Yan Gong1, Chen Cao2, Yu Guo3, Song Liu2, Zhu Jinxia4, Shuang Xia3, Xiudi Lu3, Ying Zou3, and Wen Shen3
1Tianjin Medical University NanKai Hospital, Tianjin, China, 2Department of Radiology, Tianjin Huanhu Hospital, Tianjin, China, 3Department of Radiology, Tianjin First Central Hospital, Tianjin, China, 4siemens-healthineers, Tianjin, China
Synopsis
This study compared high-resolution vessel
wall imaging (HR-VWI) and time-of-flight magnetic resonance angiography
(TOF-MRA) for evaluation of stenosis using digital subtraction angiography
(DSA) as the criterion standard. Compared with TOF-MRA, HR-VWI produced results
that more closely agreed with DSA, showed better reproducibility and accuracy
with smaller variance, and provided additional information on vessel wall
pathology. HR-VWI may therefore be
useful as an adjunct to DSA to
diagnose stenosis and evaluate changes in intracranial vessel walls.
INTRODUCTION
In patients with stroke-like symptoms,
intracranial atherosclerotic disease is the most frequent cause of vascular
stenosis. However, the predominant vascular imaging modalities, such as digital
subtraction angiography (DSA) and magnetic resonance angiography (MRA), only
display luminal narrowing and are unable to provide information on the
underlying pathology within the vessel wall. As a useful adjunct to
conventional imaging methods, intracranial high-resolution vessel wall imaging
(HR-VWI) may help diagnose the etiology of intracranial arterial narrowing 1. We
hypothesized that HR-VWI would be more accurate than time-of-flight MRA
(TOF-MRA) in evaluating different degrees of stenosis in intracranial artery
disease (ICAD) using DSA as the criterion standard. This study was conducted to
evaluate the consistency and accuracy of HR-VWI compared to TOF-MRA and 3D-DSA in
assessing stenosis of different arterial segments, stenotic degrees, and pathological
etiologies. METHODS
In this retrospective study, one hundred
forty-eight patients with available HR-VWI, TOF-MRA, and DSA images were
recruited. 3D-DSA was adopted as the gold standard for stenotic degree criteria.
The MRI data were collected on a 3T system (MAGNETOM Prisma, Siemens
Healthcare, Erlangen, Germany) with a standard 64-channel head/neck coil. HR-VWI was acquired using an inversion-recovery sampling
perfection with application-optimized contrasts using different flip angle
evolution (IR-SPACE) sequence with the following parameters: TR (repetition time) = 900 ms; TE (echo time) = 15 ms; 240
slices with a slice thickness of 0.60 mm; voxel size = 0.60×0.60×0.60 mm3;
field of view = 240×87.5 mm2; acquisition time = 7 minutes 57s.2
TOF-MRA was performed with the following parameters: TR = 21 ms; TE = 3.42 ms;
slice thickness = 0.90 mm; flip angle = 20°; field of view = 240×87.5 mm2;
and acquisition time = 6 minutes 9 seconds. All assessments were separately
rated by two radiologists and re-rated with a time interval of 2 weeks to
minimize recall bias. The degree of stenosis in the internal carotid and
intracranial arteries was assessed with the method used
in the Warfarin-Aspirin Symptomatic Intracranial Disease (WASID) trial by
measuring the diameter of the residual lumen at the maximal narrowing site,
using the formula [1 - (diameter of stenosis/diameter of normal) / 100].3 The arterial luminal diameter
distal or proximal to the maximal narrowing site was used as the normal value (Fig.
1). The degree of stenosis was classified into 3 groups: <50% (mild), 50% -
70% (moderate), and >70% (severe).4 Inter-observer agreement was assessed by interclass correlation
coefficient (ICC). Bland-Altman plots and mountain plots were used to
illustrate the concordance of HR-VWI and TOF-MRA, compared with DSA separately.
The concordance correlation coefficient (CCC) was calculated to reflect the
precision and accuracy of each method compared with DSA results. MedCalc
(Version 18.1.1.0; MedCalc Software, Mariakerke, Belgium) was used for these
analyses.5 P< 0.05 was considered statistically significant.RESULTS
A total of 250 stenotic lesions from 106 individuals were analyzed; typical images are displayed in Fig. 2. HR-VWI showed better inter-observer reproducibility in the subgroups (mild, K=0.88; moderate, K=0.95; severe, K=1.00) than TOF-MRA (mild, K=0.78; moderate, K=0.93; severe, K=0.90). HR-VWI also showed better agreement with DSA than did TOF-MRA (ICC: HR-VWI=0.97; TOF-MRA=0.74) (Fig. 3). HR-VWI showed a higher degree of concordance with DSA (CCC=0.97) than did TOF-MRA (CCC=0.74) (Figs. 4 and 5). Additionally, the inter-observer reproducibility for any stenosis degree was higher for HR-VWI than for TOF-MRA (ICC: HR-VWI=1.00; TOF-MRA=0.98).DISCUSSION
HR-VWI demonstrated greater accuracy than TOF-MRA, as
well as closer agreement with DSA in evaluating cervical and intracranial
arterial stenosis. HR-VWI performed
better in distal small vessels, provided more information on arterial
abnormalities (including plaque and luminal thrombosis) and detected arterial
stenosis with high reproducibility.5, 6 In particular, the ability of HR-VWI to assess the
pathology of vessel walls may be valuable for clinical management.
Additionally, HR-VWI is noninvasive and provides the further advantages of
convenient examination, no use of X-ray, and rapid imaging.CONCLUSION
We conclude that HR-VWI is as accurate as
DSA for the evaluation of intracranial artery stenosis and additionally can provide evidence of the underlying causative pathogenesis. HR-VWI
is therefore a promising method for the diagnosis and management of stenosis of
the carotid and intracranial arteries. Acknowledgements
This work was supported by Natural Science Foundation of China (NSFC) (grant numbers 81871342).References
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