Plaques of Nonstenotic Basilar Arteries with Isolated Pontine Infarction on Three-dimensional High Isotropic Resolution Magnetic Resonance Imaging

Assessment of the Hemodynamics of Autogenous Arteriovenous Fistulas With 4D Phase Contrast-Based Flow Quantification MRI in Dialysis Patients

BACKGROUND

Regular monitoring of autogenous arteriovenous fistulas (AVFs) for hemodialysis patients has importance. Hence, 4D flow MRI may be an alternative for assessing the hemodynamics of AVFs.

PURPOSE

To compare the hemodynamics of AVFs using Doppler ultrasound (DUS) and 4D-MRI in renal dialysis patients.

STUDY TYPE

Case-control study from October 2017 to April 2018.

POPULATION

Fifty patients (age [range] = 59.52 [39-71] years) with AVFs were included.

FIELD STRENGTH/SEQUENCE

Black-blood MRI and 4D flow MRI at 3.0T and AVF ultrasonography were also performed.

ASSESSMENT

The hemodynamics acquired from 4D flow MRI and ultrasonography by two radiologists were compared. The AVF anatomy was described through an examination of the black-blood MRI.

STATISTICAL TESTS

The consistency of AVF anatomy and hemodynamics and the consistency of the hemodynamics of AVFs from 4D flow MRI and ultrasound were analyzed by paired t-tests. The morphological parameters of AVFs acquired from black-blood MRI were used for a Pearson correlation analysis with the hemodynamic parameters obtained from 4D flow MRI data.

RESULTS

The consistency of the morphological and hemodynamic parameters measured from MRI by the two radiologists was good (all P < 0.01). The velocities and flow volumes from the 4D flow MRI and vascular ultrasound of AVFs were in moderate agreement (all P < 0.05, r = 0.292-0.569), except for the peak flow velocity at the anastomosis (P = 0.366, r = -0.078). The flow volume and WSS near the anastomotic site were closely related to the morphology of the AVFs (all P < 0.05). The hemodynamics of the complications group were significantly different from those of patients without any complications (normal patients group) (all P < 0.01).

DATA CONCLUSION

Compared with ultrasonography, 4D flow MRI is a promising technique to noninvasively estimate the AVF hemodynamics of renal dialysis patients.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:1272-1280.

Plaque Distribution of Basilar Artery Fenestration by 3D High-Resolution MR Vessel Wall Imaging

The association between fenestrations and neurovascular pathology is not well defined. The morphology of vessel wall plays an important role in the development of neurovascular pathology. We sought to explore the plaque distribution around basilar artery fenestration (BAF) by three-dimensional high-resolution MR vessel wall imaging (3D HRMRI). Patients with BAF on 3D HRMRI images were enrolled. All cross-sectional slices of basilar arteries were assessed and categorized based on the location of fenestration as proximal segment, in-bifurcation segment, and distal segment. Furthermore, plaques in the in-bifurcation segment were classified according to their orientation being centered on the lateral, interior, dorsal, or ventral wall of the vessel. In all, 12 cases with BAF involving 661 cross-sectional image slices in entire basilar arteries were included. Plaques were found in 190 image slices, with the distribution of 41 slices in the proximal segment, 144 slices in the in-bifurcation segment and 67 slices in the distal segment. Plaques were found more frequently in the proximal and in-bifurcation segments than in the distal segment (P < 0.001), but there was no statistical difference between the proximal and in-bifurcation segment (P = 0.11). In the in-bifurcation segment, plaques were more frequently located at the lateral (50.0%) than other interior (16.0%), dorsal (21.0%), and ventral (13.0%) wall (P < 0.001).Plaques of BAF tend to locate in the proximal and in-bifurcation segments, especially at the lateral wall of the in-bifurcation segment.

Interstudy reproducibility of dark blood high-resolution MRI in evaluating basilar atherosclerotic plaque at 3 Tesla

PURPOSE

We aimed to evaluate the interscan, intraobserver, and interobserver reproducibility of basilar atherosclerotic plaque employing dark blood high-resolution magnetic resonance imaging (HR-MRI) at 3 Tesla.

METHODS

Sixteen patients (14 males and 2 females) with > 30% basilar stenosis as identified by conventional magnetic resonance angiography were prospectively recruited for scan and rescan examinations on a 3 Tesla MRI system using T2-weighted turbo spin-echo protocol. Two observers independently measured the areas of vessels and lumens. Wall area was derived by subtracting the lumen area from the vessel area. Areas of vessels, lumens and walls were compared for the evaluation of interscan variability of basilar plaque. To assess the intraobserver variability, one observer reevaluated all the images of the first scan after a 4-week interval.

