Transarterial embolization (TAE) as add-on to percutaneous radiofrequency ablation (RFA) for the treatment of renal tumors: Review of the literature, overview of state-of-the-art embolization materials and further perspective of advanced image-guided tumor ablation

Radiomics and machine learning for renal tumor subtype assessment using multiphase computed tomography in a multicenter setting

OBJECTIVES

To distinguish histological subtypes of renal tumors using radiomic features and machine learning (ML) based on multiphase computed tomography (CT).

MATERIAL AND METHODS

Patients who underwent surgical treatment for renal tumors at two tertiary centers from 2012 to 2022 were included retrospectively. Preoperative arterial (corticomedullary) and venous (nephrogenic) phase CT scans from these centers, as well as from external imaging facilities, were manually segmented, and standardized radiomic features were extracted. Following preprocessing and addressing the class imbalance, a ML algorithm based on extreme gradient boosting trees (XGB) was employed to predict renal tumor subtypes using 10-fold cross-validation. The evaluation was conducted using the multiclass area under the receiver operating characteristic curve (AUC). Algorithms were trained on data from one center and independently tested on data from the other center.

RESULTS

The training cohort comprised n = 297 patients (64.3% clear cell renal cell cancer [RCC], 13.5% papillary renal cell carcinoma (pRCC), 7.4% chromophobe RCC, 9.4% oncocytomas, and 5.4% angiomyolipomas (AML)), and the testing cohort n = 121 patients (56.2%/16.5%/3.3%/21.5%/2.5%). The XGB algorithm demonstrated a diagnostic performance of AUC = 0.81/0.64/0.8 for venous/arterial/combined contrast phase CT in the training cohort, and AUC = 0.75/0.67/0.75 in the independent testing cohort. In pairwise comparisons, the lowest diagnostic accuracy was evident for the identification of oncocytomas (AUC = 0.57-0.69), and the highest for the identification of AMLs (AUC = 0.9-0.94) CONCLUSION: Radiomic feature analyses can distinguish renal tumor subtypes on routinely acquired CTs, with oncocytomas being the hardest subtype to identify.

CLINICAL RELEVANCE STATEMENT

Radiomic feature analyses yield robust results for renal tumor assessment on routine CTs. Although radiologists routinely rely on arterial phase CT for renal tumor assessment and operative planning, radiomic features derived from arterial phase did not improve the accuracy of renal tumor subtype identification in our cohort.

Automated Feeder-Detection Software for Renal Cell Carcinoma Embolization: A Retrospective Evaluation of Detection Rate Using Transarterial Time-Resolved Computed Tomography Angiography

PURPOSE

To evaluate the detection rate of feeding arteries in renal cell carcinoma with automated feeder-detection software and determine the optimal imaging phase for accurate feeder detection with transarterial time-resolved computed tomography angiography.

MATERIALS AND METHODS

The performance of automated feeder-detection software was retrospectively evaluated using transarterial renal time-resolved computed tomography angiography images of 15 renal cell carcinomas (mean size, 22.1 mm); the images were obtained via the renal artery using a hybrid angio-CT system with 320-row computed tomography, across nine phases with 0.5-s intervals over a contrast delay time of 1.0-5.0 s. Automated feeder-detection software was applied to each phase in all tumors (135 image series in total). The feeder-detection rate (i.e., sensitivity) in each phase was evaluated, and the number of false feeders demonstrated by the software was counted for each tumor.

RESULTS

A total of 22 feeders were identified. The feeder-detection rate was the highest (95.5% [21/22]) at delay times of 1.5 s and 2.0 s and lower in later phases. At delay times of 1.0 s and 1.5 s, the software demonstrated no or only a few (≤ 3) false feeders in 93.3% (14/15) of the tumors. In later phases, however, many (≥ 4) false feeders were observed in > 50% of tumors.

CONCLUSION

The automated feeder-detection software showed a favorable feeder-detection rate and may be useful in transarterial embolization for renal cell carcinoma. The optimal delay time to avoid the demonstration of false feeders and achieve a high detection accuracy was 1.5 s.

LEVEL OF EVIDENCE IV

Case Series.

Comparison of Renal Damage Following Renal Artery Embolization with Three Different Embolic Mixtures in Swine

Purpose

Renal artery embolization is a minimally invasive and effective procedure for renal ablation, a complete necrosis of the renal parenchyma. This study aims to compare the extent of renal damage in swine following renal artery embolization with ethanol and N-butyl-2-cyanoacrylate, commonly used as embolic materials in renal ablation.

