PILOT EXPERIENCE WITH REAL-TIME ULTRASOUND GUIDED PERCUTANEOUS RENAL MASS CRYOABLATION

Progress in the cryoablation and cryoimmunotherapy for tumor

With the rapid advancement of imaging equipment and minimally invasive technology, cryoablation technology is being used more frequently in minimally invasive treatment of tumors, primarily for patients with early tumors who voluntarily consent to ablation as well as those with advanced tumors that cannot be surgically removed or cannot be tolerated. Cryoablation is more effective and secure for target lesions than other thermal ablation methods like microwave and radiofrequency ablation (RFA). The study also discovered that cryoablation, in addition to causing tumor tissue necrosis and apoptosis, can facilitate the release of tumor-derived autoantigens into the bloodstream and activate the host immune system to elicit beneficial anti-tumor immunological responses against primary. This may result in regression of the primary tumor and distant metastasis. The additional effect called " Accompanying effects ". It is the basis of combined ablation and immunotherapy for tumor. At present, there is a lot of research on the mechanism of immune response induced by cryoablation. Trying to solve the question: how positively induce immune response. In this review, we focus on: 1. the immune effects induced by cryoablation. 2. the effect and mechanism of tumor immunotherapy combined with cryoablation. 3.The clinical research of this combination therapy in the treatment of tumors.

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.

Patients' radiation dose in computed tomography-fluoroscopy-guided percutaneous cryoablation for small renal tumors

PURPOSE

This study aimed to evaluate patients' radiation dose in computed tomography (CT)-fluoroscopy-guided cryoablation for small renal tumors and assess the possible factors affecting it.

METHODS

In our institution, cryoablation was performed in 152 patients between 2013 and 2020. Procedures that were not for renal tumors and did not have radiation dose records and detailed information were excluded from the analysis. The size-specific dose estimates (SSDE), volume CT dose index (CTDI_vol), dose-length product (DLP), and entrance skin dose (ESD) were evaluated for both spiral scan and CT-fluoroscopy. The effects of the number of cryoneedle punctures; combined use of hydro- and/or pneumodissection procedures; patients' characteristics, such as body-mass index (BMI); and the tumor-related factors, such as tumor location, were determined by the univariate and multivariate analyses.

RESULTS

In the 72 included procedures, the median SSDE was 658 mGy and the median CTDI_vol was 456 mGy. The median percentage dose of CT-fluoroscopy to the total procedure dose was estimated as 89.8% (591/658 mGy) with SSDE and 41.4% (611/1,475 mGy cm) with DLP. The combined use of hydro- and/or pneumodissection and number of cryoneedle punctures were significantly associated with the total ESD, and the maximum total ESD was 863 mGy in our cases.

CONCLUSIONS

Using SSDE as an index, 89.8% of patients' radiation dose was attributed to CT-fluoroscopy, and ESD for the total procedure did not exceed 1 Gy. The increased number of cryoneedle punctures and combined use of hydro- and/or pneumodissection increased the total ESD.

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.

Focal ablation therapy for renal cancer in the era of active surveillance and minimally invasive partial nephrectomy

Partial nephrectomy is the optimal surgical approach in the management of small renal masses (SRMs). Focal ablation therapy has an established role in the modern management of SRMs, especially in elderly patients and those with comorbidities. Percutaneous ablation avoids general anaesthesia and laparoscopic ablation can avoid excessive dissection; hence, these techniques can be suitable for patients who are not ideal surgical candidates. Several ablation modalities exist, of which radiofrequency ablation and cryoablation are most widely applied and for which safety and oncological efficacy approach equivalency to partial nephrectomy. Data supporting efficacy and safety of ablation techniques continue to mature, but they originate in institutional case series that are confounded by cohort heterogeneity, selection bias, and lack of long-term follow-up periods. Image guidance and surveillance protocols after ablation vary and no consensus has been established. The importance of SRM biopsy, its optimal timing, the type of biopsy used, and its role in treatment selection continue to be debated. As safety data for active surveillance and experience with minimally invasive partial nephrectomy are expanding, the role of focal ablation therapy in the treatment of patients with SRMs requires continued evaluation.

Percutaneous US-guided renal cryoablation using 3D modeling

INTRODUCTION

The article describes the first experience of performing percutaneous ultrasound (US)-guided cryoablation of renal tumor and assesses the safety and short-term results of treatment.

MATERIALS AND METHODS

Twelve patients were subjected to US-guided cryoablation of renal tumor in 2015. The tumor size in 11 patients was up to 3.0 cm (T1а); in one female patient, 4.5 cm (T1b). Tumors were assessed according to the PADUA score. In eight patients, it was 6-7 (low); in three patients, 8-9 (average); in one, 10 (high). All the patients underwent US examination using a FlexFocus 800 apparatus with convex abdominal transducers. Before surgery and 6 months later, all the patients underwent renal Doppler US and contrast-enhanced computed tomography.

