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A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
Diffusion-weighted imaging in acute stroke
Pamela W Schaefer1, Wiliam A Copen, Michael H Lev
1Massachusetts General Hospital, and Harvard Medical School, Boston, MA 02114, USA. pschaefer@partners.org
Abstract:
Diffusion MR imaging has improved evaluation of acute ischemic stroke vastly. It is highly sensitive and specific in the detection of infarction at early time points when CT and conventional MR sequences are unreliable. The initial DWI lesion is believed to represent infarction core and usually progresses to infarction unless there is early reperfusion. The initial DWI lesion volume and ADC ratios correlate highly with final infarction volume and with acute and chronic neurologic assessment tests. ADC values may be useful in differentiating tissue destined to infarct from that potentially salvageable with reperfusion therapy. ADC values also may be useful for determining tissue at risk of HT after reperfusion therapy. DTI can quantify differences in the responses of gray versus white matter to ischemia. FA may be important in determining stroke onset time, and tractography provides early detection of wallerian degeneration that may be important in determining prognosis. Finally, DWI can determine which patients who have TIA are at risk for subsequent large vessel infarction and can differentiate stroke from stroke mimics. With improvements in MR software and hardware, diffusion MR undoubtedly will continue to improve the management of patients who have acute stroke.
Insights
Diffusion MR imaging aids in early acute ischemic stroke detection and evaluation. This advanced technique helps differentiate salvageable tissue and predict outcomes, improving stroke management.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Acute ischemic stroke diagnosis relies on timely and accurate imaging.
- Conventional CT and MRI sequences have limitations in early stroke detection.
- Diffusion MR imaging offers high sensitivity and specificity for early infarction.
Purpose of the Study:
- To highlight the advancements and applications of Diffusion MR imaging in acute ischemic stroke.
- To discuss the role of Diffusion Weighted Imaging (DWI) and Apparent Diffusion Coefficient (ADC) in stroke evaluation.
- To explore the potential of Diffusion Tensor Imaging (DTI) in assessing stroke pathophysiology and prognosis.
Main Methods:
- Utilizing Diffusion MR imaging techniques, including DWI, ADC mapping, and DTI.
- Correlating initial DWI lesion volume and ADC ratios with final infarct volume and neurological assessments.
- Analyzing Fractional Anisotropy (FA) and tractography for stroke onset time and Wallerian degeneration detection.
Main Results:
- Initial DWI lesions accurately represent infarction core and predict final infarct volume.
- ADC values differentiate between infarcted and salvageable tissue, aiding reperfusion therapy decisions.
- DTI parameters like FA and tractography offer insights into gray/white matter responses and degeneration.
Conclusions:
- Diffusion MR imaging significantly enhances the evaluation of acute ischemic stroke.
- ADC values are crucial for guiding reperfusion therapy and predicting hemorrhagic transformation risk.
- Advanced diffusion techniques like DTI show promise in determining stroke onset and prognosis.
