Who’s Who of Hypoperfusion: Predictors of CTP Findings in Hyperacute Stroke Olivier Bill1,3, Nuno M Inácio2, Dimitrios Lambrou1, Patrik Michel1. 1 Neurology Service, Stroke Center, Neurology, CHUV, Lausanne, Switzerland 2 Neurology Department, Hospital Beatriz Ângelo, Loure 3Stroke Unit, GHOL, Nyon, Switzerland Stroke Center 1.Objectives Perfusion CT (CTP) may improve the performance of non-contrast CT (NCCT) in detection of acute ischemic stroke (AIS). However, little is known on the profile of patient that are more likely to benefit of this technique. We aim to describe predictors of focal hypoperfusion (FHP) in acute ischemic stroke patients. 2. Methods From the ASTRAL (Acute STroke Registry and Analysis of Lausanne) registry, all patients with an AIS and CT-based imaging within 24 hours were included. Patients with a good quality CTP were extracted. Preceding demographic, clinical, biological, radiological, and follow-up data were collected. Significant predictors of focal hypoperfusion were identified to go on to fit a multivariate analysis. 50-70% Table 1: Association of stroke mechanism with focal perfusion deficit. 3. Results Of 2216 patients with good quality CTP, 750 (33.8%) had an acute ischemic lesion on NCCT, and 1624 (73.3%) had a focal hypoperfusion on CTP. After analyzing 104 acute stroke covariates: visual field defect, aphasia, neglect, low vigilance at admission and high NIHSS at onset were associated with FHP. Posterior circulation, lacunar strokes and patients under anticoagulation had less probability to have a FHP. When radiological variables were added, neglect or visual field defect at examination, early ischemic changes on NCCT, anterior circulation stroke, and presence of significant arterial pathology were associated with a positive CTP. Prolonged Onset to CT time had less FHP. Diagnostic accuracy is 76.8% with 95%CI (74.8% - 78.7%) Table 2: Clinical Predictors of Focal Perfusion Deficit Main Effects OR 95% LL 95%UL p-value Visual fields defect at admission 7.79 4.51 13.45 <1% Aphasia at admission 2.03 1.37 3.00 Neglect at admission 4.50 2.46 8.22 Low Vigilance at admission 6.32 2.49 16.00 Posterior circulation stroke 0.32 0.22 0.47 Lacunar TOAST Mechanism 0.14 0.08 0.24 Anticoagulation 0.45 0.28 0.72 Admission NIHSS 1.12 1.08 1.16 Table 3: Combined Clinical & Radiological Predictors of FPD Main Effects OR 95% LL 95%UL p-value Onset to CT Delay 0.97 0.95 0.99 <1% Visual Fields Defect at admission 6.09 3.43 10.81 Neglect at admission 4.13 2.06 8.27 Early ischemic changes on CT 4.68 2.73 8.04 Anterior circulation stroke 3.13 2.13 4.55 Presence of significant art. pathology 2.29 1.32 3.99 4. Conclusions Stroke severity, cortical clinical deficits, and non-lacunar supratentorial strokes are independent predictors of FHP, in addition to early imaging and arterial occlusions were associated with FHP Sensitivity for infarct detection increased from 43.3% with non-contrast CT to 80.1% with CTP, thus improving early recognition of stroke and its localization. Sensitivity and PPV for subsequent radiological infarct is high, whereas specificity and NPV are moderate. 5. References Lev MH et al. Utility of perfusion-weighted CT imaging in acute middle cerebral artery stroke treated with intra-arterial thrombolysis: prediction of final infarct volume and clinical outcome. Stroke. 2001; 32: 2021-2028. Wintermark M et al. Prognostic accuracy of cerebral blood flow measurement by perfusion computed tomography, at the time of emergency room admission, in acute stroke patients. Ann Neurol, 2002; 51: 417-432. Koenig M et al. Perfusion CT of the brain: diagnostic approach for early detection of ischemic stroke. Radiology, 1998; 209: 85-93. Mayer TE et al. Dynamic CT perfusion imaging of acute stroke. AJNR Am J Neuroradiol, 2000; 21: 1441-1449. Rai AT et al The role of CT perfusion imaging in acute stroke diagnosis: a large single-center experience. J Emerg Med, 2008; 35: 287-292.