High resolution 7T MR imaging in characterizing culprit intracranial atherosclerotic plaques

Comprehensive imaging analysis of intracranial atherosclerosis

Intracranial atherosclerotic disease (ICAD) involves the build-up of atherosclerotic plaques in cerebral arteries, significantly contributing to stroke worldwide. Diagnosing ICAD entails various techniques that measure arterial stenosis severity. Digital subtraction angiography, CT angiography, and magnetic resonance angiography are established methods for assessing stenosis. High-resolution MRI offers additional insights into plaque morphology including plaque burden, hemorrhage, remodeling, and contrast enhancement. These metrics and plaque traits help identify symptomatic plaques. Techniques like transcranial Doppler, CT perfusion, computational fluid dynamics, and quantitative MRA analyze blood flow restrictions due to ICAD. Intravascular ultrasound or optical coherence tomography have a very high spatial resolution and can assess the structure of the arterial wall and the plaque from the lumen of the target vascular territory. Positron emission tomography could further detect inflammation markers. This review aims to provide a comprehensive overview of the spectrum of current modalities for atherosclerotic plaque analysis and risk stratification.

Perfusion deficit and vessel wall characteristics to predict recurrent ischemic events in medically treated patients with chronic symptomatic anterior circulation large vessel occlusion

BACKGROUND

To investigate the association between perfusion deficit, vessel wall characteristics, and risk of recurrent ischemic events in medically treated patients with chronic symptomatic anterior circulation large vessel occlusion.

METHODS

We retrospectively reviewed chronic symptomatic patients due to anterior circulation large vessel occlusion in our center. All patients received multiparametric magnetic resonance imaging (including perfusion-weighted imaging and high-resolution vessel wall imaging) within 4 weeks to 3 months after symptom onset. The association between baseline clinical or imaging variables and recurrent ischemic events was assessed in bivariate models and multivariable logistic regression to identify independent predictors of recurrence.

RESULTS

Among 71 enrolled patients, 21.1% (15/71) patients had recurrent ischemic events (nine ischemic strokes and six transient ischemic attacks) during a 2-year follow-up. In bivariate models, hypertension, occlusion with hyperintense signals, the presence of intraluminal thrombus, Tmax >4 s volume, Tmax >6 s volume, Tmax >8 s volume, and Tmax >10 s volume were associated with recurrence (all p < 0.05). In multivariate analysis, hypertension (p = 0.039, OR 10.057 (95% CI, 1.123-90.048)), higher deficit volume of Tmax >4 s (p = 0.011, OR 1.012 (95% CI, 1.003-1.021)) and occlusion with hyperintense signal (p = 0.030, OR 6.732 (95% CI, 1.200-37.772)) were still independent predictors of recurrent ischemic events.

CONCLUSIONS

Besides hypertension history, higher deficit volume of Tmax >4 s and occlusion with hyperintense signal determined using multiparametric MRI are strongly associated with risk for recurrent ischemic events in medically treated patients with chronic symptomatic anterior circulation large vessel occlusion. Future studies are needed to determine the utility of revascularization strategies in such high-risk patients.

MR Imaging of the Cerebral Aneurysmal Wall for Assessment of Rupture Risk

The evaluation of unruptured intracranial aneurysms requires a comprehensive and multifaceted approach. The comprehensive analysis of aneurysm wall enhancement through high-resolution MRI, in tandem with advanced processing techniques like finite element analysis, quantitative susceptibility mapping, and computational fluid dynamics, has begun to unveil insights into the intricate biology of aneurysms. This enhanced understanding of the etiology, progression, and eventual rupture of aneurysms holds the potential to be used as a tool to triage patients to intervention versus observation. Emerging tools such as radiomics and machine learning are poised to contribute significantly to this evolving landscape of diagnostic refinement.

Assessment of paclitaxel drug-coated balloon angioplasty for intracranial atherosclerotic disease based on high-resolution vessel wall magnetic resonance imaging

BACKGROUND

To accurately assess the treatment effect of paclitaxel drug-coated balloon (DCB) angioplasty is essential for intracranial atherosclerotic disease (ICAD) patients. This study aimed to investigate the clinical feasibility of high-resolution vessel wall MRI (HR-VWI) in assessing ICAD with DCB angioplasty.

