Combination of Plaque Characteristics, Pial Collaterals, and Hypertension Contributes to Misery Perfusion in Patients With Symptomatic Middle Cerebral Artery Stenosis

Abstract

Background: Atherosclerotic plaque in the middle cerebral artery (MCA) is linked to ischemic stroke events, but the relationship between plaque characteristics and cerebral perfusion is unclear. Purpose: To investigate MCA plaque characteristics between intracranial atherosclerotic patients with and without hypoperfusion area, and to identify the variables affecting hypoperfusion volume. Study Type: Retrospective. Population: Seventy-one patients with MCA stenosis (>50%), and all with ischemic onset in recent 2 weeks. Field Strength/Sequence: 3.0T MRI / diffusion-weighted imaging (DWI), time-of-flight magnetic resonance angiography (TOF-MRA), inversion-recovery prepared sampling perfection with application-optimized contrast using different flip angle evolutions (IR-SPACE), dynamic susceptibility contrast perfusion-weighted imaging (DSC-PWI). Assessment: Plaque characteristics including eccentric index (EI), eccentricity, plaque length, and enhancement on MCA were measured on IR-SPACE. Pial collaterals (PCs) were evaluated on axial TOF-MRA source images. Time-to-maximum (Tmax) maps with a threshold more than 6 seconds were assessed by rapid processing of perfusion and diffusion (RAPID) software. Statistical Tests: Two independent-samples t-tests, Mann-Whitney U-test, chi-square test, Z test, univariate and multivariate logistic analysis, and receiver operating characteristic (ROC) curve were used. Results: Patients with hypoperfusion had fewer eccentric plaque, lower EI, longer plaque length, and poor PCs compared with those without (P = 0.002, 0.016, 0.003, and 0.001). Eccentricity, plaque length, PCs, and hypertension were the factors independently associated with the occurrence of hypoperfusion after adjustment for risk factors of cerebrovascular disease (P = 0.014, 0.017, 0.035, and 0.018). The area under the curve (AUC) (95% confidence interval) was 0.865 (0.763-0.934) for a combination of the above four variables, which was significantly higher than any variable alone (P < 0.001, 0.016, < 0.001, and < 0.001). Patients with lower EI, concentric morphology, and grade 2 enhancement trended to have larger hypoperfusion volume (P = 0.028, 0.037, and 0.009). Data Conclusion: Plaque eccentricity, plaque length, PCs, and hypertension showed an association with the occurrence of hypoperfusion.

DSC perfusion-based collateral imaging and quantitative T2 mapping to assess regional recruitment of leptomeningeal collaterals and microstructural cortical tissue damage in unilateral steno-occlusive vasculopathy

“…Rather than providing full protection and maintaining normal tissue integrity, pial collateral vessels reflect severe hemodynamic impairment of the primary cerebral circulation. Yielding pathophysiologically plausible associations with the severity of hypoperfusion which are in line with the results of previous studies 20,21 and providing an objective and observer-independent measure of leptomeningeal collateral supply, 22 collateral imaging as performed in this study allows for investigating characteristics of pial collateralization. Since the methodological approach presented in this study in based on the calculation of an intraindividual hemispheric asymmetry index of leptomeningeal collateral supply, it can be applied both in patients with acute vessel occlusion 22 and in patients with chronic steno-occlusive vasculopathy, yielding comparably meaningful results.…”

“…These degrees of stenosis were chosen as inclusion criteria for patients with ICA, respectively, MCA steno-occlusive vasculopathy since they usually can be assumed to cause relevant perfusion abnormalities which stimulate leptomeningeal collateralization and might induce microstructural tissue damage. 14,21,23 Small subcortical embolic or hemodynamic ischaemic lesions were not expected to substantially influence cortical qT2 values and subcortical perfusion measures and were therefore not considered as an exclusion criterion. Patients were considered as asymptomatic if based on the available imaging data, patient records and outpatient reports there were 1) no evidence of ever experienced clinical symptoms attributable to the steno-occlusive vessel pathology and 2) no ischaemic lesions on diffusion-weighted imaging (DWI) and T2-weighted images in the dependent vascular territory compatible with embolic or hemodynamic stroke.…”

“…1,18 While the periventricular white matter and the basal ganglia – exclusively supplied by perforating end arteries originating from the M1 segment of the middle cerebral artey 19 – are dependent on the antegrade blood flow, the cortical tissue fraction might benefit from the recruitment of collateral vessels in the close-by leptomeningeal compartment. However, it has been demonstrated that recruitment of collateral pathways – especially the pial collateral vessels – seems to be associated with severe hemodynamic failure, 20,21 and therefore, it is questionable whether collateral recruitment in the long term is sufficient to prevent ischaemic tissue damage. 20 The aim of this study was to investigate the association between microstructural changes in normal-appearing cerebral cortex and the degree of hemodynamic impairment in patients with unilateral steno-occlusive vasculopathy of the anterior circulation with particular focus on collateral supply by applying innovative methodological MRI and postprocessing approaches.…”

Large Culprit Plaque and More Intracranial Plaques Are Associated with Recurrent Stroke: A Case-Control Study Using Vessel Wall Imaging

“…The hypoperfusion volume was defined as the hypoperfusion volume of time-to-maximum with a threshold of .6 seconds. 28…”

Leptomeningeal collateral activation indicates severely impaired cerebrovascular reserve capacity in patients with symptomatic unilateral carotid artery occlusion

“… 30 – 32 Severe hemodynamic failure has been linked with recruitment of collateral pathways, especially with leptomeningeal collaterals. 14 , 33 , 34 Many noninvasive imaging techniques are standardly used to evaluate primary and secondary collateral circulation. 35 , 36 However, digital subtraction angiography (DSA) remains the gold standard for structural and functional evaluation of collaterals, 25 , 37 in everyday clinical practice TCD is often used as method of choice to assess collateral sufficiency.…”