Validation of injection parameters for catheter-directed intraarterial gadolinium-enhanced MR angiography

• Published in: Academic radiology Vol. 9; no. 2; p. 172
• Main Authors: Omary, Reed A, Henseler, Kevin P, Unal, Orhan, Smith, Randall J, Ryu, Robert K, Resnick, Scott A, Saker, Mark B, Chrisman, Howard B, Frayne, Richard, Finn, J Paul, Li, Debiao, Grist, Thomas M
• Format: Journal Article
• Language: English
• Published: United States 01.02.2002
• Subjects: Animals; Blood Flow Velocity; Contrast Media - administration & dosage; Gadolinium DTPA - administration & dosage; Gadolinium DTPA - blood; Image Enhancement; Injections, Intra-Arterial; Magnetic Resonance Angiography; Models, Animal; Phantoms, Imaging; Swine
• ISSN: 1076-6332
• DOI: 10.1016/S1076-6332(03)80167-8

Catheter-directed intraarterial (IA) injections of gadolinium contrast agents may be used during endovascular interventions with magnetic resonance (MR) imaging guidance. Injection protocols require further validation. Using a flow phantom and swine, the authors aimed to (a) measure the optimal arterial gadolinium concentration ([Gd]) required for MR angiography and (b) validate a proposed IA injection protocol for gadolinium-enhanced MR angiography. For in vitro experiments, the authors placed a catheter in the aorta of an aorto-renal-iliac flow phantom. Injected [Gd], injection rates, and aortic blood flow rates were varied independently for 36 separate IA gadolinium injections. The authors performed 2D and 3D MR angiography with a fast spoiled gradient-recalled echo sequence. For subsequent in vivo experiments, they selectively placed catheters within the aorta, renal artery, or common iliac artery of three pigs. Injection rate and injected [Gd] were varied. The authors performed 32 separate IA gadolinium injections for 2D MR angiography. Signal-to-noise ratios (SNRs) were compared for the various combinations of injection rate and injected [Gd]. In vitro, an arterial [Gd] of 2%-4% produced an optimal SNR for 2D MR angiography, and 3%-5% was best for 3D MR angiography. In swine, an arterial [Gd] of 1%-4% produced an optimal SNR. In the phantom and swine experiments, SNR was maintained at higher injection rates by inversely varying the injected [Gd]. Dilute arterial [Gd] is required for optimal IA gadolinium-enhanced MR angiography. To maintain an optimal SNR, injection rates and injected [Gd] should be varied inversely. The postulated injection protocol was validated.