Purpose: Angiographic endpoints for chemoembolization of hepatocellular carcinoma (HCC) are subjective, and optimal endpoints remain unknown. Transcatheter intraarterial perfusion (TRIP) magnetic resonance (MR) imaging, when performed in a combined MR/interventional radiology (MR-IR) suite, offers an objective method to quantify intraprocedural tumor perfusion changes, but was previously limited to two spatial dimensions. This study prospectively tested the hypothesis that a new volumetric acquisition over time, four-dimensional TRIP MR imaging, can measure HCC perfusion changes during chemoembolization.
Materials and methods: Seven men (mean age, 53 years; range, 42-65 y) with eight tumors (mean size, 2.5 x 2.4 cm(2); diameter range, 1.5-5.2 cm) underwent chemoembolization in an MR-IR suite between February and December 2007, with intraprocedural tumor perfusion reductions monitored with four-dimensional TRIP MR imaging. Microcatheter chemoembolization was performed with a 1:1 mixture of chemotherapy agent and emulsifying contrast agent, followed by the administration of gelatin microspheres. Pre- and post-chemoembolization time-intensity curves were generated for each tumor. Semiquantitative measures of tumor perfusion, including area under the curve (AUC), peak signal intensity (SI), time to peak SI, and maximum upslope (MUS), were calculated, and mean differences before and after chemoembolization were compared with paired t tests.
Results: Four-dimensional TRIP MR imaging-monitored chemoembolization was successful in all cases. Calculated AUCs before and after chemoembolization (439 vs 221, P = .004, 50% reduction), peak SI (32 vs 19, P = .012, 41% reduction), and MUS (11 vs 3, P = .028, 73% reduction) showed significant reductions after chemoembolization. Time to peak SI did not significantly change (23 sec vs 36 sec, P = .235, 57% increase).
Conclusions: Four-dimensional TRIP MR imaging can successfully measure semiquantitative changes in HCC perfusion during MR-IR-monitored chemoembolization. Future studies may correlate changes in these objective functional parameters with tumor response.