Usefulness of Noncontrast-Enhanced Silent Magnetic Resonance Angiography (MRA) for Treated Intracranial Aneurysm Follow-up in Comparison with Time-of-Flight MRA

BACKGROUND: Flow visualization in time-of-flight magnetic resonance angiography (TOF MRA) is limited for treated intracranial aneurysms owing to magnetic susceptibility and radiofrequency shielding. OBJECTIVE: To assess the clinical usefulness of noncontrast-enhanced magnetic resonance angiography (MRA) using a silent scan (silent MRA) as a follow-up imaging modality in patients with treated intracranial aneurysms. METHODS: A total of 119 patients with 126 treated aneurysms underwent silent MRA and TOF MRA during the same scan session. Two neuroradiologists independently assessed overall image quality and visualization of the treated site using a 5-point Likert scale to compare the 2 image sets. We used receiver operating characteristic (ROC) curve analysis to investigate the diagnostic performance of the 2 MRA methods in evaluating aneurysm occlusion. Interobserver reliability was also assessed using weighted kappa statistics. RESULTS: The overall image quality scores of silent MRA and TOF MRA were 4.04 ± 0.22 and 4.64 ± 0.48, respectively (P < .001), and interobserver agreement was substantial (P < .001). For the treated site, the score of flow visualization on silent MRA was higher than that on TOF MRA, 3.94 ± 0.94 vs 2.59 ± 1.37 (P < .001), with substantial interobserver agreement (P < .001). ROC curve analysis showed that silent MRA was superior to TOF MRA in diagnostic performance (area under the curve [AUC] = 0.962; 95% CI: 0.931-0.982 vs AUC = 0.843; 95% CI: 0.792-0.886; P < .001). CONCLUSION: Silent MRA can be useful to evaluate treated intracranial aneurysms during follow-up without radiation exposure and use of contrast material. It is characterized by higher diagnostic performance and superior visualization for the treated site.