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Detectability of cerebral hemisphere ischaemic infarcts by CT within 6 h of stroke
R von Kummer1, P N Nolte, H Schnittger
1Department of Neuroradiology, University of Heidelberg, Germany.
Insights
Computed tomography (CT) can reliably detect ischemic brain infarcts within 6 hours of stroke onset. However, early detection of parenchymal low density is challenging in the initial 2 hours post-stroke.
Area of Science:
- Neurology
- Radiology
- Neuroimaging
Background:
- Early detection of ischemic stroke is crucial for timely intervention.
- Computed tomography (CT) is a primary imaging modality for acute stroke assessment.
Purpose of the Study:
- To evaluate the early detection rate and reliability of ischemic brain infarcts on CT within 6 hours of cerebral hemisphere stroke onset.
- To assess the sensitivity of CT for detecting parenchymal low density and focal brain swelling in acute ischemic stroke.
Main Methods:
- Retrospective analysis of 44 CT studies from patients with cerebral hemisphere strokes.
- Interpretation by an experienced neuroradiologist blinded to clinical signs but aware of the stroke population.
- Comparison of initial CT findings with follow-up studies confirming definite infarcts.
Main Results:
- CT demonstrated a mean sensitivity of 82% (36/44) for detecting ischemic cerebral hemisphere infarcts within 6 hours.
- Sensitivity for detecting early parenchymal low density was low within the initial 2 hours post-stroke.
- 95% of readings were true positive or true negative, with no false negatives.
Conclusions:
- CT is a reliable tool for detecting ischemic cerebral hemisphere infarcts within 6 hours of symptom onset.
- Early detection of ischemic changes on CT is limited within the first 2 hours.
- Radiologist familiarity with early ischemic signs enhances detection reliability.
Abstract:
To determine how early and how reliably ischaemic brain infarcts can be detected on CT within 6 h of the onset of cerebral hemisphere strokes, 44 such studies were interpreted by an experienced neuroradiologist blinded to clinical signs, but aware that the cohort was a stroke population. He was asked to detect and localise an area of parenchymal low density and/or focal brain swelling. A follow-up study showing the definite infarct served as a reference in each case. In 38 patients areas of slightly low density were seen, and in 36 follow-up CT confirmed infarcts in the locations indicated. In 2 patients the reading was false positive. In 6 patients no low density focus could be detected. In these 8 patients examined by CT within 180 min of the stroke, no low density could be identified, even in retrospect with the knowledge of the findings on follow-up. Thus, 42 readings (95%) were true positive or true negative; 2 were false positive; and none was a false negative. CT within 6 h of the onset of symptoms has a mean sensitivity of 82% (36/44) for ischaemic cerebral hemisphere infarcts. By contrast, its sensitivity to ischaemic parenchymal low density is low during the initial 2 h. The early development of hemispheric infarcts can be detected reliably if the radiologist is familiar with the signs.