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Arterial transit artifacts at arterial spin-labeling MRI were the only factor associated with recent ischemic symptoms in participants with carotid stenosis.

Background Amide proton transfer (APT) MRI has the potential to demonstrate antitumor effects by reflecting biologically active tumor portion, providing different information from diffusion-weighted imaging (DWI) or dynamic susceptibility contrast (DSC) imaging. Purpose To evaluate whether a change in APT signal intensity after antiangiogenic treatment is predictive of early treatment response in recurrent glioblastoma. Materials and Methods In this retrospective study, APT MRI, DWI, and DSC imaging were performed in patients with recurrent glioblastoma from July 2015 to April 2019, both before treatment and 4-6 weeks after initiation of bevacizumab (follow-up). Progression was based on pathologic confirmation or clinical-radiologic assessment, and progression patterns were defined as local enhancing or diffuse nonenhancing. Changes in mean and histogram parameters (fifth and 95th percentiles) of APT signal intensity, apparent diffusion coefficient, and normalized cerebral blood volume (CBV) between imaging time points were calculated. Predictors of 12-month progression and progression-free survival (PFS) were determined by using logistic regression and Cox proportional hazard modeling and according to progression type. Results A total of 54 patients were included (median age, 56 years [interquartile range, 49-64 years]; 24 men). Mean APT signal intensity change after bevacizumab treatment indicated a low 12-month progression rate (odds ratio [OR], 0.36; 95% confidence interval [CI]: 0.13, 0.90

Background A superselective (SS) arterial spin labeling (ASL) MRI technique can be used to monitor the revascularization area as a supplementary or alternative modality to digital subtraction angiography (DSA), with the advantage of being noninvasive. Purpose To evaluate whether SS-ASL perfusion MRI could be used to visualize the revascularization area after combined direct and indirect bypass surgery in adults with moyamoya disease compared with DSA. Materials and Methods Patients diagnosed with moyamoya disease who underwent DSA and SS-ASL 6 months after surgery between June 2017 and November 2019 in a single institution were retrospectively evaluated. Subjective grading of the revascularization area and collateral grading in 10 Alberta Stroke Program Early CT Score (ASPECTS) locations were performed. The change in perfusion status in a subgroup that underwent both preoperative and postoperative SS-ASL studies was evaluated. Intermodality agreement was analyzed by using weighted κ statistics. Results Thirty-seven hemispheres from 33 patients (mean age, 39 years ± 12 [standard deviation]; 20 women) were evaluated. The intermodality agreement of the revascularization area grading was substantial (weighted κ = 0.70; 95% confidence interval [CI]: 0.37, 1.00). The overall intermodality agreement of the postoperative collateral grading in the 10 ASPECTS locations for all vessels was substantial (weighted κ = 0.77; 95% CI: 0.74, 0.80). For the presence of postoperative collateral supplied by the ipsilateral external carotid artery in 10 ASPECTS locations (a total of 370 locations) using DSA as a reference test, the SS-ASL showed a sensitivity of 92% (183 of 199 locations; 95% CI: 87%, 95%) and a specificity of 83% (142 of 171 locations; 95% CI: 77%, 88%). The overall intermodality agreement of the changes in perfusion status was moderate (weighted κ = 0.59; 95% CI: 0.54, 0.65). Conclusion Superselective arterial spin labeling imaging precisely depicted the revascularization territory in patients with moyamoya disease who underwent bypass surgery, and it showed the changes in the vascular supplying territories before and after bypass surgery. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Hendrikse in this issue.

Background Duplex US is performed routinely for vascular mapping prior to arteriovenous fistula (AVF) creation for hemodialysis but cannot demonstrate the central vasculature. Ferumoxytol, an iron oxide nanoparticle, provides an alternative to gadolinium contrast material for MR angiography for safe use in chronic kidney disease (CKD). Purpose To assess the clinical utility of ferumoxytol-enhanced MR angiography compared with duplex US for vascular mapping before upper limb AVF creation in participants with CKD. Materials and Methods In a prospective comparative study (ClinicalTrials.gov: NCT02997046) from December 2016 to August 2018, participants with CKD underwent ferumoxytol-enhanced MR angiography and duplex US. Two independent readers evaluated vessels for diameter, stenosis or occlusion, arterial disease, and central stenosis. Intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to assess intra- and interreader variability. On the basis of accepted standards for AVF creation, an algorithm was developed to predict AVF outcome based on imaging findings. Multivariable regression models used AVF success as the dependent variable and age, sex, and duplex US or ferumoxytol-enhanced MR angiography findings as independent variables. Results Fifty-nine participants with CKD (mean age, 59 years ± 13 [standard deviation]; 30 women) were evaluated. A total of 51 fistulas were created, of which 24 (47%) were successful. Ferumoxytol-enhanced MR angiography showed excellent inter- and intrareader repeatability (ICC, 0.84-0.99) for all variables assessed. In addition to revealing 15 central vasculature stenoses, ferumoxytol-enhanced MR angiography resulted in characterization of 88 of 236 (37%) of the arterial sections examined as unsuitable for AVF creation compared with 61 of 236 (26%) sections with duplex US (

Background Collateral circulation determines tissue fate and affects treatment result in acute ischemic stroke. A precise method for collateral estimation in an optimal imaging protocol is necessary to make an appropriate treatment decision for acute ischemic stroke. Purpose To verify the value of multiphase collateral imaging data sets (MR angiography collateral map) derived from dynamic contrast material-enhanced MR angiography for predicting functional outcomes after acute ischemic stroke. Materials and Methods This secondary analysis of an ongoing prospective observational study included data from participants with acute ischemic stroke due to occlusion or stenosis of the unilateral internal carotid artery and/or M1 segment of the middle cerebral artery who were evaluated within 8 hours of symptom onset. Data were obtained from March 2016 through August 2018. The collateral grading based on the MR angiography collateral map was estimated by using six-scale MR acute ischemic stroke collateral (MAC) scores. To identify independent predictors of favorable functional outcomes, age, sex, risk factors, baseline National Institutes of Health Stroke Scale (NIHSS) score, baseline diffusion-weighted imaging (DWI) lesion volume, site of steno-occlusion, collateral grade, mode of treatment, and early reperfusion were evaluated with multiple logistic regression analyses. Results One hundred fifty-four participants (mean age ± standard deviation, 69 years ± 13; 99 men) were evaluated. Younger age (odds ratio [OR], 0.45; 95% confidence interval [CI]: 0.29, 0.70; P < .001), lower baseline NIHSS score (OR, 0.85; 95% CI: 0.78, 0.94; P < .001), MAC score of 3 (OR, 27; 95% CI: 4.0, 179; P < .001), MAC score of 4 (OR, 17; 95% CI: 2.1, 134; P = .007), MAC score of 5 (OR, 27; 95% CI: 2.5, 306; P = .007), and successful early reperfusion (OR, 7.5; 95% CI: 2.6, 22; P < .001) were independently associated with favorable functional outcomes in multivariable analysis. There was a linear negative association between collateral perfusion grades and functional outcomes (P < .001). Conclusion An MR angiography collateral map was clinically reliable for collateral estimation in patients with acute ischemic stroke. This map provided patient-specific pacing information for ischemic progression. © RSNA, 2020.

