical testing results. Good supraspinatus tendon integrity was seen in most patients: Sugaya classification grade 1 in 13 patients, grade 2 in 11 patients, and grade 3 in 6 patients. CONCLUSION: Midterm results after arthroscopic debridement and repair for PTRCTs showed high patient satisfaction, good shoulder function, and high tendon integrity for both procedures. Patients who underwent arthroscopic debridement had higher Constant, ASES, and VAS scores compared with patients who underwent tendon repair.

Detection of liver metastases on gadobenate dimeglumine-enhanced MRI: systematic review, meta-analysis, and similarities with gadoxetate-enhanced MRI.

OBJECTIVES: To determine the sensitivity and positive predictive value (PPV) of gadobenate-enhanced MR imaging for the detection of liver metastases. METHODS: This systematic review and meta-analysis was conducted according to PRISMA guidelines. A comprehensive search (EMBASE, PubMed) was performed to identify relevant articles up to December 2017. Studies eligible for inclusion were performed using appropriate methodology with complete verification by means of histopathology, intraoperative observation and/or follow-up, and sufficient information to permit determination of true-positive (TP), false-negative (FN), and false-positive (FP) values. Sources of bias were assessed using the QUADAS-2 tool. An inverse variance-weighted random-effects model was used to obtain sensitivity and PPV estimates. Information was analyzed and presented using Cochran's Q statistic, funnel plots, and modified Deeks' analysis. RESULTS: Ten articles (256 patients, 562 metastases) were included. Sensitivity estimates for pre-contrast (unenhanced) imaging, gadobenate-enhanced dynamic imaging, and combined unenhanced, dynamic, and delayed hepatobiliary phase imaging for detecting liver metastases on a per-lesion basis were 77.8% (95% CI 71.4-84.3%, 7 assessments), 88.1% (95% CI, 84.0-92.2%, 13 assessments), and 95.1% (95% CI 93.1-97.1%, 15 assessments), respectively. The addition of hepatobiliary phase images significantly improved the detection of liver metastases. The overall PPV was 90.9% (95% CI 86.6-95.1%, 11 assessments). Deeks' funnel analysis revealed no association between sample size and sensitivity (ß = 0.02, p = 0.814) indicating no significant publication bias. CONCLUSIONS: Gadobenate-enhanced MR imaging has high sensitivity and PPV for the detection of liver metastases on a per-lesion basis. The sensitivity and PPV for detection is comparable to reported values for the pure liver-specific agent gadoxetate. KEY POINTS: • Gadobenate dimeglumine is a hepatobiliary MR contrast agent that permits acquisition of contrast-enhanced liver images during the immediate post-injection dynamic phase, like any extracellular agent, and in the delayed hepatobiliary phase, after specific uptake by the hepatocytes. • The hepatobiliary phase improves detection of liver metastases when compared either to pre-contrast unenhanced images alone or to pre-contrast + gadobenate-enhanced dynamic phase images. • The meta-analysis showed an overall sensitivity of 95.1% and PPV of 90.9% of gadobenate-enhanced MRI for the detection of metastases, when based on the evaluation of all available acquisitions.

Glass-Fiber-based MR-safe Guidewire for MR Imaging-guided Endovascular Interventions: In Vitro and Preclinical in Vivo Feasibility Study.

Purpose To evaluate glass-fiber-based guidewires that are safe for magnetic resonance (MR) imaging-guided endovascular interventions by using a phantom and an in vivo swine model. Materials and Methods MR imaging-safe guidewires were made from micropultruded glass and/or aramid fibers and epoxy resin with diameters of 0.89 mm (0.035 inch) for standard and stiff guidewires and 0.36 mm (0.014 inch) for micro guidewires. MR imaging visibility and mechanical properties were assessed in a pulsatile flow model. After approval was obtained from the institutional animal care and use committee, MR imaging guidewires were evaluated for standard endovascular procedures in nine pigs. Real-time steady-state free-precession sequences were used for MR imaging-guided catheterization, balloon dilation, and stent implantation into aorto-iliac/visceral arteries and the vena cava (temporal resolution, five images per second; and spatial resolution, 150-mm field of view, and 128 × 128 matrix) with a 1.5-T clinical imager. Visualization with the guidewires was rated on a four-point scale, handling was rated on a three-point scale, and catheterization times for different vessel regions were determined by two interventional radiologists. Afterward, handling ratings and catheterization times were obtained for standard nitinol guidewires during x-ray-based fluoroscopy. Cannulation times, signal intensity in each vessel region, and visualization and handling ratings were measured for the MR imaging guidewires. Bland-Altman analysis was performed for inter- and intraobserver variability of cannulation time. Spearman rank correlation was used to compare handling of MR imaging guidewires and standard nitinol guidewires. Results MR imaging guidewires were characterized by good to excellent visibility, with a continuous artifact of 2 mm in diameter and 4 × 8-mm ball-shaped tip marker. Stiffness, flexibility, and guidance reflected comparable times for all in vitro and in vivo procedures with both the MR imaging and standard nitinol guidewires. Standard and micro MR imaging guidewires were most suitable for the iliac crossover maneuver. Phantom visceral artery cannulation was easier with standard and micro MR imaging guidewires. The stiff MR imaging guidewire provided the best support for cannulation of the swine aorta and vena cava. All interventional procedures were performed successfully without complications. Conclusion Preliminary results showed that the use of glass-fiber-based guidewires for evaluation of MR imaging-guided endovascular interventions is technically feasible and safe in a swine model, and potentially, in humans. © RSNA, 2017 Online supplemental material is available for this article.

