MR angiography with gadolinium contrast (CMRA) has been considered to be the gold-standard for measuring vessels. This sequence prolongs the study time, exposes the patient to intravenous contrast administration, and requires breath-holding (median time for an acquisition: 17 seconds). Our objective was to determine if free-breathing sequences that do not require contrast (Fast SPGR or Time Of Flight (TOF) and 3D SSFF with Navigator (Child)) provide comparable quantitative information.
Methods: 51 patients with congenital heart disease who underwent CMRA and TOF or Child sequences were analyzed independently by three observers. The ascending and descending aorta and the branch pulmonary arteries were measured by each operator at standardized locations from images obtained using each sequence.
Results: The measures obtained from CMRA and TOF/Child images were highly correlated (range of r = 0.89-0.95). Bland-Altman analysis showed excellent agreement (mean difference +0.008 mm to -1.9 mm) with a small bias toward larger measures from CMRA. This might reflect a ‘bloom’ artefact from the contrast or motion artefact due to difficulty with breath-holding in young patients, but does not seem to be of clinical importance. The interobservatory variability was inferior to 7.5% and 14.7% in the aortic and the pulmonary measures respectively.
Conclusions: Non-contrast, free-breathing volumetric sequences provide quantitative information comparable to CMRA and can be used interchangeably in clinical follow-up. Use of CMRA can be avoided in selected patients.