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Instant Outcome Evaluation of Microwave Ablation With Subtraction CT in an In Vivo Porcine Model

Bressem, Keno K., MD*; Vahldiek, Janis L., MD*; Erxleben, Christoph, MD*; Poch, Franz, MD; Hiebl, Bernhard, MD; Lehmann, Kai, MD; Hamm, Bernd, MD*; Niehues, Stefan M., MD*

doi: 10.1097/RLI.0000000000000545
Original Articles

Objectives The aim of this study was to investigate whether the accuracy of multislice contrast-enhanced computed tomography (MS-CECT) may be improved by performing additional subtraction CT.

Materials and Methods Thirty-five microwave ablations were performed under CT guidance in 12 healthy and anesthetized pigs. Preablation and postablation MS-CECT scans were obtained in arterial and venous contrast phases. These scans were reconstructed and subtracted from each other. Lesion size was measured in a region of interest drawn around the ablation area. Computed tomography measurements were compared with standardized macroscopic images of explanted liver tissue, obtained immediately after ablation. Paired correlation and Bland-Altman analyses were performed for assessing agreement between modalities and ratings.

Results The correlation between lesion size measured in CT and histology was very strong for subtracted images (r = 0.91; 95% confidence interval [CI], 0.8–0.96) and strong for standard MS-CECT images (r = 0.85; 95% CI, 0.68–0.93). Interrater agreement for all measurements was excellent (intraclass correlation coefficient, 0.99; 95% CI, 0.98–0.99 for subtraction and intraclass correlation coefficient, 0.99; 95% CI, 0.98–1.00 for MS-CECT). All differences were statistically significant (P < 0.05).

Conclusions Subtraction CT was superior to nonsubtracted MS-CECT in measurement of liver lesion size after microwave ablation in a porcine model, achieving a very strong correlation with pathologic measurement and a significantly lower overestimation of lesion size compared with MS-CECT.

From the Departments of *Radiology, and

Surgery, Charité, Berlin; and

Institute for Animal Hygiene, Animal Welfare and Farm Animal Behaviour, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany.

Received for publication October 28, 2018; and accepted for publication, after revision, December 9, 2018.

Conflicts of interest and sources of funding: This study was supported by a grant from the Deutsche Forschungsgemeinschaft (ref. no. RI1131/3-3). K.S.L. has received research grants for the Federal Ministry of Education and Research and the University of Veterinary Medicine Hannover, Foundation. B. Hamm has received research grants for the Department of Radiology, Charité–Universitätsmedizin Berlin from the following companies: (1) Abbott, (2) Actelion Pharmaceuticals, (3) Bayer Schering Pharma, (4) Bayer Vital, (5) BRACCO Group, (6) Bristol-Myers Squibb, (7) Charite Research Organisation GmbH, (8) Deutsche Krebshilfe, (9) Dt. Stiftung für Herzforschung, (10) Essex Pharma, (11) EU Programmes, (12) Fibrex Medical Inc, (13) Focused Ultrasound Surgery Foundation, (14) Fraunhofer Gesellschaft, (15) Guerbet, (16) INC Research, (17) lnSightec Ud, (18) IPSEN Pharma, (19) Kendlel MorphoSys AG, (20) Lilly GmbH, (21) Lundbeck GmbH, (22) MeVis Medical Solutions AG, (23) Nexus Oncology, (24) Novartis, (25) Parexel Clinical Research Organisation Service, (26) Perceptive, (27) Pfizer GmbH, (28) Philipps, (29) Sanofis-Aventis S.A., (30) Siemens, (31) Spectranetics GmbH, (32) Terumo Medical Corporation, (33) TNS Healthcare GMbH, (34) Toshiba, (35) UCB Pharma, (36) Wyeth Pharma, (37) Zukunftsfond Berlin (TSB), (38) Amgen, (39) AO Foundation, (40) BARD, (41) BBraun, (42) Boehring Ingelheimer, (43) Brainsgate, (44) PPD (Clinical Research Organisation), (45) CELLACT Pharma, (46) Celgene, (47) CeloNova BioSciences, (48) Covance, (49) DC Deviees, Ine. USA, (50) Ganymed, (51) Gilead Sciences, (52) GlaxoSmithKline, (53) ICON (Clinical Research Organisation), (54) Jansen, (55) LUX Bioseienees, (56) MedPass, (57) Merek, (58) Mologen, (59) Nuvisan, (60) Pluristem, (61) Quintiles, (62) Roehe, (63) Sehumaeher GmbH (Sponsoring eines Workshops), (64) Seattle Geneties, (65) Symphogen, (66) TauRx Therapeuties Ud, (67) Accovion, (68) AIO: Arbeitsgemeinschaft Internistische Onkologie, (69) ASR Advanced sleep research, (70) Astellas, (71) Theradex, (72) Galena Biopharma, (73) Chiltern, (74) PRAint, (75) lnspiremd, (76) Medronic, (77) Respicardia, (78) Silena Therapeutics, (79) Spectrum Pharmaceuticals, (80) St Jude, (81) TEVA, (82) Theorem, (83) Abbvie, (84) Aesculap, (85) Biotronik, (86) Inventivhealth, (87) ISA Therapeutics, (88) LYSARC, (89) MSD, (90) Novocure, (91) Ockham Oncology, (92) Premier-Research, (93) Psi-cro, (94) Tetec-ag, (95) Winicker-Norimed, (96) Achaogen Inc, (97) ADIR, (98) AstraZenaca AB, (99) Demira Inc, (100) Euroscreen S.A., (101) Galmed Research and Development Ltd, (102) GETNE, (103) Guidant Europe NV, (104) Holaira Inc, (105) Immunomedics Inc, (106) Innate Pharma, (107) Isis Pharmaceuticals Inc, (108) Kantar Health GmbH, (109) MedImmune Inc, (110) Medpace Germany GmbH (CRO), (111) Merrimack Pharmaceuticals Inc, (112) Millenium Pharmaceuticals Inc, (113) Orion Corporation Orion Pharma, (114) Pharmacyclics Inc, (115) PIQUR Therapeutics Ltd, (116) Pulmonx International Sárl, (117) Servier (CRO), (118) SGS Life Science Services (CRO), and (119) Treshold Pharmaceuticals Inc. The funding had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The remaining authors declare that they have no conflicts of interest and did not receive any funds. There are no patents, products in development, or marketed products to declare.

Correspondence to: Keno K. Bressem, MD, Department of Radiology, Charité, Hindenburgdamm 30, 12203 Berlin, Germany. E-mail:

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