Renal VX2 Tumors Research Articles

PD08-11 REAL-TIME MONITORING OF RADIOFREQUENCY ABLATION RANGE OF RENAL TUMORS BY THERMOSENSITIVE LIPID NANOPARTICLES

You have accessJournal of UrologyKidney Cancer: Localized: Ablative Therapy (PD08)1 Apr 2020PD08-11 REAL-TIME MONITORING OF RADIOFREQUENCY ABLATION RANGE OF RENAL TUMORS BY THERMOSENSITIVE LIPID NANOPARTICLES Linfang Yao*, Guanchen Zhu, Wenmin Cao, Wei Wang, Wei Chen, Ming Chen, Xingqun Zhao, and Hongqian Guo Linfang Yao*Linfang Yao* More articles by this author , Guanchen ZhuGuanchen Zhu More articles by this author , Wenmin CaoWenmin Cao More articles by this author , Wei WangWei Wang More articles by this author , Wei ChenWei Chen More articles by this author , Ming ChenMing Chen More articles by this author , Xingqun ZhaoXingqun Zhao More articles by this author , and Hongqian GuoHongqian Guo More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000835.011AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: To explore the feasibility of assessing intraoperative radiofrequency ablation coverage by using novel thermosensitive lipid nanoparticles contained with liquid perfluorohexane. METHODS: In this experiment, a new kind of thermosensitive lipid nanoparticle contained with liquid perfluorohexane was prepared by rotating evaporation and acoustic resonance method, which could be changed from liquid to gas quickly at 58-60 °C. Thermal phase transition of nanoparticles was observed in vitro water capsule heating experiment and agar-agar gel model radiofrequency ablation experiment. In vivo rabbit kidney VX2 tumor model was used for ultrasound imaging with the nanoparticles. Radiofrequency ablation alone and radiofrequency ablation combined with this thermosensitive nanoparticles were performed respectively. The formation of gasification area was observed with ultrasonic measuring system (Flex Focus 800 (BK Medical). The boundary temperature of the gasification zone was detected by the temperature measuring system(NATIONAL INSTRUMENTS Company, USA). The size of gasification area and gross pathology were measured, and their correlation was analyzed. RESULTS: Through in vitro characterization, the size of this nanoparticles was confirmed to be about 300nm. In vitro ultrasound experiments showed that the echo of thermosensitive lipid nanoparticles was significantly enhanced compared with that before heating. Radiofrequency ablation of rabbit renal VX2 tumor in vivo showed that thermosensitive lipid nanoparticles made the gasification zone generated by radiofrequency ablation more obvious, and the boundary temperature of the gasification zone was about 60?. The gasification zone is larger than the radiofrequency ablation range, and highly correlated with gross pathologic necrosis zone. CONCLUSIONS: Thermosensitive lipid nanoparticles contained with liquid perfluorohexane have the potential of thermosensitive phase transition. It is expected to be a new method for intraoperative real-time monitoring and evaluation of radiofrequency ablation boundaries. Source of Funding: This work was supported by the National Natural Science Foundation of China (Grant No. 81972388, 81772710) , Nanjing health science and technology development special fund project?YKK18076?,Jiangsu postdoctoral research fund?1701023B?, the Project of Invigorating Health Care through Science, Technology and Education, Jiangsu Provincial Key Medical Discipline (Laboratory) (ZDXKB2016014). © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e172-e173 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Linfang Yao* More articles by this author Guanchen Zhu More articles by this author Wenmin Cao More articles by this author Wei Wang More articles by this author Wei Chen More articles by this author Ming Chen More articles by this author Xingqun Zhao More articles by this author Hongqian Guo More articles by this author Expand All Advertisement PDF downloadLoading ...

