Three-dimensional time-of-flight MR angiography in trigeminal neuralgia on a 0.5-T system

The goal of this study was to analyze the diagnostic value of three-dimensional time-of-flight magnetic resonance angiography (3D TOF MRA), performed on a 0.5-T system in the detection of neurovascular compression in patients with trigeminal neuralgia (TN). One hundred seventy-two TN patients were examined using plain and contrast-enhanced 3D TOF MRA on a 0.5-T system. Maximum intensity projection (MIP) reconstruction was performed in three standard planes. Both the original and the reconstructed images were studied to search for vascular compression shown by close neurovascular contact and/or dislocation of the trigeminal nerve. Forty-two TN patients underwent surgical exploration of the posterior fossa. Results of MRA were compared with clinical data in all cases and to result of surgery in the surgically treated cases. Neurovascular contact at the root entry zone of the trigeminal nerve was detected on the symptomatic side in 94 patients, and on the asymptomatic side in 12 patients. Sensitivity, specificity, accuracy, as well as positive and negative predictive value of 3D TOF MRA in the detection of neurovascular compression in the patient group undergoing surgery, were 97.6, 92.5, 95.0, 93.0, and 97.4%, respectively. Three-dimensional TOF MRA performed on a 0.5-T system appears to be not less effective than similar examinations by higher field strength devices in the detection of neurovascular contact. This sequence accurately demonstrates the presence of neurovascular compression, and in this way valuable information may be achieved for the planning of surgical therapy of patients with trigeminal neuralgia.