Highly accelerated contrast-enhanced MR angiography: improved reconstruction accuracy and reduced noise amplification with complex subtraction.

Contrast-enhanced magnetic resonance angiography is routinely performed using parallel imaging to best capture the first pass of contrast material through the target vasculature, followed by digital subtraction to suppress the appearance of unwanted signal from background tissue. Both processes, however, amplify noise and can produce uninterpretable images when large acceleration factors are used. Using a phantom study of contrast-enhanced magnetic resonance angiography, we show that complex subtraction processing prior to partially parallel reconstruction improves reconstruction accuracy relative to magnitude subtraction processing for reduction factors as large as 12. Time-resolved contrast-enhanced magnetic resonance angiographic data obtained with complex subtraction in volunteers supported the results of the phantom study and when compared with magnitude subtraction processing demonstrated reduced geometry factors as well as improved image quality at large reduction factors.