The Impact of Diffusion-Weighted MRI on the Definition of Gross Tumor Volume in Radiotherapy of Non-Small-Cell Lung Cancer.

OBJECTIVE: The study was designed to evaluate diffusion-weighted magnetic resonance imaging (DWI) vs. PET-CT of the thorax in the determination of gross tumor volume (GTV) in radiotherapy planning of non-small-cell lung cancer (NSCLC). MATERIALS AND METHODS: Eligible patients with NSCLC who were supposed to receive definitive radio(chemo)therapy were prospectively recruited. For MRI, a respiratory gated T2-weighted sequence in axial orientation and non-gated DWI (b = 0, 800, 1,400 and apparent diffusion coefficient map [ADC]) were acquired on a 1.5 Tesla scanner. Primary tumors were delineated on FDG-PET/CT (stGTV) and DWI images (dwGTV). The definition of stGTV was based on the CT and visually adapted to the FDG-PET component if indicated (e.g., in atelectasis). For DWI, dwGTV was visually determined and adjusted for anatomical plausibility on T2w sequences. Beside a statistical comparison of stGTV and dwGTB, spatial agreement was determined with the "Hausdorff-Distance" (HD) and the "Dice Similarity Coefficient" (DSC). RESULTS: Fifteen patients (one patient with two synchronous NSCLC) were evaluated. For 16 primary tumors with UICC stages I (n = 4), II (n = 3), IIIA (n = 2) and IIIB (n = 7) mean values for dwGTV were significantly larger than those of stGTV (76.6 ± 84.5 ml vs. 66.6 ± 75.2 ml, p<0.01). The correlation of stGTV and dwGTV was highly significant (r = 0.995, p<0.001). Yet, some considerable volume deviations between these two methods were observed (median 27.5%, range 0.4-52.1%). An acceptable agreement between dwGTV and stGTV regarding the spatial extent of primary tumors was found (average HD: 2.25 ± 0.7 mm; DC 0.68 ± 0.09). CONCLUSION: The overall level of agreement between PET-CT and MRI based GTV definition is acceptable. Tumor volumes may differ considerably in single cases. DWI-derived GTVs are significantly, yet modestly, larger than their PET-CT based counterparts. Prospective studies to assess the safety and efficacy of DWI-based radiotherapy planning in NSCLC are warranted.

Low-dose gadobenate dimeglumine-enhanced MRI of the kidney for the differential diagnosis of localized renal lesions.

OBJECTIVE: To evaluate low-dose gadobenate dimeglumine-enhanced MRI for the differential diagnosis of malignant renal tumors. METHODS: Sixty-two consecutive patients with unclear diagnosis at MDCT/ultrasound underwent dynamic CE-MRI of the kidneys with 0.05 mmol/kg gadobenate dimeglumine. Retrospective image evaluation was performed by two blinded readers. Lesion diagnosis at CE-MRI was correlated with findings from histology following tumor resection or from imaging follow-up after at least 1 year. Assessments were performed of diagnostic quality and level of diagnostic information. RESULTS: Thirty-nine (63 %) patients were correctly diagnosed with malignant lesions (36 with RCC, 2 with renal metastases, 1 with lymphoma) while 14 (22.6 %) patients were correctly diagnosed with benign (n = 12) or no (n = 2) lesions. Eight patients were considered false positive (5 with oncocytoma, 3 with atypical AML) and 1 patient false negative (atypical RCC). The sensitivity, specificity, accuracy, PPV, and NPV for the diagnosis of malignant renal lesions were 97.5 % (39/40), 63.6 % (14/22), 85.5 % (53/62), 83.0 % (39/47), and 93.3 % (14/15), respectively. Images were excellent in 60 and good in 2 patients. Minimal artifacts that did not compromise diagnosis were noted in 4/62 patients. CONCLUSION: Low-dose gadobenate dimeglumine-enhanced MRI is effective for the differential diagnosis of malignant renal tumors.

