Volume Computed Tomography Perfusion Imaging: Evaluation of the Significance in Oncologic Follow-up of Metastasizing Renal Cell Carcinoma in the Early Period of Targeted Therapy — Preliminary Results

Introduction The aim of this study was to assess the significance of volume computed tomography perfusion imaging of metastasizing renal cell carcinoma (mRCC) in the early period after the initiation of targeted therapy. Methods Blood flow (BF), blood volume, and clearance (CL) were calculated in 10 patients with histologically verified mRCC before and 1 month after initiation of targeted therapy using compartmental analysis algorithms. In addition, the longest diameter of tumor was measured for both time points and compared. Correlation test was performed between perfusion parameters and size changes with time to progression (TTP). Results Blood flow and CL were significantly lower after therapy initiation, whereas blood volume and the long diameter remained unchanged. Median values before and after 4 weeks of therapy were 144.2 versus 99.4 mL/min/100 mL for BF (P = 0.009) and 115.5 versus 46.8 mL/min/100 mL for CL (P = 0.007). Changes in BF and CL showed very strong negative correlation with TTP (r = −0.838, P = 0.009 and r = −0.826, P = 0.011, respectively). Conclusions Our preliminary study results indicate that volume computed tomography perfusion may assess targeted therapy response of mRCC earlier than the currently used Response Evaluation Criteria in Solid Tumors. In addition, changes in BF and CL may be a promising parameter for prediction of TTP. Received for publication June 29, 2018; accepted December 19, 2018. Correspondence to: Helmut Schoellnast, MD, Division of General Radiological Diagnostics, Department of Radiology, Medical University of Graz, Auenbruggerplatz 9, Graz A-8036, Austria (e-mail: helmut.schoellnast@medunigraz.at); or Marija Balic, MD, Division of Oncology, Department of Medicine, Medical University of Graz, Auenbruggerplatz 15, A-8036 Graz, Austria (e-mail: marija.balic@medunigraz.at). Author Contributions: Conception and design: All authors. Acquisition of data: HS. Analysis and interpretation of data: AV, HS. Drafting the manuscript: AV. Revising the manuscript critically for important intellectual content: HD, MB, HS. The authors declare no conflict of interest. The study has been approved by the ethic committee of the Medical University of Graz. Patients' informed consent was obtained. The data sets used and/or analyzed during the current study are available from the corresponding author on reasonable request. All authors gave final approval of the version to be published. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.

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