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Updated: Jul 11, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
The use of diffusion-weighted magnetic resonance imaging to identify infarctions in patients with minor strokes
J M Wardlaw1, P Armitage, M S Dennis
1Department of Clinical Neurosciences, Medical Physics, Western General Hospital NHS Trust, Edinburgh, UK.
Background:
Diffusion-weighted magnetic resonance imaging (DWI) shows cerebral infarction within minutes of its occurrence, but its value in clinical management after the stroke is less clear. We evaluated DWI scans in patients with minor strokes to determine whether DWI was helpful in identifying the stroke lesion and how long after the stroke could DWI still identify the lesion.
Method:
Patients admitted to our hospital with symptoms of a lacunar or minor cortical or posterior fossa stroke underwent T2 and proton density magnetic resonance imaging (MRI) of the brain, followed by DWI on a 1.5 Tesla Siemens scanner. The individual MR sequence images were examined (blind to each other and clinical information) to identify any recent infarction.
Results:
In 40 subjects (13 lacunes, 17 cortical, 5 posterior circulation infarctions, 2 transient ischemic attacks [TIAs] and 3 non-stroke), DWI scans showed the recent infarction clearly (even tiny ones) in 24 subjects (60%), in 12 of whom no infarction was visible on the T2 or proton density images. DWI also correctly excluded infarction in patients subsequently found not to have had a stroke. The diffusion abnormality was visible for up to 23 days after the stroke.
Conclusion:
DWI is useful for pinpointing the site of small infarctions that are either not visible or not distinguishable from previous lesions on T2 or proton density MRI, up to at least 3 weeks after the stroke. This may assist with planning further management of the stroke. The clinical use of DWI should not be restricted to just the first few hours after the stroke.
Insights
Diffusion-weighted imaging (DWI) effectively identifies small cerebral infarctions, even those invisible on standard MRI. This technique remains valuable for detecting stroke lesions for up to 23 days, aiding in stroke management.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Diffusion-weighted imaging (DWI) detects acute cerebral infarction rapidly.
- Its utility in later stroke management and lesion identification beyond the acute phase is less understood.
- This study investigates DWI's role in identifying minor stroke lesions and the duration of visibility.
Purpose of the Study:
- To evaluate the effectiveness of DWI in identifying stroke lesions in patients with minor strokes.
- To determine how long after a stroke DWI can still detect the infarction.
Main Methods:
- Patients with minor stroke symptoms underwent T2, proton density, and DWI MRI.
- MR sequences were independently reviewed to identify recent infarctions.
- A 1.5 Tesla Siemens scanner was used for all imaging.
Main Results:
- DWI clearly identified recent infarctions in 60% of subjects (24/40).
- In 12 cases, DWI detected lesions not visible on T2 or proton density images.
- Diffusion abnormalities were detectable for up to 23 days post-stroke.
Conclusions:
- DWI is valuable for pinpointing small infarctions, especially those missed by conventional MRI.
- The diagnostic window for DWI extends to at least 3 weeks after stroke onset.
- DWI's clinical application should extend beyond the initial hours following a stroke.
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