Using an electrode as a lever to increase the distance between renal cell carcinoma and bowel during CT-guided radiofrequency ablation

Lever-elevating vs. liquid-isolating maneuvers during microwave ablation of high-risk benign thyroid nodules: a prospective single-center study

Aim: To compare the effects of the liquid-isolating maneuver and the lever-elevating maneuver in protecting cervical structures during microwave ablation for treating high-risk benign thyroid nodules.Methods: This prospectively study was approved by the Medical Ethics Committee of Panzhihua Central Hospital. A total of 174 patients were enrolled and randomly assigned to a liquid-isolating maneuver group (LIM, n = 87) or a lever-elevating maneuver group (LEM, n = 87). Operation time, postoperative voice change, time to recovery of baseline voice, peri-thyroid hematoma, neck tension, and intraoperative vasovagal reaction were assessed.Results: Operation time was greater in the LIM group than in the LEM group (44.75 ± 13.14 vs. 32.87 ± 10.84 min; p = .017).Voice changes were observed in 6 patients in the LIM group and 2 in the LEM group (6.9% vs. 2.3%, p = .278). The time to recovery of baseline voice was significantly greater in the LIM group compared with the LEM group (36.15 ± 10.24 vs. 24.48 ± 11.53 days, p = .014). The incidences of peri-thyroid hematoma and neck tension were higher in the LIM than in the LEM group (11.5% vs. 3.4%, 10.3% vs. 2.3%, p = .044 and p = .029). One patient (1.1%) in the LEM group and none of the patients in the LIM group experienced a vasovagal response (p = 1.000).Conclusion: The lever-elevating method is feasible and effective for the microwave ablation of benign thyroid nodules, with better protection of neck structures than observed with the liquid-isolating method.

Interventional Oncology: Keeping Out of Trouble in Ablation Techniques

Interventional radiologists provide an essential role in the therapy and management of cancer patients. Computed-tomography (CT) guided percutaneous procedures have enabled interventionalists to treat multiple solid organ malignancies with minimal risk, however, certain lesions may present challenges to physicians due to a difficult approach, or their close proximity to other vital structures. The following presents a brief summary of tips and tricks the interventionalist may use to provide their patients with safe and effective therapy.

Tips and tricks for a safe and effective image-guided percutaneous renal tumour ablation

Abstract

Image-guide thermal ablations are nowadays increasingly used to provide a minimally invasive treatment to patients with renal tumours, with reported good clinical results and low complications rate. Different ablative techniques can be applied, each with some advantages and disadvantages according to the clinical situation. Moreover, percutaneous ablation of renal tumours might be complex in cases where there is limited access for image guidance or a close proximity to critical structures, which can be unintentionally injured during treatment. In the present paper we offer an overview of the most commonly used ablative techniques and of the most important manoeuvres that can be applied to enhance the safety and effectiveness of percutaneous image-guided renal ablation. Emphasis is given to the different technical aspects of cryoablation, radiofrequency ablation, and microwave ablation, on the ideal operating room setting, optimal image guidance, application of fusion imaging and virtual navigation, and contrast enhanced ultrasound in the guidance and monitoring of the procedure. Moreover, a series of protective manoeuvre that can be used to avoid damage to surrounding sensitive structures is presented. A selection of cases of image-guided thermal ablation of renal tumours in which the discussed technique were used is presented and illustrated.

Teaching points

• Cryoablation, radiofrequency and microwave ablation have different advantages and disadvantages.

• US, CT, fusion imaging, and CEUS increase an effective image-guidance.

• Different patient positioning and external compression may increase procedure feasibility.

• Hydrodissection and gas insufflation are useful to displace surrounding critical structures.

• Cold pyeloperfusion can reduce the thermal damage to the collecting system.

Evaluation of a thermoprotective gel for hydrodissection during percutaneous microwave ablation: in vivo results

PURPOSE

To evaluate whether thermoreversible poloxamer 407 15.4 % in water (P407) can protect non-target tissues adjacent to microwave (MW) ablation zones in a porcine model.

MATERIALS AND METHODS

MW ablation antennas were placed percutaneously into peripheral liver, spleen, or kidney (target tissues) under US and CT guidance in five swine such that the expected ablation zones would extend into adjacent diaphragm, body wall, or bowel (non-target tissues). For experimental ablations, P407 (a hydrogel that transitions from liquid at room temperature to semi-solid at body temperature) was injected into the potential space between target and non-target tissues, and the presence of a gel barrier was verified on CT. No barrier was used for controls. MW ablation was performed at 65 W for 5 min. Thermal damage to target and non-target tissues was evaluated at dissection.

