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Improved MR Coronary Angiography with Use of a New Rapid Clearance Blood Pool Contrast Agent in Pigs¹

¹ From the Department of Radiology, Leiden University Medical Center, Albinusdreef 2, Rm 62, Post Zone C2-S, 2333 ZA Leiden, the Netherlands (M.S.D., H.J.L., P.K., A.d.R.); and Guerbet Research, Aulnay Sous Bois, France (P.R., C.C.). From the 2001 RSNA scientific assembly. Received June 6, 2002; revision requested July 30; revision received September 3; accepted October 25. Address correspondence to M.S.D. (e-mail: m.s.dirksen@lumc.nl).

View larger version (37K): [in a new window]   Figure 1. MR coronary angiography pulse sequences used in the present study. Upper row: native nonenhanced sequence with use of T2 preparation and navigator and breath-hold approaches. Lower row: contrast-enhanced sequences with use of navigator and breath-hold approaches. Note that for contrast-enhanced acquisitions, a 90° saturation preparation pulse was applied, whereas the T2 preparation pulse was omitted.

View larger version (37K): [in a new window]   Figure 2. A, P792 pharmacokinetics. The first-pass phase is followed by a steady-state phase and rapid renal clearance (data from one animal). P792 was below detection level after 59.5 minutes. B, Quantification of pharmacokinetics. C5/C0 represents P792 levels at 5 minutes after injection relative to P792 levels immediately after injection. The high C5/C0 ratio and the small distribution volume compared with that of gadoterate meglumine (Gd-DOTA) (26) illustrate the blood pool properties of P792 (data from two pigs). C, Molecular structure of P792 versus that of gadoterate meglumine (Gd-DOTA). P792 has four hydrophilic arms that prevent transcapillary diffusion. Alternatively, gadoterate meglumine may freely pass the capillary endothelium because of its small molecular size.

View larger version (80K): [in a new window]   Figure 3. Wash-out time series of MR coronary angiography with use of two types of contrast agents to illustrate the difference between blood pool contrast agents and extravascular contrast agents. Upper series: Application of a blood pool contrast agent (P792) results in selective enhancement of the blood pool during 15 minutes, whereas the background tissues remain unenhanced. Lower series: the conventional agent (gadoterate meglumine) extravasates within 1 minute, causing enhancement of the perivascular tissues, which makes it impossible to identify the coronary artery.

View larger version (146K): [in a new window]   Figure 4. MR images illustrate the main study results. The right coronary artery was imaged with a nonenhanced state-of-the-art T2 preparation technique (upper row); with P792 (middle row); and with gadoterate meglumine (lower row). Images were acquired with the navigator approach (each row shows four sections from a stack of 20). The arrow marks the right coronary artery on all images. Image acquisition was started immediately following bolus injection, with 8.5-second bolus arrival delay. Note the low signal intensity of the perivascular tissues on the P792-enhanced images with regard to the other two image types. Coronary background suppression appears most effective on the P792-enhanced images, thereby improving the conspicuity of the coronary vessel.