Background Next-generation sequencing (NGS) enables highly sensitive cancer genomics analysis, but its clinical implications for therapeutic options from imaging-based prediction have been limited. Purpose To predict core signaling pathways in isocitrate dehydrogenase (IDH) wild-type glioblastoma by using diffusion and perfusion MRI radiomics and NGS. Materials and Methods The radiogenomics model was developed by using retrospective patients with glioma who underwent NGS and anatomic, diffusion-, and perfusion-weighted imaging between March 2017 and February 2019. For testing model performance in predicting core signaling pathway, patients with IDH wild-type glioblastoma from a retrospective analysis from a registry (

Purpose To quantify the burden and distribution of asymptomatic atherosclerosis in a population with a low to intermediate risk of cardiovascular disease. Materials and Methods Between June 2008 and February 2013, 1528 participants with 10-year risk of cardiovascular disease less than 20% were prospectively enrolled. They underwent whole-body magnetic resonance (MR) angiography at 3.0 T by using a two-injection, four-station acquisition technique. Thirty-one arterial segments were scored according to maximum stenosis. Scores were summed and normalized for the number of assessable arterial segments to provide a standardized atheroma score (SAS). Multiple linear regression was performed to assess effects of risk factors on atheroma burden. Results A total of 1513 participants (577 [37.9%] men; median age, 53.5 years; range, 40-83 years) completed the study protocol. Among 46 903 potentially analyzable segments, 46 601 (99.4%) were interpretable. Among these, 2468 segments (5%) demonstrated stenoses, of which 1649 (3.5%) showed stenosis less than 50% and 484 (1.0%) showed stenosis greater than or equal to 50%. Vascular stenoses were distributed throughout the body with no localized distribution. Seven hundred forty-seven (49.4%) participants had at least one stenotic vessel, and 408 (27.0%) participants had multiple stenotic vessels. At multivariable linear regression, SAS correlated with age (B = 3.4; 95% confidence interval: 2.61, 4.20), heart rate (B = 1.23; 95% confidence interval: 0.51, 1.95), systolic blood pressure (B = 0.02; 95% confidence interval: 0.01, 0.03), smoking status (B = 0.79; 95% confidence interval: 0.44, 1.15), and socioeconomic status (B = -0.06; 95% confidence interval: -0.10, -0.02) (P < .01 for all). Conclusion Whole-body MR angiography identifies early vascular disease at a population level. Although disease prevalence is low on a per-vessel level, vascular disease is common on a per-participant level, even in this low- to intermediate-risk cohort. © RSNA, 2018 Online supplemental material is available for this article.

Purpose To develop a deep learning algorithm that generates arterial spin labeling (ASL) perfusion images with higher accuracy and robustness by using a smaller number of subtraction images. Materials and Methods For ASL image generation from pair-wise subtraction, we used a convolutional neural network (CNN) as a deep learning algorithm. The ground truth perfusion images were generated by averaging six or seven pairwise subtraction images acquired with (a) conventional pseudocontinuous arterial spin labeling from seven healthy subjects or (b) Hadamard-encoded pseudocontinuous ASL from 114 patients with various diseases. CNNs were trained to generate perfusion images from a smaller number (two or three) of subtraction images and evaluated by means of cross-validation. CNNs from the patient data sets were also tested on 26 separate stroke data sets. CNNs were compared with the conventional averaging method in terms of mean square error and radiologic score by using a paired t test and/or Wilcoxon signed-rank test. Results Mean square errors were approximately 40% lower than those of the conventional averaging method for the cross-validation with the healthy subjects and patients and the separate test with the patients who had experienced a stroke (P.001). Region-of-interest analysis in stroke regions showed that cerebral blood flow maps from CNN (mean ± standard deviation, 19.7 mL per 100 g/min ± 9.7) had smaller mean square errors than those determined with the conventional averaging method (43.2 ± 29.8) (P.001). Radiologic scoring demonstrated that CNNs suppressed noise and motion and/or segmentation artifacts better than the conventional averaging method did (P.001). Conclusion CNNs provided superior perfusion image quality and more accurate perfusion measurement compared with those of the conventional averaging method for generation of ASL images from pair-wise subtraction images.

Purpose To develop a three-dimensional (3D) high-spatial-resolution time-efficient sequence for use in quantitative vessel wall T1 mapping. Materials and Methods A previously described sequence, simultaneous noncontrast angiography and intraplaque hemorrhage (SNAP) imaging, was extended by introducing 3D golden angle radial k-space sampling (GOAL-SNAP). Sliding window reconstruction was adopted to reconstruct images at different inversion delay times (different T1 contrasts) for voxelwise T1 fitting. Phantom studies were performed to test the accuracy of T1 mapping with GOAL-SNAP against a two-dimensional inversion recovery (IR) spin-echo (SE) sequence. In vivo studies were performed in six healthy volunteers (mean age, 27.8 years ± 3.0 [standard deviation]; age range, 24-32 years; five male) and five patients with atherosclerosis (mean age, 66.4 years ± 5.5; range, 60-73 years; five male) to compare T1 measurements between vessel wall sections (five per artery) with and without intraplaque hemorrhage (IPH). Statistical analyses included Pearson correlation coefficient, Bland-Altman analysis, and Wilcoxon rank-sum test with data permutation by subject. Results Phantom T1 measurements with GOAL-SNAP and IR SE sequences showed excellent correlation (R

Dynamic contrast-enhanced (DCE) MR imaging pharmacokinetic parameters derived by using arterial input functions (AIFs) at dynamic susceptibility-contrast imaging showed better diagnostic performance and reliability for differentiating high-grade from low-grade astrocytoma than those derived by using AIFs at DCE MR imaging alone.

The feasibility of directly imaging the uptake of xenon by the human brain following perfusion and gas transfer across the blood-brain barrier has been demonstrated by using inhaled hyperpolarized xenon 129 MR imaging.

