European journal of radiology | 2021
Self-navigated versus navigator-gated 3D MRI sequence for non-enhanced aortic root measurement in transcatheter aortic valve implantation.
Abstract
OBJECTIVES\nTo prospectively compare image-quality, reliability and graft sizing of a prototype self-navigated and a navigator-gated non-contrast three dimensional (3D) whole-heart magnetic-resonance-angiography (MRA) sequence with computed-tomography-angiography (CTA) for planning transcatheter-aortic-valve-implantation (TAVI).\n\n\nMETHODS\nSelf- and navigator-gated 1.5\u202fT MRA were performed in 27 patients (aged 83\u202f±\u202f5 years, 41 % male) for aortic root sizing and coronary ostia height measurements; 15 (56 %) patients underwent additional CTA. Subjective-image quality was graded on a 4-point Likert scale, objective MRA image-quality was assessed by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Continuous MRA and CTA measurements were analyzed with regression and Bland-Altman analysis, valve sizing by kappa statistics.\n\n\nRESULTS\nMedian image-quality as rated by two observers was 1.5 [interquartile range (IQR) 1-3] for self-navigated MRA and 1 [IQR 1-2] for navigator-gated MRA (p\u202f=\u202f0.059). SNR and CNR were comparable between MRA sequences (p\u202f=\u202f0.471 and 0.445, respectively). Acquisition time was shorter for self-navigated MRA compared to navigator-gated MRA (5.5\u202f±\u202f1\u202fmin vs, 6.5\u202f±\u202f2\u202fmin, p\u202f=\u202f0.029). Inter-observer correlation of aortic root measurements was high to very high for both self- and navigator-gated MRA (r\u202f=\u202f0.75 to 0.94 and r\u202f=\u202f0.85 to 0.96, respectively, all p\u202f<\u202f0.0001). Theoretical prosthetic valve sizing of self-navigated MRA and CTA was equivalent (κ\u202f=\u202f1). However, in four patients (15 %) one coronary ostium each (right coronary artery 3, left main artery 1) was not clearly definable on self-navigated MRA.\n\n\nCONCLUSION\nSelf-navigated MRA enables aortic annulus TAVI measurements without significant difference to navigator-gated MRA at shortened acquisition time. Prosthesis sizing by self-navigated MRA measurements is equivalent to navigator-gated MRA and CTA-based choice.