Optimal approach for complete liver tumor ablation using radiofrequency ablation: a simulation study

Application of ultrasound-guided biopsy and percutaneous radiofrequency ablation in 2 cases with phosphaturic mesenchymal tumor and literature review

Tumor-induced osteomalacia (TIO) is a vanishingly rare paraneoplastic syndrome which is usually caused by phosphaturic mesenchymal tumors (PMTs). The conventional treatment for PMTs is total resection, and ultrasound-guided radiofrequency ablation (RFA) can also be used for the treatment of PMTs patients, especially for patients in whom complete resection may lead to serious complications. We report two cases with PMT who presented syndrome with progressive musculoskeletal complaints and performed ultrasound-guided biopsy and RFA. Ultrasound-guided RFA, which is a safe and effective minimally invasive treatment option, appears to be a valuable alternative to surgery for patients presenting with PMT. We are the first reported case of RFA guided by ultrasonography in the treatment of PMT.

Efficacy of transarterial chemoembolization compared with radiofrequency ablation for the treatment of recurrent hepatocellular carcinoma after radiofrequency ablation

Purpose: To compare the efficacy and outcome of transarterial chemoembolization (TACE) with radiofrequency ablation (RFA) in the treatment of recurrent hepatocellular carcinoma (HCC) after initial RFA.Material and methods: From January 2008 to December 2014, 199 consecutive patients with primary HCC underwent percutaneous RFA as initial treatment. One hundred and fourteen patients developed intrahepatic recurrent HCC after initial RFA. The patients with recurrent tumor size ≤3 cm and tumor numbers ≤3 who underwent RFA (n = 47) or TACE (n = 31) were included in study. Progression-free survival (PFS), tumor response to treatment and overall survival (OS) were assessed. Prognostic factors for OS were analyzed using multivariate Cox proportional hazard models.Results: The baseline data of initial HCC and the first recurrence of HCC were comparable in both groups. The complete response (CR) rate in the RFA group and the TACE group was 95.7% and 50%, respectively (p < .001). The PFS time in the RFA group and the TACE group was 424 days and 275 days, respectively (p = .004). The one-year and three-year cumulative overall survival rate was 93.5% and 45% in the TACE group, 91.3% and 68.8% in the RFA group (p = .49), respectively. Significant predictive factors for OS were tumor size (HR = 1.951, 95%CI 1.061-3.687, p = .032), prothrombin time (HR = 1.59, 95%CI 1.012-2.498, p = .044) and response to treatment (HR = 0.267, 95%CI 0.092-0.78, p = .016).Conclusion: Repeated RFA is still considered to be the first treatment choice for patients with post-RFA intrahepatic recurrence. However, TACE should also be considered due to comparable overall survival benefits. The advantages of being less invasive and highly repeatable may render TACE to be a preferred treatment for some patients with recurrent HCC after RFA.

On the cooling effect of flowing blood on hepatic tumor ablation process

One method of removing malignant tissues from human organs is radiofrequency ablation. Thermal radiofrequency is a common technique of liver tumour therapy, which depends mainly on heating the infected region. This work proposes to investigate the thermal issue, which - in instance of excessive current - leads to extra lesion in liver tissues. However, the thermal lesions and the mistakes occurred in positioning the trocar instrument in the correct and accurate place arise the need to simulate and prediction of the thermal and electrical behaviour of the ablation operation. By using COMSOL multiphysics package, the process of hepatic tumour ablation has been simulated. Results show that by virtue of higher blood electrical conductivity, the nearby liver tissue around the electrode can be heated by rising its temperature due to electrical current from the radiofrequency probe according to the Joule law. Also, in this paper, different values of blood perfusion rate have been applied in the simulation process to investigate its effect on the ablation process. It is found that the increasing of mass flow rate of blood flow tends to bring down the fraction of necrotic tissue, which is contraindicated to the tumour ablation process.