Abstract
Purpose:
To utilize a novel ex vivo perfused human renal model and quantify microwave ablation (MWA) size differences in renal tissue when combining MWA with transarterial embolization (TAE).
Materials and Methods:
Human kidneys (n = 5) declined for transplantation were obtained and connected to a fluoroscopy-compatible ex vivo perfusion system. Two ablations—1 standard MWA and 1 TAE-MWA—were performed in each kidney for 2 minutes at 100 W using a MWA system (Solero Angiodynamics). MWA alone was performed in the upper pole. In the lower pole, MWA was performed after TAE with 40–90 μm radiopaque microspheres to achieve angiographic stasis. Ablation zones of coagulative necrosis were sectioned along the long axis and segmented for maximal short-axis diameter (SAD) and long-axis diameter (LAD) measurements.
Results:
A total of 10 ablations (5 MWAs and 5 TAE-MWAs) were performed in 5 human kidneys. TAE-MWA resulted in significantly increased SAD, LAD, volume, and sphericity compared with standard MWA ± SD, with mean measurements as follows (5 standard MWAs ± SD vs 5 TAE-MWAs ± SD, 2-tailed t-test): (a) SAD, 1.8 cm (SD ± 0.1) versus 2.5 cm (SD ± 0.1) (P < .001); (b) LAD, 2.9 cm (SD ± 0.3) versus 3.2 cm (SD ± 0.1) (P = .039); (c) volume, 5.0 mL (SD ± 0.5) versus 11.0 mL (SD ± 0.7) (P < .001); and (d) sphericity, 0.4 (SD ± 0.2) versus 0.6 (SD ± 0.1) (P = .049). Histology demonstrated no differences in TAE-MWA other than concentrated microspheres.
Conclusions:
This ex vivo human kidney perfusion model confirmed that combined MWA-TAE significantly increased ablation size and spherical shape compared with MWA alone.
Renal microwave ablation (MWA) is an increasingly utilized thermal ablation modality for the treatment of renal cell carcinoma (RCC), with minimally invasive therapies becoming incorporated into treatment guidelines (1–3). The combination of MWA following transarterial embolization (TAE) has been shown to be safe and effective for the treatment of appropriately selected T1b renal tumors (4,5). The timing between MWA and TAE varies by clinical practice, with effectiveness shown in both same-day and staged procedures (6,7). This practice overcomes the effects of perfusion-mediated tissue cooling during MWA by decreasing blood flow to the ablation target zone with embolic agents, typically microspheres with or without chemotherapy. This decrease in perfusion creates a larger ablation zone with improved ablation margins (8,9).
A prior ex vivo study (10) utilized an ex vivo perfusion model for liver thermal ablation investigation, but fewer models have been described for renal MWA. A prior laboratory investigation (11) into a perfusion model for renal MWA demonstrated the ability to produce perfusion-mediated tissue cooling during ex vivo MWA, resulting in decreased MWA dimensions for perfused bovine kidneys. A systematic review (10) found that prior preclinical investigations for MWA utilized predominantly healthy nonperfused ex vivo animal organs to study MWA dimensions. In animals, the impact of TAE-MWA on overall ablation margins has been evaluated using hepatic models, with results demonstrating significantly increased ablation zones (12). As the use of MWA increases in RCC management, the use of organspecific investigations is important to examine each environment for MWA. During the procurement process of human-donor organs, many explanted organs are ultimately declined for human transplantation because of factors such as donor clinical history, organ quality at time of explant, or surgical issues identified during recipient procedure (13). Because of the increasing number of solid organ transplants performed each year, these transplant-declined organs provide an opportunity to advance translational research for preclinical studies (14). The increased ablation zones created by combined TAE-MWA have been useful for targeting T1b renal tumors. However, the quantitative benefit generated by TAE for renal MWA margins is limited by the minimally invasive nature of this procedure. A calculated increase in ablation margins would be useful to improve MWA zone prediction, potentially improving treatment planning of ablation margins.
Utilizing a previously validated ex vivo MWA model (11), the present study hypothesized a significant increase in MWA margins after performing adjunctive TAE in perfused ex vivo human kidneys.