PD08-03 EFFECTS OF DIFFERENT RADIOFREQUENCY ABLATION MODES ON NORMAL RENAL TISSUE AROUND THE ABLATION ZONE

You have accessJournal of UrologyKidney Cancer: Localized: Ablative Therapy (PD08)1 Apr 2020PD08-03 EFFECTS OF DIFFERENT RADIOFREQUENCY ABLATION MODES ON NORMAL RENAL TISSUE AROUND THE ABLATION ZONE Linfang Yao*, Wenmin Cao, Wei Wang, Wei Chen, Jiong Shi, Xingqun Zhao, and Hongqian Guo Linfang Yao*Linfang Yao* More articles by this author , Wenmin CaoWenmin Cao More articles by this author , Wei WangWei Wang More articles by this author , Wei ChenWei Chen More articles by this author , Jiong ShiJiong Shi More articles by this author , Xingqun ZhaoXingqun Zhao More articles by this author , and Hongqian GuoHongqian Guo More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000835.03AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: To explore the effects of radiofrequency ablation "slow" or "fast" mode on normal renal tissue around the ablation zone. METHODS: The animal model of rabbit renal VX2 tumor was established. Radiofrequency ablation of rabbit renal VX2 tumors was performed in a "slow" or "fast" mode. The thermocouple temperature measurement system(NATIONAL INSTRUMENTS Company, USA) monitored the temperature changes of the ablation zone and the renal tissue around the ablation zone during the radiofrequency ablation. The formation and range of radiofrequency ablation were monitored in real time by B-ultrasound imaging system (Flex Focus 800 (BK Medical).Conventional pathological hematoxylin-eosin staining was used to observe the necrosis. Cell necrosis and apoptosis were detected by trypan blue staining and TUNEL(terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling). The change of cell microstructure was examined under a transmission electron microscope. RESULTS: Radiofrequency ablation of rabbit renal VX2 tumors in either "slow" or "fast" mode formed an ideal range of ablation zone to cover the tumor.The average temperature within the ablation area reached 80 degree centigrade and a significant ablation zone could be formed. But the "fast" mode of radiofrequency ablation often leaded to a temperature of more than 60 degree centigrade in normal kidney tissue around the ablation zone. While under a "slow" mode, the temperature of normal surrounding kidney tissue was about 40 degree centigrade. The "fast" mode of radiofrequency ablation could easily lead to damage to normal renal tissue around the ablation zone followed with degeneration and necrosis. Trypan blue staining was positive in the damaged tissue cells. Apoptosis index and mitochondrial injury were increased. While the "slow" mode of radiofrequency ablation did not cause significant damage to normal renal tissue surrounding the ablation zone. CONCLUSIONS: Radiofrequency ablation of renal tumors should be performed in a "slow" mode to minimize damage to normal renal tissue around the ablation zone. Source of Funding: This work was supported by the National Natural Science Foundation of China (Grant No. 81972388, 81772710) , Nanjing health science and technology development special fund project (YKK18076), Jiangsu postdoctoral research fund (1701023B), the Project of Invigorating Health Care through Science, Technology and Education, Jiangsu Provincial Key Medical Discipline (Laboratory) (ZDXKB2016014). © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e168-e168 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Linfang Yao* More articles by this author Wenmin Cao More articles by this author Wei Wang More articles by this author Wei Chen More articles by this author Jiong Shi More articles by this author Xingqun Zhao More articles by this author Hongqian Guo More articles by this author Expand All Advertisement PDF downloadLoading ...

Evaluation of the MR and pathology characteristics immediately following percutaneous MR-guided microwave ablation in a rabbit kidney VX2 tumor implantation model

