Active contour configuration model for estimating the posterior ablative margin in image fusion of real-time ultrasound and 3D ultrasound or magnetic resonance images for radiofrequency ablation: an experimental study

Can the Entire Ablative Hyperechoic Zone be Regarded as a Necrotic Lesion After Radiofrequency Ablation of the Liver?

Developments in image fusion technology made it possible to visualize the ablative margin on ultrasound (US). The purpose of the present study was to assess the ablative area of radiofrequency ablation for hepatocellular carcinoma and compare it with the ablative hyperechoic zone with a non-enhanced area on contrast-enhanced US/contrast-enhanced computed tomography (CEUS/CECT) in the same cross-section. This retrospective study included 25 patients with 27 hepatocellular carcinomas. The long and short dimensions of the ablative hyperechoic zone were measured using B-mode US, and those of the non-enhanced area were assessed with CEUS/CECT on the same cross-section measured with B-mode US, using image fusion techniques. The technical effectiveness of ablation with an adequate ablative margin in a single session was determined in all patients. The long and short dimensions of the ablative hyperechoic zone ranged between 15.0 and 40.7 mm (mean: 27.3 ± 6.9 mm) and between 14.0 and 33.0 mm (mean: 23.3 ± 5.8 mm), respectively. R values for the long and short dimensions were 0.99 and 0.98, respectively, between B-mode US and CEUS, and 0.96 and 0.92, respectively, between B-mode US and CECT. The ablative hyperechoic zone may be regarded as a necrotic lesion after radiofrequency ablation.

Manual versus automated image fusion of real-time ultrasonography and MR/CT images for radiofrequency ablation of hepatic tumors: results of a randomized prospective trial (NCT02705118)

PURPOSE

This study compared the technical parameters and clinical outcomes of manual and automatic image fusion techniques of ultrasonography and magnetic resonance imaging/computed tomography for radiofrequency ablation (RFA) of hepatic tumors.

METHODS

Seventy consecutive patients (male:female=47:23, 67.1±10.9 years old) who underwent RFA for hepatic tumors were prospectively enrolled and randomly assigned to the manual or automatic registration group. Two operators performed RFA with one of two imaging fusion techniques. Technical parameters (the registration error, time required for image registration, number of point registrations) and clinical outcomes (technical success, technical effectiveness, local tumor progression [LTP]-free survival, and progression-free survival [PFS]) were compared.

RESULTS

The automatic group contained 35 patients with hepatocellular carcinoma, while the manual group included 34 hepatocellular carcinoma patients and a patient with colon cancer liver metastasis. The registration error, time required for registration, and number of point registrations were 5.7±4.3 mm, 147.8±78.2 seconds, and 3.26±1.20 in the automatic group, and 6.3±5.0 mm, 150.3±89.7 seconds, and 3.20±1.13 in the manual group, respectively. The technical success and effectiveness rates were both 97.1% in the automatic group and both 100.0% in the manual group. The above differences were not significant. The LTP-free survival and PFS (28.3 and 21.2 months in the automatic group, and 29.0 and 24.9 months in the manual group, respectively) showed no significant between-group differences during a median 20.1-month follow-up period.

CONCLUSION

The technical parameters and clinical outcomes of automatic image fusion were not significantly different from those of manual image fusion for RFA of hepatic tumors.

Clinical utility of real-time ultrasound-multimodality fusion guidance for percutaneous biopsy of focal liver lesions

OBJECTIVES

To prospectively evaluate the clinical value of real-time ultrasonography (US)-computed tomography (CT)/magnetic resonance imaging (MRI) fusion imaging for percutaneous needle biopsy of focal liver lesions (FLLs), and to compare its biopsy success rate with that of conventional US-guided biopsy in a propensity-score matched group.

METHODS

This study was approved by our Institutional Review Board and informed consent was obtained from all patients enrolled in the prospective study group. Ninety patients referred to the Department of Radiology for percutaneous biopsy of FLLs were enrolled in this study. Tumor visibility, attainment of a safe access route, and technical feasibility were assessed on conventional US first and later on real-time fusion imaging by one of four abdominal radiologists. Thereafter, differences in scores between real-time fusion imaging and conventional US were determined. In addition, overall diagnostic success rates of a real-time fusion imaging-guided biopsy group and a propensity-score matched, conventional US-guided biopsy group, consisting of 100 patients used as historical control, were compared.

RESULTS

With real-time fusion imaging, tumor visibility, attainment of a safe access route, and operator's technical feasibility were significantly improved compared with conventional US (P < .001). In addition, all invisible (n = 13) and not feasible (n = 10) FLLs on conventional US became visible and feasible for percutaneous US-guided biopsy after applying the fusion system. The diagnostic success rate of real-time fusion-guided biopsy was 94.4% (85/90), which was significantly better than that obtained with the conventional US-guided biopsy (94.4% vs. 83%, P < .03), with reduced biopsy procedure times (7.1 ± 3.5 vs. 9.7 ± 2.8, P < .02).

CONCLUSIONS

Real-time US-CT/MR fusion imaging guidance was able to provide clinical value for percutaneous needle biopsy of FLLs by improving the diagnostic success rate of biopsy and by reducing procedure time.