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Updated: Mar 19, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
Thin section magnetic resonance diffusion-weighted imaging in the detection of acute infratentorial stroke
Tom Entwisle1, Yuliya Perchyonok2, Greg Fitt2
1Radiology Department, Austin Health, Heidelberg, Victoria, Australia. tomentwisle@gmail.com.
Introduction:
Magnetic resonance diffusion-weighted imaging (DWI) is the most accurate technique available for demonstrating acute infarction; however, false-negative DWI is higher in the infratentorium due to the limited spatial resolution with conventional 5 mm DWI. The aim of this study was to compare 5 mm DWI with 3 mm DWI in the detection of acute infratentorial infarction.
Methods:
A 3 mm DWI sequence of the infratentorium was incorporated into the conventional MRI stroke protocol for the evaluation of patients with vertebrobasilar stroke-like deficits. The 5 mm and 3 mm DWI sequences were assessed by two neuroradiologists who were blinded to the clinical findings. Sensitivity and specificity analysis was then performed against the final clinical diagnosis.
Results:
The sensitivity for detection of infratentorial infarction was 81.1% for 5 mm DWI and 94.6% for 3 mm DWI and the specificity was 100% for 5 mm DWI and 97.7% for 3-mm DWI. The false-negative rate in detection of infratentorial infarcts was 5.6% for the 5-mm sequence and 1.6% for the 3-mm sequence. The six 5-mm DWI false-negative cases (4.8%) were less than 9 mm in diameter (3-8 mm, average 4.67 mm) and located in the brainstem. This supports the hypothesis that small lesions may not be detected on 5 mm DWI due to partial volume averaging.
Conclusion:
Where there is clinical suspicion of infratentorial infarction, 3 mm DWI of the infratentorium adds sensitivity compared to 5 mm DWI with only a small reduction in specificity.
Insights
Thinner 3 mm diffusion-weighted imaging (DWI) significantly improves detection of acute infratentorial infarction compared to standard 5 mm DWI. This enhanced resolution reduces false negatives, aiding in diagnosing small brainstem infarcts.
Area of Science:
- Neuroradiology
- Medical Imaging
Background:
- Diffusion-weighted imaging (DWI) is crucial for acute infarction detection.
- Conventional 5 mm DWI has limitations in infratentorial spatial resolution, leading to higher false-negative rates.
- Acute infratentorial infarction detection requires improved imaging techniques.
Purpose of the Study:
- To compare the diagnostic performance of 3 mm DWI versus 5 mm DWI in detecting acute infratentorial infarction.
- To evaluate the impact of reduced slice thickness on sensitivity and specificity.
Main Methods:
- A 3 mm DWI sequence was integrated into MRI stroke protocols for suspected vertebrobasilar stroke.
- Two blinded neuroradiologists assessed 5 mm and 3 mm DWI sequences.
- Sensitivity and specificity were analyzed against the final clinical diagnosis.
Main Results:
- 3 mm DWI showed higher sensitivity (94.6%) than 5 mm DWI (81.1%) for infratentorial infarction.
- Specificity remained high for both sequences (97.7% for 3 mm, 100% for 5 mm).
- The false-negative rate decreased from 5.6% with 5 mm DWI to 1.6% with 3 mm DWI, particularly for small lesions.
Conclusions:
- 3 mm DWI significantly enhances the detection of acute infratentorial infarction compared to 5 mm DWI.
- The improved sensitivity of 3 mm DWI aids in diagnosing small infarcts missed by thicker slices.
- 3 mm DWI is recommended when infratentorial infarction is clinically suspected, despite a minor specificity decrease.
