CINE MAGNETIC-RESONANCE-IMAGING AND COLOR DOPPLER FLOW MAPPING IN INFANTS AND CHILDREN WITH PULMONARY-ARTERY BANDS

Cine magnetic resonance imaging (MRI) and color Doppler flow mapping w ere performed in 12 infants and children (aged 3 to 35 months) after p ulmonary artery banding to define the anatomy and physiology of the ri ght ventricular outflow tract and evaluate the anatomy. MRI was perfor med using a 1.5 Tesla magnet in the saggital, axial and oblique views with all patients studied in the 24 cm head coil following adequate se dation. High-resolution cine MRI was obtained in all patients and the narrowest flow diameter on cine MRI correlated well with the pressure gradient measured across the band in 11 patients at cardiac catheteriz ation or surgery (r = -0.95). Signal loss was always seen distal to th e band associated with turbulent flow as seen by color Doppler flow ma pping, Signal loss in cine MRI was also seen proximal to the band. The length of this proximal signal void also correlated well with the pre ssure gradient measured across the band (r = 0 91) and was closely mat ched by the zone of proximal spatial acceleration defined by digital c omputer analysis of color Doppler flow map images (r = 0.89), which al so demonstrated low grade variance associated with the laminar acceler ating flow stream. The position of the band was accurately defined by cine MRI which identified inadequate pulmonary artery banding in 2 pat ients confirmed subsequently at cardiac catheterization and angiograph y. Cine MRI and color Doppler flow mapping when used together provide high-resolution detail about the right ventricular outflow tract and p ulmonary artery band anatomy and function. Comparative observations of spatial flow velocity information on color Doppler flow mapping allow important insights into the flow visualization characteristics Of cin e MRI.