RESULTS

The average cryoablation time was 60 min. Seven operations were performed under spinal anesthesia and five operations under local anesthesia. The follow-up period lasted 8 months on average. According to the ultrasonography and Doppler findings, after 6 months, the tumor (T1a) in 11 patients reduced in size by an average of 7-8 mm and had no blood supply.T1b patient's mass size reduces from 4.5 to 3.7 cm; however, a 1.5 cm area with a high attenuation gradient of the contrast medium was visualized. Later, the patient was subjected to laparoscopic renal resection. Histological finding revealed clear-cell carcinoma.

CONCLUSIONS

We consider percutaneous US-guided cryoablation as a method of choice for patients with stage T1a renal tumor localized on the posterior or lateral surface in the inferior or middle segment without sinus involvement and PADUA <9.

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.

Image-guided tumor ablation: emerging technologies and future directions

As the trend continues toward the decreased invasiveness of medical procedures, image-guided percutaneous ablation has begun to supplant surgery for the local control of small tumors in the liver, kidney, and lung. New ablation technologies, and refinements of existing technologies, will enable treatment of larger and more complex tumors in these and other organs. At the same time, improvements in intraprocedural imaging promise to improve treatment accuracy and reduce complications. In this review, the latest advancements in clinical and experimental ablation technologies will be summarized, and new applications of image-guided tumor ablation will be discussed.

Cryoablation vs radiofrequency ablation for the treatment of renal cell carcinoma: a meta-analysis of case series studies

Study Type - Therapy (systematic review). Level of Evidence 2b What's known on the subject? and What does the study add? The oncological success of partial nephrectomy in the treatment of small renal masses is well established. However, partial nephrectomy has largely supplanted the radical approach. In the last decade, laparoscopy has been adopted as the new surgical approach for the treatment of renal cell carcinoma. Laparoscopy offers the advantage of lower analgesic use, shorter hospital stay, and quicker recovery time. More recently, ablative technologies have been investigated as an alternative to laparoscopic partial nephrectomy. These techniques can often be performed percutaneously in the radiology suite, or laparoscopically without the need for hilar clamping. However, only the cryoablation and radiofrequency ablation modalities have had widespread use with several series reporting short to intermediate results. This review shows that both cryoablation and radiofrequency ablation are promising therapies in patients with small renal tumours (<4 cm), who are considered poor candidates for more involved surgery.

OBJECTIVE

• To determine the current status of the literature regarding the clinical efficacy and complication rates of cryoablation vs radiofrequency ablation in the treatment of small renal tumours.

METHODS

• A review of the literature was conducted. There was no language restriction. Studies were obtained from the following sources: MEDLINE, EMBASE and LILACS. • Inclusion criteria were (i) case series design with more than one case reported, (ii) use of cryoablation or radiofrequency ablation, (iii) patients with renal cell carcinoma and, (iv) outcome reported as clinical efficacy. • When available, we also quantified the complication rates from each included study. • Proportional meta-analysis was performed on both outcomes with a random-effects model. The 95% confidential intervals were also calculated.

RESULTS

• Thirty-one case series (20 cryoablation, 11 radiofrequency ablation) met all inclusion criteria. • The pooled proportion of clinical efficacy was 89% in cryoablation therapy from a total of 457 cases. There was a statistically significant heterogeneity between these studies showing the inconsistency of clinical and methodological aspects. • The pooled proportion of clinical efficacy was 90% in radiofrequency ablation therapy from a total of 426 cases. There was no statistically significant heterogeneity between these studies. • There was no statistically significant difference regarding complications rate between cryoablation and radiofrequency ablation.

CONCLUSIONS

• This review shows that both ablation therapies have similar efficacy and complication rates. • There is urgency for performing clinical trials with long-term data to establish which intervention is most suitable for the treatment of small renal masses.

Percutaneous cryoablation of renal tumors: patient selection, technique, and postprocedural imaging

Percutaneous cryoablation of renal tumors requires a number of important steps for success and relies heavily on imaging for treatment planning, intraprocedural guidance and monitoring, detection of untreated tumor, and surveillance for disease progression. Imaging-guided percutaneous cryoablation has several advantages over laparoscopic cryoablation. In particular, computed tomography (CT) and magnetic resonance (MR) imaging allow global evaluation of the ablation zone and an accurate depiction of the treatment margin. Ultrasonography allows real-time guidance of probe placement but cannot help depict ice ball formation as accurately as CT or MR imaging. Multiphasic CT or MR imaging should be performed at structured intervals following ablation. Treated tumors are expected to decrease in size over time, and lesion growth and internal or nodular enhancement are suspicious for tumor recurrence or progression. Complications include probe site pain, hematoma, incomplete ablation, and recurrent tumor. Current limitations of percutaneous cryoablation include the inability to control hemorrhage without intraarterial access and a lack of long-term follow-up data. Nevertheless, percutaneous cryoablation is an effective choice for minimally invasive nephron-sparing treatment of renal tumors.