Purpose To evaluate and compare the performance of acceleration-selective arterial spin labeling (AccASL) magnetic resonance (MR) angiography in the visualization of cerebral arteries and collateral vessels in patients with Moyamoya disease with that of time-of-flight (TOF) MR angiography, with digital subtraction angiography (DSA) as the reference standard. Materials and Methods Thirty-six cerebral hemispheres from 22 patients with Moyamoya disease underwent TOF and AccASL MR angiography and DSA. Qualitative evaluations included imaging of the terminal internal carotid artery (ICA), distal middle cerebral arteries (MCAs), Moyamoya vessels, and leptomeningeal anastomosis (LMA) collaterals with reference to DSA. Quantitative evaluations included assessment of contrast-to-noise ratio (CNR) and number of vessels in MCA branches. The linear mixed-effect model was used to compare the two methods. Results Mean scores for qualitative evaluation were significantly higher with AccASL angiography than with TOF angiography for imaging distal MCAs (3.9 ± 0.3 [standard deviation] vs 2.9 ± 1.1; P.001), Moyamoya vessels (3.6 ± 0.6 vs 2.7 ± 0.9, P.001), and LMA collaterals (3.8 ± 0.6 vs 1.8 ± 0.7, P.001). Scores for steno-occlusive degree around the terminal ICAs were better with TOF angiography than with AccASL angiography (2.6 ± 0.5 vs 2.4 ± 0.6, P = .023). CNRs in the M4 segment were significantly higher with AccASL angiography (11.9 ± 12.9, P.001) than with TOF angiography (4.1 ± 7.9). The number of vessels was significantly higher with AccASL angiography (18.3 ± 5.0, P.001) than with TOF angiography (8.9 ± 4.9). The increase in the number of vessels from TOF angiography to AccASL angiography was greater in patients with severe ICA steno-occlusion (late ICA stage group, 11.4 ± 4.5; early ICA stage group, 6.8 ± 4.0; P = .007) and well-developed leptomeningeal anastomosis (mildly developed LMA group, 7.1 ± 4.3; well-developed LMA group, 11.3 ± 4.5; P = .011). Conclusion AccASL MR angiography enables better visualization of distal cerebral arteries and collateral vessels in patients with Moyamoya disease than does TOF MR angiography, while TOF MR angiography enables better visualization of stenosis of proximal arteries. Both methods work in a mutually beneficial manner in the assessment of cerebral arteries.

BACKGROUND: Tumor perfusion may inform therapeutic response and resistance in metastatic renal cell carcinoma (RCC) treated with antiangiogenic therapy. PURPOSE: To determine if arterial spin labeled (ASL) MRI perfusion changes are associated with tumor response and disease progression in metastatic RCC treated with vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors (TKIs). MATERIALS AND METHODS: In this prospective study (ClinicalTrials.gov identifier: NCT00749320), metastatic RCC perfusion was measured with ASL MRI before and during sunitinib or pazopanib therapy between October 2008 and March 2014. Objective response rate (ORR) and progression-free survival (PFS) were calculated. Perfusion was compared between responders and nonresponders at baseline, at week 2, after cycle 2 (12 weeks), after cycle 4 (24 weeks), and at disease progression and compared with the ORR by using the Wilcoxon rank sum test and with PFS by using the log-rank test. RESULTS: Seventeen participants received sunitinib (mean age, 59 years ± 7.0 [standard deviation]; 11 men); 11 participants received pazopanib (mean age, 63 years ± 6.6; eight men). Responders had higher baseline tumor perfusion than nonresponders (mean, 404 mL/100 g/min ± 213 vs 199 mL/100 g/min ± 136; P = .02). Perfusion decreased from baseline to week 2 (−53 mL/100 g/min ± 31; P < .001), after cycle 2 (−65 mL/100 g/min ± 25; P < .001), and after cycle 4 (−79 mL/100 g/min ± 15; P = .008). Interval reduction in perfusion at those three time points was not associated with ORR (P = .63, .29, and .27, respectively) or PFS (P = .28, .27, and .32). Perfusion increased from cycle 4 to disease progression (51% ± 11; P < .001). CONCLUSION: Arterial spin labeled perfusion MRI may assist in identifying responders to vascular endothelial growth factor receptor tyrosine kinase inhibitors and may help detect early evidence of disease progression in patients with metastatic renal cell carcinoma. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Goh and De Vita in this issue.

Purpose To evaluate the diagnostic accuracy of aneurysm detection and the fidelity of morphologic characterization of three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography at 3.0 T in patients with a Glasgow coma score of 15 and noncontrast material-enhanced computed tomography (CT) findings that showed acute nontraumatic subarachnoid hemorrhage. Materials and Methods The institutional review board approved this prospective study, and patients provided informed consent. A total of 277 patients who had not experienced trauma but in whom nonenhanced CT showed subarachnoid hemorrhage, who had a Glasgow coma score of 15, and who underwent both 3D TOF MR angiography and digital subtraction angiography (DSA) (the reference standard) were included. Three observers who were blinded to clinical and DSA results independently analyzed all 3D TOF MR angiographic data sets. The receiver operating characteristic curve was applied to analysis of the detection of aneurysms with 3D TOF MR angiography by using patient- and aneurysm-based evaluations. Multivariate logistic regression analysis was performed to identify aneurysm-specific variables, including size, shape (daughter sac/lobulation/margin), neck width (wide if > 4 mm or if fundus-to-neck ratio was < 2), and relation to adjacent artery, that significantly affected morphologic assessment with 3D TOF MR angiography. Results Aneurysms were depicted with DSA in 225 patients. In patient- and aneurysm-based evaluations, respectively, 3D TOF MR angiography yielded accuracies of 96.8% (268 of 277) and 96.6% (309 of 320), sensitivities of 98.2% (219 of 223) and 98.1% (260 of 265), specificities of 91% (49 of 54) and 89% (49 of 55), positive predictive values of 97.8% (219 of 224) and 97.7% (260 of 266), and negative predictive values of 92% (49 of 53) and 91% (49 of 54). Accuracy of display of morphologic features was 92.5% (236 of 255) for size, 86.3% (220 of 255) for neck width, 94.5% for shape (241 of 255), and 96.9% (247 of 255) for relationship to adjacent vessel. Width of aneurysm neck was the only variable that significantly affected the morphologic assessment of 3D TOF MR angiography (odds ratio, 0.378; 95% confidence interval: 0.337, 8.347; P = .004). Conclusion Three-dimensional TOF MR angiography can accurately depict cerebral aneurysms and accurately display their morphologic features in stable patients with subarachnoid hemorrhage and a Glasgow coma score of 15. © RSNA, 2017.

