Percutaneous Renal Tumor Ablation: Radiation Exposure During Cryoablation and Radiofrequency Ablation

Magnetic-Resonance-Imaging-Guided Cryoablation for Solitary-Biopsy-Proven Renal Cell Carcinoma: A Tertiary Cancer Center Experience

BACKGROUND

Our purpose is to evaluate the long-term oncologic efficacy and survival rates of MRI-guided cryoablation for patients with biopsy-proven cT1a renal cell carcinoma (RCC).

MATERIALS AND METHODS

We retrospectively reviewed our renal ablation database between January 2007 and June 2021 and only included patients with solitary-biopsy-proven cT1a RCC (≤4 cm) who underwent MRI-guided cryoablation. We excluded patients with genetic syndromes, bilateral RCC, recurrent RCC or benign lesions, those without pathologically proven RCC lesions and patients who underwent radiofrequency ablation or CT-guided cryoablation. For each patient, we collected the following: age, sex, lesion size, right- or left-sided, pathology, ablation zone tumor recurrence, development of new tumor in the kidney other than ablation zone, development of metastatic disease, patient alive or not, date and cause of death. We used the Kaplan and Meier product limit estimator to estimate the survival outcomes.

RESULTS

Twenty-nine patients (median age 70 years) met our inclusion criteria. Twenty-nine MRI-guided cryoablation procedures were performed for twenty-nine tumor lesions with a median size of 2.2 cm. A Clavien-Dindo grade III complication developed in one patient (3.4%). Clear cell RCC was the most reported histology (n = 19). The median follow up was 4.5 years. No tumor recurrence or metastatic disease developed in any of the patients. Two patients developed new renal lesions separate from the ablation zone. The 5- and 10-year OS were 72% and 55.6%, respectively. The 5- and 10-year DFS were 90.5% and the 5-year and 10-year LRFS, MFS and CSS were all 100%.

CONCLUSIONS

MRI-guided cryoablation is a safe treatment with a low complication rate. Long-term follow-up data revealed long-standing oncologic control.

Percutaneous CT-Guided Renal Cryoablation: Technical Aspects, Safety, and Long-Term Oncological Outcomes in a Single Center

Background and objectives: Cryoablation is emerging as a safe and effective therapeutic option for treating renal cell carcinoma. This study analyzed the safety and long-term oncological outcomes of cryoablation in our center. Materials and methods: Patients who underwent computed tomography (CT)-guided percutaneous cryoablation between February 2011 and June 2020 for one or more clinically localized renal tumors were identified. Technical success and treatment efficacy were assessed. Post-procedural complications were classified according to the Clavien-Dindo system. Recurrence-free survival was determined for biopsy-proven malignant renal tumors. Results: A total of 174 renal tumors, 78 of which were biopsy-proven malignant carcinomas, were treated in 138 patients (97 males and 41 females, mean age: 73 years, range: 43-89 years). Mean tumor size was 2.25 cm and 54.6% of the lesions required a complex approach. Technical success was achieved in 171 out of 174 tumors (98.3%). Primary treatment efficacy was 95.3% and increased to 98.2% when retreats were taken into account. The overall complication rate was 29.8%. No complications of Clavien-Dindo grade III or more were encountered. Median follow-up was 21.92 months (range: 0.02-99.87). Recurrence-free survival was 100% at 1 year, 95.3% (95% CI: 82.1%-98.8%) at 3 years, and 88.6% (95% CI: 71.8%-95.7%) at 5 years. Conclusions: Cryoablation is a safe and effective technique for the treatment of small renal lesions, with no major complications when performed by expert interventional radiologists. The multidisciplinary discussion is essential, especially considering the high number of histologically undetermined lesions. Our long-term oncological outcomes are encouraging and in line with the literature.

Safety and Oncologic Outcomes of Magnetic Resonance Imaging-Guided Cryoablation of Renal Cell Carcinoma: A 10-Year Single-Center Experience

OBJECTIVES

Magnetic resonance imaging guidance has been sporadically reported for renal tumor cryoablation (CA); therefore, clinical experience with this modality is still limited.The aim of this study is to retrospectively analyze our 10-year experience with renal tumor CA performed on a 1.5 T magnetic resonance imaging unit with the intent of reporting procedural safety and oncologic outcomes.

MATERIALS AND METHODS

We included 143 patients (102 men; 41 women; median age, 73 years; range, 34-91 years) with 149 tumors (median size, 2.6 cm; range, 0.6-6.0 cm), treated between 2009 and 2019. Patient, tumor, procedure, and follow-up data were collected and analyzed. The Kaplan-Meier method was used to estimate local recurrence-free (LRFS), metastasis-free (MFS), disease-free (DFS), cancer-specific, and overall (OS) survival. Univariate and multivariate models were used to identify factors associated with complications, LRFS, MFS, DFS, and OS.

