Percutaneous RF Thermal Ablation of Renal Tumors: Is US Guidance Really Less Favorable Than Other Imaging Guidance Techniques?

Percutaneous Ablation of T1 Renal Masses: Comparative Local Control and Complications after Radiofrequency and Cryoablation

The efficacy and complication rates of percutaneous radiofrequency ablation (RFA) and cryoablation (CA) in the treatment of T1 renal masses in two Northern Italy hospitals were retrospectively investigated. Eighty-two patients with 80 T1a tumors and 10 T1b tumors treated with thermal ablation from 2015 through 2020 were included. A total of 43 tumors in 38 patients were treated with RFA (2.3 ± 0.9 cm), and 47 tumors in 44 patients were treated with CA (2.1 ± 0.8 cm). The mean follow-up observation period was 26 ± 19 months. The major complications and efficacy, as measured using the technical success and local tumor recurrence rates, were recorded. There were three (6.9%) technical failures with RFA and one (2.1%) with cryoablation (p = 0.30). Among the 40 tumors that were successfully treated with RFA, 1 tumor (2.5%) developed local tumor recurrence; 5/46 tumors that were treated with cryoablation (10.8%) developed local tumor recurrence (p = 0.17). T1b lesions (4.0 ± 0.7 cm) resulted in 1/6 technically unsuccessful cases with RFA and 0/4 with CA. No recurrent disease was detected in the T1b lesions. Major complications occurred after 2.3% (1/43) of RFAs and 0/47 of cryoablation procedures. RFA and cryoablation are both effective in the treatment of renal masses. Major complications with either procedure are uncommon.

Biological and Medical Disturbances Due to Exposure to Fields Emitted by Electromagnetic Energy Devices—A Review

The use of electromagnetic systems in daily life is on the rise. The immediate environment, of these electromagnetic energy devices, is exposed to their emitted fields. Environmental disturbances from such exposure could be severe in many ways; one of the most important is health. This could be directly related to the human body or to healthcare sensing and interventional devices. The review of the biological effects and disturbances of medical instruments due to electromagnetic field exposure is the subject of this article. The analysis of the different types of exposure as well as their control to meet safety requirements are investigated involving energy devices covering wide ranges of power and frequency. Thus, biological effects of both wireless telecommunications tools and inductive charging systems are reviewed. Next, we survey electromagnetic disturbances in sensing and stimulation instruments joint to the human body as well as devices used in medical interventions. Means of evaluating and controlling the effects of electromagnetic fields, through electromagnetic compatibility analysis, experimentally and by numerical modeling are conferred and assessed.

Ablation of Small Renal Masses

Renal cell carcinoma is most commonly diagnosed in the sixth or seventh decade of life. Historically, surgical extirpation was the gold standard treatment option for small renal masses. However, given the comorbidities in this elderly population, not all patients are candidates for surgery. The development of minimally invasive ablative therapies has solved the surgical dilemma in this patient population. Furthermore, the 2017 American Urological Association guidelines recommends consideration of percutaneous image guided thermal ablation as a treatment option for masses smaller than 3 cm even in healthy individuals. Percutaneous image guided thermal ablation is an attractive treatment option providing excellent local tumor control, fewer complications, better preservation of the renal functions, faster recovery and shorter hospital stay. Various ablative modalities are available in clinical practice. This includes radiofrequency ablation, cryoablation, microwave ablation, irreversible electroporation, high intensity focused ultrasound, and laser ablation. In this review, we focus on the most commonly used modalities including radiofrequency ablation and cryoablation and to a lesser extent microwave ablation and irreversible electroporation.

Percutaneous image-guided renal ablations: Current evidences for long-term oncologic efficacy

The rise in incidentally discovered small renal neoplasms has focused attention on nephron-sparing treatment strategies including partial nephrectomy and percutaneous ablation as well as active surveillance. As all treatment modality, renal ablation has matured technically. Radiofrequency ablation, microwave ablation or cryoablation are now performed in many institutions under imaging guidance. The long-term results allow them to be now recommended as a therapeutic option whatever the patients' condition if complete ablation can reliably be achieved.

