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Updated: Sep 29, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
CT and diffusion-weighted MR imaging in randomized order: diffusion-weighted imaging results in higher accuracy and
J B Fiebach1, P D Schellinger, O Jansen
1Department of Neuroradiology, University of Heidelberg Medical School, Heidelberg, Germany. Jochen_Fiebach@med.uni-heidelberg.de
Background And Purpose:
Diffusion-weighted MRI (DWI) has become a commonly used imaging modality in stroke centers. The value of this method as a routine procedure is still being discussed. In previous studies, CT was always performed before DWI. Therefore, infarct progression could be a reason for the better result in DWI.
Methods:
All hyperacute (<6 hours) stroke patients admitted to our emergency department with a National Institutes of Health Stroke Scale (NIHSS) score >3 were prospectively randomized for the order in which CT and MRI were performed. Five stroke experts and 4 residents blinded to clinical data judged stroke signs and lesion size on the images. To determine the interrater variability, we calculated kappa values for both rating groups.
Results:
A total of 50 patients with ischemic stroke and 4 patients with transient symptoms of acute stroke (median NIHSS score, 11; range, 3 to 27) were analyzed. Of the 50 patients, 55% were examined with DWI first. The mean delay from symptom onset until CT was 180 minutes; that from symptom onset until DWI was 189 minutes. The mean delay between DWI and CT was 30 minutes. The sensitivity of infarct detection by the experts was significantly better when based on DWI (CT/DWI, 61/91%). Accuracy was 91% when based on DWI (CT, 61%). Interrater variability of lesion detection was also significantly better for DWI (CT/DWI, kappa=0.51/0.84). The assessment of lesion extent was less homogeneous on CT (CT/DWI, kappa=0.38/0.62). The differences between the 2 modalities were stronger in the residents' ratings (CT/DWI: sensitivity, 46/81%; kappa=0.38/0.76).
Conclusions:
CT and DWI performed with the same delay after onset of ischemic stroke resulted in significant differences in diagnostic accuracy. DWI gives good interrater homogeneity and has a substantially better sensitivity and accuracy than CT even if the raters have limited experience.
Insights
Diffusion-weighted MRI (DWI) significantly improves acute ischemic stroke detection compared to CT, offering higher accuracy and interrater reliability. This advanced imaging technique is valuable even for less experienced raters in emergency settings.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Diffusion-weighted MRI (DWI) is increasingly used in stroke centers, but its routine value is debated.
- Prior studies often performed CT before DWI, potentially confounding results due to infarct progression.
Purpose of the Study:
- To prospectively evaluate the diagnostic performance of DWI versus CT in hyperacute stroke patients.
- To compare interrater variability and lesion detection accuracy between CT and DWI.
Main Methods:
- Hyperacute stroke patients (NIHSS >3) were randomized for CT or MRI (DWI) order.
- Five experts and four residents, blinded to clinical data, assessed stroke signs and lesion size.
- Interrater variability was quantified using kappa values.
Main Results:
- DWI demonstrated significantly higher sensitivity (91% vs. 61%) and accuracy (91% vs. 61%) for infarct detection compared to CT.
- DWI showed superior interrater reliability (kappa=0.84 vs. 0.51) and lesion extent assessment (kappa=0.62 vs. 0.38).
- These benefits were also observed in ratings by less experienced residents.
Conclusions:
- DWI offers substantially better diagnostic accuracy and interrater homogeneity than CT for hyperacute ischemic stroke.
- DWI's superior performance is evident even with limited rater experience and comparable imaging delays.
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