A novel mono-modality fusion imaging method based on three-dimensional contrast-enhanced ultrasound for the evaluation of ablation margins after microwave ablation of hepatocellular carcinoma

Abstract

Background: To investigate the feasibility and accuracy of using preoperative and postoperative threedimensional contrast-enhanced ultrasound (3D CEUS) fusion imaging in the evaluation of safety margins after thermal ablation of hepatocellular carcinoma (HCC). Methods: A total of the 24 patients with HCC who underwent microwave ablation (MWA) between June 2020 and December 2020 were enrolled in this study. All patients received preoperative and postoperative 3D CEUS. The preoperative and postoperative 3D CEUS images were then fused. The success rate and evaluation time were recorded. The ablation margin and whether or not the safety margin was reached were calculated and recorded. If the ablation safety margin was not reached, the residual ablation volume needed to cover the safety margin was calculated automatically. The agreement between contrast-enhanced computed tomography(CECT) and 3D CEUS fusion imaging in the evaluation of ablation margins was explored using the kappa coefficient.Results: The 3D CEUS fusion success rate was 95.8% (23/24), with a mean fusion time of (4.1±1.8) minutes. Twenty-three tumors were completely ablated, and the safety margin was achieved for 9 tumors. The ablation margin of 14 tumors was <5 mm. The mean uncovered safety margin volume was (2.27±2.11) mL, and the mean proportion of the uncovered safety margin to the whole safety margin was 16.8%. According to the results of preoperative and postoperative CECT fusion imaging, the ablation margin of 13 tumors was <5 mm, and the ablation margin of 10 tumors was >5 mm. The 2 methods showed excellent consistency, with a Kappa value of 0.911 (P=0.000012). Conclusions: This study has presented a novel mono-modality fusion imaging method based on CEUS.We demonstrated that 3D CEUS fusion has a short fusion time and a high success rate, as well as good consistency with enhanced CT fusion. Therefore, 3D CEUS fusion is a feasible and accurate tool for evaluating the immediate efficacy of thermal ablation of HCC.

Efficacy of fusion imaging for immediate post‐ablation assessment of malignant liver neoplasms: A systematic review

“…Two studies examined CT fusion, and one study explored MR‐CT fusion, nine studies investigated CT/MR‐US/CEUS FI, eight studies examined US/CEUS‐US/CEUS fusion, and two studies investigated both US‐CEUS and CT/MRI‐CEUS in assessing the immediate post‐ablation response. There are three studies with US‐US overlay fusion, 53 , 54 , 61 four with 3D US‐CEUS FI, 45 , 46 , 52 , 58 and two with 3D‐CEUS FI 48 , 56 focusing on the immediate therapeutic evaluation post‐ablation. The feasibility and efficacy of CT/MRI‐CEUS FI have been compared with CEUS or US in four studies 33 , 45 , 49 , 50 and CT/MRI‐CEUS or CEUS FI with CT–CT/MR‐MR in four studies.…”

“…It has been acknowledged that the ability to display spatial relationships makes three‐dimensional(3D) imaging more valuable than 2D imaging. Through the 3D technique, the ablated zone and the index tumor can be viewed from all angles 30,48 . This technique can be adapted to volumetric software that can calculate the AM automatically, thereby assisting clinicians in determining the next step.…”

“…Tumor type There are three studies with US-US overlay fusion, 53,54,61 four with 3D US-CEUS FI, 45,46,52,58 and two with 3D-CEUS FI 48,56 focusing on the immediate therapeutic evaluation post-ablation. The feasibility and efficacy of CT/MRI-CEUS FI have been compared with CEUS or US in four studies 33,45,49,50 and CT/MRI-CEUS or CEUS FI with CT-CT/MR-MR in four studies.…”

“…Quantitative 3D assessment of AM immediately post-ablation was reported in five studies involving CT-CT fusion and four studies with US FI. 30,48,51,56,58 Two studies compared the clinical impact of image fusion software with conventional visual comparison for the assessment of AM. 11,53 Safety margin achieved is the buffer zone around the tumor that includes both the tumor and the ablative margin.…”

Ultrasonography of Hepatocellular Carcinoma: From Diagnosis to Prognosis

“…of 3D-CEUS fusion has been excellent in terms of time efficiency and a success rate consistent with contrast-enhanced CT fusion. 49 …”