Contrast-enhanced ultrasound (CEUS) in abdominal intervention

The introduction of ultrasound contrast agents has rendered contrast-enhanced ultrasound (CEUS) a valuable complementary technique to address clinically significant problems. This pictorial review describes the use of CEUS guidance in abdominal intervention and illustrates such application for a range of clinical indications. Clinical application of CEUS discussed include commonly performed abdominal interventional procedures, such as biopsy, drainage, nephrostomy, biliary intervention, abdominal tumor ablation and its subsequent monitoring, and imaging of vascular complications following abdominal intervention. The purpose of this article is to further familiarize readers with the application of CEUS, particularly its specific strength over alternative imaging modalities, in abdominal intervention.

[Ablative therapy in urology: Good practice and perspective]

INTRODUCTION

To expose the main point of discussion from present ablative therapies' guidelines and propose global perspectives.

MATERIALS AND METHODS

A review of the scientific literature was performed in Medline database (http://www.ncbi.nlm.nih.gov) and Embase (http://www.embase.com/) using different associations of keywords "ablative therapy" ; "prostate cancer"; "kidney cancer"; "guidelines"; "hybrid operating room". Publications obtained were selected based on methodology, language and relevance.

RESULTS

Present guidelines on ablative therapies in urology are, considering authors and organs, either particularly prudent (EAU guidelines for prostate and kidney) or relatively optimistic (CIRSE guidelines). This discrepancy is related to a low level of proof. So, a new approach is mandatory: more homogeneous in methodology, and especially more open to a new organization sparing economic efficiency. The objective will be to get multifunctional and multidisciplinaries platforms, in facts and in minds. It will induce, in the future, a deep reflection about training and boundaries' specialties.

CONCLUSION

Ablative therapies represent a crucial stake for urology and a clear example of medicosurgical evolution in future, based on new technologies (energy, robotic, imaging). A serious and deep reflection is necessary to prepare it and be deeply involved in.

Ultrasound-guided genitourinary interventions: principles and techniques

Ultrasound (US) is often used to guide various interventional procedures in the genitourinary (GU) tract because it can provide real-time imaging without any radiation hazard. Moreover, US can clearly visualize the pathway of an aspiration or biopsy needle to ensure the safety of the intervention. US guidance also helps clinicians to access lesions via the transabdominal, transhepatic, transvaginal, transrectal, and transperineal routes. Hence, US-guided procedures are useful for radiologists who wish to perform GU interventions. However, US-guided procedures and interventions are difficult for beginners because they involve a steep initial learning curve. The purpose of this review is to describe the basic principles and techniques of US-guided GU interventions.

Improved outcome with combined US/CT guidance as compared to US guidance in percutaneous radiofrequency ablation of small renal masses

BACKGROUND

When performing percutaneous radiofrequency ablation (RFA) of small renal masses (SRM), use of optimized periprocedural image guidance is essential to secure curative outcome of the treatment.

PURPOSE

To retrospectively compare the short-term radiological and clinical outcomes of RFA under combined ultrasound (US) and computed tomography (CT) guidance with that of a previously performed US-guided series at the same institution.

MATERIAL AND METHODS

From November 2009 to November 2013, 60 patients (mean age, 70.1 years; range, 34-86 years) with renal masses measuring in the range of 13-50 mm in maximal diameter (mean diameter, 25.4 ± 6.8 mm) underwent percutaneous RFA with combined US/CT guidance. The technical success rate, recurrence-free survival, rate of complications, and the percentage change in the estimated glomerular filtration rate (eGFR) were compared with that of a previously published series of 41 patients with SRM treated with US-guided RFA between November 2002 and December 2008.