MATERIALS AND METHODS
Following standard transplant research protocols, the local organ procurement center allocated human research kidneys from brain-dead deceased human organ donors that were declined for organ transplantation. This project was deemed exempt by the local institutional review board (IRB) because of nonhuman subject research determination and anonymity of donors to the researchers. Before explant, research consent was obtained from the organ donor’s designated consenting party by the organ procurement center. Each organ was procured following standard surgical and transplant preservation techniques. Exclusion criteria included the presence of transmissible infectious organisms or prolonged cold ischemic time (>72 hours). After procurement with organ transplant intent, kidneys declined for transplantation were screened for exclusion criteria and then accepted by the research team for inclusion in this protocol. Kidneys were stored at 0°C before initiation of the organ perfusion protocol. Standard organ characteristics were provided. A total of 5 human research kidneys were obtained from 3 organ donors.
Organ Preparation
Before perfusion, organs were cannulated on ice in standard surgical fashion. The renal artery, renal vein, and ureter were prepared, and branch vessels were ligated (Fig 1). The native aorta, inferior vena cava, perirenal fascia, and retroperitoneal fat were dissected and freed from the kidney and ligated using 2–0 silk ties. Branch vessels were ligated, followed by cannulation of the renal artery with an 8-F (Bio-Medicus; Medtronic, Minneapolis, Minnesota) or 12-F pediatric arterial extracorporeal membrane oxygenation (ECMO) cannula (DLP; Medtronic), depending on native vessel size, and the renal vein with a 22-F venous ECMO cannula (DLP, Medtronic). The ureter was cannulated with a 5-F vascular sheath for continuous urine collection. Organs were weighed after cannulation and removal of excess tissue for baseline weight on a digital scale (MeasureTek, Toronto, Canada) (Fig 2). A 5-F vascular sheath (Super Sheath; Boston Scientific, Marlborough, Massachusetts) was inserted into the perfusion tubing to introduce a 5-F diagnostic catheter (Boston Scientific).
Figure 1.
Preparing the research kidney for cannulation and perfusion. (a) Deceased donor kidney with renal artery (red arrow) attached to the aorta before preparation and branch vessel ligation. Atherosclerotic disease was also noted along the aortic wall (white arrow). (b) The renal vein (blue arrow) was identified with the inferior vena cava (black arrow).
Figure 2.
Ex vivo human kidney undergoing perfusion with cannulas in the renal artery (red arrow), vein (blue arrow), and ureter (yellow arrow).
Organ Perfusion and Quality Assessment
Using a previously published ex vivo perfusion system, kidneys were connected to a fluoroscopy-compatible ex vivo perfusion system consisting of pulsatile cardiovascular perfusion pump (Cobe Laboratories, Lakewood, Colorado), membrane oxygenator (Quadrox-iD Adult; Maquet, Rastatt, Germany), and warmer (T/Pump; Gaymar, Orchard Park, New York) (Fig 3). There was continuous blood pressure and temperature monitoring performed using a blood pressure monitor (Avante Waveline Touch; DRE, Louisville, Kentucky). Perfusate solution consisted of 50% defibrinated bovine red blood cells (Hemostat Laboratories, Dixon, California), 50% normal saline, and 50 g of glucose. Continuous urine production was measured throughout the experiment and collected in a 400-mL beaker.
Figure 3.
Ex vivo renal perfusion model. (a) Peristaltic perfusion pump used to perfuse ex vivo organs. (b) Membrane oxygenator (black arrow) used to receive deoxygenated venous blood (blue arrow) and send oxygenated arterial blood (red arrow) to the kidney. A 5-F vascular sheath (green arrow) was inserted into the arterial tubing for angiographic experiments.
Perfusion was initiated at 5 rpm for a goal flow rate of 25 rpm, corresponding to a mean flow of 144 mL/min, which was manually calibrated using pulsatile perfusion tubing and a 1-L beaker. Perfusion was performed until organs were warmed to physiologic temperature.
Initial digital subtraction angiography (DSA) was performed in the main renal artery using iohexol (Omnipaque 350; GE Healthcare, Chicago, Illinois) to assess for arterial or renal parenchymal injury (Fig 4). The renal parenchyma was then assessed by ultrasound (US) using a linear transducer to plan for appropriate MWA probe placement (iU22; Philips, Bothell, Washington).
