Diagnosis of Unruptured Intracranial Aneurysms Using Proton-Density Magnetic Resonance Angiography : A Comparison With High-Resolution Time-of-Flight Magnetic Resonance Angiography

Abstract

Objective: Differentiating intracranial aneurysms from normal variants using CT angiography (CTA) or MR angiography (MRA) poses significant challenges. This study aimed to evaluate the efficacy of proton -density MRA (PD-MRA) compared to highresolution time -of -flight MRA (HR-MRA) in diagnosing aneurysms among patients with indeterminate findings on conventional CTA or MRA. Materials and Methods: In this retrospective analysis, we included patients who underwent both PD-MRA and HR-MRA from August 2020 to July 2022 to assess lesions deemed indeterminate on prior conventional CTA or MRA examinations. Three experienced neuroradiologists independently reviewed the lesions using HR-MRA and PD-MRA with reconstructed voxel sizes of 0.25 3 mm 3 or 0.2 3 mm 3 , respectively. A neurointerventionist established the gold standard with digital subtraction angiography. We compared the performance of HR-MRA, PD-MRA (0.25 3 -mm 3 voxel), and PD-MRA (0.2 3 -mm 3 voxel) in diagnosing aneurysms, both per lesion and per patient. The Fleiss kappa statistic was used to calculate inter -reader agreement. Results: The study involved 109 patients (average age 57.4 +/- 11.0 years; male:female ratio, 11:98) with 141 indeterminate lesions. Of these, 78 lesions (55.3%) in 69 patients were confirmed as aneurysms by the reference standard. PD-MRA (0.25 3 -mm 3 voxel) exhibited significantly higher per -lesion diagnostic performance compared to HR-MRA across all three readers: sensitivity ranged from 87.2%-91.0% versus 66.7%-70.5%; specificity from 93.7%-96.8% versus 58.7%-68.3%; and accuracy from 90.8%-92.9% versus 63.8%-69.5% ( P <= 0.003). Furthermore, PD-MRA (0.25 3 -mm 3 voxel) demonstrated significantly superior per -patient specificity and accuracy compared to HR-MRA across all evaluators ( P <= 0.013). The diagnostic accuracy of PD-MRA (0.2 3 -mm 3 voxel) surpassed that of HR-MRA and was comparable to PD-MRA (0.25 3 -mm 3 voxel). The kappa values for inter -reader agreements were significantly higher in PD-MRA (0.820-0.938) than in HR-MRA (0.447-0.510). Conclusion: PD-MRA outperformed HR-MRA in diagnostic accuracy and demonstrated almost perfect inter -reader consistency in identifying intracranial aneurysms among patients with lesions initially indeterminate on CTA or MRA.