CLINICAL STUDY Transcatheter CT Arterial Portography and CT Hepatic Arteriography for Liver Tumor Visualization during Percutaneous Ablation Aukje A.J.M. van Tilborg, MD, Hester J. Scheffer, MD, Karin Nielsen, MD, Jan Hein T.M. van Waesberghe, MD, PhD, Emile F. Comans, MD, PhD, C. van Kuijk, MD, PhD, Petrousjka M. van den Tol, MD, PhD, and Martijn R. Meijerink, MD, PhD ABSTRACT Purpose: To evaluate the feasibility of combining transcatheter computed tomography (CT) arterial portography or transcatheter CT hepatic arteriography with percutaneous liver ablation for optimized and repeated tumor exposure. Materials and Methods: Study participants were 20 patients (13 men and 7 women; mean age, 59.4 y; range, 40–76 y) with unresectable liver-only malignancies—14 with colorectal liver metastases (29 lesions), 5 with hepatocellular carcinoma (7 lesions), and 1 with intrahepatic cholangiocarcinoma (2 lesions)—that were obscure on nonenhanced CT. A catheter was placed within the superior mesenteric artery (CT arterial portography) or in the hepatic artery (CT hepatic arteriography). CT arterial portography or CT hepatic arteriography was repeatedly performed after injecting 30–60 mL 1:2 diluted contrast material to plan, guide, and evaluate ablation. The operator confidence levels and the liver-to-lesion attenuation differences were assessed as well as needle-to-target mismatch distance, technical success, and technique effectiveness after 3 months. Results: Technical success rate was 100%; there were no major complications. Compared with conventional unenhanced CT, operator confidence increased significantly for CT arterial portography or CT hepatic arteriography cases (P o .001). The liver-to- lesion attenuation differences between unenhanced CT, contrast-enhanced CT, and CT arterial portography or CT hepatic arteriography were statistically significant (mean attenuation difference, 5 HU vs 28 HU vs 70 HU; P o .001). Mean needle-to-target mismatch distance was 2.4 mm  1.2 (range, 0–12.0 mm). Primary technique effectiveness at 3 months was 87% (33 of 38 lesions). Conclusions: In patients with technically unresectable liver-only malignancies, single-session CT arterial portography–guided or CT hepatic arteriography–guided percutaneous tumor ablation enables repeated contrast-enhanced imaging and real-time contrast- enhanced CT fluoroscopy and improves lesion conspicuity. ABBREVIATIONS CRLM = colorectal liver metastases, DLP = dose-length product, HCC = hepatocellular carcinoma, IRE = irreversible electro- poration, MW = microwave, RF = radiofrequency An important prerequisite for all ablation techniques is the coverage of all tumor cells, with tumor size representing the most important limiting factor. Although the results of established thermal ablation techniques, such as radiofrequency (RF) ablation and microwave (MW) ablation, are approaching the results of surgical resection (1–3), the frequency of local site recurrence, especially for percutaneous procedures, is still considered relatively high (5%–10% for lesions o 3 cm and 4 10% for lesions 4 3 cm in diameter) (4–7). Apart from careful planning before the procedure and detailed evaluation after the procedure, accurate intra- procedural targeting, monitoring, and control of ablation play a critical role in the success of percutaneous ablation & SIR, 2014 J Vasc Interv Radiol 2014; XX:]]]–]]] http://dx.doi.org/10.1016/j.jvir.2014.02.008 None of the authors have identified a conflict of interest. Figure E1 and Table E1 are available online at www.jvir.org. From the Departments of Radiology and Nuclear Medicine (A.A.J.M.v.T., H.J.S., J.H.T.M.v.W., E.F.C., C.v.K., M.R.M.) and Surgical Oncology (K.N., P.M.v.d.T.), VU University Medical Center, De Boelelaan 1117, 1081HV Amsterdam, the Netherlands. Received September 20, 2013; final revision received January 31, 2014; accepted February 3, 2014. Address correspon- dence to A.A.J.M.v.T.; E-mail: a.vantilborg@vumc.nl