Workflow-friendly free-breathing whole-chest cardiovascular MRI using inner-volume balanced T1 relaxation-enhanced steady-state

BACKGROUND: Free-breathing cardiovascular magnetic resonance (CMR) may provide useful volumetric information. This study evaluated acquisition time and the feasibility of incorporating highly accelerated free-breathing inner-volume balanced T1 relaxation-enhanced steady-state (bT1RESS) imaging into a standard CMR protocol during the post-contrast interval before late gadolinium enhancement (LGE). METHODS: A prototype ECG-gated, navigator-gated inner-volume bT1RESS sequence was added to 1.5T CMR examinations in 45 patients; 30 were included in the paired comparison with breath-hold bT1RESS. Series-start timing was assessed in 14 of the 45 patients. Three readers assessed image quality. Aortic diameters were compared between bT1RESS protocols and, in an additional cohort of 15 subjects, with CEMRA. Agreement was assessed separately at five aortic levels using Bland-Altman analysis. RESULTS: Median inner-volume bT1RESS acquisition time was 1.82minutes (range, 0.78-3.72). In the series-start timing subset, median intervals from perfusion/CEMRA start to TI scout and first LGE series were 6.49minutes (n=13) and 8.46minutes (n=14), respectively. Reader preferences favored the inner-volume over breath-hold bT1RESS protocol. In the CEMRA comparison, mean differences (inner-volume bT1RESS minus CEMRA) ranged from 0.00 to 0.93mm; the lower and upper 95% limits of agreement ranged from -2.47 to -1.16mm and from 2.06 to 3.02mm, respectively. CONCLUSION: Inner-volume bT1RESS provided rapid volumetric cardiovascular imaging within the evaluated post-contrast workflow. A primary benefit is the capability for 3D vessel measurement without a separate first-pass CEMRA acquisition. The technique may also help identify coronary artery origins, characterize morphological abnormalities in congenital heart disease and other cardiovascular disorders, and help to detect and characterize extracardiac lesions. Larger studies are needed to establish reproducibility and diagnostic performance.