Comparison of Transcatheter Intraarterial Perfusion MR Imaging and Fluorescent Microsphere Perfusion Measurements during Transcatheter Arterial Embolization of Rabbit Liver Tumors Sumeet Virmani, MD, Dingxin Wang, MS, Kathleen R. Harris, BS, Robert K. Ryu, MD, Kent T. Sato, MD, Robert J. Lewandowski, MD, Albert A. Nemcek, Jr, MD, Barbara Szolc-Kowalska, MD, Gayle Woloschak, PhD, Riad Salem, MD, MBA, Andrew C. Larson, PhD, and Reed A. Omary, MD, MS PURPOSE: Transcatheter intraarterial perfusion (TRIP) magnetic resonance (MR) imaging is clinically used in the interventional MR imaging setting to verify distribution of injected embolic or chemoembolic material during liver-directed transcatheter therapies and to monitor reductions in perfusion. The accuracy of this technique remains unknown. In the present study, rabbit VX2 liver tumors were used to test the hypothesis that TRIP MR imaging accurately measures changes in tumor perfusion during transcatheter arterial embolization (TAE), with injection of fluorescent microspheres used as the gold-standard technique. MATERIALS AND METHODS: Five New Zealand White rabbits were used for this study (two donor rabbits and three with VX2 liver tumors). In three rabbits with implanted VX2 liver tumors, catheters were superselectively placed under digital subtraction angiographic guidance into the left hepatic artery supplying the targeted tumor. Fluorescent microspheres were injected into each rabbit’s left ventricle before and after TAE. TRIP MR images were obtained at baseline and after embolizations for all rabbits with intraarterial injections of 2.5% gadopentetate dimeglumine solution. Linear regression was used to compare relative reductions in tumor perfusion between TRIP MR imaging and fluorescent microspheres. Results were considered statistically significant at a P value less than .05. RESULTS: There was good correlation between TRIP MR imaging and fluorescent microsphere measurements of reduction in tumor perfusion (r  0.722, P < .012). CONCLUSIONS: TRIP MR imaging provides accurate semiquantitative measurement of perfusion reduction during TAE in rabbit liver tumors. J Vasc Interv Radiol 2007; 18:1280 –1286 Abbreviations: DSA = digital subtraction angiography, TACE = transcatheter arterial chemoembolization, TAE = transcatheter arterial embolization, TRIP = transcatheter intraarterial perfusion TRANSCATHETER arterial emboliza- tion (TAE) and transcatheter arterial chemoembolization (TACE) are mini- mally invasive treatments for hepato- cellular carcinoma (1,2) and metastatic liver tumors (3). These therapies pref- erentially deliver embolic or chemo- embolic agents to liver tumors via catheters positioned within the hepatic arteries. Presently, no consensus has been reached regarding the optimal embolic endpoints for TAE and TACE. Embolization to an endpoint of com- plete stasis of blood flow on x-ray dig- ital subtraction angiography (DSA) potentially induces release of tumor angiogenic growth factors (4,5); might lead to arterial occlusion, precluding future transcatheter therapies (6); can induce liver failure in patients with underlying cirrhosis; and could possi- From the Departments of Radiology (S.V., D.W., K.R.H., R.K.R., K.T.S., R.J.L., A.A.N., R.S., A.C.L., R.A.O.), Biomedical Engineering (D.W., A.C.L., R.A.O.), and Radiation Oncology (B.S.K., G.W.), and the Robert H. Lurie Comprehensive Cancer Center (G.W., R.S., A.C.L., R.A.O.), Northwestern University, 448 E Ontario St, Suite 700, Chicago, Illinois 60611. Received March 29, 2007; final revision received July 13, 2007; accepted July 19, 2007. Address correspon- dence to R.A.O.; E-mail: reed@northwestern.edu R.A.O. was supported in part by the American Can- cer Society Illinois Chapter Grant Program; G.W. was supported in part by National Institutes of Health grants U54 CA119341, EB002100, and CA81375. None of the authors have identified a conflict of interest. © SIR, 2007 DOI: 10.1016/j.jvir.2007.07.008 1280