Radiofrequency Thermoablation On Ex Vivo Animal Tissues: Changes on Isolated Swine Thyroids

Saline-Infused Radiofrequency Ablation: A Review on the Key Factors for a Safe and Reliable Tumour Treatment

Radiofrequency ablation (RFA) combined with saline infusion into tissue is a promising technique to ablate larger tumours. Nevertheless, the application of saline-infused RFA remains at clinical trials due to the contradictory findings as a result of the inconsistencies in experimental procedures. These inconsistencies not only magnify the number of factors to consider during the treatment, but also obscure the understanding of the role of saline in enlarging the coagulation zone. Consequently, this can result in major complications, which includes unwanted thermal damages to adjacent tissues and also incomplete ablation of the tumour. This review aims to identify the key factors of saline responsible for enlarging the coagulation zone during saline-infused RFA, and provide a proper understanding on their effects that is supported with findings from computational studies to ensure a safe and reliable cancer treatment.

Heat sink effects in thyroid bipolar radiofrequency ablation: an ex vivo study

The study aimed to investigate heat sink effects in radiofrequency ablation (RFA) under thyroid-specific conditions. In an ex vivo model, bovine thyroid lobes were ablated using bipolar RFA with 2.0 kJ energy input at a power level set to 10 W (n = 35) and 25 W (n = 35). Glass vessels (3.0 mm outer diameter) placed within the ablation zone were used to deliver tissue perfusion at various flow rates (0, 0.25, 0.5, 1, 5, 10, 20 ml/min). Temperature was measured in the proximity of the vessel (Tv) and in the non-perfused contralateral region of the ablation zone (Tc), at equal distances to the ablation electrode (d = 8 mm). Maximum temperature within the perfused zone was significantly lowered with Tv ranging from 54.1 ± 1.5 °C (20 ml/min) to 56.9 ± 1.5 °C (0.25 ml/min), compared to Tc from 63.2 ± 3.5 °C (20 ml/min) to 63.2 ± 2.6 °C (0.25 ml/min) (10 W group). The cross-sectional ablation zone area decreased with increasing flow rates from 184 ± 12 mm2 (0 ml/min) to 141 ± 20 mm2 (20 ml/min) at 10 W, and from 207 ± 22 mm2 (0 ml/min) to 158 ± 31 mm2 (20 ml/min) in the 25 W group. Significant heat sink effects were observed under thyroid-specific conditions even at flow rates ≤ 1 ml/min. In thyroid nodules with prominent vasculature, heat dissipation through perfusion may therefore result in clinically relevant limitations to ablation efficacy.

The Severity of Interstitial Inflammation in the Renal Parenchyma of Albino Rats Is Subjected to the Dose of Heavy Metals

Aim

This study aimed to determine the relationship between irreversible morphological changes in the renal interstitium and the duration of exposure to heavy metals such as copper in albino rats.

Materials and methods

An experimental research design was used to conduct this study from November 2019 to May 2020. All experiments were performed in the Department of Pathology of the Services Institute of Medical Sciences, University of Health Sciences (UHS) (animal house), Lahore, Pakistan. A total of 30 albino rats equally divided into three groups were included in the study. Group I (control) was given tap water and a typical rodent pellet diet. Groups II and III (experimental) were fed with copper (heavy metal) at a dose of 0.15 and 0.30 mg/kg body weight, respectively, for 18 weeks on alternate days. At the end of the experiment, the kidneys were extracted from the rats, stained with hematoxylin and eosin, and processed for histological observation. Renal histopathological changes were evaluated in terms of edema, inflammation, and fibrosis.

Results

The collected data were analyzed using the Chi-square test, with p < 0.05 considered significant. Renal histopathology in terms of interstitium showed that edema, inflammation, and fibrosis were significantly different in all groups. In Group I, none of the rats had edema, inflammation, and fibrosis, while in Groups II and III, these characteristics were observed; the difference was significant between the experimental and control groups.

Conclusions

Heavy metals, such as copper, can induce renal parenchymal changes in a dose-dependent manner, resulting in edema, fibrosis, and inflammation.