Trans-Arterial Embolization of Renal Cell Carcinoma prior to Percutaneous Ablation: Technical Aspects, Institutional Experience, and Brief Review of the Literature

Effect of iodized oil embolization on temperature change during cryoablation for renal cell carcinoma

INTRODUCTION

We aimed to evaluate the effect of transcatheter arterial embolization (TAE) with iodized oil (Lipiodol) on temperature change during cryoablation (CA) for renal cell carcinoma (RCC).

MATERIAL AND METHODS

We retrospectively reviewed patients receiving CA for RCC from February 2020 to July 2021, including those who received Lipiodol TAE prior to CA (TAE group) and those who underwent only CA with comparable clinical and tumor characteristics (non-TAE group). Clinical data and tumor characteristics of both groups were recorded. The temperature readings of each cryoprobe at every 15 s and 'time to -100 °C' were compared between the groups.

RESULTS

A total of 17 patients with 18 RCCs were recruited (seven in the TAE group and 11 in the non-TAE group). The 'time to -100 °C' was significantly longer in the TAE group than in the non-TAE group (64.5 ± 24.3 s vs. 48.8 ± 9.7 s, p = 0.018). Positive correlation between 'time to -100 °C' and tumor maximal diameter, RENAL nephrometry and PADUA score were observed in the non-TAE group, while no corresponding correlation was found in the TAE group.

CONCLUSIONS

Pre-embolization with iodized oil influences the temporal temperature changes during cryoablation by disrupting the positive correlation between the time to reach the target temperature and tumor characteristics.

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.

Percutaneous cryoablation combined with prior transcatheter arterial embolization for renal cell carcinomas of 3 cm or larger: a prospective study

BACKGROUND

We prospectively evaluated the safety and efficacy of percutaneous cryoablation combined with transcatheter renal arterial embolization for the treatment of tumors ≥ 3 cm in diameter.

METHODS

We included patients aged ≥ 20 years with histologically proven renal cell carcinoma with a tumor diameter ≥ 3 cm who were inoperable or refused surgery. Prior to ablation, transcatheter arterial embolization was performed using a mixture of absolute ethanol and iodized oil. All cryoablation procedures were performed percutaneously under computed tomography fluoroscopy guidance. The primary endpoint was safety, which was evaluated for adverse events using CTCAE version 4.0. The secondary endpoint was survival; overall survival, progression-free survival, and cancer-specific survival were calculated.

RESULTS

From October 2013 to March 2016, 19 patients (mean age, 75 ± 13 years; 5 women, 14 men) were prospectively enrolled. The mean tumor diameter was 3.9 ± 0.7 (range 3.1-5.3) cm. Four grade 3 hematologic adverse events occurred, while no symptomatic grade ≥ 3 events occurred. The median follow-up period was 68 (range 52-84) months. During the follow-up period, two patients developed local tumor progression at 3 and 42 months after the initial ablative procedure; no patient showed distant metastasis. Two patients died from causes other than RCC. Overall survival, progression-free survival, and cause-specific survival were 100%, 95%, and 100% at 3 years, and 95%, 84%, and 100% at 5 years, respectively.

CONCLUSION

Percutaneous cryoablation combined with prior TAE for the treatment of tumors ≥ 3 cm in diameter was safe and achieved favorable survival.

Imaging considerations for thermal and radiotherapy ablation of primary and metastatic renal cell carcinoma

Ablative (percutaneous and stereotactic) thermal and radiotherapy procedures for management of both primary and metastatic renal cell carcinoma are increasing in popularity in clinical practice. Data suggest comparable efficacy with lower cost and morbidity compared to nephrectomy. Ablative therapies may be used alone or in conjunction with surgery or chemotherapy for treatment of primary tumor and metastatic disease. Imaging plays a crucial role in pre-treatment selection and planning of ablation, intra-procedural guidance, evaluation for complications, short- and long-term post-procedural surveillance of disease, and treatment response. Treatment response and disease recurrence may differ considerably after ablation, particularly for stereotactic radiotherapy, when compared to conventional surgical and chemotherapies. This article reviews the current and emerging role of imaging for ablative therapy of renal cell carcinoma.

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.

External Validation of the Renal Ablation-Specific (MC)2 Risk Scoring System in Predicting Complications from Percutaneous Renal Cryoablation

PURPOSE

The (MC)2 score is a renal ablation-specific risk scoring system to predict major complications from percutaneous renal cryoablation (PRCA). However, it is untested in an external population of patients. The purpose of this study is to validate the ability of the (MC)2 score to predict major complications after PRCA in an external population.

MATERIALS AND METHODS

Retrospective review of patients who underwent PRCA from 2004 to 2019. Patient demographics, medical histories, and tumor characteristics were collected. The (MC)2 score was calculated and patients were assigned to low risk (< 5), moderate risk (5-8) and high-risk (> 8) groups. Complications were recorded. Major complications were classified according to CIRSE guidelines.

RESULTS

Two hundred and one patients [M = 116; F = 85; median age = 65 (range 27-90)] met inclusion criteria. Eleven patients (5.5%) developed major complications and 50 patients (24.9%) developed minor complications. Of patients with major complications, mean tumor diameter was 39 mm (± 10.4), seven patients (63.6%) had a central tumor, four patients (36.4%) had complicated diabetes, and one patient (9.1%) had a prior MI. Major complication rates were 2.1%, 14%, and 14.3% in the (MC)2 low risk, moderate risk, and high risk groups, respectively. The mean (MC)2 score for patients with major complications [6.2 (± 2.4)] was higher than the mean score for patients with minor complications [4.7 (± 2.4) (p = 0.07)] and no complications [3.9 (± 1.9) (p < 0.01)]. The area under the ROC curve to predict major complications was 0.78.

CONCLUSION

The (MC)2 risk scoring system appropriately identifies patients at risk for major complications from PRCA in this external patient population.

Is There a Role for Combination, Single-Session Selective Transarterial Embolization and Microwave Ablation for Large Renal Masses?

PURPOSE

Thermal ablation of small renal tumors is safe and efficacious. Thermoablation of tumors greater than 3 cm has decreased efficacy and a greater risk of complications. Combined embolization and radiofrequency ablation has shown encouraging results. We report on the use of combined single-session transarterial embolization and microwave ablation to treat large renal masses.

MATERIALS AND METHODS

After obtaining IRB approval, a review of the medical record between October 2016 and January 2020 was performed. Patients with renal tumors who underwent combined transarterial embolization and microwave ablation were assessed retrospectively. Patient demographic information, intraoperative, postoperative, and follow-up data were recorded.

RESULTS

Eleven patients were identified meeting inclusion criteria. The mean age was 73 years, with 64% male, an average BMI of 26.5, and average Charleston Comorbidity Index of 6.7. Nine tumors were identified as clear cell carcinoma, one as papillary carcinoma and one as an oncocytic neoplasm. Average tumor size was 4.5 cm (2.7-8.3), with an average RENAL score of 8.5. Successful ablation with a 5 mm margin was achieved in all patients, and in all cases, ablation and embolization were performed on the same day. The only related post-procedure complication was a single groin hematoma. Surveillance was performed with CT or MRI. Average follow-up was 419.5 days (range 27-747), with no patients showing evidence of recurrence to date.

CONCLUSIONS

Combined single-session transarterial embolization and microwave ablation is technically feasible, safe, and efficacious in treating large renal tumors in a series of 11 patients with no recurrence to date.

LEVEL OF EVIDENCE

Level 4, case series.