RESULTS

The tumor and patient characteristics were similar between the two treatment groups. The primary and secondary technical success rate was significantly higher in the group treated with combined US/CT guidance compared with the group treated with US guidance alone (100% and 100% vs. 82% and 91%, respectively). The local recurrence-free survival was significantly better in the combined US/CT-guided group than in the US-guided group (P = 0.016). There was no significant difference in the rate of overall complications (13% vs. 17%) or the mean percentage decrease in the eGFR after the respective treatment (1.1 ± 18.3% vs. 5.0 ± 11.7%).

CONCLUSION

The use of combined US/CT guidance when performing renal RFA resulted in superior primary and short-term outcome compared to the use of US guidance alone in patients treated at the same institution.

Ten-year experience of percutaneous image-guided radiofrequency ablation of malignant renal tumours in high-risk patients

OBJECTIVES

To evaluate survival and outcomes after percutaneous radiofrequency ablation (RFA) of malignant renal tumours in high-risk patients with long-term follow-up.

METHODS

Between 2002 and 2009, 62 patients (71 tumours), with a median age of 73.5 years (20-87), consecutively treated with RFA under ultrasound or computed tomography guidance for malignant renal tumours were retrospectively selected and prospectively followed until 2012, including 25 patients (40.3 %) with solitary kidney and 7 cystic cancers. Maximal tumour diameters were between 8 and 46 mm (median: 23 mm).

RESULTS

Radiofrequency ablation was technically possible for all patients. Mean follow-up was 38.8 months (range: 18-78 months). Primary and secondary technique effectiveness was 95.2 % and 98.4 % per patient respectively. The rates of local tumour progression and metastatic evolution were 3.2 % and 9.7 % per patient and were associated with tumour size >4 cm (P = 0.005). The disease-free survival rates were 88.3 % and 61.9 % at 3 and 5 years. No significant difference in glomerular filtration rates before and after the procedure was observed (P = 0.107). The major complications rate was 5.9 % per session with an increased risk in the case of central locations (P = 0.006).

CONCLUSIONS

Percutaneous renal RFA appears to be safe and effective with useful nephron-sparing results.

KEY POINTS

• Radiofrequency ablation (RFA) is a well-tolerated technique according to mid-term results. • RFA for malignant renal tumours preserved renal function in high-risk patients. • Mid-term efficacy of RFA was close to that of formal conservative surgery. • Tumour size and central location limit the efficacy and safety of RFA.

Thermal ablation of unresectable liver tumors: factors associated with partial ablation and the impact on long-term survival

Background

Thermal ablation procedures, including radiofrequency ablation (RFA) or laser-induced interstitial thermotherapy (LITT), are now well established in the treatment of malignant unresectable hepatic tumors. But the impact of partial ablation (PA) on long-term survival following computed tomography (CT)-guided radiofrequency ablation and laser- induced interstitial thermotherapy of unresectable malignant liver lesions and the associated risk factors of PA remain partially unknown.

Material/Methods

This study included 254 liver tumors in 91 consecutive patients (66 men and 25 women; age 60.9±10.4 years; mean tumor size 25±14 mm [range 5–70 mm]) who underwent thermal ablation (RFA or LITT) between January 2000 and December 2007. Mean follow-up period was 21.1 month (range 1–69 months). Survival rate and local progression-free survival (PFS) were calculated for patients with complete ablation (CA) vs. patients with partial ablation (PA) to assess the impact on long-term survival.

Results

Median survival after CA was 47 months compared to 25 months after PA (P=0.04). The corresponding 5-year survival rates were 44% vs. 20%. Median PFS for CA was 11 months compared to 7 months for PA (P=0.118). The sole statistically significant risk factor for PA was tumor size (>30 mm; P=0.0003). Sustained complete ablation was achieved in 71% of lesions ≤30 mm vs. 47% of lesions >30 mm.