Figure 4.
Digital subtraction angiography (DSA) performed for preablation assessment. (a) DSA of a deceased donor kidney demonstrated arterial perfusion and region of extravasation from a wedge biopsy (arrow). (b) Subsequent selective arteriography performed through the microcatheter (arrow) before transarterial embolization.
Microwave Ablation
An MWA probe was inserted under US guidance to avoid the collecting system and to center the probe in the renal parenchyma (Fig 5). Preliminary experiments demonstrated significant tissue retraction and extension of the MWA zone to the renal capsule at MWA settings greater than 100 W. After probe placement, 1 standard MWA was performed in the superior aspect of each kidney for 2 minutes at 100 W using a commercial 2.45-GHz MWA system (Solero; AngioDynamics, Latham, New York). Following the initial ablation, a 2.4-F microcatheter (Renegade STC 18; Boston Scientific) was introduced into the inferior branch of the kidney where selective arteriography was performed (Fig 4). One vial of 40–90 μm radiopaque microspheres (Lumi M0; Boston Scientific) was prepared using iodixanol (Visipaque 320; GE Healthcare) following manufacturer recommendations and then injected in the inferior branch of the renal artery using a microcatheter until stasis was observed. A final DSA was performed to ensure complete embolization of this region. Under US and fluoroscopic guidance, the MWA probe was placed in the embolized region, avoiding the renal collecting system and centering the probe in the renal parenchyma (Fig 6). TAE-MWA was performed for 2 minutes at 100 W. Before each probe removal, a spinal needle was placed alongside the ablation probe to mark the trajectory of the standard MWA and TAE-MWA. Final renal arteriography and retrograde urography were performed before removal from the perfusion system. After completion of the perfusion protocol, each organ was disconnected from the perfusion apparatus and weighed on the same digital scale.
Figure 5.
A sonographic image demonstrating the use of ultrasound (US) for guided needle placement (arrow) within the kidney before ablation.
Figure 6.
Tissue staining with radiopaque microspheres and confirmation of transarterial embolization (TAE) zone. (a) A sonographic image displaying the kidney after TAE but before microwave ablation (MWA) for planning probe placement. Numerous echogenic foci were noted related to microsphere infusion (white arrow). (b) Fluoroscopic image demonstrating the ablation probe (black arrow) in place during MWA-TAE. The radiopaque microspheres were visible within the embolized renal parenchyma (white arrowheads). A spinal needle marked the trajectory of the first MWA probe placement in the pole that did not undergo TAE (white arrow).
Ablation Assessment
Ablation zones of coagulative necrosis were sectioned along the long-axis trajectory and segmented for maximal short-axis diameter (SAD) and long-axis diameter (LAD) measurements (Fig 7) using digital calipers. Ellipsoid volume and sphericity were calculated using methods previously published (15).
Figure 7.
Microwave ablation (MWA) performed in the same human kidney at the same time and wattage settings with the short-axis diameter and long-axis diameter labeled with white arrows, demonstrating an increased short-axis diameter and spherical shape. (a) The sectioned MWA zone after standard MWA without transarterial embolization. (b) The sectioned MWA zone after transarterial embolization–MWA.
Histology
Ablation zones from standard MWA and TAE-MWA from each kidney were then placed in formalin and submitted to pathology for standard processing, sectioning, and staining. Histologic samples from each ablation zone were stained with hematoxylin and eosin, and interpreted by a renal pathologist for the presence of microspheres and to assess for coagulative necrosis.
Analysis
Analysis was performed using a previously published method in a perfused versus nonperfused dataset from a bovine ex vivo model, using anticipated ablation zone volume measurements at the same setting. A power analysis for a 2-tailed t-test with a significance level of 0.05 was conducted using prior data from the authors’ ex vivo renal ablation model aimed to achieve 80% power to detect a difference of 5 mm (11). Based on this analysis, the required sample size was calculated to be N = 5. MWA SAD, LAD, volume, and sphericity were compared using a t-test. Final fluoroscopic images were also analyzed for contrast staining of the microspheres in the tissue to assess the region of ablation. Standard statistical analysis was performed using Stata BE 17.0 (StataCorp, College Station, Texas).
