Transcatheter Intraarterial Perfusion Research Articles

Transcatheter Intraarterial Perfusion: MR Monitoring of Chemoembolization for Hepatocellular Carcinoma—Feasibility of Initial Clinical Translation

To prospectively test the hypothesis that intraprocedural transcatheter intraarterial perfusion (TRIP) magnetic resonance (MR) imaging can be used to successfully measure reductions in perfusion to the targeted hepatocellular carcinoma (HCC) and the adjacent surrounding liver tissue during MR-interventional radiology (IR)-monitored transcatheter arterial chemoembolization (TACE). This HIPAA-compliant prospective study was approved by the institutional review board. An MR-IR unit was used to perform TACE in 10 patients with HCC (seven male, three female; eight younger than 69 years, two older than 69 years). Intraprocedural reductions in tumor perfusion before and after TACE were monitored with TRIP MR imaging. Time-signal intensity curves were derived, and semiquantitative spatially resolved area under the time-signal intensity curve maps of tumor perfusion before and after TACE were produced. Mean perfusion values before and after TACE for liver tumors and adjacent liver tissue were compared by using a mixed-model analysis, with alpha = .05. Perfusion reductions were measured successfully with TRIP MR imaging in 18 separate tumors during 13 treatment sessions. Perfusion maps showed significant perfusion reductions for tumors (P < .013) but not for adjacent nontumorous liver tissue (P = .21). For tumors, the mean perfusion value was 193 arbitrary units (AU) +/- 223 (standard deviation) before TACE and 45.3 AU +/- 91.9 after TACE, with a mean reduction in baseline perfusion of 74.6% +/- 24.8. For adjacent liver tissue, the mean perfusion value was 124 AU +/- 93.5 before TACE and 93.2 AU +/- 72.3 after TACE, with a mean reduction in baseline perfusion of 24.2% +/- 14.5. TRIP MR imaging can be used to detect intraprocedural changes in perfusion to HCC and surrounding liver parenchyma during MR-IR-monitored TACE.

Abstract No. 215: Comparison of TRIP-MRI and Fluorescent Microsphere Perfusion Measurements during TAE of Rabbit Liver Tumors

Transcatheter Intraarterial Perfusion (TRIP)-MRI is clinically used in the interventional MRI setting to verify distribution of injected (chemo)embolic material during liver-directed transcatheter therapies and to monitor reductions in perfusion. The accuracy of this technique remains unknown. In rabbit VX2 liver tumors, we tested the hypothesis that TRIP-MRI accurately measures changes in tumor perfusion during transcatheter arterial embolization (TAE), using fluorescent microspheres as the gold standard technique.

Abstract No. 214: Four Dimensional Transcatheter Intra-Arterial Perfusion MRI (4D TRIP-MRI) for Monitoring Hepatic Chemoembolization

Conventional angiographic endpoints for transcatheter arterial chemoembolization (TACE) of hepatocellular carcinoma (HCC) are subjective, and optimal endpoints remain unknown. Transcatheter intra-arterial perfusion magnetic resonance imaging (TRIP-MRI), when performed in a combined magnetic resonance/digital subtraction angiography unit (termed MR-IR suite), offers an objective method to quantify tumor perfusion changes during TACE. This perfusion technique uses catheter-directed injections of gadolinium contrast, and has previously been performed with two dimensional (2D) acquisitions.

Liver Tumors: Monitoring Embolization in Rabbits with VX2 Tumors—Transcatheter Intraarterial First-Pass Perfusion MR Imaging

To prospectively test the hypothesis that transcatheter intraarterial first-pass perfusion (TRIP) magnetic resonance (MR) imaging can depict serial reductions in rabbit liver tumor perfusion during transcatheter arterial embolization (TAE). All experiments had institutional animal care and use committee approval. In four rabbits implanted with eight VX2 liver tumors, catheters were positioned in the hepatic arteries with conventional angiographic guidance. After transfer to the MR imaging suite, serial TAE was performed, with approximately 0.5 million 40-120-microm embolic particles injected at each embolic stage. TRIP MR imaging was performed at baseline and after each subsequent embolic stage (10 minutes between stages). Serial TAE and TRIP MR imaging were repeated until stasis. The first-pass time course of signal enhancement was measured in both tumors and hepatic arteries. Tumor area under the curve (AUC) and maximum upslope (MUS) values, each normalized by arterial input, were measured to assess iterative perfusion reduction. Perfusion measurements across TAE stages were compared with paired t tests and linear regression. AUC decreased from a pre-TAE baseline of 0.408 (95% confidence interval [CI]: 0.330, 0.486) to 0.065 (95% CI: 0.046, 0.085) (P<.001) after TAE. MUS decreased from a pre-TAE baseline of 0.151 (95% CI: 0.121, 0.181) to 0.027 (95% CI: 0.022, 0.031) (P<.001) after TAE. Reductions to AUC and MUS after each embolic stage were statistically significant (P<.006 for each group of paired comparisons). AUC strongly correlated with MUS (r=0.966, P<.001). TRIP MR imaging can depict serial reductions in liver tumor perfusion during TAE. TRIP MR imaging offers the potential to target functional embolic end points during TAE.

Comparison of Transcatheter Intraarterial Perfusion MR Imaging and Fluorescent Microsphere Perfusion Measurements during Transcatheter Arterial Embolization of Rabbit Liver Tumors

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. 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. There was good correlation between TRIP MR imaging and fluorescent microsphere measurements of reduction in tumor perfusion (r = 0.722, P < .012). TRIP MR imaging provides accurate semiquantitative measurement of perfusion reduction during TAE in rabbit liver tumors.