Material and Methods

Three different embolic mixtures were prepared for renal artery embolization in swine: 33% ethanol-Lipiodol mixture (ethanol:Lipiodol = 1:2; Group A), 67% ethanol-Lipiodol mixture (ethanol:Lipiodol = 2:1; Group B), and 10% N-butyl-2-cyanoacrylate-Lipiodol mixture (N-butyl-2-cyanoacrylate:Lipiodol = 1:9; Group C). Three swine were assigned to each group and underwent embolization of the unilateral renal artery. Renal arteriography was performed before, immediately after, and two days after renal artery embolization. After two days, the kidneys were removed to determine the macroscopic necrosis rate and for histologic examination. Dark tissue regions were considered necrotic.

Results

The macroscopic necrosis rate of the kidneys was 50.3%±7.4%, 100%±0%, and 100%±0% in Groups A, B, and C, respectively. The necrosis rates were higher in Groups B and C than in Group A. Histologically, the renal tubules were damaged in the necrotic areas. In addition, the glomeruli were damaged in Groups A and B but were preserved in Group C.

Conclusions

Sixty-seven percent ethanol-Lipiodol mixture and 10% N-butyl-2-cyanoacrylate-Lipiodol mixture are effective embolic materials in renal artery embolization for renal ablation in swine. Also, ethanol caused partial glomerular necrosis, whereas N-butyl-2-cyanoacrylate preserved the glomeruli. Therefore, ethanol should be used for renal ablation.

CT renal arteriography as a novel imaging guidance for the percutaneous ablation of small renal tumors

PURPOSE

To report procedural data and outcomes of a novel image guidance technique, CT renal arteriography (CTRA), performed to target and ablate small intraparenchymal renal tumors.

MATERIALS AND METHODS

We retrospectively analyzed data of 2 patients undergoing CTRA-guided ablation for 3 renal intraparenchymal tumors, from February to March 2023. We previously evaluated tumor visibility with US/CEUS, and in all cases conspicuity was poor, whereas contrast-enhanced CT (CECT) clearly depicted all hypervascular nodules. Our primary endpoint was CTRA-guidance feasibility for renal ablation, defined as the precise probe deployment inside the target tumor. The secondary endpoint was CTRA-guided ablation technical success, intended as the inclusion of the whole tumor inside the necrotic volume, with 5 mm safety margins. RENAL scores, complications, procedural time, dose length product (DLP), serum creatinine variation and hospital stay length were also recorded.

RESULTS

A confident deployment of the probe tip inside the nodule was accomplished in all 3 cases, with a 100% of correct targeting. We observed immediate technical success after all 3 ablations. The 3 nodules had a RENAL score <7 points, and we encountered no complications due to line placement or ablation. The average time from preablative to postablative CTRA was 54 min (50-58min), with a DLP of 3632mGy*cm (2807-4458mGy*cm). Serum creatinine didn't show a significant variation after the procedures; both patients were hospitalized for 2 days.

CONCLUSION

Preliminary data showed that CTRA-guidance might provide unique advantages over conventional CECT-guidance to assist the ablation of small renal intraparenchymal tumor not visualized on US/CEUS.

Tips and Tricks for Successful Percutaneous Cryoablation of Large Renal Cell Carcinomas

Percutaneous cryoablation has proved to be safe and effective for the treatment of stage T1a renal cell carcinoma (RCC). Patients with larger-sized RCCs may not be good surgical candidates or may have tumors located in anatomically unfavorable locations, which makes partial nephrectomy more challenging. In this patient population, percutaneous cryoablation can be considered a treatment option, given its less invasive nature when compared to surgery. The ablation of larger-sized RCCs requires careful planning to ensure that the tumor volume is completely covered within the ablation zone, while minimizing the risks of non-target injury to the surrounding critical organs. In this article, we share our institutional experience in treating larger-sized RCCs (> 4 cm) using percutaneous cryoablation alone. We discuss strategies to maximize the volume of the ablation zone through the precise placement of the probes. We also shed light on different techniques to protect the surrounding structures during cryoablation.

