High-Resolution Time-of-Flight Magnetic Resonance Angiography with a Volume Rendering Algorithm for Detection of Unruptured Aneurysms: Correlations with Digital Subtraction Angiography

Objective: We investigated the diagnostic accuracy of high-resolution magnetic resonance angiography (HR-MRA) with volume rendering (VR) post-processing techniques for the detection of cerebral aneurysms compared with conventional MRA (C-MRA) using digital subtraction angiography (DSA) as the gold standard.Methods: HR-MRA was performed for 51 possible aneurysms of 38 patients on C-MRA. For each possible aneurysm, readers recorded their level of confidence on a 5-point scale. All patients underwent DSA, which was used as the standard of reference. Receiver-operating characteristic (ROC) analysis and the area under the ROC curves (AUC) were used to determine the effectiveness of C-MRA and HR-MRA in detecting cerebral aneurysm with and without VR algorithm. The increased discriminative value was examined by calculation of Net Reclassification Index (NRI) and Integrated Discrimination Improvement (IDI) index.Results: DSA revealed 37 aneurysms in 26 patients. In aneurysm-based analysis, HR-MRA showed higher diagnostic accuracy than C-MRA, and increased diagnostic accuracy on adding VR (C-MRA vs. HR-MRA, P< 0.01; C-MRA with VR vs. HR-MRA with VR, P< 0.01, respectively). The differences in AUC, IDI (19.38%, Z= 3.18, P< 0.01) and NRI (46.3%, Z= 6.32, P< 0.01), on adding VR to the HR-MRA, were also statistically significant. The application of HR-MRA with VR increased the detection rate of aneurysms less than 3 mm.Conclusion: The application of HR-MRA with VR algorithm improves diagnostic performance for the detection of intracranial aneurysms, especially when the aneurysm is less than 3 mm. Clinically, HR-MRA with VR algorithm could facilitate the accurate differentiation of aneurysms from infundibula and prevent unnecessary, invasive procedure before aneurysmal rupture.