Purpose: This study aimed to evaluate the immediate efficacy of magnetic resonance (MR)-guided microwave ablation (MWA) in rabbit kidneys implanted with VX2 tumors.Materials and methods: MR-guided MWA was performed in eight VX2 tumor-bearing rabbits. MR images after ablation were obtained and analyzed. The differences between the tissue specimens and MR images obtained after ablation were compared.Results: On the three-dimensional volumetric interpolated breath-hold T1-weighted (3D-VIBE-T1WI) sequence, a low signal intensity indicated the primary tumor at the center of the ablation area, which was surrounded by a peripheral high-signal area. The signal for the primary tumor in the fast spin-turbo spin-echo T2-weighted (FS-TSE-T2WI) sequence was lower than before, and the ablation zone showed a low signal that completely covered the primary tumor. There was no significant difference in volume among the low-signal areas of the primary tumor on FS-TSE-T2WI before MWA, the central low-signal area on 3D-VIBE-T1WI after MWA, and the tumor coagulation necrosis area on the tissue specimens (p > 0.05). No significant difference was found in the volume of ablation zones among the tissue specimens, the high-signal area around the lesion on the 3D-VIBE-T1WI sequence, and the low-signal area covering the lesion on the FS-TSE-T2WI sequence (p > 0.05).Conclusion: Magnetic resonance imaging (MRI) is an effective method for immediate efficacy evaluation of rabbit renal VX2 tumors after MWA and can serve as a valuable reference for the clinical assessment of post-ablative renal tumors.

Transarterial embolization of renal VX2 tumors with liquid embolic agent poly 2-hydroxymethyl methacrylate-co-methyl methacrylate in a rabbit model

Objective To study the feasibility and effectiveness of liquid embolic agent HEMA-MMA in the arterial embolization therapy for the rabbit renal VX2 tumor models. Methods Renal VX2 tumor models were inoculated with the method of percutaneous CT-guided implantation of a small fragment of tumor into the inferior pole of the right kidney and were embolized when the max diameter was 1.5 cm. One model was embolized with the mixture of HEMA-MMA and carbonyl iron powder and was harvested immediately after embolization, the sample was fixed by paraformaldehyde for histopathological examination with methylene blue staining and HE staining to demonstrate the sizes of the vessels that the HEMA-MMA could reach. The remaining models were treated with pure HEMA-MMA by superselective or nonselective embolization (SSE or NSE). In SSE group, only the renal artery branch supplying the tumor was superselectively catheterized and embolized until the presence of artery casting change. In NSE group, the microcatheter was catheterized into the main renal artery then the whole renal artery branches and the renal capsular artery were embolized simultaneously until the presence of artery casting shape. Non-enhanced CT scans at immediate postoperation, on postoperative day 1 and day 3 were performed. The enhanced CT scans at the postoperative 1, 2, 4 and 6 weeks were performed. Necrotic zone of the tumor was defined as non-enhancement in parenchyma phase, residual tumor was defined as delayed enhancement around the necrotic zone or obvious thickness and enhancement of the adjacent renal capsule. When detecting residual tumor, the model was followed up another 1 week and then harvested for histopathological examination. If there was no residual tumor and lung metastasis in 6 weeks follow-up after operation, we defined this as complete necrosis and then harvested the kidney for histopathological examination. Results Eleven of the 12 rabbits were successfully inoculated VX2 tumors. The mixture of HEMA-MMA and carbonyl iron powder deposited in the arterial vessels demonstrated mazarine in methylene blue staining and brownness in HE staining. The diameter of the tumor vessels which the agent could reach was 30—150 μm, there was no embolic agent detected in the venous blood vessels. 5 models were performed with superselective embolization and the other 5 were embolized with nonselective embolization. The embolic agent demonstrated high density and obviously deposited in the surrounding zone of the tumor on immediate postoperative CT images, density of the surrounding zone decreased accompanied by density increase in the central area of the tumor on the first day postoperative CT images. Density difference between the embolism zone and normal renal tissue disappeared on the third day postoperative CT images accompanied by swelling changes of the embolized area. Residual tumor was detected in all 5 superselectively treated cases (2 in 1 week, 3 in 2 weeks), which located in the area of junctional zone and subrenal capsule. The necrotic zone was demonstrated coagulative necrosis on histopathologic images, the boundary between the residual tumor and the necrotic zone was clearly showed both on histopathologic images and gross specimen. Renal capsular artery participating in the residual tumor blood supply was also shown on gross specimen. There was no residual tumor and lung metastasis detected in nonselective treated group during the period of 6 weeks follow-up. Atrophy of the whole tumor-burdened kidney was shown on gross specimen and complete coagulative necrosis of the total tumor and the renal capsule adjacent to the tumor was demonstrated on histopathologic images. Conclusions Liquid embolic agent HEMA-MMA can embolize tumor blood vessels with a diameter of 30—150 μm. The renal capsular artery participates in the blood supply of the VX2 kidney tumor, so only superselective embolization of the renal artery branch with this liquid embolic agent may not induce the whole necrosis of the tumor, but complete necrosis of the tumor can be obtained by embolizing of all the tumor vessels and the adjacent normal renal arteries with this liquid embolic agent. Key words: Kidney neoplasms; Embolization, therapeutic; Rabbits