RESULTS

Antennas were placed 7 ± 3 mm from the organ surface for both control and gel-protected ablations (p = 0.95). The volume of gel deployed was 49 ± 27 mL, resulting in a barrier thickness of 0.8 ± 0.5 cm. Ablations extended into non-target tissues in 12/14 control ablations (mean surface area = 3.8 cm(2)) but only 4/14 gel-protected ablations (mean surface area = 0.2 cm(2); p = 0.0005). The gel barrier remained stable at the injection site throughout power delivery.

CONCLUSION

When used as a hydrodissection material, P407 protected non-targeted tissues and was successfully maintained at the injection site for the duration of power application. Continued investigations to aid clinical translation appear warranted.

Percutaneous radiofrequency ablation of renal cell carcinomas in patients with von Hippel Lindau disease: indications, techniques, complications, and outcomes

Renal cell carcinoma (RCC) in patients with von Hippel Lindau (VHL) disease tends to be multifocal, bilateral, and recur or develop new tumors after removal. These characteristics make treating hereditary RCCs difficult for urologists or radiologists compared to treating a sporadic RCC. Radiofrequency ablation (RFA) is a minimally-invasive treatment for small hereditary RCCs associated with a low complication rate and a minimal decrease in renal function. No RFA guidelines have been established about what to treat and when and how to ablate RCCs in patients with VHL disease. Besides, reports on complications and treatment outcomes in this patient group are rare. The purpose of this review is to discuss the indications, techniques, complications, and outcomes of RFA in treating RCC in patients with VHL disease.

An overview of image-guided percutaneous ablation of renal tumors

Although nephron-sparing surgery remains the gold standard treatment for small renal tumors, minimally invasive image-guided percutaneous ablation is becoming a viable alternative to operative resection. Percutaneous radiofrequency ablation (RFA) and cryoablation show high technical success rates, a relatively low incidence of residual or recurrent tumor, and competitive rates of patient survival. In this review, an overview of the current status of image-guided percutaneous ablation of renal tumors is presented, with a focus on procedure indications and patient selection, technical aspects of ablation procedures, and treatment outcomes and patient follow-up.

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.

Ablative therapies for renal tumors

Owing to an increased use of diagnostic imaging for evaluating patients with other abdominal conditions, incidentally discovered kidney masses now account for a majority of renal tumors. Renal ablative therapy is assuming a more important role in patients with borderline renal impairment. Renal ablation uses heat or cold to bring about cell death. Radiofrequency ablation and cryoablation are two such procedures, and 5-year results are now emerging from both modalities. Renal biopsy at the time of ablation is extremely important in order to establish tissue diagnosis. Real-time temperature monitoring at the time of radiofrequency ablation is very useful to ensure adequacy of ablation.

Percutaneous radiofrequency ablation of a small renal mass complicated by appendiceal perforation

Percutaneous radiofrequency ablation (RFA) has gained wide acceptance as nephron-sparing therapy for small renal masses in select patients. Generally, it is a safe procedure with minor morbidity and acceptable short-term oncologic outcome. However, as a result of the close proximity of vital structures, such as the bowel, ureter, and large vessels, to the ablative field, complications regarding these structures may occur. This is the first article describing appendiceal perforation as a complication of computed tomography-guided RFA despite hydrodissection. When performing this innovative and promising procedure one should be aware of the possibility of particular minor and even major complications.

Percutaneous radiofrequency ablation of renal cell carcinomas in patients with von Hippel Lindau disease previously undergoing a radical nephrectomy or repeated nephron-sparing surgery

BACKGROUND

Radiofrequency ablation (RFA) is accepted as a minimally invasive treatment of renal cell carcinoma (RCC). However, RFA is not fully evaluated for treating RCC in patients with von Hippel Lindau (VHL) disease who cannot undergo surgery due to serious postoperative morbidity or mortality.

PURPOSE

To evaluate the role of RFA of RCC in patients with VHL disease previously undergoing renal surgery.

MATERIAL AND METHODS

Percutaneous RFA was performed for treating 14 RCCs in six patients who had undergone radical nephrectomy (n = 3) or repeated nephron-sparing surgery (n = 3). Treatment feasibility, complications, outcome, and the change of renal function were evaluated.

RESULTS

To completely ablate 14 RCCs, 23 ablations during 12 sessions were necessary. Of 14 RCCs, nine were in proximity (<5 mm) to one or more following organs: bowel (n = 4), ureteropelvic junction or pelvis (n = 2), psoas muscle (n = 2), vascular pedicle (n = 1), and pancreas (n = 1). Of 12 sessions, one major complication (pneumothorax) developed in one session (8%). No residual or recurrent tumors were identified at the ablation areas. However, new three solid tumors less than 1 cm in diameter developed during the follow-up period but ablation was withheld until these tumors had grown to more than 1 cm in size. The mean level of serum creatinine increased with 6.4% and the mean estimated glomerular filtration rate decreased by 12.8% after the last ablation compared to those before the initial ablation (P < 0.05).