RESULTS

The overall complication rate was 10.7% (16/149 tumors), with 1 major (1/149 [0.7%]; 95% confidence interval, 0.0%-3.7%) hemorrhagic complication. Other minor complications (15/149 [10.1%]; 95% confidence interval, 0.6%-16.1%) did not include any cases of injury to nearby organs. There were no factors associated with complications.Five-year estimates of LRFS (primary/secondary), MFS, DFS, cancer-specific survival, and OS were 82.8%/91.5%, 91.1%, 75.1%, 98.2%, and 89.6%, respectively. Increasing tumor size (hazard radio [HR], 1.8; P = 0.02) and intraparenchymal tumor location (HR, 5.6; P < 0.01) were associated with lower LRFS; increasing patient's age (HR, 0.5; P = 0.01), high tumor grade (HR, 23.3; P < 0.01) and non-clear-cell/nonpapillary histology (HR, 20.1; P < 0.01) with metastatic disease; and high tumor grade (HR, 3.2; P = 0.04) with lower DFS.

CONCLUSION

Magnetic resonance imaging-guided CA of renal tumors is associated with acceptable morbidity and high survival estimates at 5-year follow-up. Given the absence of complications resulting from injuries to nearby organs, further studies are required to evaluate whether the potential reduced incidence of these adverse events justifies large-scale implementation of this interventional modality.

Percutaneous cryoablation for renal cell carcinoma using ultrasound-guided targeting and computed tomography-guided ice-ball monitoring: radiation dose and short-term outcomes

BACKGROUND

Usefulness of ultrasound (US)-guided mass targeting and computed tomography (CT)-guided ice-ball monitoring in percutaneous cryoablation (PCA) for renal cell carcinoma (RCC) is still uncertain.

PURPOSE

To assess radiation dose and short-term outcomes of PCA for RCC using US-guided targeting and CT-guided ice-ball monitoring.

MATERIAL AND METHODS

Thirty-nine consecutive patients who underwent PCA for biopsy-proven RCC were included. Mass targeting was performed with US and ice-ball was monitored with CT guidance. Effective radiation dose of CT during PCA was recorded. Follow-up was conducted with contrast-enhanced CT or magnetic resonance imaging (MRI) (mean follow-up time = 10.1 ± 7.0 months). Local tumor progression was defined by the presence of focal enhancing areas at the ablation zone (CT, ≥ 20 HU; MRI, presence of focal enhancement on subtraction contrast-enhanced image). Technical success, major complication rate (e.g. Clavien-Dindo classification ≥ 3), and one-year local tumor progression-free survival (PFS) rate were analyzed.

RESULTS

Mean effective radiation dose in association with PCA was 12.1 ± 4.5 mSv (range = 7.0-25.2 mSv). Technical success was achieved in 100%. Local tumor progression occurred in a single patient (2.6%, 1/39), and one-year local tumor PFS rate was 95.7%. No major complication was found.

CONCLUSION

PCA using US-guided targeting and CT-guided ice-ball monitoring may allow acceptable local tumor control for RCC, as a radiation-reducing strategy.

Imaging following renal ablation: what can we learn from recurrent tumors?

PURPOSE

The purpose of the study was to evaluate the post-contrast appearance of local tumor progression (LTP) following renal ablation to better understand patterns of tumor recurrence and to optimize follow-up imaging protocols.

METHODS

From 2002 to 2015, 913 patients underwent 988 renal ablation procedures for treatment of 1064 tumors. LTP was identified in 24 (2.6%) patients during median imaging follow-up of 30 months (range 0-139). One patient with LTP was followed with non-contrast MRI only and was excluded from evaluation. Three body radiologists reviewed the contrast-enhanced CT and/or MRI follow-up imaging in the remaining 23 patients to determine the timing and imaging appearance of the recurrent tumor.

RESULTS

Local tumor progression was identified on contrast-enhanced CT or MRI at median 11 months (range 1 and 68) after renal ablation. Corticomedullary phase imaging was performed in 16/23 (70%) patients. LTP was identified on the corticomedullary phase in all cases, and was most conspicuous on the corticomedullary phase compared to any other phase of imaging in 15/16 (94%) patients. No cases of LTP were best visualized on non-contrast or excretory phase images.

CONCLUSIONS

Delayed recurrence following renal ablation is possible; therefore, extended follow-up is indicated in ablation patients. Almost all cases of LTP were best visualized on the corticomedullary phase of imaging, which should be included in any post-ablation imaging protocol. Excretory phase images were not required to diagnose LTP in any case and could be excluded from routine post-ablation follow-up.

