3D Enhancement Color Maps in the Characterization of Intracranial Atherosclerotic Plaques

Abstract

BACKGROUND AND PURPOSE: High-resolution MR imaging allows the identification of culprit symptomatic plaques after the administration of gadolinium. Current high-resolution MR imaging methods are limited by 2D multiplanar views and manual sampling of ROIs. We analyzed a new 3D method to objectively quantify gadolinium plaque enhancement. MATERIALS AND METHODS:Patients with stroke due to intracranial atherosclerotic disease underwent 7T high-resolution MR imaging. 3D segmentations of the plaque and its parent vessel were generated. Signal intensity probes were automatically extended from the lumen into the plaque and the vessel wall to generate 3D enhancement color maps. Plaque gadolinium (Gd) uptake was quantified from 3D color maps as gadolinium uptake ¼ (m Plaque T1 1 Gd Àm Plaque T1 /SD Plaque T1 ). Additional metrics of enhancement such as enhancement ratio, variance, and plaque-versus-parent vessel enhancement were also calculated. Conventional 2D measures of enhancement were collected for comparison.RESULTS: Thirty-six culprit and 44 nonculprit plaques from 36 patients were analyzed. Culprit plaques had higher gadolinium uptake than nonculprit plaques (P , .001). Gadolinium uptake was the most accurate metric for identifying culprit plaques (OR, 3.9; 95% CI 2.1-8.3). Gadolinium uptake was more sensitive (86% versus 70%) and specific (71% versus 68%) in identifying culprit plaques than conventional 2D measurements. A multivariate model, including gadolinium uptake and plaque burden, identified culprit plaques with an 83% sensitivity and 86% specificity. CONCLUSIONS:The new 3D color map method of plaque-enhancement analysis is more accurate for identifying culprit plaques than conventional 2D methods. This new method generates a new set of metrics that could potentially be used to assess disease progression.

Qualitative and quantitative plaque enhancement on high‐resolution vessel wall imaging predicts symptomatic intracranial atherosclerotic stenosis

“…In addition, Sanchez et al. (2022) created a multivariate model, concluding plaque gadolinium (Gd) uptake and plaque burden, and showed that plaque enhancement analysis was more accurate for identifying symptomatic plaques. In this study, both plaque enhancement and plaque burden were found to be significantly associated with symptomatic ICAS, and this result was similar to previous studies.…”

Comprehensive imaging analysis of intracranial atherosclerosis

“…Sanchez et al analyzed 36 patients imaged with 7T HR-MRI and reported that a higher PB was associated with the presence of symptomatic plaque in patients with multiple plaques (OR 6.1). 44 The mean PB for symptomatic plaques was 85±13 and for non-symptomatic plaques was 65±14. 44 Monitoring changes in PB over time may provide valuable information regarding disease progression or response to medical therapy.…”

“…Studies have confirmed that the degree of stenosis alone may not fully capture the complexity and hemodynamic significance of intracranial atherosclerotic changes. [42][43][44] Notably, certain features of atherosclerotic plaques are better observed through HR-MRI. PB, enhancement after contrast-Gd administration, and the presence of IPH have emerged as potential biomarkers of plaque instability (figure 2).…”

“…A plaque is usually labeled as symptomatic if it is in the territory of the ischemic stroke. 42 44 Two studies, one by Huang et al involving 91 plaques 48 and another by Sanchez et al who studied 80 plaques, 44 found that PB and enhancement after the administration of Gd were correlated with the presence of symptomatic plaques in patients with stroke symptoms due to ICAD. In contrast, the degree of luminal stenosis did not reliably identify symptomatic plaques.…”

“…46 In our experience, the adjudication of IPH is challenging due to the small size of atherosclerotic plaques (average thickness 1.4 mm), artifact introduced by movement and venous contamination, incomplete suppression of the cerebrospinal fluid and blood, and the subjectivity of the adjudicator. 44 Furthermore, hyperacute IPH may initially appear T1-isointense and transition to T1-hyperintensity during subacute and chronic stages. 3 PB quantifies the amount of arterial remodeling or wall thickening in relation to the arterial lumen and is assessed by measuring the reduction in the cross-sectional area of the lumen at the site of the plaque compared with a reference arterial segment.…”