Objective:Evaluation of the effectiveness of domestic ultrapulsed thulium laser ablation of isolated porcine kidneys.Methods:Forty-two fresh porcine kidneys were taken. One porcine kidney was dissected along the sagittal plane at the renal hilum, and then dissected along the coronal plane and divided into four pieces.A total of 168 pieces of renal tissues were obtained, of which 162 pieces were selected for the domestic hyperpulsed thulium laser ablation of isolated porcine kidneys using the single-needle method and the double-needle method, respectively. The ablation was carried out with different ablation modes (single-needle and double-needle methods), ablation power (4, 5, and 6 W), ablation modes (continuous, low-energy and high-frequency mode, and high-energy and low-frequency mode), and ablation time (10, 15, and 20 s). The size of the ablation area in terms of the long diameter, the short diameter, and the thick diameter were measured and recorded. The embedded tissues were sectioned and stained with HE to study the microscopic pathological characteristics of the ablation foci. The ablation foci volume and sphericity coefficient (Φ) were calculated, and the ablation foci volume and sphericity coefficient were statistically analyzed by analytic factorial design and one-way ANOVA.Results:The gross specimen showed that the single-needle ablation foci were elliptical in shape, containing black carbonized areas and gray-white necrotic areas with clear boundaries, and the peripheral renal tissues were pink, and the ablation focus was clearly demarcated from the normal tissues. The double-needle ablation foci were a large ellipse containing two small ellipse ablation foci, and the structure was similar to that of the single-needle method. Under the light microscope, the center of the ablation focus was a "cavity-like" carbonized area, outside of which was an area of coagulation necrosis, with deepened cell staining, reduced cell volume, disorganized arrangement, loose nuclei, nuclear consolidation, and some cell nuclei were cleaved and ablated. Ablation mode ( P<0.001), ablation pattern ( P <0.001), ablation time ( P <0.001), and ablation power ( P <0.001) all significantly affected ablation focus volume. The volume of the ablation foci increased with increasing number of needle feeds, longer ablation time, higher ablation power, and with the ablation mode being continuous mode. Single-needle ablation produced the largest volume of ablation foci (259.56 mm 3) in continuous mode, ablation time of 20 s, and ablation power of 6 W. Double-needle ablation produced the largest volume of ablation foci (452.00 mm 3) in continuous mode, ablation time of 20 s, and ablation power of 6 W. The analysis of the sphericity coefficient showed that in single-needle ablation, the sphericity coefficient was the largest (Φ=0.76) under the conditions of continuous mode, ablation power of 4 W, and ablation time of 15 s. The sphericity coefficient was the smallest (Φ=0.56) under the conditions of high-energy, low-frequency mode, ablation time of 10 s, and ablation power of 6 W, and the morphology of the ablation foci were more close to ellipsoid shape. When ablated by the double-needle method, the ablation foci morphology was closer to spherical shape (Φ=0.91) under the conditions of continuous mode, ablation time of 10 s, and ablation power of 5 W. The combined main effect and interaction results showed that ablation mode ( P<0.001), ablation pattern ( P<0.001), and ablation power ( P<0.001) significantly affected the sphericity coefficient of the ablation foci, and ablation time did not affect the ablation foci morphology. Conclusions:Domestic ultrapulsed thulium laser ablates isolated porcine kidney tissues with precise effect, the tissue morphology of the unablated area is normal, the thulium laser ablated foci have a definite safe boundary. Choosing double needle method, continuous mode, ablation power 6 W for 20 s, can ablate spherical cancer foci within 1 cm in diameter, which can be used for spherical small kidney cancer ablation. Selecting the single-needle method, high-frequency, low-energy mode and ablation power of 6 W, the ablation foci were similar to the oval volume, and could be used for the ablation of oval small renal cancer. However, this study is only limited to the animal ex vivo model, which needs to be confirmed by further study.