Degree of Agreement between Perfusion CT and Delayed CT in Early Detection of Cerebral Ischemia in Patients with Clinical Signs of Stroke
Keywords:
Brain, CT Brain, Infarction, Cerebral blood vessels, Computed tomography (CT),, Perfusion study.Abstract
Stroke is the third most common cause of death and the first leading cause of disability in developed and developing countries.1 A comprehensive evaluation of stroke may be performed with a combination of Computed Tomography (CT) or Magnetic Resonance (MR) Imaging techniques. Unenhanced CT (NECT) can be performed quickly, can help identify early signs of stroke and can rule out hemorrhage. CT angiography and CT perfusion imaging, respectively, can depict intravascular thrombi and salvageable tissue indicated by a penumbra. The present study highlights the importance of utilization of CT perfusion imaging technique in the detection of stroke at a time when plain CT is less likely to be helpful and urgent medical treatment can significantly alter the course of this catastrophic event.
Objectives: The aim of this study was to determine the degree of agreement between perfusion CT and delayed CT in early detection of cerebral ischemia in patients with clinical signs of stroke having negative early NECT scan.
Results: This study was conducted on 150 patients with clinical suspicion of stroke but having no or early signs of infarction on NECT scan during a period of six months from August 2013 to February 2014. The age of patients ranged from 29 to 90 years with mean age 63.80 ± 13.62 years with maximum number of patients aged between 71 – 80 years i.e. 61 (40.7%) and Minimum number of patients aged between 20 – 30 years i.e. 4 (2.7%). 74 patients (49.3%) out of total number of patients included in the study had signs of infarct on NECT while 76 patients (50.7%) had no signs of infarct on NE CT. 138 patients (92.0%) showed signs of infarct on perfusion CT while 12 patients (8.0%) had no signs of infarct on perfusion CT. Out of the 138 patients positive on perfusion CT, 131 proved to be positive on follow up CT and were thus true positive while 7 patients were false positive. Cohen ? coefficients were calculated to determine the agreement between NECT and perfusion CT. A value of .607 was derived for ? with standard error of ± .113 which shows substantial agreement between perfusion CT and delayed CT.
Conclusion: Because CT is still the primary imaging modality in patients with acute stroke, perfusion CT evaluation improves the rate of detection of infarction in comparison with NECT alone. The use of multi-detector row CT demonstrated improved detection rate of perfusion deficit, particularly in patients with minor neurologic symptoms. We believe multimodal CT evaluation can aid decision making for treatment of patients suspected of having a stroke.
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