Pulse Wave Velocity Measurements by Magnetic Resonance Imaging in Neonates and Adolescents: Methodological Aspects and Their Clinical Implications.

Pulse wave velocity (PWV) by cardiovascular magnetic resonance (CMR) lacks standardization. The aim of this study was to investigate methodological aspects of PWV measurements by CMR in neonates and adolescents. A computer phantom was created to validate the temporal resolution required for accurate PWV. Fifteen neonates and 71 adolescents underwent CMR with reference standard 3D angiography and phase-contrast flow acquisitions, and in a subset coronal overview images. Velocity and flow curves, transit time methods (time-to-foot (TTF), maximum upslope, and time-to-peak (TTP)), and baseline correction methods (no correction, automatic and manual) were investigated. In neonates, required timeframes per cardiac cycle for accurate PWV was 42 for the aortic arch and 41 for the thoracic aorta. In adolescents, corresponding values were 39 and 32. Aortic length differences by overview images and 3D angiography in adolescents were - 16-18 mm (aortic arch) and - 25-30 mm (thoracic aorta). Agreement in PWV between automatic and manual baseline correction was - 0.2 ± 0.3 m/s in neonates and 0.0 ± 0.1 m/s in adolescents. Velocity and flow-derived PWV measurements did not differ in either group (all p > 0.08). In neonates, transit time methods did not differ (all p > 0.19) but in adolescents PWV was higher for TTF (3.8 ± 0.5 m/s) and maximum upslope (3.7 ± 0.6 m/s) compared to TTP (2.7 ± 1.0 m/s; p < 0.0001). This study is a step toward standardization of PWV in neonates and adolescents using CMR. It provides required temporal resolution for phase-contrast flow acquisitions for typical heartrates in neonates and adolescents, and supports 3D angiography and time-to-foot with automatic baseline correction for accurate PWV measurements.