On-line flow quantification by low-resolution phase-contrast MR imaging and model-based postprocessing

Over the past decade, magnetic resonance (MR) imaging has been developed to ward a tool for guiding and evaluating diagnostic and therapeutic intervent ions. Within the field of vascular MR-guided interventions, MR has potentia l for providing on-line monitoring of the blood volume flow rate, which is relevant during procedures such as balloon angioplasty and stent placement. We recently reported a hardware and software environment for enabling flow quantification every 8 seconds using nontriggered phase-contrast imaging. In the present study, the objective was to increase temporal resolution fur ther to one evaluation per 4 seconds. We achieve this by lowering spatial r esolution to 3 pixels per lumen diameter. The accuracy of the measurements is preserved by applying model-based postprocessing for quantification of t he volume flow rate. Phantom and volunteer studies are presented, demonstra ting the accuracy of the model-driven approach for the applied short acquis itions. The capabilities of the presented approach are illustrated by the r esults of several hypercapnia experiments and carotid compression tests per formed on healthy volunteers. (C) 2000 Wiley-Liss, Inc.