Non-Contrast Magnetic Resonance Angiography for Endovascular Aneurysm Repair Planning in Abdominal Aortic Aneurysms: Acquisition Development and Comparison to Contrast-Enhanced Computed Tomography Angiography

Objective: To develop a non-contrast magnetic resonance angiography (NC-MRA) that offers an ionizing radiation and contrast agent-free alternative to computed tomography angiography (CTA) for detailed assessment of abdominal aortic aneurysms (AAAs). Secondly, the suitability of NC-MRA for endovascular aneurysm repair (EVAR) planning compared to CTA was assessed. Methods: A motion-resolved 3-dimensional balanced steady-state free precession (bSSFP) magnetic resonance angiography (MRA) was performed at 3.0 T and optimized to achieve image quality comparable to CTA without requiring breath-holding. Nineteen morphometric measurements (diameter, length, and angle) in 9 prospectively included male patients (median age 66 [8] years; maximum AAA diameter 57 [10] mm, ClinicalTrials.gov ID: NCT05976711) were assessed by 5 observers and 3 aortic sizing specialists based on NC-MRA and standard CTA. The suitability of NC-MRA for EVAR planning was assessed through qualitative observer evaluation, interobserver agreement (2-way random-effects, absolute-agreement, single-measure intraclass correlation coefficient [ICC]), non-inferiority analysis with a 1-sided 1-sample t test, and agreement in Medtronic Endurant II/IIs endograft selection. Results: The acquisition parameters of the resulting NC-MRA sequence are comparable to standard CTA. Image suitability was rated as excellent in 11 (20.4%) cases, good in 28 (51.9%) cases, and moderate in 15 (27.8%) cases. The interobserver variability for assessing morphometric parameters was comparable between NC-MRA (mean = 0.74) and CTA (mean = 0.73). The NC-MRA was non-inferior to CTA for all neck diameters, half of the iliac artery diameters, one of the length diameters, and for vessel angulation. Regarding stent selection: 1 observer showed complete agreement between modalities, 3 observers showed 1 discrepancy, and 2 observers showed 1 discrepancies. Conclusion: The developed NC-MRA sequence demonstrated interobserver variability comparable to CTA and was non-inferior for the majority of morphometric measurements. The sequence demonstrates potential for routine clinical use, as it is easily implementable within the current clinical workflow, with additional observer training likely to further enhance performance. Clinical Impact This study demonstrates a rapid, 3D non-contrast magnetic resonance angiography (NC-MRA) acquisition developed for endovascular aneurysm repair (EVAR) planning. Unlike most previously developed techniques the resulting acquisition parameters are highly comparable to computed tomography angiography (CTA), facilitating both implementation in the clinical workflow and reliable morphometric assessment. Morphometric parameters were assessed by EVAR specialists from diverse clinical backgrounds who were primarily experienced in CTA and received NC-MRA training, reflecting real-world clinical adoption. NC-MRA showed interobserver variability similar to CTA and was non-inferior for most morphometric measurements. With additional observer training, this technique may be suitable for clinical implementation.