Selective Arterial Embolization with N-Butyl Cyanoacrylate Prior to CT-Guided Percutaneous Cryoablation of Kidney Malignancies: A Single-Center Experience

The study’s purpose was to assess the safety, feasibility and efficiency of selective arterial embolization (SAE) using N-butyl cyanoacrylate (NBCA) glue before percutaneous cryoablation (PCA) of renal malignancies in patients whose tumor characteristics and/or comorbidities resulted in an unacceptable risk of bleeding. In this single-center retrospective study of 19 consecutive high-risk patients (median age, 74 years) with renal malignancies managed in 2017–2020 by SAE with NBCA followed by PCA, data about patients, tumor and procedures characteristics, complications, renal function and hemoglobin concentration before and after treatment, as well as recurrence were collected. Charlson comorbidity index was ≥4 in 89.5% of patients. Ten patients were treated by antiplatelet and/or anticoagulant therapy. Median tumor largest diameter was 3.75 cm (range, 1–6.5 cm) and R.E.N.A.L. nephrometry score was ≥7 in 80%, indicating substantial tumor complexity. No major complications were recorded and minor complications occurred in 7 patients. No residual tumor was found at 6-week imaging follow-up in 18/19 patients. Tumor recurrence was visible in 1/16 patients at 6-month imaging follow-up. No significant difference was found for renal function after treatment (p = 0.07), whereas significant decrease in hemoglobin concentration was noted (p = 0.00004), although it was relevant for only one patient who required only blood transfusion and no further intervention. SAE prior to PCA is safe and effective for managing renal malignancies in high-risk patients.

Combined Angio-CT Systems: A Roadmap Tool for Precision Therapy in Interventional Oncology

Combined angiography-CT (angio-CT) systems, which combine traditional angiographic imaging with cross-sectional imaging, are a valuable tool for interventional radiology. Although cone-beam CT (CBCT) technology from flat-panel angiography systems has been established as an adjunct cross-sectional imaging tool during interventional procedures, the intrinsic advantages of angio-CT systems concerning superior soft-tissue imaging and contrast resolution, along with operational ease, have sparked renewed interest in their use in interventional oncology procedures. Owing to increases in affordability and usability due to an improved workflow, angio-CT systems have become a viable alternative to stand-alone flat-panel angiographic systems equipped with CBCT. This review aims to provide a comprehensive technical and clinical guide for the use of angio-CT systems in interventional oncology. The basic concepts related to the use of angio-CT systems, including concepts related to workflow setup, imaging characteristics, and acquisition parameters, will be discussed. Additionally, an overview on the clinical applications and the benefits of angio-CT systems in routine therapeutic and palliative interventional oncology procedures will be reviewed. Keywords: Ablation Techniques, CT-Angiography, Interventional-Body, Interventional-MSK, Chemoembolization, Embolization, Radiation Therapy/Oncology, Abdomen/GI, Skeletal-Axial Supplemental material is available for this article. © RSNA, 2021.

The earlier, the better: The beneficial effect of different timepoints of the preoperative transarterial embolization on ameliorating operative blood loss and operative time for carotid body tumors

BACKGROUND

To explore the effect of the optimal time interval from preoperative transarterial embolization to surgery of carotid body tumors by analyzing surgery-related indicators.

METHODS

This single-center retrospective review included 103 patients and 108 carotid body tumor resections performed between June 2010 and June 2020. All carotid body tumors were divided into three groups based on interval time between transarterial embolization and surgery: 1-day group (G1), 2-day group (G2), and 3-day group (G3). Demographics, inflammatory biomarkers, periprocedural details, and postoperative outcomes were analyzed.

RESULTS

Among 103 patients, 48.54% were women, and the mean age was 37.07 years. The tumor sizes were 43.83, 44.31, and 42.84 mm in G1, G2, and G3, respectively, and the blood loss and operative time were 163.68, 331.54, and 683.68 mL, and 182.32, 216.31, and 280.79 mins with the prolonged time interval, respectively. Compared with pretransarterial embolization, the expression of white blood cells (10⁹/L) and neutrophils (10⁹/L) were obviously increased post-transarterial embolization in the three groups (G1: white blood cells 6.81 vs 9.32; neutrophils 0.54 vs 0.74, all P < .05. G2: white blood cells 7.19 vs 10.01, P = .118; neutrophils 0.54 vs 0.77, P < .05. G3: white blood cells 7.08 v. 12.37; neutrophils 0.59 vs 0.80, all P < .05), and those in G3 were significantly higher than those in G1. The incidences of revascularization, which was 30.26%, 53.85%, and 42.10%, and adverse events (26.32%, 30.77%, and 21.05%) were not significantly different among G1, G2, and G3.