A Novel Operative Procedure for Pelvic Organ Prolapse Utilizing a MRI-Visible Mesh Implant: Safety and Outcome of Modified Laparoscopic Bilateral Sacropexy.

INTRODUCTION: Sacropexy is a generally applied treatment of prolapse, yet there are known possible complications of it. An essential need exists for better alloplastic materials. METHODS: Between April 2013 and June 2014, we performed a modified laparoscopic bilateral sacropexy (MLBS) in 10 patients using a MRI-visible PVDF mesh implant. Selected patients had prolapse POP-Q stages II-III and concomitant OAB. We studied surgery-related morbidity, anatomical and functional outcome, and mesh-visibility in MRI. Mean follow-up was 7.4 months. RESULTS: Concomitant colporrhaphy was conducted in 1/10 patients. Anatomical success was defined as POP-Q stage 0-I. Apical success rate was 100% and remained stable. A recurrent cystocele was seen in 1/10 patients during follow-up without need for intervention. Out of 6 (6/10) patients with preoperative SUI, 5/6 were healed and 1/6 persisted. De-novo SUI was seen in 1/10 patients. Complications requiring a relaparoscopy were seen in 2/10 patients. 8/10 patients with OAB were relieved postoperatively. The first in-human magnetic resonance visualization of a prolapse mesh implant was performed and showed good quality of visualization. CONCLUSION: MLBS is a feasible and safe procedure with favorable anatomical and functional outcome and good concomitant healing rates of SUI and OAB. Prospective data and larger samples are required.

Safety and adverse effects during 24 hours after contrast-enhanced MRI with gadobenate dimeglumine (MultiHance) in children.

BACKGROUND: Gadolinium-based MR contrast agents have long been considered safe for routine diagnostic imaging. However, the advent of nephrogenic systemic fibrosis (NSF) among certain patients with severe renal insufficiency has brought the issue of safety into question. Nowhere is safety of greater concern than among children who frequently require multiple contrast-enhanced MRI examinations over an extended period of time. OBJECTIVE: To retrospectively evaluate the safety of gadobenate dimeglumine for contrast-enhanced (CE) MRI across a range of indications. MATERIALS AND METHODS: Two hundred pediatric inpatients (age: 4 days to 15 years) underwent CE MRI as part of clinical routine. The children received a gadobenate dimeglumine dose of either 0.05 mmol/kg body weight (liver, abdominal imaging, musculoskeletal imaging, brain and other rare indications) or 0.1 mmol/kg bodyweight (cardiovascular imaging, MR-urography). Young (< 8 years) children with congenital heart disease were intubated and underwent MRA evaluation with controlled ventilation. Monitoring for adverse events was performed for at least 24 h after each gadobenate dimeglumine injection. Depending on clinical necessity, laboratory measurements and, in some cases, vital sign and ECG determinations were made before and after contrast injection. Safety was evaluated by age group, indication and dose administered. RESULTS: No clinically adverse events were reported among children who had one MRI scan only or among children who had several examinations. There were no changes in creatinine or bilirubin levels even in very young children. CONCLUSIONS: No adverse events were recorded during the first 24 h following administration of gadobenate dimeglumine in 200 children.

Gadobenate dimeglumine and gadofosveset trisodium for MR angiography of the renal arteries: Multicenter intraindividual crossover comparison.

