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Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia
Published on: September 20, 2015
Fluid-attenuated inversion recovery and diffusion- and perfusion-weighted MRI abnormalities in 117 consecutive
C J Perkins1, E Kahya, C T Roque
1Department of Neurology, SUNY at Stony Brook, Stony Brook, NY, USA. cjerkins@notes.cc.sunysb.edu
Background And Purpose:
Diffusion-weighted MRI (DWI) is highly sensitive to early cerebral ischemia, but its dependence on lesion location, acuity, and etiology remains unknown. Furthermore, although a marked perfusion-weighted MRI (PWI)-DWI mismatch may exist in a subset of acute strokes, the frequency and distribution of these mismatches have never been methodically characterized in an unselected population. To address these 2 issues, we evaluated echo-planar imaging in 117 consecutive patients with signs and symptoms of acute stroke.
Methods:
Clinical diagnoses were determined by chart review. Fluid-attenuated inversion recovery (FLAIR), DWI, and PWI sequences were scored for lesion acuity, neuroanatomy, and vascular territory. Lesion and PWI-DWI mismatch volumes were determined by image analysis.
Results:
DWI was more sensitive than was FLAIR for the detection of stroke for all subtypes in all anatomic distributions and at all tested time intervals. Although DWI exhibited its greatest benefit over FLAIR during the first 6 hours, it was still superior to FLAIR even after 24 hours. PWI abnormalities were detected in 49% of patients with DWI abnormalities. In the majority of these cases, the PWI-DWI mismatch was substantially larger than the DWI lesion itself. Both the largest DWI lesion volumes and the largest mismatch volumes occurred in patients with carotid disease.
Conclusions:
DWI nearly doubles the likelihood of detecting acute ischemic stroke lesions compared with FLAIR for all etiologies and in all anatomic locations. In the hyperacute period (0 to 6 hours), DWI more than triples the likelihood of acute-stroke detection over FLAIR. PWI reveals a measurable mismatch compared with DWI nearly 50% of the time; and in more than half of these patients, the ratio of the volume of the PWI lesion to the DWI lesion is several times larger than the core ischemic lesion itself. In the final analysis, approximately one fourth of all stroke patients present with a large volume of potentially salvageable tissue at risk for infarction.
Insights
Diffusion-weighted MRI (DWI) significantly improves acute ischemic stroke detection compared to FLAIR, especially within 6 hours. Perfusion-weighted MRI (PWI) reveals a mismatch with DWI in nearly half of patients, indicating potentially salvageable tissue.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Diffusion-weighted MRI (DWI) is sensitive to early cerebral ischemia.
- The location, acuity, and etiology dependence of DWI is not well understood.
- Perfusion-weighted MRI (PWI)-DWI mismatch frequency and distribution in unselected acute stroke populations are largely uncharacterized.
Purpose of the Study:
- To evaluate echo-planar imaging in 117 consecutive patients with acute stroke symptoms.
- To determine the diagnostic utility of DWI compared to FLAIR for stroke detection.
- To characterize the frequency and volume of PWI-DWI mismatches in acute stroke.
Main Methods:
- Clinical diagnoses were confirmed via chart review.
- FLAIR, DWI, and PWI sequences were analyzed for lesion acuity, neuroanatomy, and vascular territory.
- Lesion and PWI-DWI mismatch volumes were quantified through image analysis.
Main Results:
- DWI demonstrated superior sensitivity for stroke detection across all subtypes, locations, and time intervals compared to FLAIR.
- DWI's benefit over FLAIR was most pronounced within the first 6 hours but remained significant even after 24 hours.
- PWI abnormalities were present in 49% of patients with DWI abnormalities, with PWI-DWI mismatches often substantially larger than DWI lesions, particularly in cases of carotid disease.
Conclusions:
- DWI nearly doubles the detection rate of acute ischemic stroke lesions compared to FLAIR, irrespective of etiology or location.
- In the hyperacute phase (0-6 hours), DWI more than triples the detection rate over FLAIR.
- Approximately 25% of stroke patients exhibit a large PWI-DWI mismatch, signifying a substantial volume of potentially salvageable brain tissue at risk of infarction.
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