Ultrasonography Fusion Imaging System Increases the Chance of Radiofrequency Ablation for Hepatocellular Carcinoma with Poor Conspicuity on Conventional Ultrasonography

Abstract

Objectives: To investigate the usefulness of the ultrasonography (US) fusion imaging system for radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC). Methods: Since the US fusion imaging system became available in 2010, we have conducted RFA with this system in all cases. The characteristics of 75 patients with 120 HCCs and 89 patients with 123 HCCs who underwent RFA before the introduction of this system (period A) and after it (period B), respectively, were retrospectively compared. Results: Significant difference in the characteristics of the patients and HCCs between the two periods was found only in the proportion of HCCs with poor conspicuity on grayscale US treated with RFA (1.7%, 2/120 for period A vs. 15.4%, 19/123 for period B, p < 0.01). Among the 19 HCCs with poor conspicuity on grayscale US for period B, 5 and 9 HCCs were identified on grayscale US and contrast-enhanced US, respectively, by the use of the US fusion imaging system, whereas the 5 remaining undetectable HCCs were treated by using the system in conjunction with reference images displayed side-by-side with grayscale US. Conclusion: Since the introduction of the US fusion imaging system, it has become possible to perform RFA for HCCs with poor conspicuity on grayscale US.

Contrast-enhanced ultrasound-guided radiofrequency ablation in inconspicuous hepatocellular carcinoma on B-mode ultrasound

“…There are some new techniques to overcome the limitation of B-mode US-guided RFA (22)(23)(24)(25)(26)(27)(28)(29). One of the new techniques is fusion imaging-guided RFA.…”

“…One of the new techniques is fusion imaging-guided RFA. In one retrospective study, the proportion of HCCs with poor conspicuity was higher in fusion imaging-guided RFA (15.4% vs. 1.7%), indicating that inconspicuous HCCs could be treated with fusion imaging-guided RFA (28). In another study that included 46 HCCs treated with US fusion imaging-guided RFA, the technical success rate was 100% and the tumor progression rate was 8.7%, with a mean follow-up period of 18.2 months (29).…”

Usefulness of the Extracted-Overlay Function in CT/MR-Ultrasonography Fusion Imaging for Radiofrequency Ablation of Hepatocellular Carcinoma

“…Although registration accuracy should be originally confirmed by the overlay display, background US images often become too obscure for practical use, because of the simple overlaying of different imaging modalities. Although we can use the global positioning system (GPS) tool of Volume Navigation for indicating the tumor location of CT/MR reference images on US images, the GPS marker cannot indicate the tumor three-dimensionally [1,3,15]. On the other hand, the extracted-overlay function could overlay an entire tumor extracted from CT/MR images on US, and background US images did not become indistinct, leading to good treatment results of RFA in this study.…”

“…First, the visualization of an extracted tumor from reference images, with a virtual ablative safety margin, on real-time US enables effective treatment planning since the site, angle, depth and number of times of electrode insertion can be efficiently planned before RFA puncture. This advantage is considered to be especially apparent in HCCs which are not conspicuous on US [1,2,4,15]. Second, the tumor remains visible, despite spreading hyperechoic bubbles, during and after ablation.…”

Advances in Liver Fibrosis Imaging and Hepatocellular Carcinoma: Update in 2013

“…Makino et al [7] discuss how RFA can be performed for HCCs, which have poor conspicuity on grayscale ultrasonography (US), by introducing US fusion imaging with CT/MRI.…”