Letter by Du et al Regarding Article, “Magnetic Resonance Imaging of Plaque Morphology, Burden, and Distribution in Patients With Symptomatic Middle Cerebral Artery Stenosis”
To the Editor:
The study by Dieleman et al1 recruited patients with symptomatic middle cerebral artery stenosis, revealed plaque morphological characteristics, and compared the features between symptomatic and asymptomatic lesions using a 3T vessel wall sequence. The authors found that eccentricity was associated with asymptomatic lesions, whereas there was no relationship between symptomatic lesions and any specific morphological features. With great interest, we have some opinions about the study.
First, this study is a lack of quantitative magnetic resonance imaging measurements (eg, lumen area, wall area, wall thickness, plaque burden rate, arterial remodeling rate, and luminal stenosis) that may minimize the operator dependence and validate the qualitative results. The applied 3-dimensional volumetric isotropic turbo spin echo acquisition (VISTA, Philips) has been identified in a previous study2 that could provide reliable morphological measurements of intracranial vessels at high isotropic resolution. In an attempt to examine the plaque characteristic, the authors classified into 4 categories (enhancement, configuration, thickening, and magnetic resonance angiography) and the results showed by number of lesions at location. However, in our opinion, the assessment methods were too rough and failed to provide sufficient information on plaques morphological features. In particular, it would be important to assess more precisely the plaque burden and arterial remodeling (expansive/constructive) in symptomatic middle cerebral artery stenosis, which unfortunately were not investigated by Dieleman et al.1
Second, the current evidence has demonstrated that contrast enhancement of intracranial atherosclerotic plaque is associated with a recent ischemic event and may reflect plaque vulnerability and plaques at risk.3,4 However, the findings of the study by Dieleman et al1 were inconsistent with previous reports and showed no correlation between plaque enhancement and symptomatic presentation. We consider that the results should be interpreted with the following considerations. For one thing, in their study, plaque enhancement patterns were categorized by visual inspection, neither graded qualitatively nor quantitative analyzed by calculating the percentage of contrast enhancement, which may bring out the inaccurate results. For another, this study included most patients with chronic stroke; nevertheless, the plaque enhancement associated with vulnerability is more likely to occur in acute stroke.3 Therefore, differentiation the plaque features between acute and chronic stroke could be a meaningful extension in this study.
Third, this study did not describe the plaque vulnerability (shown by intraplaque heterogeneous signal intensity and plaque enhancement)5 and its relationship with ischemic events. However, this information may help to select patients at high risk of recurrent stroke, which would be of great clinical significant.5
In conclusion, we would like to express our respect to Dieleman et al1 for their interesting and meaningful study and suggest that the findings presented in their study should be interpreted with caution. Larger, prospective, longitudinal studies are required to further determine the differentiation between symptomatic and asymptomatic atherosclerotic middle cerebral artery lesions, especially on plaque stability and vessel wall properties, using high-resolution magnetic resonance imaging.
Juan Du, MD
Fang Yang, MD, PhD
Xinfeng Liu, MD, PhD
Department of Neurology
Jinling Hospital, Second Military Medical University
- © 2016 American Heart Association, Inc.