OBJECTIVE: This prospective multicenter intraindividual crossover study was designed to compare gadobenate dimeglumine and gadofosveset trisodium at approved doses with respect to the image quality and diagnostic performance of contrast-enhanced MR angiography (CE-MRA) in the detection of clinically relevant renal artery stenosis. SUBJECTS AND METHODS: Thirty-nine subjects (17 men, 22 women; age range, 30-86 years; mean 62 +/- 13.3 [SD] years) with known or suspected renovascular disease underwent a first CE-MRA examination with 0.1 mmol/kg gadobenate dimeglumine and a second examination 3-12 days later with 0.03 mmol/kg gadofosveset. Identical T1-weighted spoiled gradient-refocused echo coronal first-pass images were acquired for 38 of the 39 patients. For 15 of the 38 patients, additional sagittal or axial images or both were acquired with gadofosveset during the steady-state phase. Thirty-four patients underwent digital subtraction angiography, which was the reference standard. Three independent blinded readers assessed source images and maximum-intensity-projection reconstructions to detect clinically relevant (> 50%) renal artery stenosis. Diagnostic performance (sensitivity, specificity, accuracy, positive and negative predictive values) was evaluated with the McNemar and Wald tests. Matched-pair determinations of diagnostic preference were evaluated with Wilcoxon's signed rank test. Reader agreement was determined with kappa analysis, and safety was assessed. RESULTS: Comparison of first-pass images revealed superior sensitivity (75.7-86.5% vs 68.4-76.3%), specificity (92.1-98.6% vs 90.5-93.9%), accuracy (88.9-96.2% vs 85.9-90.3%), positive predictive value (70.0-94.1% vs 65.0-76.3%), and negative predictive value (94.0-96.6% vs 91.7-93.9%) with gadobenate dimeglumine. Significant superiority was noted for specificity (p < or = 0.02), accuracy (p < or = 0.005), and positive predictive value (p < or = 0.018). Steady-state images showed no benefit of gadofosveset. Reader agreement was good to excellent (gadobenate dimeglumine, kappa = 0.855; gadofosveset, kappa = 0.776). Reader preference was for gadobenate dimeglumine in 11, 17, and 13 patients and for gadofosveset in five, four, and five patients. No safety concerns were noted. CONCLUSION: Better diagnostic performance and reader preference were found for gadobenate dimeglumine than gadofosveset in first-pass renal CE-MRA.

Intracranial irregularities beside hydrocephalus in H-Tx rats.

INTRODUCTION: It has been well documented that up to 70% of H-Tx rats' offspring suffer from severe hydrocephalus, which can be fatal if it remains untreated. Some offspring also have non-fatal moderate hydrocephalus allowing a normal life expectancy. The objective of this study was finding other morphological intracranial abnormalities that are not directly related to hydrocephalus. METHOD: An MRT for small animals (Bruker, Biospec, Erlangen Germany) with a 2.4 T magnet at 100 MHz has been used to study 98 apparently non-hydrocephalic H-Tx rats. T2-weighted 2D-RARE, T2-weighted 3D-Turbo-RARE sequence and T1-weighted 3D-gradient-echo sequences were used. RESULTS: Apart from 36% of animals with moderate or mild hydrocephalus, we found one animal with a cystic cerebellar malformation similar to an arachnoid cyst with minimal space occupying effects. Nine rats had a mild or moderate-sized unilateral enlargement of one lateral ventricle, but a causative occlusion of the Foramen of Monroe could not be verified. Finally, one animal with huge hydrocephalus had a midline cystic malformation between both cerebral hemispheres. CONCLUSION: Aside from the well-documented hydrocephalus, H-Tx rats may develop other intracranial malformations that have not yet been documented in the literature.

Contrast-enhanced sonography of adrenal masses: differentiation of adenomas and nonadenomatous lesions.

OBJECTIVE: The aim of this proof-of-principle study was to evaluate contrast-enhanced sonography in the characterization of adrenal masses. SUBJECTS AND METHODS: Thirty-five consecutively registered patients with newly detected adrenal masses underwent hormonal evaluation and duplex and Doppler sonography followed by contrast-enhanced sonography and CT or MRI. The dynamics of contrast enhancement were analyzed with time-intensity curves. CT and MRI were used as the reference methods for the diagnosis of adenoma and myelolipoma. Metastasis was diagnosed with fine-needle biopsy, and all other adrenal masses were diagnosed at adrenalectomy. Fisher's exact test was used to evaluate the criteria for diagnosis of malignant adrenal masses. RESULTS: Size greater than 4 cm and hypervascularization were found significantly more often in malignant than in benign lesions (71% vs 21% for size; 57% vs 7% for hypervascularization). At contrast-enhanced sonography, early arterial or arterial contrast enhancement and rapid washout were seen in all patients with primary or secondary malignant lesions of the adrenal gland and in only 22% of patients with benign adrenal masses (p < 0.05). All primary malignant lesions were confirmed at histologic examination. In 32 of 35 patients (91%), findings at CT or MRI were congruent with those at contrast-enhanced sonography in regard to characterization of adenoma versus nonadenomatous lesion (p < 0.001). In two of the 35 cases, however, all imaging methods favored the diagnosis of nonadenomatous lesion, but the histologic result after adrenalectomy was adrenal adenoma. The sensitivity and specificity of contrast-enhanced sonography in the diagnosis of malignant adrenal mass were 100% and 82%. CONCLUSION: Contrast-enhanced sonography can be used to differentiate adenomas and nonadenomatous lesions with a sensitivity comparable with that of CT and MRI and may be a cost-effective method for preselection of patients with adrenal masses.