[Ablative therapy in kidney cancer: Oncological, functional, perioperative outcomes and cost]

INTRODUCTION

The incidence of kidney cancer has increased significantly over the past few decades presumably due to the increased use of imaging. The aim of this article is to describe contemporary outcomes of ablative therapy and to compare them to other therapeutic options in terms of oncological, functional, perioperative outcomes and cost.

MATERIAL AND METHODS

We searched MEDLINE^®, Embase^®, using (MeSH) words; from January 2005 through May 2017, and we looked for all the studies. Investigators graded the strength of evidence in terms of methodology, language and relevance.

RESULTS

Ninety-one articles were analyzed. We described the outcomes of ablative therapy in relation to the energy used and the approach, and compared these outcomes to the other therapeutic options in terms of oncological, functional and perioperative outcomes. We analyzed these studies in order to search for predictive factors influencing the results of ablative therapy. We also analyzed the economic burden of small renal tumor management.

CONCLUSION

The strength of evidence is based almost entirely on retrospective studies and is susceptible to the inherent limitations of this study design. Although, the evidence was low among studies, our revue showed that, in elderly patients treated with ablative therapy for cT1a tumors, the cancer-specific survival was comparable to partial nephrectomy with differences in overall survival that are explained by competing risks of death in the old population. Considering the functional results, the renal function preservation seems to be comparable between the 2 groups while the perioperative morbidity is higher in the partial nephrectomy group. The evidence base medicine at this time cannot support the extension of the indications of ablative therapy beyond the actual implementations.

Low-dose CT protocols for guiding radiofrequency ablation for the treatment of small renal cell carcinomas

OBJECTIVE

Computed tomography (CT)-guided radiofrequency ablation (RFA) results in a high radiation dose. This study aimed to assess low-dose CT protocols for guiding RFA and oncologic outcomes for the treatment of small renal cell carcinoma (RCC).

MATERIALS AND METHODS

Between December 2011 and December 2014, CT-guided RFA was performed in 31 patients with 31 biopsy-proven RCCs (median, 2.1 cm). RFA included planning, targeting, monitoring and survey phases. The dose length product (DLP), CT dose index volume (CTDIvol), effective dose, number of scans, scan range, tube current and exposure time of RFA phases were compared. The 3-year recurrence-free survival rate was recorded. Nonparametric or parametric repeated-measures ANOVA with Dunn's or Tukey-Kramer multiple comparisons and Kaplan-Meier analysis were used for statistical analysis.

RESULTS

The median total DLP, CTDIvol and effective dose of CT-guided RFA procedures per session were 1238.8 mGy (range 517.4-3391.7 mGy), 259.7 mGy (10.7-67.9 mGy) and 18.6 mSv (7.8-50.9 mSv), respectively. The median DLP, CTDIvol, effective dose, number of scans, tube current and exposure time during the targeting phase were higher than those during the other phases (p < 0.001). The scan range in the targeting phase was the same as that in the monitoring phase (p > 0.05) but smaller than those in the planning and survey phases (p < 0.001). The 3-year recurrence-free survival rate was 96.7%.

CONCLUSIONS

Low-dose CT protocols for guiding RFA may reduce radiation dose without compromising oncologic outcomes. Reducing the number of scans during the targeting phase contributes to dose reduction.

Radiation Exposure of Interventional Radiologists During Computed Tomography Fluoroscopy-Guided Renal Cryoablation and Lung Radiofrequency Ablation: Direct Measurement in a Clinical Setting

INTRODUCTION

Computed tomography (CT) fluoroscopy-guided renal cryoablation and lung radiofrequency ablation (RFA) have received increasing attention as promising cancer therapies. Although radiation exposure of interventional radiologists during these procedures is an important concern, data on operator exposure are lacking.

MATERIALS AND METHODS

Radiation dose to interventional radiologists during CT fluoroscopy-guided renal cryoablation (n = 20) and lung RFA (n = 20) was measured prospectively in a clinical setting. Effective dose to the operator was calculated from the 1-cm dose equivalent measured on the neck outside the lead apron, and on the left chest inside the lead apron, using electronic dosimeters. Equivalent dose to the operator's finger skin was measured using thermoluminescent dosimeter rings.

RESULTS

The mean (median) effective dose to the operator per procedure was 6.05 (4.52) μSv during renal cryoablation and 0.74 (0.55) μSv during lung RFA. The mean (median) equivalent dose to the operator's finger skin per procedure was 2.1 (2.1) mSv during renal cryoablation, and 0.3 (0.3) mSv during lung RFA.

CONCLUSION

Radiation dose to interventional radiologists during renal cryoablation and lung RFA were at an acceptable level, and in line with recommended dose limits for occupational radiation exposure.