Purpose To investigate whether multivariate pattern recognition analysis of arterial spin labeling (ASL) perfusion maps can be used for classification and single-subject prediction of patients with Alzheimer disease (AD) and mild cognitive impairment (MCI) and subjects with subjective cognitive decline (SCD) after using the W score method to remove confounding effects of sex and age. Materials and Methods Pseudocontinuous 3.0-T ASL images were acquired in 100 patients with probable AD; 60 patients with MCI, of whom 12 remained stable, 12 were converted to a diagnosis of AD, and 36 had no follow-up; 100 subjects with SCD; and 26 healthy control subjects. The AD, MCI, and SCD groups were divided into a sex- and age-matched training set (n = 130) and an independent prediction set (n = 130). Standardized perfusion scores adjusted for age and sex (W scores) were computed per voxel for each participant. Training of a support vector machine classifier was performed with diagnostic status and perfusion maps. Discrimination maps were extracted and used for single-subject classification in the prediction set. Prediction performance was assessed with receiver operating characteristic (ROC) analysis to generate an area under the ROC curve (AUC) and sensitivity and specificity distribution. Results Single-subject diagnosis in the prediction set by using the discrimination maps yielded excellent performance for AD versus SCD (AUC, 0.96; P < .01), good performance for AD versus MCI (AUC, 0.89; P < .01), and poor performance for MCI versus SCD (AUC, 0.63; P = .06). Application of the AD versus SCD discrimination map for prediction of MCI subgroups resulted in good performance for patients with MCI diagnosis converted to AD versus subjects with SCD (AUC, 0.84; P < .01) and fair performance for patients with MCI diagnosis converted to AD versus those with stable MCI (AUC, 0.71; P > .05). Conclusion With automated methods, age- and sex-adjusted ASL perfusion maps can be used to classify and predict diagnosis of AD, conversion of MCI to AD, stable MCI, and SCD with good to excellent accuracy and AUC values. (©) RSNA, 2016.

Purpose To assess cerebral microbleed (CMB) prevalence in patients with multiple sclerosis (MS) and clinically isolated syndrome (CIS) and associations with clinical outcomes. Materials and Methods CMBs are associated with aging and neurodegenerative disorders. The prevalence of CMBs has not previously been well established. In this study, 445 patients with MS (266 with relapsing-remitting MS, 138 with secondary progressive MS, and 41 with primary progressive MS), 45 patients with CIS, 51 patients with other neurological diseases, and 177 healthy control subjects (HCs) underwent 3-T magnetic resonance (MR) imaging and clinical examinations. A subset of 168 patients with MS and 50 HCs underwent neuropsychological testing. Number of CMBs was assessed on susceptibility-weighted minimum intensity projections by using the Microbleed Anatomic Rating Scale; volume was calculated by using quantitative susceptibility maps. Differences between groups were analyzed with the χ2 test, Fisher exact test, Student t test, and analysis of variance; associations of CMBs with clinical and other MR imaging outcomes were explored with correlation and regression analyses. Because CMB frequency increases with age, prevalence was investigated in participants at least 50 years of age and younger than 50 years. Results Significantly more patients with MS than HCs had CMBs (19.8% vs 7.4%, respectively; P = .01) in the group at least 50 years old. A trend toward greater presence of CMBs was found in patients with MS (P = .016) and patients with CIS who were younger than 50 years (P = .039) compared with HCs. In regression analysis adjusted for age, hypertension, and normalized brain volume, increased number of CMBs was significantly associated with increased physical disability in the MS population (R2 = 0.23, P < .0001). In correlation analysis, increased number of CMBs was significantly associated with deteriorated auditory and verbal learning and memory (P = .006) and visual information processing speed trends (P = .049) in patients with MS. Conclusion Monitoring CMBs may be relevant in patients with MS and CIS at higher risk for developing cognitive and physical disability. © RSNA, 2016 Online supplemental material is available for this article.

Background Unruptured intracranial aneurysms (UIAs) are relatively common and are being increasingly diagnosed, with a significant proportion in older patients (˃ 65 years old). Serial imaging is often performed to assess change in size or morphology of UIAs since growing aneurysms are known to be at high risk for rupture. However, the frequency and duration of surveillance imaging have not been established. Purpose To evaluate the cost-effectiveness of routine treatment (aneurysm coil placement) versus four different strategies for imaging surveillance of UIAs in adults older than 65 years. Materials and Methods A Markov decision-analytic model was constructed from a societal perspective. Age-dependent input parameters were obtained from published literature. Analysis included adults older than 65 years, with incidental detection of UIA and no prior history of subarachnoid hemorrhage. Five different management strategies for UIAs in older adults were evaluated: (a) annual MR angiography, (b) biennial MR angiography, (c) MR angiography every 5 years, (d) coil placement and follow-up, and (e) limited MR angiography follow-up for the first 2 years after detection only. Outcomes were assessed in terms of quality-adjusted life-years (QALYs). Probabilistic, one-way, and two-way sensitivity analyses were performed. Results Imaging follow-up for the first 2 years after detection is the most cost-effective strategy (cost = $24 572, effectiveness = 13.73 QALYs), showing the lowest cost and highest effectiveness. The conclusion remains robust in probabilistic and one-way sensitivity analyses. Time-limited imaging follow-up remains the optimal strategy when the annual growth rate and rupture risk of growing aneurysms are varied. If annual rupture risk of nongrowing aneurysms is greater than 7.1%, coil placement should be performed directly. Conclusion Routine preventive treatment or periodic, indefinite imaging follow-up is not a cost-effective strategy in all adults older than 65 years with unruptured intracranial aneurysms. More aggressive management strategies should be reserved for patients with high risk of rupture, such as those with aneurysms larger than 7 mm and those with aneurysms in the posterior circulation. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Cloft in this issue.

Background A major technical challenge of prostatic arterial embolization (PAE) is the identification and catheterization of the prostatic arteries (PAs). Recently, MR angiography has been shown to help visualize PAs, but the clinical utility of MR angiography for this purpose is not known. Purpose To determine the efficacy of contrast material-enhanced MR angiography in identifying the PA and to evaluate its role in PAE for benign prostatic hyperplasia (BPH). Materials and Methods In this prospective study, 100 consecutive men who were scheduled to undergo PAE for BPH from January 2015 to May 2017 were assigned by using a randomized block design to either group A (n = 50; mean age, 71.7 years ± 11.9 [standard deviation]) without MR angiography or group B (n = 50; mean age, 72.3 years ± 12.2) with MR angiography prior to PAE. MR angiography findings of the PA anatomy were compared with those of digital subtraction angiography (DSA). The Student t test and Wilcoxon rank-sum test were used to compare the differences between the parameters indicating the performance of PAE. Results The mean age of the 100 men in the study was 72.0 years ± 11.8 (range, 51-88 years). Compared with DSA as the reference standard, MR angiography identified PAs with a sensitivity of 91.5% (97 of 106) and a positive predictive value of 100% (97 of 97). With the knowledge of tube obliquity and anatomy, group B had lower procedure times than group A (82.3 minutes ± 5.4 vs 123.9 minutes ± 12.4, P < .001) and shorter fluoroscopy times (13.8 minutes ± 2.7 vs 28.5 minutes ± 8.0, P < .001). Additionally, radiation dose was reduced for group A versus group B, from a median of 920 to 339 mGy (P = .004). Conclusion Contrast-enhanced MR angiography can accurately show anatomy for the prostate arteries, leading to shorter prostatic artery embolization times and lower radiation dose than when preprocedural prostate MR angiography is not performed. Published under a CC BY 4.0 license. Online supplemental material is available for this article. See also the editorial by Prince in this issue.

