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Evaluation of vascular compression in trigeminal neuralgia by 3D time-of-flight MRA
1Department of Radiology, Kumamoto University School of Medicine, Japan.
Objective:
Our goal was to assess the usefulness of 3D images in the preoperative evaluation of 16 patients with surgically confirmed trigeminal neuralgia.
Materials And Methods:
The axial source images from 3D TOF MRA were evaluated for a total of 32 sides by two observers in a blinded manner, focusing on the presence of the neurovascular compression and the identification of compressing vessels. All 3D images including coronal orientation and gadolinium-enhanced images were reviewed retrospectively by another two observers together with the surgical findings.
Results:
In the blinded study with axial 3D images, the sensitivity was 75 and 75% with a specificity of 75 and 69% for observers A and B, respectively. By reviewing the coronal images, the relationship between trigeminal nerve and vessels became clearer, especially in sandwich-type compression. With gadolinium-enhanced images, three vessels that were not shown in the nonenhanced images could be identified. On the asymptomatic side, vascular compression could not be excluded retrospectively in five cases.
Conclusion:
Nonenhanced axial images may not display small arteries or veins that are compressing the trigeminal nerve. Gadolinium enhancement will be necessary for those patients without demonstrable compression on nonenhanced examination. Coronal images are also helpful in the evaluation of vascular compression.