CONCLUSION

The optimal time interval between preoperative transarterial embolization and surgical resection resulted as 1 day as patients in this group showed obvious lower blood loss and shorter duration of operation than patients in other groups. Both inflammation and recanalization provided support for these results at some extent.

Formosanin C promotes the curative efficacy of ultrasound-guided radiofrequency ablation in a mouse model of breast cancer

Breast cancer is the leading cause of tumor-associated death among women worldwide, and new therapeutic strategies are required to improve the post-surgery prognosis and quality of life of patients. Radiofrequency ablation (RFA) is a less invasive approach compared with traditional surgical resection to treat malignancies, and the combination of RFA and chemotherapeutic agents, including formosanin C (FC), can synergistically improve the curative effects against breast carcinoma. However, the detailed mechanisms remain unclear. In the present study, nude mice were used to identify the influence of FC on the therapeutic efficacy of RFA for breast cancer. Flow cytometry was performed to demonstrate the proportional alteration of CD8⁺ and CD45⁺ T cells with different biomarkers, including CD107a, IFNγ and TNFα. It was demonstrated that FC enhanced the therapeutic efficacy of RFA in breast cancer, while RFA combined with FC improved the proportion of IFNγ⁺ and TNFα⁺ CD8⁺ T cells and CD107a⁺ CD8⁺ T cells in tumor-infiltrating lymphocytes, thus increasing the immune responses caused by surgery and chemotherapy. The present study indicated that FC may promote the curative efficacy of ultrasound-guided RFA against breast tumor by regulating adaptive immune responses.

Percutaneous Irreversible Electroporation for Treatment of Small Hepatocellular Carcinoma Invisible on Unenhanced CT: A Novel Combined Strategy with Prior Transarterial Tumor Marking

INTRODUCTION

To explore the feasibility, safety, and efficiency of ethiodized oil tumor marking combined with irreversible electroporation (IRE) for small hepatocellular carcinomas (HCCs) that were invisible on unenhanced computed tomography (CT).

METHODS

A retrospective analysis of the institutional database was performed from January 2018 to September 2018. Patients undergoing ethiodized oil tumor marking to improve target-HCC visualization in subsequent CT-guided IRE were retrieved. Target-HCC visualization after marking was assessed, and the signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNR) were compared between pre-marking and post-marking CT images using the paired t-test. Standard IRE reports, adverse events, therapeutic endpoints, and survival were summarized and assessed.

RESULTS

Nine patients with 11 target-HCCs (11.1-18.8 mm) were included. After marking, all target-HCCs demonstrated complete visualization in post-marking CT, which were invisible in pre-marking CT. Quantitatively, the SNR of the target-HCCs significantly increased after marking (11.07 ± 4.23 vs. 3.36 ± 1.79, p = 0.006), as did the CNR (4.32 ± 3.31 vs. 0.43 ± 0.28, p = 0.023). In sequential IRE procedures, the average current was 30.1 ± 5.3 A, and both the delta ampere and percentage were positive with the mean values of 5.8 ± 2.1 A and 23.8 ± 6.3%, respectively. All procedures were technically successful without any adverse events. In the follow-up, no residual unablated tumor (endpoint-1) was observed. The half-year, one-year, and two-year local tumor progression (endpoint-2) rate was 0%, 9.1%, and 27.3%. The two-year overall survival rate was 100%.

CONCLUSIONS

Ethiodized oil tumor marking enables to demarcate small HCCs that were invisible on unenhanced CT. It potentially allows a safe and complete ablation in subsequent CT-guided IRE.

Chinese expert consensus on technical recommendations for the standard operation of drug-eluting beads for transvascular embolization

Liver cancer is among the 10 most common tumors globally. In China, liver cancer ranks 4^th for prevalence and 3^rd for mortality among all malignant tumors. With respect to the treatment of primary liver cancer, there are a number of therapies currently available, including surgical resection, liver transplantation, ablation, transarterial chemoembolization (TACE), systemic chemotherapy, radiation therapy, targeted drug therapy and immunotherapy. Clinical practice and research have shown that, compared with conventional TACE (cTACE), drug-eluting bead TACE (DEB-TACE) can achieve a higher response rate and longer survival time in patients with primary liver cancer. Compared with that of cTACE, DEB-TACE has more favorable basic conditions for achieving uniformity, which could facilitate the standardization of operation techniques. China is the country with the highest incidence of primary liver cancer, accounting for more than 50% of the global patients, and its etiology and epidemiology in Chinese patients differ from those in Europeans and Americans. Therefore, experts in China have drafted these technical recommendations for the standard operation of drug-eluting beads for the treatment of liver cancer on the basis of accumulated abundant clinical experience and evidence-based medical data.