RESULTS
Organ Conditions and Measurements
A total of 10 ablations (5 standard MWAs and 5 TAE-MWAs) were performed in 5 human kidneys. Mean final creatinine before explant was 2.6 mg/dL (SD ± 1.6) for donor renal kidneys (n = 3). Mean cold ischemic time was 44.5 hours (range, 35–66 hours). Mean arterial blood pressures were 170 mm Hg (SD ± 50) before TAE and 216 mm Hg (SD ± 77) after TAE (P = .29). Mean flow rate was 0.63 mL/g/min (SD ± 0.14). Continuous urine production was noted from each kidney, and mean urine production was 1.60 mL/min (SD ± 2.57; range, 0.14–6.13 mL/min; n = 5).
TAE-MWA resulted in significantly increased SAD, LAD, volume, and sphericity compared with standard MWA, with the following mean gross specimen comparisons (5 standard MWAs ± SD vs 5 TAE-MWAs ± SD, 2-tailed t-test): (a) SAD, 1.8 cm (SD ± 0.1) versus 2.5 cm (SD ± 0.1) (P < .001); (b) LAD, 2.9 cm (SD ± 0.3) versus 3.2 cm (SD ± 0.1) (P = .039); volume, 5.0 mL (SD ± 0.5) versus 11.0 mL (SD ± 0.7) (P < .001); and (c) sphericity, 0.4 (SD ± 0.2) versus 0.6 (SD ± 0.1) (P = .049) (Table).
Table 1.
| Standard MWA (n = 5) |
TAE-MWA (n = 5) |
% change | P-Value | |
|---|---|---|---|---|
| Short axis diameter (cm) | 1.8 ± 0.1 | 2.5 ± 0.1 | 38.9 | 0.001 |
| Long axis diameter (cm) | 2.9 ± 0.3 | 3.2 ± 0.1 | 10.3 | 0.039 |
| Volume (mL) | 5.0 ± 0.5 | 11.0 ± 0.7 | 120 | 0.001 |
| Sphericity | 0.4 ± 0.2 | 0.6 ± 0.1 | 50 | 0.049 |
Digital Subtraction Angiography
No evidence of MWA-associated vascular injury was identified, as assessed by postprocedural arteriography. Probes were successfully placed parallel to the collecting system, and ablations did not extend to the renal capsule (Fig 7). Final arteriogram, spot radiograph, and ultrasound imaging demonstrated successful microsphere delivery to the planned TAE-MWA regions (Fig 6).
Histology
Histologic evaluation for coagulative necrosis was limited by acute tubular necrosis in Kidneys 1–4 and severe diabetic glomerulosclerosis with tubular atrophy in Kidney 5. Patchy coagulative necrosis was identified in Kidneys 3 and 4, which were obtained from the same donor. Histologic confirmation of concentrated microspheres in large-caliber vessels of the TAE-MWA zones was observed (Figure E1, available online on the article’s Supplemental Material page at www.jvir.org.). No histologic differences were observed between standard MWA and TAE-MWA.
DISCUSSION
This ex vivo model demonstrated a statistically significant increase in MWA SAD, LAD, volume, and sphericity, representing the ability of TAE-MWA to overcome the effects of perfusion-mediated tissue cooling and to augment MWA zones. This is secondary to a targeted decrease in ablation zone perfusion and is an important consideration when increased and predictable MWA zones are required to create sufficient ablation margins.
An advantage of this human model for MWA translational research is the ability to utilize research organs that are comparable with the clinical population of interest. Organs procured for this protocol were minimally atrophic with underlying renal disease and generally hypertensive during experiments, more notably after TAE was performed. These organs had varying degrees of continuous urine production throughout each experiment. A prior ex vivo MWA study (16) performed in animal models primarily occurred in healthy organs with tissue properties likely differing from human organ characteristics. This model provides a platform for translational research to integrate perfusion-mediated tissue cooling and human tissues in a low-risk setting. An additional benefit of this MWA model is the ability to perform arteriography and urography after the intervention to assess for injury, which may be technically challenging in animal models and clinical studies. Use of this model in future translational research is possible to study embolic distribution in renal parenchyma and provide an alternative model to create reference measurements for preclinical MWA testing (16).
