ORIGINAL RESEARCH n EXPERIMENTAL STUDIES Radiology: Volume 287: Number 1—April 2018 n radiology.rsna.org 137 1 From the Department of Radiology, Feinberg School of Medicine, Northwestern University, 737 N Michigan Ave, 16th Floor, Chicago, IL, 60611 (X.W.). The complete list of author affiliations is listed at the end of the article. Re- ceived April 19, 2017; revision requested June 14; revision received July 31; accepted September 1; final version accepted September 25. Address correspondence to Zhuoli Zang (e-mail: zhuoli-zhang@northwestern.edu). Supported by the National Cancer Institute (grants R01CA209886, R01CA196967). X.W. and Z.S. contributed equally to this work. q RSNA, 2017 Purpose: To test the hypothesis that biomarkers of fluorine 18 ( 18 F) fluorodeoxyglucose (FDG) positron emission tomography (PET) can be used for the early detection of therapeutic response to irreversible electroporation (IRE) of liver tu- mor in a rodent liver tumor model. Materials and Methods: The institutional animal care and use committee approved this study. Rats were inoculated with McA-RH7777 liver tumor cells in the left median and left lateral lobes. Tumors were allowed to grow for 7 days to reach a size typically at least 5 mm in longest diameter, as verified with magnetic resonance (MR) imaging. IRE electrodes were inserted, and eight 100-msec, 2000-V pulses were applied to ablate the tumor tissue in the left median lobe. Tumor in the left lat- eral lobe served as a control in each animal. PET/computed tomography (CT) and MR imaging measurements were performed at baseline and 3 days after IRE for each ani- mal. Additional MR imaging measurements were obtained 14 days after IRE. After 14-day follow-up MR imaging, rats were euthanized and tumors harvested for hematoxylin-eo- sin, CD34, and caspase-3 staining. Change in the maximum standardized uptake value (SUV max ) was calculated 3 days after IRE. The maximum lesion diameter change (D max ) was measured 14 days after IRE by using axial T2-weighted imaging. SUV max and D max were compared. The apopto- sis index was calculated by using caspase-3–stained slices of apoptotic tumor cells. Pearson correlation coefficients were calculated to assess the relationship between SUV max at 3 days and D max (or apoptosis index) at 14 days after IRE treatment. Results: SUV max , D max , and apoptosis index significantly differed between treated and untreated tumors (P , .001 for all). In treated tumors, there was a strong correlation between SUV max 3 days after IRE and D max 14 days after IRE (R = 0.66, P = .01) and between SUV max 3 days after IRE and apoptosis index 14 days after IRE (R = 0.57, P = .04). Conclusion: 18 F-FDG PET imaging biomarkers can be used for the early detection of therapeutic response to IRE treatment of liver tumors in a rodent model. q RSNA, 2017 Xifu Wang, MD, PhD Zhanliang Su, MD Tianchu Lyu, MS Matteo Figini, PhD Daniel Procissi, PhD Junjie Shangguan, BS Chong Sun, MD Bin Wang, MD Na Shang, PhD Shanzhi Gu, MD Quanhong Ma, PhD Andrew C. Gordon, PhD Kai Lin, MD Jian Wang, MD, PhD Robert J. Lewandowski, MD Riad Salem, MD Vahid Yaghmai, MD Andrew C. Larson, PhD Zhuoli Zhang, MD, PhD 18 F-FDG PET Biomarkers Help Detect Early Metabolic Response to Irreversible Electroporation and Predict Therapeutic Outcomes in a Rat Liver Tumor Model 1 This copy is for personal use only. To order printed copies, contact reprints@rsna.org