Image registration of pre-procedural MRI and intra-procedural CT images to aid CT-guided percutaneous cryoablation of renal tumors

PURPOSE

To determine whether a non-rigid registration (NRR) technique was more accurate than a rigid registration (RR) technique when fusing pre-procedural contrast-enhanced MR images to unenhanced CT images during CT-guided percutaneous cryoablation of renal tumors.

METHODS

Both RR and NRR were applied retrospectively to 11 CT-guided percutaneous cryoablation procedures performed to treat renal tumors (mean diameter; 23 mm). Pre-procedural contrast-enhanced MR images of the upper abdomen were registered to unenhanced intra-procedural CT images obtained just prior to the ablation. RRs were performed manually, and NRRs were performed using an intensity-based approach with affine and Basis-Spline techniques used for modeling displacement. Registration accuracy for each technique was assessed using the 95% Hausdorff distance (HD), Fiducial Registration Error (FRE) and the Dice Similarity Coefficient (DSC). Statistical differences were analyzed using a two-sided Student's t-test. Time for each registration technique was recorded.

RESULTS

Mean 95% HD (1.7 mm), FRE (1.7 mm) and DSC (0.96) using the NRR technique were significantly better than mean 95% HD (6.4 mm), FRE (5.0 mm) and DSC (0.88) using the RR technique (P < 0.05 for each analysis). Mean registration times of NRR and RR techniques were 15.2 and 5.7 min, respectively.

CONCLUSIONS

The non-rigid registration technique was more accurate than the rigid registration technique when fusing pre-procedural MR images to intra-procedural unenhanced CT images. The non-rigid registration technique can be used to improve visualization of renal tumors during CT-guided cryoablation procedures.

Laparoscopic renal cryoablation: 8-year, single surgeon outcomes

PURPOSE

We present 5 to 11-year (median 8) oncological outcomes after laparoscopic renal cryoablation.

MATERIALS AND METHODS

Between September 1997 and October 2008 we performed renal cryoablation in 340 patients, of whom 80 treated laparoscopically by a single surgeon before October 2003 had a minimum 5-year followup. Followup involved magnetic resonance imaging on postoperative day 1, at 3, 6 and 12 months, and annually thereafter. Cryolesion biopsy was performed at 6 months. All data were prospectively accrued.

RESULTS

In the 80 patients with minimum 5-year followup mean age was 66 years, mean tumor size was 2.3 cm (range 0.9 to 5.0), median American Society of Anesthesiologists score was 3 and mean body mass index was 28 kg/m(2). Five patients had local recurrence, 2 had locoregional recurrence with metastasis and 4 had distant metastasis without locoregional recurrence. Six patients died of cancer. In the 55 patients with biopsy proven renal cell cancer at a median followup of 93 months (range 60 to 132) 5-year overall, disease specific and disease-free survival rates were 84%, 92% and 81%, and 10-year rates were 51%, 83% and 78%, respectively. On multivariate analysis previous radical nephrectomy for RCC was the only significant predictor of disease-free and disease specific survival (p = 0.023 and 0.030, respectively).

CONCLUSIONS

Laparoscopic renal cryoablation is effective oncological treatment for a renal mass in select patients. A disease specific survival rate of 92% at 5 years and 83% at 10 years is possible. Preceding radical nephrectomy for renal cell carcinoma was the only independent factor predicting disease-free and disease specific survival.

Cryoablation or radiofrequency ablation of the small renal mass : a meta-analysis

BACKGROUND

The incidence of renal cell carcinoma is rising because of incidental detection of small renal masses (SRMs). Although surgical resection remains the standard of care, cryoablation and radiofrequency ablation (RFA) have emerged as minimally invasive treatment alternatives. The authors of this report performed a comparative meta-analysis evaluating cryoablation and RFA as primary treatment for SRMs.

METHODS

A search of the MEDLINE database was performed reviewing the world literature for clinically localized renal masses treated by cryoablation or RFA.

