Intraindividual comparison of 1.5 T and 3 T non-contrast MR angiography for monitoring of aortic root diameters in Marfan patients

BACKGROUND: Reproducible aortic diameter measurements are crucial for assessment of aortic growth and aneurysm formation in patients with Marfan syndrome. The objective of this study was to perform an intraindividual comparison of aortic measurements at 1.5 T and 3 T using non-contrast magnetic resonance angiography (MRA) in pre-surgical and post-surgical Marfan patients.

METHODS: Forty consecutive Marfan patients were retrospectively evaluated by ECG-gated 2D balanced steady-state free precession (bSSFP) MRA at 1.5 T and 3 T after 363 ± 58 days. 24 patients were before and 16 patients after aortic root surgery. Two readers independently measured aortic diameters at seven aortic levels and rated the image quality/image artifacts (1 = poor/severe, 4 = excellent/none). Contrast-to-noise ratio (CNR) and signal intensity slopes between aortic lumen and vessel walls were semiautomatically determined.

RESULTS: In pre-surgical Marfan patients, interobserver agreement of aortic root diameter measurements was significantly higher at 3 T compared to 1.5 T (p < 0.05). In post-surgical Marfan patients, image quality and artifacts were significantly worse at 3 T compared to 1.5 T (p < 0.05). CNR was higher at 3 T compared to 1.5 T at all aortic levels. Significantly steeper slopes of signal intensity curves were observed at 3 T at all aortic levels (p < 0.001).

CONCLUSIONS: In pre-surgical Marfan patients, non-contrast MRA provides higher reproducibility of aortic diameter measurements at 3 T compared to 1.5 T. In post-surgical Marfan patients, metallic implants result in significantly worse imaging artifacts and reduced image quality at 3 T compared to 1.5 T. Therefore, we propose to monitor the thoracic aorta with non-contrast MRA at 3 T in pre-surgical Marfan patients and at 1.5 T in post-surgical Marfan patients.