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Diffusion-weighted magnetic resonance imaging in acute stroke
K J van Everdingen1, J van der Grond, L J Kappelle
1Department of Radiology, University Hospital Utrecht, The Netherlands. K.vanEverdingen@rrn.azu.nl
Background And Purpose:
Diffusion-weighted MRI (DWI) is highly sensitive in detecting early cerebral ischemic changes in acute stroke patients. In this study we compared the sensitivity of DWI with that of conventional MRI techniques. Furthermore, we investigated the prognostic value of the volume of ischemic lesions on DWI scans and of the apparent diffusion coefficient (ADC).
Methods:
We performed DWI, fluid-attenuated inversion recovery, spin-echo T2-weighted MRI, and spin-echo proton density-weighted MRI in 42 patients with acute stroke and 15 control subjects. The volume of ischemic lesions was measured on early (<60 hours after onset) and follow-up MRI scans. Clinical outcome was measured 4 months after onset of symptoms with the National Institutes of Health Stroke Scale, the Barthel Index, and the Rankin Scale.
Results:
With DWI, 98% of the ischemic lesions were detected, and with fluid-attenuated inversion recovery, 91% were detected, whereas with early T2-weighted or proton density-weighted scans, only 71% (P=0.002, chi2) and 80% (P=0.02, chi2) of lesions, respectively, were found. Lesion volume on early DWI scans correlated significantly with clinical outcome ratings (P<0.01). In patients with a first-ever stroke, a lesion volume of < or =22 mL on DWI predicted good outcome with a 75% sensitivity and a 100% specificity. The mean ADC of ischemic lesions was 29% lower than the ADC of normal-appearing parts of the brain (P<0.001). The ADC ratio correlated significantly with clinical outcome (P<0.05).
Conclusions:
DWI is a better imaging method than conventional MRI in detecting early ischemic lesions in stroke patients. Lesion size as measured on DWI scans and, to a lesser extent, ADC values are potential parameters for predicting clinical outcome in acute stroke patients.
Insights
Diffusion-weighted MRI (DWI) detects early stroke lesions better than conventional MRI. Lesion volume on DWI and apparent diffusion coefficient (ADC) predict patient outcomes.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Acute stroke requires sensitive detection of cerebral ischemic changes.
- Conventional MRI techniques have limitations in early stroke detection.
Purpose of the Study:
- Compare the sensitivity of Diffusion-weighted MRI (DWI) with conventional MRI for acute stroke.
- Investigate the prognostic value of ischemic lesion volume and apparent diffusion coefficient (ADC) on DWI.
Main Methods:
- 42 acute stroke patients and 15 controls underwent DWI, FLAIR, T2-weighted, and PD-weighted MRI.
- Ischemic lesion volume measured on early and follow-up MRI scans.
- Clinical outcomes assessed using NIH Stroke Scale, Barthel Index, and Rankin Scale at 4 months.
Main Results:
- DWI detected 98% of lesions; FLAIR detected 91%; T2-weighted 71%; PD-weighted 80%.
- Early DWI lesion volume significantly correlated with clinical outcomes (P<0.01).
- Mean ADC was 29% lower in lesions (P<0.001); ADC ratio correlated with outcomes (P<0.05).
Conclusions:
- DWI is superior to conventional MRI for detecting early ischemic lesions in stroke.
- DWI lesion size and ADC values are potential predictors of clinical outcome in acute stroke.