Background Autosomal dominant polycystic kidney disease (ADPKD) affects one in 400 to one in 1000 individuals; 10%-11% of these individuals have intracranial aneurysms. The frequency and patterns of screening for intracranial aneurysms have not been defined. Purpose To evaluate different MR angiography screening and surveillance strategies for unruptured intracranial aneurysms in patients with ADPKD. Materials and Methods A Markov decision-analytic model was constructed accounting for both costs and outcomes from a societal perspective. Five different management strategies were evaluated: (a) no screening for intracranial aneurysm, (b) one-time screening with annual MR angiography follow-up in patients with intracranial aneurysm, (c) MR angiographic screening every 5 years with endovascular treatment in detected intracranial aneurysm, (d) MR angiography screening every 5 years with annual MR angiography follow-up in patients with intracranial aneurysm, and (e) MR angiography screening every 5 years with biennial follow-up in patients with intracranial aneurysm. One-way, two-way, and probabilistic sensitivity analyses were performed. Results Base case calculation shows that MR angiography screening of patients with ADPKD every 5 years and annual follow-up in patients with detected intracranial aneurysm is the optimal strategy (cost, $19 839; utility, 25.86 quality-adjusted life years), which becomes more favorable as the life expectancy increases beyond 6 years. The conclusion remains robust in probabilistic and one-way sensitivity analyses. When the prevalence of intracranial aneurysms is greater than 10%, annual rupture risk is 0.35%-2.5%, and the rate of de novo aneurysm detection is lower than 1.8%, MR angiography screening every 5 years with annual MR angiography follow-up is the favorable strategy. Conclusion Screening for intracranial aneurysms with MR angiography in patients with autosomal dominant polycystic kidney disease is cost-effective. Repeat screening every 5 years should be performed after a negative initial study. Annual surveillance MR angiography is optimal in patients with detected, incidental intracranial aneurysm, and treatment may be considered in patients with growing, high-risk aneurysms. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Anzai in this issue.

Purpose To identify whether arterial enhancement pattern at MRI could predict the prognosis after surgical resection of intrahepatic mass-forming cholangiocarcinoma (IMCC). Materials and Methods Patients who underwent curative hepatic resection and preoperative MRI for IMCC from November 2007 to September 2016 were retrospectively evaluated. MRI enhancement pattern was classified by two radiologists. Recurrence and death data were retrieved until September 31, 2017. Prognostic factor analysis was performed by using preoperative and postoperative clinical-pathologic factors, as well as imaging findings. Results Data in 134 patients (median age, 63.0 years; 87 men and 47 women) were evaluated; median tumor size was 4.5 cm. Arterial phase MRI showed diffuse hypoenhancement in 33 patients, peripheral rim enhancement in 81 patients, and diffuse hyperenhancement in 20 patients. The 5-year risk of death in patients with IMCC with diffuse hyperenhancement was lower than that of patients with diffuse hypoenhancement or peripheral rim enhancement (5-year risk of death: 5.9% vs 87.9% vs 59.2%). Diffuse hypoenhancement (hazard ratio [HR], 41; 95% confidence interval [CI]: 5, 312; P < .01) and peripheral rim enhancement (HR, 11; 95% CI: 2, 85; P = .02) were associated with an increased risk of death compared with diffuse hyperenhancement. Patients with diffuse hyperenhancement of IMCCs had more frequent chronic liver disease (13 of 20; 65%), less frequent vascular invasion (six of 20; 30%), and less frequent tumor necrosis (three of 20; 15%) than other enhancement group (P < .05 for all). Conclusion The MRI arterial enhancement pattern was a prognostic marker in the preoperative evaluation of patients with resectable intrahepatic mass-forming cholangiocarcinoma. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Yoon and Lee .

To better understand the effect of bevacizumab therapy on tumor blood flow and oxygenation status in patients with recurrent glioblastoma.Retrospective data evaluation was approved by the local ethics committee of the University of Heidelberg (ethics approval number, S-320/2012), and informed consent was waived. A total of 71 patients who received a diagnosis of recurrent glioblastoma underwent conventional anatomic magnetic resonance (MR) imaging and dynamic susceptibility contrast material-enhanced MR imaging at baseline and at the first follow-up examination after initiation of bevacizumab therapy. Parametric response maps (PRMs) were created with multistep (nonlinear) registration of patients' post- to pretreatment images and voxel-wise subtraction between Gaussian-normalized relative cerebral blood volume (nrCBV) and Gaussian-normalized relative cerebral blood flow (nrCBF) maps. Intratumor voxels were stratified as being increased (PRM[+]) or decreased (PRM[-]) if they exceeded a threshold that represented the 95% confidence interval in the normal-appearing brain. Correlation with progression-free and overall survival was performed with Cox proportional hazards models.The risks for disease progression and death significantly increased with (a) higher baseline nrCBV (hazard ratio [HR] = 1.86, P.01; HR = 1.52, P.01) and nrCBF (HR = 1.78, P.01; HR = 1.86, P.01) values and (b) higher PRM(-) of nrCBV (HR = 1.03, P = .01; HR = 1.02, P = .03) and nrCBF (HR = 1.04, P.01; HR = 1.03, P.01), but not with higher PRM(+) of nrCBV and nrCBF, and not for the relative change in mean nrCBV and nrCBF, confirming the superiority of the PRM approach. The magnitude of PRM(-) for both nrCBV and nrCBF significantly increased for higher baseline values (P.01).Pretreatment hemodynamic parameters are the principal determinant of response to bevacizumab therapy in patients with recurrent glioblastoma. Although the magnitude of PRM(-) is a function of the corresponding pretreatment parameter, the finding of higher PRM(-) and a lack of change in PRM(+) in nonresponders to bevacizumab therapy implies that tumors with a high degree of angiogenesis before bevacizumab therapy retain a higher level of angiogenesis during therapy, despite a greater antiangiogenic effect of bevacizumab, such that a reversal of the biologic behavior and relative prognosis of these tumors does not occur.

To compare the success rates of percutaneous coronary interventions (PCIs) for chronic total occlusion (CTO) lesions according to the different signal intensity (SI) patterns seen at coronary magnetic resonance (MR) angiography.Institutional review board approval was obtained, and all patients gave written informed consent. This study included 95 CTO lesions in 93 consecutive patients who underwent steady-state free-precession coronary MR angiography with a 1.5-T imager before PCI. The SI and length of CTO lesions were evaluated at coronary MR angiography, and the lesions were classified into two groups according to the continuity of the areas of high SI in the CTO lesions. Invasive angiographic findings including lesion length and collateral grades were analyzed. A multivariable logistic regression analysis was performed to identify variables associated with successful PCI.Seventy-eight (82%) of 95 CTO lesions were treated successfully with PCI. On coronary MR angiograms, areas of continuous high SI were found in 42 lesions (44%), and 40 (95%) of them were treated successfully with PCI. Thirty-eight (72%) of 53 lesions with low SI or interrupted high SI throughout the CTO segments were successfully treated with PCI. The presence of areas of continuous high SI in the CTO segments was the only independent predictor of PCI success (odds ratio, 8.20; 95% confidence interval: 1.08, 62.15; P = .042).Continuous areas of high SI in CTO lesions on coronary MR angiograms are predictive of better success rates with PCI than are discontinuous or absent areas of high SI.