Similar to a previously published animal TAE-MWA model, these ex vivo human experiments demonstrated a 38.9% change in SAD (Table), compared with a 29.2% change in SAD for a hepatic animal model after TAE (12). Supplied manufacturer guidelines report an SAD MWA size of 3.0 cm when performed in bovine renal tissues at 100 W for 2 minutes. Compared with manufacturer data at the same setting, the results of the present study demonstrate mean SADs of 1.8 cm for standard MWA and 2.5 cm for TAE-MWA, representing manufacturer overestimation of MWA SAD by 50% and 18.2%, respectively. Overall, the observed measurements are considerably smaller than those reported by the manufacturer, which is likely related to manufacturer data being obtained from nonperfused ex vivo animal organs. This is an important consideration when considering ablation settings for RCC tumors because of the high degree of perfusion-mediated tissue cooling in this very vascular organ (10,16).
Limitations of these results arise from the nontumor model for these experiments. Despite the lack of tumoral tissue, MWA is dependent on dielectric tissue properties and vascularity of the tissue, which is partially comprised of normal tissue when extending the MWA zone into normal renal parenchyma to create sufficient margins. In addition, the presence of perfusion may vary in renal tumors because of their varying degree of vascularity. A prior investigation utilizing perfusion computed tomography (CT) demonstrated that renal tumors had decreased regional blood flow compared with normal parenchyma—possibly indicating a lesser impact of MWA-TAE on MWA zones in RCC than that of MWA of normal renal parenchyma (17). Compared with the clinical setting, lower-power ablations were performed to prevent capsular retraction of renal tissue in these experiments (18). Capsular retraction was observed in the authors’ preliminary ex vivo human kidney experiments at higher-power settings, limiting final measurements because the expected MWA zones could not extend beyond the renal capsule. US-guided placement of the probe allowed consistent probe positioning away from the collecting system and renal capsule. By preventing extension of the renal MWA to the cortex, the measurements were more accurate than those obtained if significant capsular retraction and tissue contracture were permitted.
Overall histologic evaluation for this model was limited by the degree of acute kidney injury in rejected donor research organs, which constrained evaluation for coagulative necrosis. Minimal histologic findings in samples taken immediately after ablative injury have been previously described, likely related to the time it takes for histologic changes to occur after thermal ablation (19). Histologic analysis in future experiments may be improved by tissue staining for cell viability (20) and decreasing cold ischemic time to limit renal injury. However, the final zone of coagulative necrosis was measured using gross pathology and identifiable ablation zone, which is a reliable method to record zone measurements (21,22). These experiments also did not incorporate chemotherapeutic agents into the embolic agent because the final timepoint was completion of the TAE-MWA. A single ablation setting was utilized for this protocol because of the complexity of obtaining human research organs and limited space in human kidneys to perform multiple ablations for comparison. In addition, MWA was performed immediately after TAE, which varies by practice, and interval from TAE to subsequent MWA has not been investigated to determine the best practice. Final limitations for this ex vivo human model are the small sample size and complexity to reproduce this model.
These unique human ex-vivo organs provide a clinically relevant environment to study MWA and other locoregional treatments. In this ex vivo model of renal MWA, TAE as an adjunctive treatment increased ablation margins and spherical shape.
Supplementary Material
Figure E1. Histopathology slide demonstrated numerous embolic beads (black arrow) within a distal arterial branch. Several glomeruli were noted (white arrows).
STUDY DETAILS.
Study type: Laboratory investigation
RESEARCH HIGHLIGHTS.
Microwave ablation (MWA) combined with transarterial embolization (TAE) increased MWA margins and spherical shape.
Compared with the manufacturer reference guide, produced from nonperfused ex vivo animal organs, this ex vivo perfused human model produced smaller MWA zones for both standard MWA and TAE–MWA.
The ex vivo human perfusion model utilizing organs declined for transplantation was useful in this preclinical investigation of MWA, and may be applicable to other interventional radiology therapies.
