AMRI using DWI and T1w-HBP has a clinically acceptable sensitivity and NPV for HCC detection. This could serve as the basis for a future study assessing AMRI for HCC screening and surveillance.

Purpose To develop a highly accelerated phase contrast cardiac-gated volume flow measurement (4D flow) MR imaging technique based on spiral sampling and dynamic compressed sensing, and to compare with established phase contrast imaging techniques for the quantification of blood flow in abdominal vessels. Methods In this prospective IRB approved study, 10 subjects (9 males, mean age 51 y) including 7 patients with liver disease were enrolled. Two 4D flow acquisitions were performed, one using Cartesian sampling with respiratory tracking, the other using spiral sampling and acquired in a breath hold. Cartesian 2D cine phase contrast was also acquired in the portal vein. Two independent observers assessed vessel conspicuity on phase contrast 3D angiogram. Quantitative flow parameters were measured by two independent observers in major abdominal vessels. Inter-technique concordance was quantified using Bland-Altman analysis and Pearson correlation. Results There was no significant difference in vessel conspicuity between 4D flow acquisitions (p >0.069, for both observers), while more artifacts were observed with spiral 4D flow (p <0.016). Quantitative measurements in abdominal vessels showed strong correlation between spiral and Cartesian 4D flow techniques (for total flow r = 0.96, p <0.001). For portal venous flow, spiral 4D flow was in better agreement with 2D cine phase contrast (−8.8/9.3 mL/s) than was Cartesian 4D flow (−10.6/14.6 mL/s). Conclusion Combining highly efficient spiral sampling with dynamic compressed sensing results in major acceleration for 4D flow MR imaging, which allows comprehensive assessment of abdominal vessel hemodynamics in a breath hold.

BackgroundGadolinium enhancement on high‐resolution magnetic resonance imaging (MRI) has been proposed as a marker of inflammation and instability in intracranial atherosclerotic plaque. We performed a systematic review and meta‐analysis to summarize the association between intracranial atherosclerotic plaque enhancement and acute ischemic stroke.Methods and ResultsWe searched the medical literature to identify studies of patients undergoing intracranial vessel wall MRI for evaluation of intracranial atherosclerotic plaque. We recorded study data and assessed study quality, with disagreements in data extraction resolved by a third reader. A random‐effects odds ratio was used to assess whether, in any given patient, cerebral infarction was more likely in the vascular territory supplied by an artery with MRI‐detected plaque enhancement as compared to territory supplied by an artery without enhancement. We calculated between‐study heterogeneity using the Cochrane Q test and publication bias using the Begg‐Mazumdar test. Eight articles published between 2011 and 2015 met inclusion criteria. These studies provided information about plaque enhancement characteristics from 295 arteries in 330 patients. We found a significant positive relationship between MRI enhancement and cerebral infarction in the same vascular territory, with a random effects odds ratio of 10.8 (95% CI 4.1–28.1, P<0.001). No significant heterogeneity (Q=11.08, P=0.14) or publication bias (P=0.80) was present.ConclusionsIntracranial plaque enhancement on high‐resolution vessel wall MRI is strongly associated with ischemic stroke. Evaluation for plaque enhancement on MRI may be a useful test to improve diagnostic yield in patients with ischemic strokes of undetermined etiology.

BACKGROUND: CTA is a widely available imaging examination that may allow the evaluation of high-risk carotid plaque features.

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Purpose To evaluate the performance of a high spatial resolution 2D phase-contrast (PC) MRI technique accelerated with compressed sensing for portal vein (PV) and hepatic artery (HA) flow quantification in comparison with a standard PC MRI sequence. Patients and Methods In this IRB approved prospective study, two sequences were compared, one with parallel imaging acceleration and low spatial resolution (PC-GRAPPA), and one with compressed sensing acceleration and high spatial resolution (PC-SPARSE). 76 patients were assessed, including 37 with cirrhosis. Two observers evaluated PC image quality. Quantitative analysis yielded mean velocity, flow and vessel area for PV and HA, and arterial fraction. PC techniques were compared using Wilcoxon test and Bland-Altman statistics. Flow parameter sensitivity to severity of cirrhosis was also assessed. Results Vessel delineation was significantly improved using PC-SPARSE (p <0.034). For both in vitro and in vivo measurements, PC-SPARSE yielded lower estimates for vessel area and flow, with larger differences observed in the HA. PV velocity and flow were significantly lower in cirrhosis for both sequences (p <0.001 and p<0.04 respectively). PV velocity correlated negatively with Child-Pugh class (r = −0.50, p < 0.001), while ART measured with PC-SPARSE was higher in Child-Pugh B/C patients compared to Child Pugh A, with trend towards significance (p=0.055). Conclusion A highly accelerated/high spatial resolution compressed sensing technique allows for total hepatic blood flow measurement in a breath hold with improved delineation of hepatic vessels compared to a standard PC MRI sequence, and can potentially be used for noninvasive assessment of liver cirrhosis.

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Background Thromboembolism from nonstenosing carotid plaques may be an underrecognized cause of embolic strokes of undetermined source ( ESUS ). We evaluated the association between features of nonstenosing atherosclerotic plaque on computed tomographic angiography and ESUS . Methods and Results We identified consecutive acute ischemic stroke patients from 2011 to 2015 who had unilateral anterior territory infarction on brain magnetic resonance imaging and a neck computed tomographic angiography. We included ESUS cases and as controls, cardioembolic strokes. Patients with ≥50% internal carotid artery atherosclerotic stenosis ipsilateral to the stroke were excluded from this analysis. Reviewers blinded to infarct location and stroke cause retrospectively evaluated computed tomographic angiography studies for specific plaque features including thickness of the total, soft, and calcified plaque; presence of ulceration; and perivascular fat attenuation. Paired t tests and McNemar's test for paired data were used to compare plaque features ipsilateral versus contralateral to the side of infarction. Ninety‐one patients with ESUS or cardioembolic stroke were included in this study. Total plaque thickness was greater on the infarcted side (2.1±2.0 mm) than the contralateral side (1.2±1.5 mm) ( P =0.006) among ESUS cases, but not among cardioembolic cases (1.9±1.6 mm versus 1.8±1.6 mm) ( P =0.32). Conclusions Among ESUS cases, total plaque thickness was greater ipsilateral to the side of infarction than on the contralateral, stroke‐free side. No such side‐to‐side differences were apparent in cardioembolic strokes. Our findings suggest that nonstenosing large‐artery atherosclerotic plaques represent one underlying mechanism of ESUS .