Avinash R Kambadakone MD, FRCR, Presenter: Nothing to Disclose

Nisha Sainani MD, Abstract Co-Author: Nothing to Disclose

Ronald Steven Arellano MD, Abstract Co-Author: Nothing to Disclose

Dushyant V. Sahani MD, Abstract Co-Author: Grant, General Electric Company

Peter Raff Mueller MD, Abstract Co-Author: Consultant, Cook Group Incorporated

Debra Ann Gervais MD, Abstract Co-Author: Research grant, Covidien AG

To study the role of image subtraction on CT/MRI in the evaluation of residual tumor/ tumor recurrence following percutaneous ablation of renal cell carcinoma and assess it impact on reader confidence and routine workflow.

In this ongoing IRB approved retrospective study, we included 98 patients (M: F- 66:32, Age 26-91yrs, mean =69yrs) treated with percutaneous ablation of renal cell carcinoma and who underwent contrast enhanced CT (n=70patients) and/or MRI (n=28patients) for postprocedure imaging surveillance. MDCT and MRI scans were performed at 1, 3, 6 and 12 months in the first year followed by yearly surveillance. Subtracted images were generated at the scanner console using the pre-contrast and post-contrast images. Blinded review of the standard images (non-contrast and contrast enhanced) and subtracted images were done to determine their value in identifying enhancement in the ablation zone along with reader confidence for evaluation. Final confirmation of residual disease/ recurrence/ disease free status was obtained either by biopsy or stability over follow up imaging studies.

A total of 110 renal cell carcinomas (mean size-2.7cm, range 0.8 - 7cm) were ablated in the 98 patients. Residual tumor / tumor recurrence in the ablation zone was seen in 14 tumors (mean size of residual tumor-1.4cm) on CT and in 9 tumors (mean size of residual tumor-1.2cm) on MRI. Combined evaluation of the standard with the subtraction images improved the conspicuity and sensitivity in the determination of enhancement in the ablation zone. Addition of subtraction images to the routine images on CT/MRI also enhanced reader confidence in determining both presence and absence of enhancement in the ablation zone. Both generation and interpretation of the subtracted images were found to be feasible with the routine workflow.

Image subtraction on CT/MRI is a valuable adjunct in the determination of treatment response in percutaneous ablation for renal cell carcinoma. The addition of subtraction images improves lesion conspicuity and enhances reader confidence in detecting enhancement.

Post procedure imaging surveillance for detection of tumor recurrence/ residual disease is a crucial aspect of percutaneous ablative treatment of RCC. Inclusion of subtracted images on CT/MRI in post procedure imaging surveillance is an effective tool which allows confident and accurate detection of recurrence/ residual disease thus empowering appropriate intervention.

Kambadakone, A, Sainani, N, Arellano, R, Sahani, D, Mueller, P, Gervais, D, Imaging Surveillance Following Percutaneous Ablation of Renal Cell Carcinoma: Value of Image Subtraction on CT/MRI.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9015959.html