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[Diffusion-weighted magnetic resonance imaging (MRI) in acute brain stem infarction]
A Narisawa1, H Shamoto, H Shimizu
1Department of Neurosurgery, Kohnan Hospital, 4-20-1 Nagamachi-Minami, Taihaku-ku, Sendai 982-8523, Japan.
Abstract:
Diffusion-weighted magnetic resonance imaging (DWI) provides one of the earliest demonstrations of ischemic lesions. However, some lesions may be missed in the acute stage due to technical limitation of DWI. We therefore conducted the study to clarify the sensitivity of DWI to acute brain stem infarctions. Twenty-eight patients with the final diagnosis of brain stem infarction(midbrain 2, pons 9, medulla oblongata 17) who had been examined by DWI within 24 hours of onset were retrospectively analyzed for how sensitively the initial DWI demonstrated the final ischemic lesion. Only obvious(distinguishable with DWI alone without referring clinical symptoms and other informations) hyperintensity on DWI was regarded to show an ischemic lesion. Sixteen(57.1%) out of 28 patients had brain stem infarctions demonstrated by initial DWI. In the remaining 12 cases, no obvious ischemic lesion was evident on initial DWI. Subsequent MRI studies obtained 127 hours, on average after the onset showed infarction in the medulla oblongata in 11 cases and in the pons in one case. Negative findings of DWI in the acute stage does not exclude possibility of the brain stem infarction, in particulary medulla oblongata infarction.
Insights
Diffusion-weighted imaging (DWI) can miss acute brain stem infarctions, particularly in the medulla oblongata. Later MRI scans confirmed lesions in most cases initially missed by DWI, highlighting its limitations in early detection.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Context:
- Diffusion-weighted imaging (DWI) is a key MRI technique for detecting acute ischemic lesions.
- Technical limitations of DWI can lead to missed diagnoses in the early stages of stroke.
- Brain stem infarctions present unique diagnostic challenges due to their location and potential for subtle imaging findings.
Purpose:
- To evaluate the sensitivity of initial diffusion-weighted imaging (DWI) in detecting acute brain stem infarctions within 24 hours of symptom onset.
- To determine the rate of missed ischemic lesions on acute DWI in patients with confirmed brain stem infarctions.
- To assess the utility of follow-up MRI in diagnosing brain stem infarctions initially not visualized on DWI.
Summary:
- This retrospective study analyzed 28 patients with confirmed brain stem infarctions who underwent DWI within 24 hours of onset.
- Only 57.1% of acute brain stem infarctions were clearly visualized on initial DWI; 12 cases showed no obvious lesions.
- Follow-up MRI, performed an average of 127 hours later, confirmed infarction in 11 of the 12 initially negative DWI cases, predominantly in the medulla oblongata.
Impact:
- Acute DWI has limited sensitivity for detecting brain stem infarctions, especially in the medulla oblongata.
- Negative acute DWI findings do not rule out brain stem infarction and warrant further investigation with follow-up imaging.
- Understanding DWI limitations is crucial for timely diagnosis and management of acute stroke in the brain stem.