To demonstrate the feasibility of free-breathing three-dimensional (3D) radial ultrashort echo time (UTE) magnetic resonance (MR) imaging in the simultaneous detection of pulmonary embolism (PE) and high-quality evaluation of lung parenchyma.The institutional animal care committee approved this study. A total of 12 beagles underwent MR imaging and computed tomography (CT) before and after induction of PE with autologous clots. Breath-hold 3D MR angiography and free-breathing 3D radial UTE (1.0-mm isotropic spatial resolution; echo time, 0.08 msec) were performed at 3 T. Two blinded radiologists independently marked and graded all PEs on a four-point scale (1 = low confidence, 4 = absolutely certain) on MR angiographic and UTE images. Image quality of pulmonary arteries and lung parenchyma was scored on a four-point-scale (1 = poor, 4 = excellent). Locations and ratings of emboli were compared with reference standard CT images by using an alternative free-response receiver operating characteristic curve (AFROC) method. Areas under the curve and image quality ratings were compared by using the F test and the Wilcoxon signed-rank test.A total of 48 emboli were detected with CT. Both readers showed higher sensitivity for PE detection with UTE (83% and 79%) than with MR angiography (75% and 71%). The AFROC area under the curve was higher for UTE than for MR angiography (0.95 vs 0.89), with a significant difference in area under the curve of 0.06 (95% confidence interval: 0.01, 0.11; P = .018). UTE image quality exceeded that of MR angiography for subsegmental arteries (3.5 ± 0.7 vs 2.9 ± 0.5, P = .002) and lung parenchyma (3.8 ± 0.5 vs 2.2 ± 0.2, P.001). The apparent signal-to-noise ratio in pulmonary arteries and lung parenchyma was significantly higher for UTE than for MR angiography (41.0 ± 5.2 vs 24.5 ± 6.2 [P.001] and 10.2 ± 1.8 vs 3.5 ± 0.8 [P.001], respectively). The apparent contrast-to-noise ratio between arteries and PEs was higher for UTE than for MR angiography (20.3 ± 5.2 vs 15.4 ± 6.7, P = .055).In a canine model, free-breathing 3D radial UTE performs better than breath-hold 3D MR angiography in the detection of PE and yields better image quality for visualization of small vessels and lung parenchyma. Free-breathing 3D radial UTE for detection of PE is feasible and warrants evaluation in human subjects.

Further Implications of Off-Label Use of Acetazolamide in the Management of Moyamoya Disease in Japan : Response.

Purpose To develop and evaluate a supportive algorithm using deep learning for detecting cerebral aneurysms at time-of-flight MR angiography to provide a second assessment of images already interpreted by radiologists. Materials and Methods MR images reported by radiologists to contain aneurysms were extracted from four institutions for the period from November 2006 through October 2017. The images were divided into three data sets: training data set, internal test data set, and external test data set. The algorithm was constructed by deep learning with the training data set, and its sensitivity to detect aneurysms in the test data sets was evaluated. To find aneurysms that had been overlooked in the initial reports, two radiologists independently performed a blinded interpretation of aneurysm candidates detected by the algorithm. When there was disagreement, the final diagnosis was made in consensus. The number of newly detected aneurysms was also evaluated. Results The training data set, which provided training and validation data, included 748 aneurysms (mean size, 3.1 mm ± 2.0 [standard deviation]) from 683 examinations; 318 of these examinations were on male patients (mean age, 63 years ± 13) and 365 were on female patients (mean age, 64 years ± 13). Test data were provided by the internal test data set (649 aneurysms [mean size, 4.1 mm ± 3.2] in 521 examinations, including 177 male patients and 344 female patients with mean age of 66 years ± 12 and 67 years ± 13, respectively) and the external test data set (80 aneurysms [mean size, 4.1 mm ± 2.1] in 67 examinations, including 19 male patients and 48 female patients with mean age of 63 years ± 12 and 68 years ± 12, respectively). The sensitivity was 91% (592 of 649) and 93% (74 of 80) for the internal and external test data sets, respectively. The algorithm improved aneurysm detection in the internal and external test data sets by 4.8% (31 of 649) and 13% (10 of 80), respectively, compared with the initial reports. Conclusion A deep learning algorithm detected cerebral aneurysms in radiologic reports with high sensitivity and improved aneurysm detection compared with the initial reports. © RSNA, 2018 See also the editorial by Flanders in this issue.

Purpose To determine whether arterial spin-labeling (ASL) magnetic resonance (MR) imaging could be used to identify changes in cerebral blood flow (CBF), collateral blood flow, and anastomosis site patency after revascularization in patients with moyamoya disease. Materials and Methods This retrospective study was conducted in 145 patients with moyamoya disease who underwent middle cerebral artery (MCA)-superficial temporal artery anastomosis. Preoperative, early postoperative, and late postoperative ASL and digital subtraction angiography images were analyzed. In the MCA territory, absolute CBF (hereafter, CBF

To determine whether histogram analysis of amide proton transfer (APT) imaging provides increased accuracy of magnetic resonance (MR) perfusion imaging for the identification of contrast material-enhancing low-grade tumor (World Health Organization grades 1 and 2) that mimics high-grade tumor (World Health Organization grades 3 and 4).This retrospective study was approved by the institutional review board. Forty-five patients with pathologically proven, solitary, contrast-enhancing tumors were enrolled in this study. APT-derived signal intensity from the calculated APT asymmetry at the offset frequency of 3.5 ppm and normalized cerebral blood volume (nCBV) were measured on solid portions of the tumor by using a 90% histogram cutoff (denoted as APT90 and nCBV90, respectively). The diagnostic performance of the imaging parameters was determined with leave-one-out cross validation. Interobserver agreement was assessed by using the intraclass correlation coefficient.APT90 demonstrated a significant difference between contrast-enhancing low-grade and high-grade tumors for both readers (P.001 for both readers). Compared with nCBV90, adding APT90 significantly improved the area under the receiver operating characteristic curve (AUC) for the identification of contrast-enhancing low-grade tumor from 0.80 to 0.97 for reader 1 (P = .023) and from 0.82 to 0.97 for reader 2 (P = .035), respectively. By using leave-one-out cross-validation, the cross-validated AUC of the combination of nCBV90 and APT90 was 0.95 for reader 1 and 0.96 for reader 2. The intraclass correlation coefficient for the APT90 calculations was 0.89.Histogram analysis of APT imaging provided increased accuracy of MR perfusion imaging for the identification of contrast-enhancing low-grade tumor that mimics high-grade tumor.