RESULTS

Fourteen patients were included in the final analysis. No clinically significant difference was observed for interscan, intraobserver, and interobserver measurements. The intraclass correlations for vessel, lumen, and wall areas were excellent and ranged from 0.973 to 0.981 for the interscan measurements, 0.997 to 0.998 for the intraobserver measurements and 0.979 to 0.985 for the interobserver measurements. The coefficients of variation for quantitative basilar morphology measurements were 4.31%-10.35% for the interscan measurements, 1.41%-4.62% for the intraobserver measurements and 3.79%-8.46% for the interobserver measurements. Compared with the interscan and interobserver measurements, narrow intervals of the scatterplots were observed for the intraobserver measurements by Bland-Altman plots.

CONCLUSION

Basilar atherosclerotic plaque imaging demonstrates excellent reproducibility at 3 Tesla. The study proves that dark blood HR-MRI may serve as a reliable tool for clinical studies focused on the progression and treatment response of basilar atherosclerosis.

Current Status and Future Perspective of Stenting for Symptomatic Intracranial Atherosclerotic Disease: A Meta-Analysis

The aim of this study was to evaluate the safety and effectiveness of percutaneous transluminal angioplasty and stenting (PTAS) for intracranial atherosclerotic disease (ICAD) by conducting a meta-analysis. Two independent observers searched PubMed, EMBASE, and Cochrane Library for relevant studies up to 31 December 2016. A meta-analysis was conducted using Review Manager 5.3. Three studies involving 581 cases were included. The meta-analysis indicated that any stroke (RR = 3.13; 95% CI: 1.80-5.42), ischemic stroke (RR = 2.15; 95% CI: 1.19-3.89), and intracranial hemorrhage (RR = 14.71; 95% CI: 1.96-110.48) within 30 days in medical therapy alone were lower compared with PTAS plus medical therapy, but there were no significant differences in any stroke and ischemic stroke beyond 30 days between the two groups. There were also no significant differences in any death and myocardial infarction between the two groups. This meta-analysis demonstrated that, compared with medical therapy alone, PTAS for ICAD had a high risk of complication, but most complications in PTAS group occurred within 30 days after the operation, and beyond 30 days the PTAS was not inferior compared with medical therapy alone. Further studies are needed to reduce the periprocedural complications and reappraise the PTAS.

High-resolution Magnetic Resonance Vessel Wall Imaging for Intracranial Arterial Stenosis

OBJECTIVE

To discuss the feasibility and clinical value of high-resolution magnetic resonance vessel wall imaging (HRMR VWI) for intracranial arterial stenosis.

DATE SOURCES

We retrieved information from PubMed database up to December 2015, using various search terms including vessel wall imaging (VWI), high-resolution magnetic resonance imaging, intracranial arterial stenosis, black blood, and intracranial atherosclerosis.

STUDY SELECTION

We reviewed peer-reviewed articles printed in English on imaging technique of VWI and characteristic findings of various intracranial vasculopathies on VWI. We organized this data to explain the value of VWI in clinical application.

RESULTS

VWI with black blood technique could provide high-quality images with submillimeter voxel size, and display both the vessel wall and lumen of intracranial artery simultaneously. Various intracranial vasculopathies (atherosclerotic or nonatherosclerotic) had differentiating features including pattern of wall thickening, enhancement, and vessel remodeling on VWI. This technique could be used for determining causes of stenosis, identification of stroke mechanism, risk-stratifying patients, and directing therapeutic management in clinical practice. In addition, a new morphological classification based on VWI could be established for predicting the efficacy of endovascular therapy.

CONCLUSIONS

This review highlights the value of HRMR VWI for discrimination of different intracranial vasculopathies and directing therapeutic management.

Wall thickening pattern in atherosclerotic basilar artery stenosis

Our aim was to investigate wall thickening (WT) pattern of atherosclerotic basilar artery stenosis with three-dimensional volumetric isotropic turbo spin echo acquisition (3D VISTA), and the relationship with clinical characteristics. Twenty consecutive patients with atherosclerotic basilar artery stenosis were prospectively enrolled. All cross-sectional slices on VISTA images of basilar arteries were assessed, and classified as eccentric or concentric WT. Clinical characteristics and degree of stenosis were compared between the patients with different wall WT pattern. Wall abnormalities were identified in 568 cross-sectional slices in basilar arteries of 20 patients including eccentric WT in 497 (87.5 %) slices, and concentric WT in 71 (12.5 %) slices. In 11 of 20 patients, all the cross-sectional slices (293 slices) showed eccentric WT. In 9 of 20 patients, the cross-sectional slices (275 slices) showed both eccentric WT (204 slices, 74.2 %) and concentric WT (71 slices, 25.8 %). No lesion showed only concentric WT. At the slices of maximum luminal narrowing sites, only one patient showed concentric WT. Symptomatic stenosis was more common in the patients with mixed WT (eccentric and concentric), compared to patients with only eccentric WT (100 vs 54.5 %, p = 0.038). Atherosclerotic basilar artery stenosis could show both eccentric and concentric WT based on each slice analysis. Concentric WT was found in near half of the patients, but tended to locate in minimal slices. No lesion was entirely concentric. Lesions with mixed WT (concentric and eccentric) might represent advanced atherosclerosis with high risk of ischemic event.