iREACT: A Non-contrast Non-triggered MR Angiography Technique with Reduced RF Deposition

Relaxation enhanced angiography without contrast and triggering (REACT) is a non-contrast-enhanced angiography technique that highlights blood and suppresses the low T2 and T1 background tissues by using a combination of T2prep and inversion modules, respectively. In this work, the T2prep module is modified to effectively perform both T2prep and inversion. This eliminates the need for a separate inversion pulse. The modified sequence (iREACT) is compared with REACT through a subjective evaluation based on blood vessel delineation, muscle and fat suppression efficacy. Further an objective analysis was performed for these parameters by measuring the blood-muscle and water-fat contrast ratios. iREACT shows comparable suppression of muscle and delineation of blood vessels whereas fat suppression efficacy is reduced at tissue boundaries and the edge of larger field of views. Efficient background suppression is achieved with a reduced RF load. This is a step towards safe and easy non-contrast MR angiography.