A new management strategy for renal angiomyolipomas: superselective arterial embolization in combination with radiofrequency ablation

Background

The present study analyzed the safety and efficacy of superselective arterial embolization (SAE) combined with radiofrequency ablation (RFA) to treat renal angiomyolipoma (RAML).

Methods

This retrospective study included the clinical data of 6 patients with RAML treated between March 2016 and October 2017. All patients underwent RFA treatment immediately after SAE guided by angio-computed tomography (angio-CT). The tumor size, renal function and complications, and time to recurrence were compared before and after treatment.

Results

The success rate of the SAE + RFA technique was 100%, and no serious complications were found during or after surgery. After treatment, the patients' symptoms, including low back pain and hematuria, were relieved. The pre-treatment creatinine level (55.6±11.0 µmol/L) did not differ significantly from the post-treatment creatinine level (68.2±13.7 µmol/L), which was measured 1 day after surgery (t=1.75, P=0.109). The mean follow-up time was 29.5±6.1 months. By the end of the follow-up period, the maximum diameter of the tumor was 3.1±0.6 cm, which was significantly smaller than the pre-treatment diameter of 5.9±1.01 cm (t=5.83, P<0.001). At 3 months after surgery, the maximum diameter of the tumor was reduced by 22-38% in all 6 patients. At the last follow-up examination, the maximum diameter of the tumor was reduced by 36-61%. Contrast-enhanced CT or magnetic resonance imaging scans showed that the enhanced part of the original lesion had disappeared, the renal parenchyma was full of even fat signals, and only one patient had new enhanced lesions at the site of the original lesions.

Conclusions

SAE combined with RFA is a safe and effective treatment for RAML, and its strengths qualify it to become a new treatment strategy for RAML.

A comparison between radiofrequency ablation combined with transarterial chemoembolization and surgical resection in hepatic carcinoma: A meta-analysis

Objective

This study determined whether the effect of combination therapy for hepatic carcinoma (HCC) is comparable to surgical resection (SR). According to the guidelines of the American Association for the Study of Liver Disease, radiofrequency ablation (RFA) and SR are recommended for early HCC. However, patients treated with RFA had worse long-term survival than those who received SR. Many studies utilizing the combination therapy with RFA and transarterial chemoembolization (TACE) have reported better prognosis as compared to RFA alone.

Materials and Methods

A comprehensive search in databases was conducted. Six retrospective studies and one cohort were enrolled in this meta-analysis. The overall survival (OS), disease-free survival (DFS), and major complications were compared between RFA plus TACE and SR. The pooled hazard ratio and 95% confidence interval (CI) were calculated and analyzed.

Results

After comparison, no significant difference in the OS and DFS at 1 and 3 years between the combination therapy and SR was observed (OS1: pooled relative risk [RR]: 0.82, 95% CI [0.56, 1.21]; OS3: pooled RR: 1.07, 95% CI [0.82, 1.39]; DFS1: pooled RR: 0.92, 95% CI [0.58, 1.45]; DFS3: pooled RR: 1.18, 95% CI [1.00, 1.40]). SR had better clinical outcomes than combination therapy with respect to long-term survival and disease progression (OS5: pooled RR: 1.12, 95% CI [1.03, 1.23]; DFS5: pooled RR: 1.15, 95% CI [1.03, 1.28]). Major complications were reduced with combination therapy (pooled RR: 0.46, 95% CI [0.25, 0.85]).

Conclusion

SR should remain as the first-line therapy for early HCC.

Computed tomography and histopathological findings after embolization with inherently radiopaque 40μm-microspheres, standard 40μm-microspheres and iodized oil in a porcine liver model

Purpose

The present study compared standard computed tomography (CT) and histopathological findings after endovascular embolization using a prototype of inherently radiopaque 40μm-microspheres with both standard 40μm-microspheres and iodized oil in a porcine liver model.