Experimental study of CT-guided percutaneous ethanol ablation in rabbit renal VX2 tumor

CT-guided percutaneous ethanol ablation (PEA) has been widely used in treating solid tumors such as hepatoma, lung cancer, adrenal nonfunctional adenoma. This study was to explore the efficacy, safety and feasibility of CT-guided PEA in treating renal tumor in rabbit. Twenty-five rabbits carrying VX2 tumor were randomized into PEA group (15 rabbits) and control group (10 rabbits). After CT-guided PEA, the area of the largest cross section lipiodol deposition in PEA group was measured. After one week, the kidneys carrying VX2 tumor were removed, tumor size in both groups and the area of the largest cross section coagulation necrosis in PEA group were measured. Wound infection and the changes of living habits of the rabbits were observed after experiment. A total of 25 VX2 tumors were developed in the 25 rabbits. The area of the largest cross section was 1.38-2.25 cm(2), with an average of (1.61+/-0.04) cm(2). There was no significant difference in tumor size between the two groups. After ablation, the area of lipiodol deposition in PEA group was 1.31-1.85 cm(2), with an average of (1.56+/-0.05) cm(2). At one week after ablation, the area of the largest cross section of tumors was significant smaller in PEA group than in control group [(1.58+/-0.03) cm(2) vs. (1.94+/-0.03) cm(2), P<0.05]; the area of coagulation necrosis in PEA group was 1.27-1.78 cm(2), with an average of (1.54 +/-0.04) cm(2), and was similar to the area of lipiodol deposition (P>0.05). Tumor tissue in ablation areas showed acidophilia changes and irregular coagulation necrosis. There was no obvious complication in PEA group. CT-guided PEA can effectively inactivate rabbit kidney VX2 tumors, and it is a safe and feasible treatment without obvious complications.

Radiofrequency Ablation of Renal VX2 Tumors With and Without Renal Artery Occlusion in a Rabbit Model: Feasibility, Therapeutic Efficacy, and Safety

The purpose of this study was to determine the therapeutic efficacy of radiofrequency ablation for treating renal VX2 tumors with and without renal artery occlusion in a rabbit model. Twenty-four New Zealand White rabbits were percutaneously implanted with renal VX2 tumors. Fifteen days after implantation, both kidneys were surgically exposed, and radiofrequency ablation was conducted. Group A (n=12) was treated with renal artery occlusion, and group B (n=12) was treated without occlusion. In each rabbit, the serum creatinine was measured to evaluate renal damage after arterial occlusion. Two days after radiofrequency ablation, computed tomography was performed to evaluate the difference in therapeutic results between the two groups. We also compared histopathologic findings after radiofrequency ablation. The mean tumor size was 2.4 cm (range, 1.2-3.1 cm). Radiofrequency ablation of renal tumors was technically feasible in all cases. Complete ablation was achieved in 11 of the 12 rabbits (92%) in group A but in only eight of the 12 rabbits (67%) in group B (P<0.05). The average time of radiofrequency application was shorter in group A (mean, 547 s) than in group B (mean, 826 s) (P<0.05). After radiofrequency ablation, the serum creatinine increased from 1.54 to 1.82 mg/dl in group A and from 1.46 to 1.78 mg/dl in group B. However, there was no significant difference between the two groups (P>0.05). In conclusion, radiofrequency ablation with renal artery occlusion can decrease the duration of treatment and increase the therapeutic efficacy for renal VX2 tumors.

