MRI Research Today is a free monthly online journal that collates and summarizes the latest research about MRI, including details on magnetic resonance imaging, neuroimaging, brain tumors.

MRI measurement of change in vascular parameters in the 9L rat cerebral tumor after dexamethasone administration.

Ewing JR, Brown SL, Nagaraja TN, Bagher-Ebadian H, Paudyal R, Panda S, Knight RA, Ding G, Jiang Q, Lu M, Fenstermacher JD

Department of Neurology, Henry Ford Hospital, Detroit, Michigan 48202, USA. jre@neurnis.neuro.hfh.edu

PURPOSE: To demonstrate in the rat 9L cerebral tumor model that repeated MRI measurements can quantitate acute changes in the blood-brain distribution of Gadomer after dexamethasone administration. MATERIALS AND METHODS: A total of 16 Fischer 344 rats were studied at 7T, 15 days after cerebral implantation of a 9L tumor. MRI procedures employed a T-One by Multiple Read Out Pulses (TOMROP) sequence to estimate R(1) (R(1) = 1/T(1)) at 145-second intervals before and after administration of Gadomer (Bayer), a macromolecular contrast agent (CA). Two baseline studies preceded Gadomer administration and 10 subsequent R(1) maps tracked CA concentration in blood and brain for 25 minutes. Thereafter, either dexamethasone (N = 10) or normal saline (N = 6) was administered intravenously. A total of 90 minutes later a second series of 12 TOMROP measurements of Gadomer distribution was performed. The influx constant, K(1), plasma distribution volume, v(D), backflux constant, k(b), and interstitial space, v(e), were determined, and the test-retest differences of each of four vascular parameters were calculated. RESULTS: Dexamethasone decreased K(1) approximately 60% (P = 0.02), lowered k(b) and v(D) (P = 0.03 and P < 0.01, respectively), and marginally but insignificantly decreased v(e). CONCLUSION: This noninvasive MRI technique can detect drug effects on blood-brain transfer constants of CAs within two hours of administration.

Published 2 June 2008 in J Magn Reson Imaging, 27(6): 1430-8.
Full-text of this article is available online (may require subscription).

© 2005-2008 MRI Research Today. All Rights Reserved.