MRA: Current Applications in Body Vascular Imaging

Abstract

Computed tomography (CT) angiography (CTA) and magnetic resonance (MR) angiography (MRA) are 2 modalities that have revolutionized the field of diagnostic vascular imaging. Conventional catheter angiography, which was once the gold standard, is now being replaced by CTA and MRA because of their lower cost and noninvasiveness. Advancements in cross-sectional imaging include higher spatial and temporal resolution, as well as the ability to construct three-dimensional (3D) images from volumetric data and to view vessels from multiple angles [1]. CTA is traditionally more widely used than MRA, mainly because of availability and greater CT expertise. Other advantages of CTA over MRA include faster acquisition times, higher spatial resolution, and utility in patients with contraindications to MR imaging, including certain aneurysm clips, cochlear implants, pacemakers, and claustrophobia [1,2]. Current uses of CTA are many, including perioperative imaging and planning of endovascular aneurysm repairs (EVAR) and imaging of the abdominal aorta and visceral vessels [3]. Disadvantages of CTA include the use of ionizing radiation and iodinated nephrotoxic contrast material, 2 factors that make MRA a more desirable modality. Using MR to delineate vascular anatomy has changed dramatically since first described in 1985 by Wedeen et al [4]. Technology continuously evolves and provides more advanced equipment and complex software, which is faster and provides more detailed information. MR sequences such as phase-contrast (PC) MRA (PC-MRA) and time-of-flight (TOF) MRA (TOF-MRA) provide reasonable depictions of the vascular anatomy without contrast. Research into nonnephrotoxic, gadolinium-based contrast agents has paved the way for contrast-enhanced MRA (CE-MRA), which today is widely used in clinical practice [5]. MRA is gaining popularity as applications increase image quality and decrease acquisition time. Dynamic MRA