Application of Radiofrequency Ablation of Renal VX2 Tumors by Cooled-Tip Electrode in a Rabbit Model

This study has two purposes: (1) To compare the use of tumor cell suspensions and excised tumor tissue for generating renal tumors suitable for radiofrequency ablation (RFA) studies and (2) to assess the effectiveness of RFA for ablation of renal VX2 tumors in a rabbit model. VX2 tumor masses were used to inoculate 17 rabbits. The renal VX2 tumors of 13 rabbits were subsequently treated with a cooled-tip radiofrequency system at a power of 15 to 30 W for 3 to 6 minutes, and 4 rabbits served as controls. After RFA, rabbits were observed by contrast-enhanced CT to ascertain the ablative range. Rabbits were divided into three groups and sacrificed at 3, 7, and 14 days post-treatment for histopathologic studies. Both tumor implant methods had a 100% success rate in generating tumors. The average lesion produced was 1.3 x 1.8 x 1.5 cm. Complete tumor ablation occurred in 76.9%, and local tumor growth in 23.1%. Depending on the position of the tumors, the complications after RFA treatment included infarction, perirenal hematoma, hydronephrosis, and abscess. The overall complication rate was 38.5%. In histopathologic studies, a central needle track, tumor coagulation, renal tissue coagulation, peripheral hemorrhage, and an inflammatory layer could be observed. Application of RFA to destroy renal VX2 tumors in this rabbit model has a relatively high cure rate. It can be used to destroy small renal tumors in a precise and noninvasive manner. We hope to apply this procedure in selected human renal tumors in the future.

Application of Radiofrequency Ablation of Renal VX2Tumors by Cooled-Tip Electrode in a Rabbit Model.

Objective. This study has two purposes: (a) to compare the use of tumor cell suspensions and excised tumor tissue for generating renal tumors suitable for radiofrequency ablation (RFA) studies and (b) to assess the efficacy of RFA for ablation of renal VX2 tumors in a rabbit model. Procedures. VX2 tumor masses were used to inoculate 17 rabbits. The renal VX2 tumors of 13 rabbits were subsequently treated with a cooled-tip RF system at a power of 15-30 W for 3-6 minutes, and 4 rabbits served as control. After RFA, rabbits were observed by contrast-enhanced CT to ascertain the ablative range. Rabbits were divided into three groups and sacrificed at 3, 7, and 14 days post-treatment for histopathological studies. Results. Both tumor implant methods had a 100% success rate in generating tumors. The average lesion produced was 1.3x1.8x1.5 cm. Complete tumor ablation occurred in 76.9%, and local tumor growth in 23.1%. Depending on the position of the tumors, the complications after RFA treatment included infarction, perirenal hematoma, hydronephrosis, and abscess. The over-all complication rate was 38.5%. In histopathological studies, a central needle track, tumor coagulation, renal tissue coagulation, peripheral hemorrhage, and an inflammatory layer could be observed. Conclusion and clinical relevance. Application of RFA to destroy renal VX2 tumors in this rabbit model has a relatively high cure rate. It can be used to destroy small renal tumors in a precise and non-invasive manner. Impact on human medicine. We hope to apply this procedure in selected human renal tumors in the future.

