Feasibility of Extracted-Overlay Fusion Imaging for Intraoperative Treatment Evaluation of Radiofrequency Ablation for Hepatocellular Carcinoma

Abstract

Background and Aims: Extracted-overlay fusion imaging is a novel computed tomography/magnetic resonance-ultrasonography (CT/MR-US) imaging technique in which a target tumor with a virtual ablative margin is extracted from CT/MR volume data and synchronously overlaid on US images. We investigated the applicability of the technique to intraoperative evaluation of radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC). Methods: This retrospective study analyzed 85 HCCs treated with RFA using extracted-overlay fusion imaging for guidance and evaluation. To perform RFA, an electrode was inserted targeting the tumor and a virtual 5-mm ablative margin overlaid on the US image. Following ablation, contrast-enhanced US (CEUS) was performed to assess the ablative margin, and the minimal ablative margins were categorized into three groups: (I) margin <0 mm (protrusion), (II) margin 0 to <5 mm, and (III) margin ≥5 mm. Margin assessment was based on the positional relationship between the overlaid tumor plus margin and the perfusion defect of the ablation zone. Tumors in group I underwent repeat ablation until they were in groups II or III. The final classifications were compared with those obtained by retrospectively created fusion images of pre- and post-RFA CT or MR imaging (CT-CT/MR-MR fusion imaging). Results: Treatment evaluation was impossible using CEUS in six HCCs because the tumors were located far below the body surface. Of the remaining 79 HCCs, the categorizations of minimal ablative margins between CEUS extracted-overlay fusion imaging and CT-CT/MR-MR fusion imaging were in agreement for 72 tumors (91.1%) (Cohen's quadratic-weighted kappa coefficient 0.66, good agreement, p<0.01). Conclusions: Extracted-overlay fusion imaging combined with CEUS is feasible for the evaluation of RFA and enables intraoperative treatment evaluation without the need to perform contrast-enhanced CT.

Intraprocedural computed tomography/magnetic resonance–contrast‐enhanced ultrasound fusion imaging improved thermal ablation effect of hepatocellular carcinoma: Comparison with conventional ultrasound

“…In addition, CT/MR‐CEUS FI can overlay the index tumor and the ablation zone, and also can produce a 3‐D reconstruction, displaying the tumor position and its proximity to vital structures, even if there are hyperechoic bubbles present on the ultrasound. Furthermore, the ablation needle can be more accurately arranged in accordance with the preoperative planning without interference by bubbles, even if the tumor is located in a challenging position . Accurate planning can not only lead to complete ablation, but also reduce the risk of off‐target ablative injuries.…”

Non-Hypervascular Hypointense Hepatic Nodules during the Hepatobiliary Phase of Gadolinium-Ethoxybenzyl-Diethylenetriamine Pentaacetic Acid-Enhanced MRI as a Risk Factor of Intrahepatic Distant Recurrence after Radiofrequency Ablation of Hepatocellular Carcinoma

“…The warmed contrast medium was administered intravenously with a mechanical power injector at 2.5-5 mL/s with a fixed injection duration of 30 s through a 20-gauge catheter inserted into an arm vein. Dynamic triple-phase CT was performed immediately before contrast medium administration and during the hepatic arterial-dominant, portal venous-dominant, and equilibrium phases 30-45, 65-80, and 180-205 s, respectively, after initiating the contrast material injection [31,32] .…”

“…Gd-EOB-DTPA-enhanced MRI was performed using a 1.5 T MR scanner (Signa EXCITE HD version 12; GE Healthcare) [32,33] . Unenhanced, arterial, portal, late, and hepatobiliary phase images were obtained just before and 25, 70, 180 s, and 20 min, respectively, after bolus injection of 25 μmol/kg body weight (0.1 mL/kg) Gd-EOB-DTPA (Primovist; Bayer-Schering Pharma, Osaka Japan) at a rate of 2.0 mL/s, using T1-weighted 3-dimensional gradient-echo sequences in a single breath hold (18-20 s).…”

Preoperative Visceral Adiposity and Muscularity Predict Poor Outcomes after Hepatectomy for Hepatocellular Carcinoma

“…Today, surgical treatment, including hepatectomy and liver transplantation, is the only effective treatment for HCC, because there is no successful systemic chemotherapy for patients with advanced HCC [2][3][4]. Although advances in preoperative diagnosis, surgical technique and devices, and perioperative management have dramatically improved overall survival (OS) after partial hepatectomy for HCC, the HCC recurrence rate remains high even in patients with curative resection, with a 5-year recurrence rate as high as 70% [5][6][7].…”