Clinical outcome and imaging follow-up in acute stroke patients with normal perfusion CT and normal CT angiography

Abstract

Acute stroke multimodal CT imaging (MMCT: non-enhanced CT, CT angiography, and CT perfusion (CTP)) may show normal results despite persistent clinical stroke. We prospectively evaluated the sensitivity/specificity of MMCT infarct detection and the clinical outcome in patients with normal MMCT findings. From April 2007 to April 2008, all patients with acute hemispheric stroke within 6 h of symptom onset who underwent complete MMCT and MRI follow-up imaging were included. MMCT analysis included occlusion type, early infarct hypodensities (EIH), mean transit time (MTT), and cerebral blood volume (CBV) maps according to Alberta Stroke Program Early CT Score (ASPECTS). Clinical assessment included symptom onset to CT scan (≤3 h/>3 h), the National Institute of Health Stroke Scale score (admission/discharge), and the modified Rankin scale (mRS) 90 days after stroke onset. One hundred seven were included (mean age, 68.4 years; ≤3 h, n = 84; >3 h, n = 23; intravenous thrombolysis (IVT), n = 51; ≤3 h, n = 40; >3 h, n = 11). In patients with normal MMCT on admission (n = 54), follow-up MRT detected brain infarctions in 23 patients (lacunar strokes, n = 16; infratentorial strokes, n = 4; territorial infarction, n = 3). Sensitivity/specificity/positive predictive value/negative predictive value of any infarct detection was 69.5%/99.8%/99.9%/57.2% and of a any territorial infarct detection was 93.9%/99.9%/99.9%/93.6%, respectively. In univariate regression analysis (time to CT scan, ≤3 h/>3 h; IVT: yes/no; ASPECTS EIH/CBV/MTT, 10/<10), only the evidence of normal CTP (ASPECTS MTT = 10) had a statistically significant impact (p = 0.02) on a good outcome (mRS 0.1). MMCT sensitivity in acute lacunar or infratentorial stroke was poor. But, we found a high specifity and a fairly good sensitivity in territorial infarct detection. In acute stroke patients with normal MMCT findings on admission, a good clinical prognosis can be expected.