Materials and methods

Twelve pigs were divided into six study groups, of two pigs each. Four pigs were embolized with iodized oil alone and four with radiopaque microspheres; two animals in each group were sacrificed at 2 hours and two at 7 days. Two pigs were embolized with radiopaque microspheres and heparin and sacrificed at 7 days. Two pigs were embolized with standard microspheres and sacrificed at 2 hours. CT was performed before and after segmental embolization and before sacrifice at 7 days. The distribution of embolic agent, inflammatory response and tissue necrosis were assessed histopathologically.

Results

Radiopaque microspheres and iodized oil were visible on standard CT 2 hours and 7 days after embolization, showing qualitatively comparable arterial and parenchymal enhancement. Quantitatively, the enhancement was more intense for iodized oil. Standard microspheres, delivered without contrast, were not visible by imaging. Radiopaque and standard microspheres similarly occluded subsegmental and interlobular arteries and, to a lesser extent, sinusoids. Iodized oil resulted in the deepest penetration into sinusoids. Necrosis was always observed after embolization with microspheres, but never after embolization with iodized oil. The inflammatory response was mild to moderate for microspheres and moderate to severe for iodized oil.

Conclusion

Radiopaque 40μm-microspheres are visible on standard CT with qualitatively similar but quantitatively less intense enhancement compared to iodized oil, and with a tendency towards less of an inflammatory reaction than iodized oil. These microspheres also result in tissue necrosis, which was not observed after embolization with iodized oil. Both radiopaque and standard 40μm-microspheres are found within subsegmental and interlobar arteries, as well as in hepatic sinusoids.

[Percutaneous renal ablation: Pre-, per-, post-interventional evaluation modalities and adapted management]

OBJECTIVES

Ablative treatment (AT) rise is foreseen, validation of steps to insure good proceedings is needed. By looking over the process of the patient, this study evaluates the requirements and choices needed in every step of the management.

METHODS

We searched MEDLINE^®, Embase^®, using (MeSH) words and we looked for all the studies. Investigators graded the strength of evidence in terms of methodology, language and relevance.

RESULTS

Explanations of AT proposal rather than partial nephrectomy or surveillance have to be discussed in a consultation shared by urologist and interventional radiologist. Per-procedure choices depend on predictable ballistic difficulties. High volume, proximity of the hilum or of a risky organ are in favor of general anesthesia, cryotherapy and computed tomography/magnetic resonance imaging (CT/MRI). Percutaneous approach should be privileged, as it seems as effective as the laparoscopic approach. Early and delayed complications have to be treated both by urologist and radiologist. Surveillance by CT/MRI insure of the lack of contrast-enhanced in the treated area. Patients and tumors criteria, in case of incomplete treatment or recurrence, are the key of the appropriate treatment: surgery, second session of AT, surveillance.

CONCLUSION

AT treatments require patient's comprehension, excellent coordination of the partnership between urologist and radiologist and relevant choices during intervention.

[What can/should be treated in kidney tumors and when]

CLINICAL/METHODICAL ISSUE

In the treatment of localized renal cell carcinoma, the lack of randomization in controlled trials on thermal ablation is a major limitation. The latter leads to significant study bias and it ultimately remains unclear whether the improved overall survival in favor of partial nephrectomy can actually be attributed to the treatment method.

STANDARD RADIOLOGICAL METHODS

For T1a (≤4 cm) renal cell carcinoma without lymph node and distant metastases, excellent technical and clinical results have been described after imaging-guided radiofrequency ablation and cryoablation.

METHODICAL INNOVATIONS

Low major complication rates, preservation of renal function and three-dimensional confirmation of negative ablation margins (A0 ablation) are the advantages of computed tomography (CT)-guided thermal ablation.

PERFORMANCE

According to the results of controlled (non-randomized) trials on T1a renal cell cancer, the cancer-specific survival rates are comparable between ablative and surgical techniques.

ACHIEVEMENTS

It is high time for prospective randomized controlled trials to define the actual value of percutaneous thermal ablation and partial nephrectomy in the treatment of T1a renal cell carcinoma.

PRACTICAL RECOMMENDATIONS

Apart from localized renal cell carcinoma, angiomyolipoma and oncocytoma can be treated by thermal ablation. Transarterial embolization extends the radiological spectrum for the treatment of renal tumors, either as complementary embolization (e. g. before thermal ablation of T1a and T1b renal cell carcinoma), prophylactic embolization (e. g. angiomyolipoma >6 cm), preoperative embolization (e. g. before laparoscopic partial nephrectomy) or palliative embolization (e. g. in patients with symptomatic macrohematuria due to renal cell carcinoma).