STEPS IN THE EVOLUTION OF EXTRACRANIAL TIME-OF-FLIGHT MR-ANGIOGRAPHY

Magnetic resonance (MR) angiography is not a set technique but is cons tantly evolving. This article illustrates changes in image quality in extracranial MR angiography that have been achieved over the past few years by the introduction of several technical developments. Images fr om patients examined at intervals of 12 months or more demonstrate the improvements in image quality that have resulted from these technical changes. These include bandwidth optimization for operation at 1.0 T and changes in flip angle, section thickness, repetition time, and ech o time. Improved image quality was assessed with objective measures of contrast-to-noise and signal-to-noise ratios. The cases illustrated s how the use of MR angiography to evaluate the portal or systemic veins in patients being evaluated for liver transplantation, venous occlusi on, and other venous disease. Improvements in image quality are subjec tively apparent and emphasize the importance of keeping pace with tech nical improvements in MR angiography.