CONCLUSION

Despite technical difficulties, percutaneous RFA is a promising treatment for VHL patients who cannot undergo surgery because of excellent treatment outcome and minimal change of renal function.

Bowel displacement and protection techniques during percutaneous renal tumor thermal ablation

Although bowel injury is a rare complication of renal radiofrequency ablation, the potential consequences can be devastating. Therefore, it is prudent to perform bowel displacement/protection procedures when feasible. The main bowel displacement techniques include hydrodissection, gas-insufflation, balloon interposition, and electrode torquing. In this article, these techniques are discussed and the steps involved in performing these procedures are enumerated.

Management and prevention of renal ablative therapy complications

INTRODUCTION

The increasing diagnosis of incidental small renal masses has contributed to energy ablative techniques being increasingly utilized as a primary surgical modality. Despite promise associated with thermal ablation, complications related to both cryoablation (CA) and radiofrequency ablations (RFA) do occur.

METHODS

Contemporary literature on renal ablative procedures (CA and RFA) was reviewed to highlight diagnosis, management, and prevention of complications associated with these procedures.

RESULTS

While morbidity for renal thermal ablation is typically less than extirpative renal surgery, a range of complications of varying severity may exist. Such complications can include sequelae from choice of access site, procedural bleeding, visceral injury, or damage to the collecting system or ipsilateral ureter.

CONCLUSIONS

An understanding of complications secondary to renal ablation is essential for urologists and radiologists to facilitate prompt diagnosis, appropriate management, and future prevention.

Bowel displacement for CT-guided tumor radiofrequency ablation: techniques and anatomic considerations

PURPOSE

To describe safety and efficacy of bowel displacement techniques and determine lesion characteristics that are likely to necessitate bowel displacement.

PATIENTS AND METHODS

A retrospective review of patients who underwent CT-guided renal tumor radiofrequency ablation (RFA) (January 2006-August 2008) was conducted. Techniques included hydrodissection, additional manual torquing of the RFA probe, and additional angioplasty balloon interposition. The goal was to displace bowel from the probe by at least 10 to 20 mm. Air-filled balloon interposition was intended as a thermal barrier. Pre- and postbowel displacement distances were measured by CT. Saline volumes were recorded. Multivariate stepwise regression analysis was used to determine the influence of laterality, renal location, and morphology of renal lesions on their proximity to the colon and use of bowel displacement techniques.

RESULTS

RFA was performed on 57 consecutive patients. Eleven (19%) patients had bowel displacement attempts. Median pre-RFA lesion edge to colon distance for nondisplaced vs displaced was 43 mm (range 10-100 mm) vs 6 mm (range 0-16 mm), respectively (P < 0.05). Two variables were significant for bowel displacement (F-ratio = 4.681, P = 0.006): Tumor position within the kidney in the craniocaudal plane (P = 0.014) and anterior-posterior plane (P = 0.007). Lower pole and posterior lesions tended to be closer to the colon and more likely to necessitate bowel displacement. Orientation in the medial-lateral plane (P = 0.77) and exophytic nature of the lesion (P = 0.83) were not significant features. Hydrostatic bowel displacement was always the first-line technique and was completely and partly successful in 8 (73%) and 1 (9%) attempts, respectively. Partial success was augmented by probe torquing (distance increased from 1 mm to 16 mm and then to 23 mm with torquing). Mean saline injection: 105 mL (range 55-440 mL). There were two complete failures (18%) in which bowel was displaced only by 0 to 2 mm despite injection of 280 to 440 mL. Balloon interposition was attempted in these two cases. Five minor complications occurred in the nondisplaced cohort. No complications occurred in the bowel displacement cohort.

CONCLUSION

Lower pole, posterior renal lesions are more likely to necessitate bowel displacement. Bowel displacement techniques are effective and safe in displacing bowel.

Complications of image-guided radiofrequency ablation of renal cell carcinoma: causes, imaging features and prevention methods

Radiofrequency (RF) ablation is an alternative treatment for renal cell carcinoma (RCC) in patients unable to undergo surgery. Although RF ablation has a low complication rate because of its minimally invasive nature, unintended heat may be conducted by several critical organs during ablation procedures, leading to a variety of complications. Major complications that usually require treatment include bowel injury, ureteral injury, massive bleeding and residual or recurrent tumour. Minor complications that may require only observation include pain, haematoma, haematuria, neuromuscular injury, pneumothorax, infarction and inflammatory tract mass. The most common cause of complications is the tumour's proximity to neighbouring organs. In addition, careless electrode manipulation and the patient's comorbidities may also lead to complications. To avoid many of these complications, the distance between the tumour and neighbouring organs should be widened using methods such as changing the patient's position, using the RF electrode as a lever and hydrodissection. Furthermore, carefully manipulating the RF electrode and assessing the patient's general condition help to prevent complications. In this review, we discuss the complications resulting from RF ablation of RCC with an emphasis on causes, imaging features and prevention methods.