Magnetic resonance imaging of the spine at 3 Tesla.

Magnetic resonance imaging (MRI) has developed dramatically in the 25 years since its clinical introduction. Advances in hardware design have included the development of high field magnets and more sophisticated and sensitive coils. Improvements in sequences, data sampling, and postprocessing software have benefited the attainable spatial and temporal resolution to the point at which the fine depiction of anatomical structure and pathological processes is now routine. As in other radiological areas, the most recent advances in MRI have proven highly valuable in the field of musculoskeletal radiology where the lack of radiation, high soft tissue contrast, and capacity for multiplanar or three-dimensional imaging have made MRI the imaging modality of choice. Particular benefits are seen in diagnostic imaging of the spine where MRI is clearly superior to both conventional radiography and computed tomography. In this article, we discuss the impact of the most recent technological advance in MRI, namely the advent of 3 Tesla (3-T) imaging, on diagnostic imaging of the spine. Comparisons are drawn with imaging at 1.5 T, and emphasis is placed on MR physics and on the benefits and principal difficulties associated with spine imaging at high field strength.

MR angiography for detection of pulmonary arteriovenous malformations in patients with hereditary hemorrhagic telangiectasia.

OBJECTIVE: The purpose of our study was to evaluate contrast-enhanced MR angiography (CE-MRA) as a screening procedure for the detection of pulmonary arteriovenous malformations (AVMs) in patients with hereditary hemorrhagic telangiectasia (HTT). MATERIALS AND METHODS: Two hundred three consecutive subjects (patients with diagnosed HHT or first-degree relatives; 87 males, 116 females; 6-83 years old) underwent pulmonary CE-MRA with 0.1 mmol/kg of gadobenate dimeglumine. The presence of pulmonary AVM was scored as 0 (none present), 1 (definitely present), or 2 (uncertain) and was evaluated by patient sex and pulmonary AVM size (< 5, 5-10, 11-15, 16-20, > 20 mm). Patients scored as 1 or 2 with at least one pulmonary AVM of > or = 5 mm underwent conventional pulmonary angiography for possible embolization. Pulmonary AVM detection on CE-MRA and pulmonary angiography was compared using paired Student's t tests. RESULTS: The presence of pulmonary AVM was considered definite in 56 of 203 (27.6%) patients and uncertain in one of 203 patients on CE-MRA. Of 156 pulmonary AVMs detected on CE-MRA, 124 (49 in 27 males, 75 in 30 females) were detected on first screening CE-MRA and 32 on follow-up CE-MRA. Pulmonary AVMs on CE-MRA were solitary in 25 patients, multiple in 31 patients, and predominantly small (< 5 mm, n = 32; 5-10 mm, n = 45). Significantly (p < 0.0001) fewer pulmonary AVMs were detected on pulmonary angiography (76/96 [79.2%] evaluable pulmonary AVMs in 40 patients before first pulmonary angiography; 92/119 [77.3%] pulmonary AVMs overall). Three-dimensional maximum-intensity-projection reconstructions permitted improved pulmonary AVM visualization and embolization planning of complex pulmonary AVMs. CONCLUSION: CE-MRA is suitable for screening patients with HHT. It permits accurate detection and staging of pulmonary AVMs, appropriate differentiation of lesions requiring embolization and accurate orientation, and visualization and planning of embolization therapy.

Biliary cystadenoma of the left intrahepatic duct (2007: 2b).

Biliary cystadenoma is a rare epithelial cystic neoplasm representing only 5% of intrahepatic cystic lesions of biliary origin. Commonly, the lesions are solitary cystic structures with multiple thin-walled septa predominantly arising from the right hepatic duct. Although the lesions are generally intrahepatic, extrahepatic tumors have been reported. Biliary cystadenomas range in diameter from 1.5 to 35 cm. The tumor usually affects middle-aged women. Clinical symptoms are related to the mass effect and comprise episodes of jaundice due to biliary obstruction and intermittent upper abdominal pain. Laboratory parameters are nonspecific. As the tumor is considered a premalignant lesion, complete surgical resection is the treatment of choice. We report a case of typical biliary cystadenoma of the left hepatic duct.