Acknowledgements
C.B.O. reports RSNA Resident/Fellow Foundation Grant. A.D. reports training support from South Texas Medical Scientist Training Program National Institutes of Health T32GM113896 Grant. L.B. is Chief Innovation Officer of Vascular Perfusion Solutions and reports stock from Vascular Perfusion Solutions. J.W. reports grants or contracts from Boston Scientific and support for attending meetings and/or travel from HistoSonics.
ABBREVIATIONS
- CT
computed tomography
- DSA
digital subtraction angiography
- IRB
institutional review board
- LAD
long-axis diameter
- MWA
microwave ablation
- RCC
renal cell carcinoma
- SAD
short-axis diameter
- TAE
transarterial embolization
- US
ultrasound
Footnotes
Figure E1 can be found by accessing the online version of this article on www.jvir.org and selecting the Supplemental Material tab.
From the 2023 SIR Annual Scientific Meeting (Abstract No. 550, “Understanding the Margins: Evaluation of Microwave Ablations Changes after Transarterial Embolization Utilizing Perfused Ex Vivo Human Kidneys”).
Contributor Information
Carlos B. Ortiz, Department of Radiology, Long School of Medicine, The University of Texas Health Sciences Center San Antonio, San Antonio, Texas.
Kade Derrick, Long School of Medicine, The University of Texas Health Sciences Center San Antonio, San Antonio, Texas.
Annie Dang, Long School of Medicine, The University of Texas Health Sciences Center San Antonio, San Antonio, Texas.
Marina Borrego, Department of Radiology, The University of Texas Health Sciences Center San Antonio, San Antonio, Texas.
Seiji Yamaguchi, Long School of Medicine, University Transplant Center, The University of Texas Health Sciences Center San Antonio, San Antonio, Texas.
Daniel Grosser, Department of Pathology, Case Western Reserve University, Cleveland, Ohio.
Leon Bunegin, Long School of Medicine, The University of Texas Health Sciences Center San Antonio, San Antonio, Texas, Vascular Perfusion Solutions, San Antonio, Texas.
John Walker, Department of Radiology, Long School of Medicine, The University of Texas Health Sciences Center San Antonio, San Antonio, Texas.
Jorge Lopera, Department of Radiology, Long School of Medicine, The University of Texas Health Sciences Center San Antonio, San Antonio, Texas.
REFERENCES
- 1.Motzer RJ, Jonasch E, Agarwal N, et al. Kidney cancer, version 3.2022, NCCN clinical practice guidelines in oncology. J Natl Compr Canc Netw 2022; 20:71–90. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Campbell SC, Clark PE, Chang SS, Karam JA, Souter L, Uzzo RG. Renal mass and localized renal cancer: evaluation, management, and follow-up: AUA guideline: part I. J Urol 2021; 206:199–208. [DOI] [PubMed] [Google Scholar]
- 3.Morris CS, Baerlocher MO, Dariushnia SR, et al. Society of Interventional Radiology position statement on the role of percutaneous ablation in renal cell carcinoma: endorsed by the Canadian Association for Interventional Radiology and the Society of Interventional Oncology. J Vasc Interv Radiol 2020; 31:189–194.e3. [DOI] [PubMed] [Google Scholar]
- 4.Guo J, Arellano RS. Percutaneous microwave ablation of stage T1b renal cell carcinoma: Short-term assessment of technical feasibility, short-term oncologic outcomes, and safety. J Endourol 2020; 34:1021–1027. [DOI] [PubMed] [Google Scholar]
- 5.Wells SA, Wheeler KM, Mithqal A, Patel MS, Brace CL, Schenkman NS. Percutaneous microwave ablation of T1a and T1b renal cell carcinoma: short-term efficacy and complications with emphasis on tumor complexity and single session treatment. Abdom Radiol (NY) 2016; 41: 1203–1211. [DOI] [PubMed] [Google Scholar]
- 6.LaRussa S, Vanden Berg RW, Craig KM, Madoff DC, McClure TD. Is there a role for combination, single-session selective transarterial embolization and microwave ablation for large renal masses? Cardiovasc Intervent Radiol 2020; 43:1468–1473. [DOI] [PubMed] [Google Scholar]