Failed splenic switch-off with adenosine is a new, simple observation that identifies understressed patients who are at risk for false-negative findings on myocardial perfusion MR images.

Purpose To evaluate the effect of middle meningeal artery (MMA) embolization on chronic subdural hematoma (CSDH) and compare the treatment outcomes of MMA embolization and conventional treatment. Materials and Methods All consecutive patients 20 years or older with CSDH were assessed for eligibility. CSDHs with a focal location, a thickness of 10 mm or less, no mass effect, or underlying conditions were excluded. Seventy-two prospectively enrolled patients with CSDH underwent MMA embolization (embolization group; as the sole treatment in 27 [37.5%] asymptomatic patients and with additional hematoma removal for symptom relief in 45 [62.5%] symptomatic patients). For comparison, 469 patients who underwent conventional treatment were included as a historical control group (conventional treatment group; close, nonsurgical follow-up in 67 [14.3%] and hematoma removal in 402 [85.7%] patients). Primary outcome was treatment failure defined as a composite of incomplete hematoma resolution (remaining or reaccumulated hematoma with thickness10 mm) or surgical rescue (hematoma removal for relief of symptoms that developed with continuous growth of initial or reaccumulated hematoma). Secondary outcomes included surgical rescue as a component of the primary outcome and treatment-related complication for safety measure. Six-month outcomes were compared between the study groups with logistic regression analysis. Results Spontaneous hematoma resolution was achieved in all of 27 asymptomatic patients undergoing embolization without direct hematoma removal. Hematoma reaccumulation occurred in one (2.2%) of 45 symptomatic patients receiving embolization with additional hematoma removal. Treatment failure rate in the embolization group was lower than in the conventional treatment group (one of 72 patients [1.4%] vs 129 of 469 patients [27.5%], respectively; adjusted odds ratio [OR], 0.056; 95% confidence interval [CI]: 0.011, 0.286; P = .001). Surgical rescue was less frequent in the embolization group (one of 72 patients [1.4%] vs 88 of 469 patients [18.8%]; adjusted OR, 0.094; 95% CI: 0.018, 0.488; P = .005). Treatment-related complication rate was not different between the two groups (0 of 72 patients vs 20 of 469 patients [4.3%]; adjusted OR, 0.145; 95% CI: 0.009, 2.469; P = .182). Conclusion MMA embolization has a positive therapeutic effect on CSDH and is more effective than conventional treatment.

Purpose To evaluate the feasibility of directly imaging perfusion of human brain tissue by using magnetic resonance (MR) imaging with inhaled hyperpolarized xenon 129 (

Purpose To evaluate the diagnostic performance of self-navigated whole-heart coronary 3-T magnetic resonance (MR) angiography by using conventional invasive coronary angiography (ICA) as the reference gold standard. Materials and Methods This study was approved by the local ethics committee. Written informed consent was obtained from each patient before the study. Thirty-nine consecutive patients underwent coronary MR angiography and later underwent ICA. Coronary MR angiography was performed with a 3-T imager with contrast agent enhancement during free breathing with self-navigated affine motion correction reconstruction. Coronary segments with reference diameters larger than 1.5 mm were included in the comparison between coronary MR angiography and ICA. The coronary MR angiography images were evaluated by two experienced readers blinded to the ICA results to identify significant luminal narrowing (>50% diameter reduction in reference ICA). Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were performed to detect significant coronary artery stenosis. Results Coronary MR angiography examinations were successfully performed in all 39 patients. A total of 327 coronary segments had reference luminal diameter larger than 1.5 mm. Of these 327 coronary segments, 303 (92.7%) segments had a quality score greater than 1 at coronary MR angiography and were included in the analysis. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 78.2%, 75.0%, 81.8%, 70.6%, and 76.9%, respectively, on a per-patient basis. Conclusion Contrast-enhanced self-navigated coronary 3-T MR angiography is a promising technique for the noninvasive detection of clinically significant coronary stenosis. © RSNA, 2016.

PURPOSE: To prospectively compare the black-blood ( BB black blood ) imaging efficiency of a delay alternating with nutation for tailored excitation ( DANTE delay alternating with nutation for tailored excitation ) preparation module with conventional double inversion-recovery ( DIR double inversion recovery ) and motion-sensitive driven equilibrium ( MSDE motion-sensitive driven equilibrium ) preparation modules and to introduce a new three-dimensional ( 3D three-dimensional ) T1-weighted magnetic resonance (MR) imaging sequence. MATERIALS AND METHODS: Carotid artery wall imaging was performed in 10 healthy volunteers and 15 patients in accordance with an institutional review board-approved protocol. Two-dimensional ( 2D two-dimensional ) turbo spin-echo ( TSE turbo spin echo ) and 3D three-dimensional fast low-angle shot ( FLASH fast low-angle shot ) sequences served as readout modules. DANTE delay alternating with nutation for tailored excitation -prepared T1-, T2-, and proton density-weighted 2D two-dimensional TSE turbo spin echo images, as well as T1-weighted 3D three-dimensional DANTE delay alternating with nutation for tailored excitation -prepared FLASH fast low-angle shot (hereafter, 3D three-dimensional DASH DANTE-prepared FLASH ) images, were acquired in the region of the carotid artery bifurcation. For comparison, 2D two-dimensional DIR double inversion recovery -prepared, 2D two-dimensional MSDE motion-sensitive driven equilibrium -prepared multicontrast TSE turbo spin echo , and 3D three-dimensional MSDE motion-sensitive driven equilibrium -prepared FLASH fast low-angle shot (hereafter, 3D three-dimensional MERGE MSDE-prepared FLASH ) MR images were also acquired. The effective contrast-to-noise ratio ( CNReff effective contrast-to-noise ratio ) per unit time was calculated for all sequences. Paired t tests were performed to test within-group differences in vessel wall CNReff effective contrast-to-noise ratio . RESULTS: The CNReff effective contrast-to-noise ratio of DANTE delay alternating with nutation for tailored excitation -prepared T1-, T2-, and proton density-weighted sequences was 27.3, 14.7, and 25.7 mm(-1)min(-1/2), respectively; this represented an improvement of approximately 25%-100% (P < .05) when compared with the CNReff effective contrast-to-noise ratio attained with existing methods. The 3D three-dimensional DASH DANTE-prepared FLASH technique proved to be a fast (