Conclusions

We conclude that achievement of complete ablation is a highly important predictor of long-term survival and that tumor size is by far the most important predictor of the likelihood of achieving complete ablation.

Pretreatment imaging can be used to select imaging guidance, ultrasound alone versus CT plus ultrasound, for percutaneous renal radiofrequency ablation

OBJECTIVE

Although CT is most commonly used for guidance of radiofrequency ablation (RFA) of renal masses, other publications have shown that ultrasound alone may be used. Therefore, we compared the complications and technical effectiveness of renal RFA guided by ultrasound alone versus combined CT and ultrasound guidance.

MATERIALS AND METHODS

We retrospectively analyzed outcomes and complications of percutaneous renal RFA in two groups of patients for whom RFA was guided by either ultrasound alone (group 1) or combined CT and ultrasound (group 2). The sole factor in determining the method of guidance was preablation imaging. All other technical factors were consistent between the two groups.

RESULTS

There were 28 masses in 27 patients in group 1 and 32 masses in 29 patients in group 2. There was an overall major complication rate of 3.3% (2/60). Major complications occurred equally in group 2 (3.1% [1/32]) compared with group 1 (3.6% [1/28]). Overall ablative effectiveness was 93% (26/28) in group 1 and 84% (27/32) in group 2. There was no statistical difference between the two groups.

CONCLUSION

In proper hands, sonography guidance alone is a safe and effective method for performance of renal RFA in preselected cases and can decrease CT utilization. The use of CT is reserved for situations in which pretreatment RFA imaging suggests difficulty in ultrasound mass visualization or when the mass is in close proximity to structures that may be injured by thermal ablation.

Percutaneous radiofrequency ablation of renal parenchyma: experimental study on the optimal temperature and the impact of vasoactive drugs

BACKGROUND AND PURPOSE

Radiofrequency (RF) is an efficient, inexpensive, safe, and friendly option for the management of small renal tumors. The objective was to evaluate the ideal temperature for renal cell destruction in dogs by RF and to verify whether the injection of vasoactive drugs, such as prostaglandin E1 and adrenaline, can help to improve the results, compared with "dry" RF ablation.

MATERIALS AND METHODS

The study was divided into three phases: Initially, 16 dogs of comparable weight underwent RF ablation of the renal parenchyma at temperatures of 80°C, 90°C, and 100°C. After that, seven other dogs received adrenaline (vasoconstrictor) and seven received prostaglandin E1 (vasodilator). Finally, the results from 14 animals were compared with those of the 16 (dry RF) dogs at the optimum temperature found. After 14 days, the animals underwent nephrectomy to evaluate the size of the lesions (width and depth), histology examination, and were then sacrificed.

RESULTS

There were no clinical or surgical complications in any of the dogs, and none died before the 14th day after the procedure. The optimum temperature was found to be 90°C. Prostaglandin E1 resulted in significantly larger lesions (in depth and width) than adrenaline, with lower impedance. Prostaglandin did not increase the lesions compared with dry RF. All the kidneys presented total coagulation necrosis, with no viable cells in the histologic analysis of the treated tissue.

CONCLUSION

In the ablation of renal cells by RF, prostaglandin produced larger lesions (in depth and width) than the same procedure using adrenaline, and its performance was similar to that of RF without injection of drugs.

Effectiveness of ultrasound-guided radiofrequency ablation in the treatment of 36 renal cell carcinoma tumours compared with published results of using computed tomography guidance

