Abstract No. 340: Contrast-enhanced and non-contrast MR angiography for the interventionalist

Abstract

1) Review techniques for contrast-enhanced MR Angiography. 2) Review techniques for non-contrast MR Angiography. 3) Provide clinical examples highlighting advantages and differences between contrast-enhanced and non-contrast MR Angiography. 4) Provide suggested guidelines for use of gadolinium agents in patients with renal insufficiency undergoing MR Angiography. Contrast-enhanced MR Angiography is a reference standard for the assessment of arterial disease. Once the examination of choice in patients with renal insufficiency, contrast-enhanced MR Angiography is now limited to patients with a glomerular filtration rate > 30 mL/min. Patients with renal insufficiency can be imaged with MR using non-contrast angiographic techniques which rely on a combination of stationary tissue suppression, flow-related enhancement, and bright-blood sequences. a) Contrast-enhanced MR Angiography: Performed using subtracted gradient echo 3-D datasets following the administration of a gadolinium chelate. The technique is flexible, enabling adjustment of the temporal and spatial resolutions for a given field of view and contrast kinetics. Use of blood pool agents enables prolonged data acquisitions with high spatial resolution. b) Non-contrast MR Angiography: Quiescent interval steady state (QISS) has been used for lower extremity angiography. Native space relies on bright blood sequences and differs from QISS in that it acquires a three-dimensional dataset. Flow-sensitive dephasing is a ECG triggered technique that relies on differences in flow in the arteries and veins between systole and diastole. Navigator gated three dimensional bright blood imaging enables assessment of the thoracoabdominal aorta. c) Comparison of contrast-enhanced and non-contrast techniques in assessment of the thoracic aorta, abdominal aorta, and arteries of the lower extremities. d. Guidelines for MR angiography protocols based on patient renal function will be reviewed. Contrast-enhanced MR angiography can be adapted for arterial assessment in any region of the body. By integrating non-contrast sequences into the clinical workflow, MR angiography can be performed safely in patients with renal insufficiency.