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Detectability and detection rate of acute cerebral hemisphere infarcts on CT and diffusion-weighted MRI
1Department of Radiology/Neuroradiology, University Bonn, Germany. urbach@uni-bonn.edu
Abstract:
Our purpose was to compare the detectability and detection rate of acute ischaemic cerebral hemisphere infarcts on CT and diffusion-weighted MRI (DWI). We investigated 32 consecutive patients with acute hemisphere stroke with unenhanced CT and DWI within 6 h of stroke onset. The interval between CT and DWI ranged from 15 to 180 min (mean 60 min). Infarct detectability on CT and DWI was determined by comparing the initial CT, DWI and later reference images in a consensus reading of five independent examiners. The "true" detection rate was assessed by analysing all single readings. Two patients had intracerebral haematomas on DWI and CT and were excluded. There were 27 patients with ischaemic infarcts; all were visible on DWI and proven by follow-up. DWI was negative in three patients without a final diagnosis of infarct (100% sensitivity, 100% specificity, chi2 = 30, P < 0.0001). Ischaemic infarcts were visible on 15 and not seen on 12 CT studies (55 % sensitivity, 100% specificity, chi2 = 1.48, P = 0.224). With regard to the single readings (30 examinations x 5 examiners = 150 readings), 63 CT readings were true positive and 72 false negative (sensitivity 47 %, specificity 86%, chi2 = 2.88, P = 0.089). Of the DWI readings 128 were true positive and 7 false negative (sensitivity 95%, specificity 87 %, chi2 = 70.67, P < 0.0001). Interobserver agreement was substantial for CT (chi = 0.72, 95 % confidence interval, 0.6-0.84) and DWI (chi = 0.82, 95 % confidence interval, 0.46-1). Taken together, detectability and detection rate of acute (< 6 h) hemisphere infarcts are significantly higher with DWI than with CT.
Insights
Diffusion-weighted MRI (DWI) significantly improves the detection of acute ischemic stroke in the cerebral hemisphere compared to CT scans. DWI offers higher sensitivity and detection rates for early infarcts within 6 hours of stroke onset.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Acute ischemic stroke diagnosis relies on timely and accurate imaging.
- Computed tomography (CT) is a common initial imaging modality for stroke.
- Diffusion-weighted magnetic resonance imaging (DWI) shows promise for early stroke detection.
Purpose of the Study:
- To compare the detectability and detection rates of acute ischemic cerebral hemisphere infarcts using CT and DWI.
- To evaluate the diagnostic performance of DWI versus CT in the hyperacute stroke phase.
Main Methods:
- A prospective study of 32 patients with suspected acute hemisphere stroke within 6 hours of onset.
- Patients underwent unenhanced CT and DWI, with a mean interval of 60 minutes between scans.
- Infarct detection was assessed by five independent examiners comparing initial scans with follow-up imaging.
Main Results:
- Diffusion-weighted MRI (DWI) detected all 27 ischemic infarcts (100% sensitivity).
- CT identified only 15 of 27 infarcts (55% sensitivity).
- DWI demonstrated significantly higher sensitivity (95%) and detection rates compared to CT (47%) in single readings.
Conclusions:
- Diffusion-weighted MRI (DWI) is superior to CT for detecting acute ischemic cerebral hemisphere infarcts within 6 hours of stroke onset.
- DWI offers significantly higher sensitivity and detection rates, improving early stroke diagnosis.
- The findings support the use of DWI as a primary imaging tool in the hyperacute stroke setting.