Evaluation of radiofrequency pulses and contrast agent doses for use in 3Dpulmonary magnetic resonance angiography

Ten healthy volunteers were imaged with breath-hold, three-dimensional (3D) time-of-night (TOF) magnetic resonance angiography (MRA) using single-vari able-angle uniform signal excitation (VUSE), double-VUSE, and flat radio-fr equency (RF) pulses with various doses of contrast agent. The ability of ea ch technique to display pulmonary vasculature was evaluated. Images were se gmented to isolate lungs, and maximum intensity projections (MIPs) were com puted. All MIPs were assigned an image quality (IQ) rating, and signal-to-n oise ratios (SNRs) were measured in pulmonary vessels, Without contrast age nt, subsegmental vessels were displayed in single- and double-VUSE images w hile no vessels were visible In hat Images. With equal doses of contrast ag ent, SNRs and IQ ratings were comparable for images obtained with VUSE and hat pulses. In addition, single-VUSE pulses produced more uniform signal fr om vessels than hat pulses in contrast-enhanced images. The results Indicat e that non-contrast-enhanced 3D TOF pulmonary MRA with VUSE RF pulses may b e a useful screening tool. In addition, contrast-enhanced 3D TOF MRA with V USE pulses may be useful as a stand-alone technique for assessing the pulmo nary vasculature or as an adjunct to contrast-enhanced 3D TOF MRA with flat pulses. (C) 1999 Wiley-Liss, Inc.