Contrast-enhanced ultrasonic parametric perfusion imaging detects dysfunctional tissue at risk in acute MCA stroke

Ultrasonic perfusion imaging predicts size and localization of acute stroke. It is unclear whether irreversibly damaged tissue can be differentiated from tissue at risk. Thirty-four patients (ischemic stroke <12 h) were included (Phase Inversion Harmonic Perfusion Imaging; bolus kinetic; fitted model function). Three patterns of perfusion were defined in 14 prespecified regions of interest (ROI): 'normal', 'hypoperfusion', and 'no perfusion'. Clinical status was assessed using the National Institutes of Health Stroke Scale (NIHSS) (at baseline and at days 2 to 4). Cranial Computed Tomography (CCT) (days 2 to 4) displayed final infarction. The pattern 'hypoperfusion' (ROIs presumably representing tissue at risk) was tested twofold: (i) Functional impairment by correlating their number with baseline NIHSS. (ii) Viability by correlating their recruitment rate to infarction with clinical course (DeltaNIHSS days 2 to 4). In addition, various predictive values were assessed. Twenty-seven patients were eligible for analysis. The sum of ROIs with 'no perfusion' and 'hypoperfusion' correlated highest with baseline NIHSS (rho=0.78, P<0.001). Recruitment of hypoperfused ROIs to infarction highly correlated with clinical course (rho=0.79, P<0.001). Clinical course dichotomized the patients into subgroups A ('stable', DeltaNIHSS>or=-3) and B ('improved', DeltaNIHSS