Intraprocedural contrast-enhanced ultrasound (CEUS) in liver percutaneous radiofrequency ablation: clinical impact and health technology assessment

Our results show that the intraprocedural use of CEUS can reduce the number of incomplete treatments and consequently the number of re-treatments, as well as the total costs of RFA for HCC. RFA has been shown to be effective in the treatment of small HCC lesions, with results comparable to surgical resection [1‐6]. However, given that the assessment of the completeness of ablation is generally performed after the treatment, often more than one ablation session is required to achieve complete response [9, 10], with increasing risk of complications for the patient and increasing costs. In our series we achieved complete ablation of 96.6 % of lesions in 94.6 % of patients at 24 h, which is comparable with results reported in the literature [1‐5].

CEUS can be performed in the operating room after the ablation, and has been used in different fields for the immediate assessment of completeness of ablation [19, 24]. Particularly, CEUS has been proven to be as accurate as other contrast-enhanced imaging modalities for the assessment of technical success after RFA [13‐18]. For this reason some authors recommend CEUS immediately after RFA to permit re-treatment during the same interventional session if incomplete ablation is detected [17‐19]. We adopted this strategy at our institution and, by using CEUS immediately after RFA, were able to detect incomplete ablation in 29.0 % of lesions in 36.5 % of patients. In these patients we were able to perform an immediate CEUS-guided targeted re-treatment that led to complete ablation in 94.6 % of patients based on 24-h follow-up. Thus, a second session of treatment was avoided in 31.1 % of patients. The need of a second intervention—that we performed in the same session—in our group is slightly higher than other series reported in the literature [1‐9]. Several factors may have contributed to this result. Firstly, being a second-level centre, with high expertise in the treatment of liver diseases, patients are often referred to our department from other hospitals. Thus, our group included a high proportion of “complex cases” compared with cases at more general interventional radiology departments, with an increased mean technical difficulty of cases to be treated. Moreover, 37.6 % of patients in our series were treated for more than one tumour in the same session. Third, the result of CEUS was judged by the interventional radiologist performing the treatment, and equivocal cases were generally considered as incompletely ablated, and underwent a second ablative treatment. Thus, the rate of incomplete treatment after the first ablation may have been slightly overestimated. Moreover, we finally achieved complete ablation at 24 hours in 94.6 % of patients.

From an economic point of view, compared with the standard procedure, the introduction of intraprocedural CEUS resulted in a 3.7 % increase in costs, due to a longer procedural time and the cost of the contrast agent. However, the use of intraprocedural CEUS resulted in better cost-effectiveness compared with the standard procedure and a higher probability of being cost-effective, with a € 575 threshold of willingness to pay.

From a hospital perspective, the intraprocedural use of CEUS resulted in a 21.95 % reduction in costs due to a lower number of re-treatments. This would result in the possibility of performing ablations on a greater number of patients, with consequently more effective use of resources and shortening of waiting lists. From the point of view of the Health Service, the use of intraprocedural CEUS allows a lower cost per patient for complete treatment, resulting in savings for the entire service.

The introduction of intraprocedural CEUS in centres where CEUS is already employed for other purposes would result in a low organisational impact, but to a relevant impact on equity, since the avoided re-treatments would have a positive impact on the quality-of-life of patients, decreasing their stress levels and reducing the number of hospitalisations.

Even though CEUS has a diagnostic accuracy similar to CE-CT in the assessment of treatment results [13‐18], there are only few studies that compare CEUS with other contrast-enhanced modalities immediately after RFA. A second possible limitation of our study is that being a second-level centre, with a larger number of “complex cases” compared with more general interventional radiology departments, the same analysis performed in a different hospital might lead to different results. Moreover, the decision to perform a new ablation immediately, in the same session, was made on the basis of the critical analysis of the result of intraprocedural CEUS made by the interventional radiologists. In some cases with an easy path to the target and a safely located tumour, even with equivocal result of incomplete ablation at CEUS a second ablation was performed. Thus, the need for immediate re-treatment and, consequently, the clinical and economic impacts of CEUS, could have been overestimated in our series. As a consequence, unnecessary repetition of treatment in a significant number of patients would have happened. A fourth limitation is the absence of a true control group in which CEUS was not performed, as our results were obtained by comparing a real group in which CEUS was performed with a hypothetical one in which CEUS was not performed. A further bias in our study derives from the inclusion of only small (<2.5 cm) HCCs in our series.

In conclusion, the intraprocedural use of CEUS may have a relevant clinical impact in reducing the number of second ablative sessions needed to achieve a complete ablation of the tumour to be treated. Moreover, the intraprocedural use of CEUS may significantly reduce the costs per patient related to the percutaneous treatment with RFA of patients with HCC, being also characterised by a low organisational impact, and in a relevant impact on equity