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Published on: September 16, 2017
Diagnosis of Unruptured Intracranial Aneurysms Using Proton-Density Magnetic Resonance Angiography: A Comparison With
Pae Sun Suh1, Seung Chai Jung2, Hye Hyeon Moon3
1Department of Radiology, Research Institute of Radiological Science and Center for Clinical Imaging Data Science, Yonsei University College of Medicine, Seoul, Republic of Korea.
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 high-resolution 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 0.253 mm3 or 0.23 mm3, respectively. A neurointerventionist established the gold standard with digital subtraction angiography. We compared the performance of HR-MRA, PD-MRA (0.253-mm3 voxel), and PD-MRA (0.23-mm3 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 (0.253-mm3 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 (0.253-mm3 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 (0.23-mm3 voxel) surpassed that of HR-MRA and was comparable to PD-MRA (0.253-mm3 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.
Insights
Proton-density MRA (PD-MRA) significantly improves the diagnosis of intracranial aneurysms compared to high-resolution MRA (HR-MRA). PD-MRA offers higher accuracy and reader agreement for indeterminate findings on conventional imaging.
Area of Science:
- Neuroimaging and Radiology
- Vascular Neurology
- Medical Diagnostics
Background:
- Distinguishing intracranial aneurysms from normal vascular variants using CT angiography (CTA) and MR angiography (MRA) presents diagnostic challenges.
- Conventional CTA and MRA can yield indeterminate findings, necessitating advanced imaging techniques for accurate aneurysm diagnosis.
- High-resolution time-of-flight MRA (HR-MRA) is a standard technique, but its efficacy in equivocal cases requires further evaluation.
Purpose of the Study:
- To compare the diagnostic performance of proton-density MRA (PD-MRA) against HR-MRA in identifying intracranial aneurysms.
- To evaluate PD-MRA's efficacy in patients with indeterminate findings on prior conventional CTA or MRA examinations.
- To assess inter-reader agreement and diagnostic accuracy of PD-MRA versus HR-MRA.
Main Methods:
- Retrospective analysis of 109 patients with indeterminate lesions on conventional angiography, who underwent both PD-MRA and HR-MRA.
- Independent review of lesions by three neuroradiologists using HR-MRA and PD-MRA with specific voxel sizes (0.25³ mm³ and 0.2³ mm³).
- Digital subtraction angiography served as the gold standard; Fleiss kappa statistic calculated inter-reader agreement.
Main Results:
- PD-MRA (0.25³ mm³ voxel) demonstrated significantly higher per-lesion sensitivity (87.2%-91.0% vs. 66.7%-70.5%) and specificity (93.7%-96.8% vs. 58.7%-68.3%) compared to HR-MRA.
- Per-patient diagnostic accuracy and specificity were significantly superior with PD-MRA (0.25³ mm³ voxel) over HR-MRA across all readers (P ≤ 0.013).
- PD-MRA showed significantly higher inter-reader agreement (kappa 0.820-0.938) compared to HR-MRA (kappa 0.447-0.510).
Conclusions:
- Proton-density MRA (PD-MRA) significantly outperforms HR-MRA in the diagnostic accuracy of intracranial aneurysms, particularly in challenging indeterminate cases.
- PD-MRA exhibits superior inter-reader consistency, indicating improved reliability for aneurysm detection.
- PD-MRA is a valuable advanced imaging tool for clarifying indeterminate findings and improving diagnostic confidence in neurovascular evaluations.
