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[FLAIR images of subarachnoid hemorrhage]
Abstract:
We studied MR fluid attenuated inversion recovery (FLAIR) pulse sequences in 37 cases with subarachnoid hemorrhage caused by aneurysmal rupture. FLAIR sequence suppressed the CSF signal and produced very heavy T2 weighted images. This has been of particular benefit in identifying lesions at the margins of the brain, around the basal cisterns, in the brain stem and at the gray-white matter junction. Based on these findings, we were able to detect the subarachnoid hemorrhage. Subarachnoid hemorrhage was able to be demonstrated as high signal intensity on FLAIR sequences in all patients. Clear visualization of acute subarachnoid hemorrhage was able to be obtained by MR FLAIR sequences in not only Fisher's group 3 or 4, but also Fisher's group 2. Moreover it was suited for the detection of intraaxial hematoma, Sylvian hematoma, subdural hematoma and subarachnoid hemorrhage in the posterior fossa and interhemispheric fissure. Especially, it was useful for detecting intraventricular hemorrhage. Therefore, if patients suffering from subarachnoid hemorrhage present slight headache or atypical symptoms, sometimes it may be more suitable to perform MRI FLAIR pulse sequences first. Aneurysms were found in 21 cases (56.8%). When the aneurysmal size is more than 7 mm, the rate of detection becomes 100%. Aneurysms present various MR appearances because of flow characteristics. Aneurysms were demonstrated as low signal intensity except in 3 cases. In one out of 3 cases, aneurysms were revealed as high signal intensity and in the other two cases, it was revealed as mixed signal intensity. According to the previous studies, rapid flow was demonstrated as low signal intensity by vascular flow void, and delayed flow was demonstrated as high or mixed signal intensity by flow related enhancement and even echo rephasing. MR clearly delineates the size, the lumen, the flow, and the extraaxial location of aneurysms. In conclusion, MR FLAIR pulse sequences could be reliable and useful for diagnosis of subarachnoid hemorrhage, especially as screening tests for outpatients.
Insights
Magnetic Resonance Imaging (MRI) Fluid Attenuated Inversion Recovery (FLAIR) pulse sequences effectively detect subarachnoid hemorrhage, even in early stages. This advanced MRI technique aids in identifying aneurysms and various hematoma types, improving diagnostic accuracy.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Subarachnoid hemorrhage (SAH) is a critical neurological condition often caused by ruptured aneurysms.
- Accurate and timely diagnosis of SAH is crucial for patient outcomes.
- Traditional imaging methods may have limitations in detecting subtle SAH.
Observation:
- MR Fluid Attenuated Inversion Recovery (FLAIR) pulse sequences were evaluated in 37 patients with suspected aneurysmal rupture.
- FLAIR sequences demonstrated suppressed cerebrospinal fluid (CSF) signals, enhancing T2-weighted image contrast.
- Specific anatomical regions, including basal cisterns and gray-white matter junctions, showed improved lesion visualization.
Findings:
- SAH was detected as high signal intensity on FLAIR sequences in all patients, including early Fisher groups.
- FLAIR sequences effectively identified various hematoma types: intraaxial, Sylvian, subdural, and intraventricular.
- Aneurysms were detected in 56.8% of cases, with 100% detection for those larger than 7 mm.
Implications:
- MRI FLAIR pulse sequences are a reliable and useful tool for diagnosing SAH, particularly in patients with atypical symptoms.
- FLAIR sequences offer superior visualization of SAH and associated pathologies compared to conventional methods.
- Consideration of MRI FLAIR as a primary screening tool for SAH in outpatient settings is recommended.