To assess image quality and diagnostic performance of unenhanced magnetic resonance (MR) angiography with use of flow-sensitive dephasing (FSD)-prepared steady-state free precession (SSFP) of the foot arteries in patients with diabetes.This prospective study was approved by institutional review board. Informed consent was obtained from all subjects. Thirty-two healthy volunteers and 38 diabetic patients who had been scheduled for lower-extremity contrast material-enhanced MR angiography were recruited to undergo unenhanced MR angiography with a 1.5-T MR unit. Image quality and diagnostic accuracy of unenhanced MR angiography in the detection of significant arterial stenosis (≥50%) were assessed by two independent reviewers. Contrast-enhanced MR angiography was used as the reference standard. The difference in the percentage of diagnostic arterial segments at unenhanced MR angiography between healthy volunteers and diabetic patients was evaluated with the McNemar test and generalized estimating equation for correlated data. Signal-to-noise ratio (SNR) and artery-to-muscle contrast-to-noise ratio (CNR) of pedal arteries were measured and compared between the two MR angiography techniques by using the paired t test.All subjects successfully underwent unenhanced MR angiography of the foot. Unenhanced MR angiography yielded a high percentage of diagnostic arterial segments in both healthy volunteers (303 of 320 segments, 95%) and patients (341 of 370 segments, 92%), and there was no difference in the percentage between the two populations (P = .195). In patients, the average SNR and CNR at unenhanced MR angiography were higher than those at contrast-enhanced MR angiography (SNR: 90.7 ± 38.1 vs 81.7 ± 34.7, respectively, P = .023; CNR: 85.2 ± 33.2 vs 76.6 ± 33.5, respectively, P = .013). The average sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of unenhanced MR angiography were 88% (35 of 40 segments), 93% (107 of 115 segments), 81% (35 of 43 segments), 96% (107 of 112 segments), and 92% (142 of 155 segments), respectively. Interobserver agreement between the two readers for diagnostic accuracy was good (κ = 0.83).Unenhanced MR angiography with use of FSD-prepared SSFP allows clear depiction of the foot arterial tree and accurate detection of significant arterial stenosis. The technique has the potential to be a safe and reliable screening tool for the assessment of foot arteries in diabetic patients without the use of gadolinium-based contrast material.

To determine the feasibility of using real-time fluoroscopic tracking for bolus-chase magnetic resonance (MR) angiography of peripheral vasculature to image three stations from the aortoiliac bifurcation to the pedal arteries.This prospective study was institutional review board approved and HIPAA compliant. Eight healthy volunteers (three men; mean age, 48 years; age range, 30-81 years) and 13 patients suspected of having peripheral arterial disease (five men; mean age, 67 years; age range, 47-81 years) were enrolled and provided informed consent. All subjects were imaged with the fluoroscopic tracking MR angiographic protocol. Ten patients also underwent a clinical computed tomographic (CT) angiographic runoff examination. Two readers scored the MR angiographic studies for vessel signal intensity and sharpness and presence of confounding artifacts and venous contamination at 35 arterial segments. Mean aggregate scores were assessed. The paired MR angiographic and CT angiographic studies also were scored for visualization of disease, reader confidence, and overall diagnostic quality and were compared by using a Wilcoxon signed rank test.Real-time fluoroscopic tracking performed well technically in all studies. Vessel segments were scored good to excellent in all but the following categories: For vessel signal intensity and sharpness, the abdominal aorta, iliac arteries, distal plantar arteries, and plantar arch were scored as fair to good; and for presence of confounding artifacts, the abdominal aorta and iliac arteries were scored as fair. The MR angiograms and CT angiograms did not differ significantly in any scoring category (reader 1: P = .50, .39, and .39; reader 2: P = .41, .61, and .33, respectively). CT scores were substantially better in 20% (four of 20) and 25% (five of 20) of the pooled evaluations for the visualization of disease and overall image quality categories, respectively, versus 5% (one of 20) for MR scores in both categories.Three-station bolus-chase MR angiography with real-time fluoroscopic tracking provided high-spatial-resolution arteriograms of the peripheral vasculature, enabled precise triggering of table motion, and compared well with CT angiograms.

To evaluate the ability to depict anatomy and complications of renal vascular transplant with unenhanced magnetic resonance (MR) angiography with spatial labeling with multiple inversion pulses (SLEEK) and to compare the results with color Doppler (CD) ultrasonography (US), digital subtraction angiography (DSA), and intraoperative findings.This study was approved by the institutional review board, and written informed consent was received before examination. Seventy-five patients who underwent renal transplantation were examined with unenhanced MR angiography with SLEEK and CD US. DSA was performed in 15 patients. Surgery was performed in eight patients. The ability of SLEEK to show transplant renal vascular anatomy and complications was evaluated by two experienced radiologists who compared the results with CD US, DSA, and intraoperative findings.Patients successfully underwent SLEEK MR angiography. Transplant renal vascular anatomy was assessed in 87 arteries and 78 veins. Renal vascular complications from transplantation were diagnosed in 23 patients, which included 14 with arterial stenosis, three with arterial kinking, two with arteriovenous fistulas, two with venous stenosis, one with pseudoaneurysms, and one with fibromuscular dysplasia. Three patients had two renal transplants and nine patients had nine accessory renal arteries. More accessory renal arteries were detected with SLEEK than with CD US. Correlation was excellent between the stenosis degree with SLEEK and DSA (r = 0.96; P.05). For those with significant artery stenosis (50% narrowing) proved with DSA (n = 7) or surgery (n = 3), positive predictive value was 91% (10 of 11).Unenhanced MR angiography with SLEEK preliminarily proved to be a reliable diagnostic method for depiction of anatomy and complications of renal vascular transplant. It may be used for evaluation of patients with renal transplant, and in particular for those with renal insufficiency.

To evaluate the diagnostic accuracy of three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography at 3.0 T in the detection of small cerebral aneurysms.The institutional review board approved the study protocol, and patients or qualifying family members provided informed consent. A total of 403 consecutive patients undergoing 3D TOF MR angiography and digital subtraction angiography (DSA) were prospectively enrolled. Small aneurysms were those 5 mm in diameter or smaller. DSA served as the reference standard. Three observers were blinded to clinical and DSA results, and they independently analyzed all 3D TOF MR angiographic data sets. Interobserver agreement was expressed in terms of Cohen κ value for categorical variables. Accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 3D TOF MR angiography in the detection of cerebral aneurysms were determined by using patient-, aneurysm-, and location-based evaluations.Of 403 patients, 273 aneurysms were detected with DSA in 230 patients. Patient-based evaluation with 3D TOF MR angiography at 3.0 T yielded an accuracy of 96%-97%, a sensitivity of 98.2%-98.7%, a specificity of 93.2% -94.8%, a PPV of 94.9%-96.2%, and an NPV of 97.6%-98.2% in the detection of cerebral aneurysms. Aneurysm-based evaluation yielded an accuracy of 96.4%-97.3%, a sensitivity of 98.5%-98.9%, a specificity of 93.2%-94.9%, a PPV of 95.7%-96.8%, and an NPV of 97.6%-98.2%. Aneurysm-location evaluations yielded similar results.Three-dimensional TOF MR angiography is a noninvasive method that shows promising diagnostic accuracy in the detection of small cerebral aneurysms.