METHODS

Forty-five patients with intracranial atherosclerotic stenosis ≥ 70% confirmed by digital subtraction angiography (DSA) underwent HR-VWI before and after DCB angioplasty. Postoperative follow-up was performed after 6 months (±1 month). The differences of pre- and postoperative HR-VWI characteristics, including vessel and lumen area at maximal lumen narrowing (MLN), plaque area and length, degree of stenosis, plaque burden (PB), remodeling index, and plaque enhancement amplitude (PEA) were compared. The relationship between stenotic rate obtained using HR-VWI and DSA was evaluated. Each HR-VWI characteristic and clinical factor before DCB angioplasty was separately evaluated for the association with postoperative restenosis.

RESULTS

After six months, lumen area of MLN, plaque length and area, degree of stenosis, PB, and PEA showed a significantly difference relative to the value before DCB angioplasty (all P < 0.05). Spearman correlation coefficients of 0.865 and 0.932 were revealed between DSA and HR-VWI regarding the stenotic rate analysis pre- and post-operation (both P < 0.05). ROC analysis showed PEA, plaque length, and PB before DCB angioplasty separately provided robust prediction of postoperative restenosis (area under the curve = 0.909, 0.814 and 0.743; all P < 0.05). Multivariable analysis revealed that PEA was an independent predictor of prognosis.

CONCLUSIONS

The HR-VWI can accurately assess the treatment effect of DCB and robustly predict prognosis.

Priorities for Advancements in Neuroimaging in the Diagnostic Workup of Acute Stroke

STAIR XII (12th Stroke Treatment Academy Industry Roundtable) included a workshop to discuss the priorities for advancements in neuroimaging in the diagnostic workup of acute ischemic stroke. The workshop brought together representatives from academia, industry, and government. The participants identified 10 critical areas of priority for the advancement of acute stroke imaging. These include enhancing imaging capabilities at primary and comprehensive stroke centers, refining the analysis and characterization of clots, establishing imaging criteria that can predict the response to reperfusion, optimizing the Thrombolysis in Cerebral Infarction scale, predicting first-pass reperfusion outcomes, improving imaging techniques post-reperfusion therapy, detecting early ischemia on noncontrast computed tomography, enhancing cone beam computed tomography, advancing mobile stroke units, and leveraging high-resolution vessel wall imaging to gain deeper insights into pathology. Imaging in acute ischemic stroke treatment has advanced significantly, but important challenges remain that need to be addressed. A combined effort from academic investigators, industry, and regulators is needed to improve imaging technologies and, ultimately, patient outcomes.

Exploration of the etiology of single small subcortical infarctions using high-resolution vessel wall MRI

Objective

We aimed to explore imaging indicators for diagnosing the etiology of single small subcortical infarctions (SSI) using high-resolution vessel wall imaging (HR-VWI).

Methods

Patients with acute isolated subcortical cerebral infarction were prospectively enrolled and classified as having large artery atherosclerosis (LAA), stroke of undetermined etiology (SUD), or small artery disease (SAD). The infarct information, the cerebral small vessel disease (CSVD) score, morphological characteristics of the lenticulostriate arteries (LSAs), and plaque characteristics were compared between the three groups.

Results

Seventy seven patients were enrolled (30 LAA, 28 SUD, and 19 SAD). The total CSVD score of the LAA (P = 0.001) and SUD groups (P = 0.017) was significantly lower than that of the SAD group. The number and total length of LSA branches in the LAA and SUD groups were shorter than in the SAD group. Moreover, the total length laterality index (LI) of the LSAs in the LAA and SUD groups was greater than in the SAD group. The total CSVD score and LI of total length were independent predictors for the SUD and LAA groups. The remodeling index of the SUD group was significantly higher than that of the LAA group (P = 0.002); positive remodeling was dominant in the SUD group (60.7%), whereas remodeling in the LAA group was primarily non-positive (83.3%).

Conclusions

SSI with and without plaques on the carrier artery may have different modes of pathogenesis. Patients with plaques may also have a coexisting mechanism of atherosclerosis.