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Yield of diffusion-weighted MRI for detection of potentially relevant findings in stroke patients
G W Albers1, M G Lansberg, A M Norbash
1Stanford Stroke Center, Palo Alto, CA 94304, USA. albers@leland.stanford.edu
Objective:
To determine whether diffusion-weighted imaging (DWI) could identify potentially clinically relevant findings in patients presenting more than 6 hours after stroke onset when compared with conventional MRI.
Methods:
MRI with both conventional (T2 and proton density images) and echoplanar imaging (DWI and apparent diffusion coefficient maps) was performed 6 to 48 hours after symptom onset (mean, 27 hours) in 40 consecutive patients with acute stroke. All acute lesions were identified first on conventional images, then on DWI, by a neuroradiologist who was provided with the suspected lesion location, based on a neurologist's examination before imaging. Abnormalities were rated as potentially clinically relevant if they were detected only on DWI and 1) confirmed the acute symptomatic lesion to be in a different vascular territory than suspected clinically, 2) revealed multiple lesions in different vascular territories suggestive of a proximal source of embolism, or 3) clarified that a lesion, thought to be acute on conventional imaging, was not acute.
Results:
The initial clinical impression of lesion localization was incorrect in 12 patients (30%). Clinically significant findings were detected by DWI alone in 19 patients (48%). DWI demonstrated the symptomatic lesion in a different vascular territory than suspected clinically or by conventional MRI in 7 patients (18%) and showed acute lesions in multiple vascular distributions in 5 patients (13%). In 8 patients (20%), DWI clarified that lesions thought to be acute on conventional MRI were actually old.
Conclusion:
In patients imaged 6 to 48 hours after stroke onset, DWI frequently provided potentially clinically relevant findings that were not apparent on conventional MRI.
Insights
Diffusion-weighted imaging (DWI) frequently reveals clinically significant findings in stroke patients presenting after 6 hours, offering crucial insights beyond conventional MRI. This advanced imaging technique aids in accurate lesion localization and characterization.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Acute stroke diagnosis relies on timely and accurate imaging.
- Conventional MRI may have limitations in detecting subtle or early ischemic changes.
- Diffusion-weighted imaging (DWI) offers advanced capabilities for visualizing acute ischemic lesions.
Purpose of the Study:
- To evaluate the utility of diffusion-weighted imaging (DWI) in identifying clinically relevant findings in acute stroke patients presenting more than 6 hours after symptom onset.
- To compare the diagnostic performance of DWI against conventional MRI sequences in this patient cohort.
Main Methods:
- MRI including conventional sequences (T2, proton density) and echoplanar imaging (DWI, ADC maps) was performed in 40 acute stroke patients between 6 and 48 hours post-onset.
- A neuroradiologist identified lesions on conventional MRI and DWI, with suspected lesion location provided by a neurologist.
- Clinical relevance of DWI findings was assessed based on accurate localization, detection of multiple embolic sources, or differentiation of acute from old lesions.
Main Results:
- The initial clinical localization of the stroke lesion was incorrect in 30% of patients.
- DWI alone provided clinically significant findings in 48% of patients.
- DWI correctly localized the symptomatic lesion in 18% of cases, identified multiple lesions in 13%, and reclassified old lesions as non-acute in 20%.
Conclusions:
- Diffusion-weighted imaging (DWI) frequently uncovers clinically relevant information not visible on conventional MRI in patients presenting 6-48 hours after stroke.
- DWI enhances diagnostic accuracy for lesion localization and characterization in the hyperacute and acute stroke phases.
- The findings support the integration of DWI into the standard MRI protocol for evaluating patients with suspected acute stroke, even beyond the 6-hour window.