From the Guidelines
Diffusion-weighted imaging (DWI) is the most sensitive and specific MRI sequence for diagnosing cerebral stroke (cerebrovascular accident), with a high sensitivity (88% to 100%) and specificity (95% to 100%) for detecting infarcted regions. This is because DWI can detect acute infarction within minutes after its occurrence, allowing for early identification of the lesion size, site, and age 1. The use of DWI in diagnosing cerebral stroke is supported by the American Heart Association/American Stroke Association guidelines, which recommend DWI as the most sensitive and specific imaging technique for acute infarct 1.
Some of the key benefits of using DWI in diagnosing cerebral stroke include:
- High sensitivity and specificity for detecting infarcted regions
- Ability to detect acute infarction within minutes after its occurrence
- Ability to identify the lesion size, site, and age
- Ability to detect relatively small cortical lesions and small deep or subcortical lesions, including those in the brain stem or cerebellum
- Ability to identify subclinical satellite ischemic lesions that provide information on stroke mechanism
Other MRI sequences, such as T1-weighted, T2-weighted, and fluid-attenuated inversion recovery (FLAIR), are relatively insensitive to the changes of acute ischemia and are not as effective as DWI in diagnosing cerebral stroke 1. However, these sequences may still be useful in certain situations, such as identifying subarachnoid hemorrhage or evaluating the age of the bleeding.
In terms of the overall diagnostic approach, the American Heart Association recommends that MRI, including DWI, be used in the diagnosis of cerebral stroke, particularly in patients who are within 3 hours of onset of symptoms 1. The guidelines also recommend that a vascular study be performed during the initial imaging evaluation of the acute stroke patient, even if within 3 hours from ictus, to further determine the diagnosis of acute stroke.
Overall, DWI is the most important MRI sequence for diagnosing cerebral stroke, and its use is supported by the American Heart Association/American Stroke Association guidelines. Its high sensitivity and specificity make it an essential tool in the diagnosis and management of cerebral stroke.
From the Research
MRI Sequences for Cerebral Stroke Diagnosis
The following MRI sequences are used in the diagnosis of cerebral stroke:
Key Findings
- The combination of DWI and PWI resulted in a sensitivity of 97.5% for the ischemic stroke diagnosis 2
- DWI is more sensitive than CT in detecting acute ischemia 6
- PWI can provide additional information on the infarct extent and perfusion deficit 3, 4
- The volume of the ischemic lesion on admission perfusion CT was correlated with the volume of admission DWI abnormalities 4