- 7.Zheng L, Li HL, Guo CY, Luo SX. Comparison of the efficacy and prognostic factors of transarterial chemoembolization plus microwave ablation versus transarterial chemoembolization alone in patients with a large solitary or multinodular hepatocellular carcinomas. Korean J Radiol 2018; 19:237–246. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Zaitoun MMA, Elsayed SB, Zaitoun NA, et al. Combined therapy with conventional trans-arterial chemoembolization (cTACE) and microwave ablation (MWA) for hepatocellular carcinoma >3-<5 cm. Int J Hyperthermia 2021; 38:248–256. [DOI] [PubMed] [Google Scholar]
- 9.Wang L, Ke Q, Lin N, Huang Q, Zeng Y, Liu J. The efficacy of transarterial chemoembolization combined with microwave ablation for unresectable hepatocellular carcinoma: a systematic review and meta-analysis. Int J Hyperthermia 2019; 36:1288–1296. [DOI] [PubMed] [Google Scholar]
- 10.Ruiter SJS, Heerink WJ, de Jong KP. Liver microwave ablation: a systematic review of various FDA-approved systems. Eur Radiol 2019; 29: 4026–4035. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Ortiz CB, Dang A, Derrick K, et al. Creation of an ex vivo renal perfusion model to investigate microwave ablation. J Vasc Interv Radiol 2023; 34: 40–45.e2. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Knavel EM, Green CM, Gendron-Fitzpatrick A, Brace CL, Laeseke PF. Combination therapies: quantifying the effects of transarterial embolization on microwave ablation zones. J Vasc Interv Radiol 2018; 29: 1050–1056. [DOI] [PubMed] [Google Scholar]
- 13.Mohan S, Chiles MC, Patzer RE, et al. Factors leading to the discard of deceased donor kidneys in the United States. Kidney Int 2018; 94: 187–198. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Organ Procurement and Transplantation Network. National data. Available at: https://optn.transplant.hrsa.gov/data/view-data-reports/national-data/. Accessed August 25, 2023.
- 15.Hines-Peralta AU, Pirani N, Clegg P, et al. Microwave ablation: results with a 2.45-GHz applicator in ex vivo bovine and in vivo porcine liver. Radiology 2006; 239:94–102. [DOI] [PubMed] [Google Scholar]
- 16.Kim C Understanding the nuances of microwave ablation for more accurate post-treatment assessment. Future Oncol 2018; 14:1755–1764. [DOI] [PubMed] [Google Scholar]
- 17.Das CJ, Thingujam U, Panda A, Sharma S, Gupta AK. Perfusion computed tomography in renal cell carcinoma. World J Radiol 2015; 7:170–179. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Sommer CM, Sommer SA, Mokry T, et al. Quantification of tissue shrinkage and dehydration caused by microwave ablation: experimental study in kidneys for the estimation of effective coagulation volume. J Vasc Interv Radiol 2013; 24:1241–1248. [DOI] [PubMed] [Google Scholar]
- 19.Kuromatsu R, Tanaka M, Shimauchi Y, et al. Light and electron microscopic analyses of immediate and late tissue damage caused by radiofrequency ablation in porcine liver. Int J Mol Med 2003; 11:199–204. [PubMed] [Google Scholar]
- 20.Gravante G, Ong SL, Metcalfe MS, Strickland A, Dennison AR, Lloyd DM. Hepatic microwave ablation: a review of the histological changes following thermal damage. Liver Int 2008; 28:911–921. [DOI] [PubMed] [Google Scholar]
- 21.Burns SK, Dodd GD 3rd, McManus LM, et al. 3T magnetic resonance imaging accurately depicts radiofrequency ablation zones in a blood-perfused bovine liver model. J Vasc Interv Radiol 2012; 23:801–808. [DOI] [PubMed] [Google Scholar]
- 22.Cha CH, Lee FT Jr, Gurney JM, et al. CT versus sonography for monitoring radiofrequency ablation in a porcine liver. AJR Am J Roentgenol 2000; 175:705–711. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Figure E1. Histopathology slide demonstrated numerous embolic beads (black arrow) within a distal arterial branch. Several glomeruli were noted (white arrows).