This study aimed to analyse the outcomes of ultrasound (US) guided radiofrequency ablation (RFA) in patients with renal lesions and to compare our outcomes with published results of ablations carried out when using computed tomography (CT) guidance. This retrospective study evaluated RFA of 36 renal tumours in 32 patients (M = 21, F = 11). The mean patient age was 70 years (range, 39-89 years). Ablations were performed by using either multi-tined applicators or cooled and/or cluster applicators under US guidance. Applicator size varied from 2-5 cm, depending on the size of the index tumour. Conscious sedation was administered by an anesthetist. Follow-up imaging by using contrast-enhanced CT was performed 1, 3, 6, and 12 months after RFA, and yearly thereafter. The mean tumour follow-up time was 12 months (range, 1-35 months). The mean tumour size was 2.7 cm (range, 1-5 cm). Primary effectiveness was achieved in 31 cases (86.1%), with patients in 5 cases (11.1%) demonstrating residual disease. Three patients had repeated sessions, which were technically successful. The remaining 2 patients were not re-treated because of patient comorbidities. As a result, secondary effectiveness was achieved in 34 patients (94.4%). In 1 patient, a new lesion developed in the same kidney but remote from the 2 prior areas of treatment. Hydrodissection was performed in 3 patients (8.3%), manipulation or electrode repositioning in 11 patients (30.6%), and ureteric cooling in 1 patient (2.8%). Minor and major complications occurred in 3 (8.3%) and 3 (8.3%) patients, respectively. Correlation coefficients were calculated for distance from skin to tumour and risk of complication as well as compared with primary and secondary effectiveness. This study demonstrates that US-guided RFA is an effective treatment for renal lesions, with rates of effectiveness and complication rates comparable with published CT-guided RFA results.

Limitation for performing ultrasound-guided radiofrequency ablation of small renal masses

PURPOSE

To evaluate which factor is involved in limiting ultrasound (US)-guided radiofrequency (RF) ablation of small renal masses.

MATERIALS AND METHODS

Twenty-five patients with 31 renal masses underwent image-guided RF ablation. If a lesion was visible on US, US-guided RF ablation was performed. If a lesion was invisible on US or if the lesion was incompletely ablated or recurred following US-guided RF ablation, CT-guided RF ablation was performed. We analyzed the various factors which were involved in US-guided RF ablation.

RESULTS

Of 31 masses, thirteen were US-visible lesions and underwent US-guided RF ablation whereas thirteen were US-invisible lesions and thus underwent CT-guided RF ablation. The remaining five lesions were US-visible but needed additional CT-guided RF ablation, due to incomplete ablation (n=4) or recurrence (n=1); these renal masses (3.1+/-1.0 cm) were significantly larger than those (1.8+/-0.6 cm) ablated with US alone (p<0.05). Steam bubbles (4.4 cm+/-0.7 cm) of the masses requiring additional CT-guided RF ablation were significantly larger than those (2.9 cm+/-0.7 cm) of the tumors completely ablated with US alone in size (p<0.05).

CONCLUSIONS

US-invisibility, lesion size, and steam bubbles may limit to perform US-guided RF ablation of small renal masses.

Minimally invasive surgery using ablative modalities for the localized renal mass

Due to a number of evolving devices and modalities to treat the small, localized renal mass, the physician and patient have the opportunity to choose an appropriate therapy from several treatment options. Minimally invasive surgery to ablate a localized renal tumor is an alternative strategy to nephron-sparing surgery for the small renal mass. Even though partial nephrectomy has been established as an optimal technique for nephron-sparing surgery, patients who have comorbidities and renal insufficiency would potentially benefit from less invasive treatment. With respect to those concerns, several articles are discussed here regarding thermal ablative therapy for the small renal mass along with oncological outcomes and complications among these modalities compared to conventional procedures. In this review, a comprehensive PubMed search was conducted. For the purposes of reviewing the current status of thermal ablative modalities for the small renal mass, only articles written in English published from 1992 to 2009 were considered. Cryoablation and radiofrequency ablation are the most utilized and potentially promising therapies that are evolving as nephron-sparing minimally invasive surgery for patients with a localized renal tumor. High-intensity focused ultrasound, a relatively new modality to treat the renal mass, needs further study. All modalities require long-term follow up with unified reporting methods in terms of patient selection, pre- and post-treatment evaluation, treatment description, and analysis of outcome.