Radiofrequency Ablation of Unilateral Kidney VX2 Tumors in the Rabbit Model

Purpose: The aim of this study was to evaluate the effectiveness and indication of radiofrequency ablation (RFA) using renal VX2 tumors by implantation of VX2 tumor cells under the renal capsule in rabbits. Materials and Methods: Ten rabbits were injected with 30-40μl VX2 tumor cells (1.2x10 viable cells/ml) under the renal capsule of the right kidney by right subcostal incision. On the 14th day after the tumor cells were implanted, we checked for the development of renal tumors, and the sizes and shapes (exophytic or central) of the tumors by the use of computed tomography. We performed RFA in the renal VX2 tumors with a 17G StarBurst electrode through kidney exposure. After the first and third day following RFA, renal function was checked. On the third day, we performed CT and harvested the kidneys for gross and microscopic evaluation. Results: We confirmed the development of renal VX2 tumors in nine cases. Tumor shapes were exophytic in seven cases and central in two cases; the mean size of the tumors was 2.1cm (range, 1.1-3.8cm). In all tumors, RFA was performed. From the use of enhanced CT after RFA on the third day, all of the lesions treated with RFA showed no enhancement. From the pathological findings, coagulative necroses were seen on all of the lesions treated with RFA. The necrotized tumor size after RFA was not different statistically as measured by CT and a pathological examination (p=0.833). Conclusions: In centrally located renal tumors, we experienced thermal injury in pelvocalyceal systems. RFA is an effective method for nephron sparing surgery as the tumor cells completely disappear and there is preserved renal function and the procedure is easy to apply. We suggest that the RFA method for exophytic renal tumors is more effective than other procedures. (Korean J Urol 2008;49:208-214) 󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏󰠏

Open radio-frequency thermal ablation of renal VX2 tumors in a rabbit model using a cooled-tip electrode: feasibility, safety, and effectiveness.

The purpose of this study was to evaluate the feasibility, safety, and effectiveness of radio-frequency (RF) ablation using an internally cooled-tip electrode on renal VX2 tumors implanted in rabbits. Thirty-three rabbits with implanted renal VX2 tumors were divided into two groups: an RF ablation (RFA) group ( n=27) and a control group ( n=6). In the RFA group, RFA was performed on 27 implanted VX2 tumors using a cooled RF electrode and they were divided into three subgroups according to the follow-up period: acute (1-3 days, n=12); subacute (1-4 weeks, n=9); and chronic (2-7 months, n=6). Contrast-enhanced spiral CT was performed before the RFA and at the day, day 3, weeks 1, 2, 4, and months 2 and 7, after the RFA. The therapeutic efficacy was evaluated by the survival rate, CT, and pathologic findings. The RFA of renal tumors was technically successful in each instance. Complete tumor ablation was achieved in 22 of the 27 rabbits (81.5%) in the RFA group: 5 rabbits survived longer than 8 weeks without any evidence of viable tumor (18.5%) and 17 rabbits were found free of viable tumors when killed (63.0%). Five rabbits showed local tumor relapse and/or hematogenous lung metastasis after ablation (a recurrence rate of 18.5%). There were 11 (40.7%) complications related to the procedure. This experimental study demonstrates the feasibility of RFA therapy to treat renal VX2 tumors in rabbits, although RFA for central tumors carries some major potential complications, including renal arterial injury.

Parenchymal enhancement and tumor visualization using a new sonographic contrast agent.

The purpose of this study was to assess the ability of a sonographic contrast agent to increase parenchymal echogenicity and improve tumor visibility. The agent is an emulsion that changes at body temperature from nonechogenic submicrometer liquid droplets to echogenic 1 to 5 microns microbubbles, capable of transversing the pulmonary and capillary circulations. Peripheral venous injections (dosages of 0.05 to 0.8 ml/kg) were administered to five woodchucks (three with multiple hepatomas), 12 rabbits (with renal VX-2 tumors), and four dogs. Ultrasonograms were acquired from kidney, liver, tumors (including tumor vessels) and normal vessels. Uptake and washout curves were generated via videodensitometry. Finally, Doppler shifts from a cuff transducer around the celiac trunk were analyzed to provide an in vivo dose-response curve. Vascular enhancement, including hepatoma and VX-2 tumor vessels, was seen for 2 to 3 min. Maximum enhancement was 18.7 dB for a 0.6 ml/kg dose. Enhancement of normal liver and kidney parenchyma was observed in all three species for up to 20 min. Small hepatomas became more echogenic centrally, but larger tumors showed no increase in central echogenicity. In conclusion, improved tumor visibility and parenchymal enhancement was demonstrated in animals.