RESULTS

Forty-seven studies representing 1375 kidney lesions treated by cryoablation or RFA were analyzed. No differences were detected between ablation modalities with regard to mean patient age (P = .17), tumor size (P = .12), or duration of follow-up (P = .53). Pretreatment biopsy was performed more often for cryoablated lesions (82.3%) than for RFA (62.2%; P < .0001). Unknown pathology occurred at a significantly higher rate for SRMs that underwent RFA (40.4%) versus cryoablation (24.5%; P < .0001). Repeat ablation was performed more often after RFA (8.5% vs 1.3%; P < .0001), and the rates of local tumor progression were significantly higher for RFA (12.9% vs 5.2%; P < .0001) compared with cryoablation. The higher incidence of local tumor progression was found to be correlated significantly with treatment by RFA on univariate analysis (P = .001) and on multivariate regression analysis (P = .003). Metastasis was reported less frequently for cryoablation (1.0%) versus RFA (2.5%; P = .06). Cryoablation usually was performed laparoscopically (65%), whereas 94% of lesions that were treated with RFA were approached percutaneously.

CONCLUSIONS

Ablation of SRMs is a viable strategy based on short-term oncologic outcomes. Although extended oncologic efficacy remains to be established for ablation modalities, the current data suggest that cryoablation results in fewer retreatments and improved local tumor control, and it may be associated with a lower risk of metastatic progression compared with RFA.

Percutaneous renal cryoablation: current status

Over the last 13 years, renal cryoablation has emerged as a promising technique for the treatment of solid renal tumors. The improvement in imaging modalities such as ultrasound, computed tomography and MRI, as well as the introduction of thinner probes, has led to the spread of the minimally invasive percutaneous approach. We review the historical background of percutaneous renal cryoablation (PRC), present its basic principles, mention the contemporary clinical data and outcomes of this technique and suggest future directions for its wider application in renal tumors. Early results have demonstrated that it may offer an alternative for the treatment of small renal masses with the advantages of minimal complications, spared renal function, decreased overall costs and equivalent oncologic efficacy. Long-term results are required in order to apply this minimally invasive technique to a broader spectrum of patients.

Case report: percutaneous cryoablation of a small renal lesion necessitating modified lateral decubitus position

When performing percutaneous cryoablation for renal masses, the standard patient positioning has been the prone position. We present a case in which placing the patient in a modified lateral decubitus position aided in the access of probe placement for percutaneous cryoablation.

A Protocol for the Assessment of Diagnostic Accuracy in Tele-echocardiography Imaging

Tele-echocardiography could be a useful means for investigating heart pathologies on remotely-located patients. At present, the main drawback with tele-echocardiography is the lack of a thorough protocol for the assessment of the diagnostic accuracy of the transmitted images. Diagnostic accuracy in tele-echocardiography is not only a function of quantitative parameters but also of the subjective decision of the operator depending on his/her a priori knowledge based on complex internal models. In the framework of three Italian projects, we defined and validated a wide-ranging protocol that considers not only the most common quantitative parameters in medical imaging, but also the use of a dynamic phantom, and subjective/partially subjective evaluations. The validation of tele-echocardiography systems chosen from those evaluated in the projects showed that the protocol was feasible. It permitted access to the degradation of the transmitted images and correlate quantitative and subjective analyses. The protocol was found suitable for tele-echocardiography systems but also for other tele-imaging applications, where medical decision making is based on dynamic images.

Pilot Experience with Transhepatic Percutaneous Renal Cryoablation

BACKGROUND AND PURPOSE

Percutaneous renal cryoablation has been shown to be a feasible therapeutic option for small renal tumors. Despite advances in equipment design and imaging capabilities, tumor location can present challenges to the percutaneous approach. We present our pilot experience with transhepatic percutaneous cryoablation of right upper-pole renal tumors.

PATIENTS AND METHODS

Three patients aged 75 to 87 years with American Society of Anesthesiologists scores of III or IV underwent transhepatic percutaneous cryoablation between November 2005 and February 2006. Tumor size ranged from 2 to 5 cm. Cryoprobe placement was guided by CT imaging, and two freeze-thaw cycles were used. Additionally, 60-second freeze-thaw cycles were used to assist with hemostasis in the transhepatic tract.

RESULTS

The procedure was completed percutaneously in all cases with the patient under conscious sedation. The procedure time ranged from 67 to 167 minutes. Postoperative pain was managed with minimal use of nonnarcotic oral medications. Although one patient developed a moderate perinephric hematoma and required a blood transfusion, no hepatic complications were manifest. Local treatment failure was evident in one patient with a 5-cm mass showing enhancement at follow-up imaging.

CONCLUSIONS

Transhepatic access for percutaneous cryoablation of renal tumors is feasible. Limitations include tumor size, as larger tumors may introduce prohibitive risks.

Laparoscopic Management of Renal Tumors

Laparoscopy has become commonplace in the management of genitourinary malignancies and, in some institutions, has largely replaced open surgery as the primary treatment method for renal tumors. Outside of laparoscopic radical nephrectomy, other modalities, such as nephron-sparing partial nephrectomy and energy-based ablative procedures, have been extended to laparoscopy. In this article, we present our experience and review the literature regarding the utility of laparoscopy in the management of renal tumors.

Oncologic outcomes for ablative therapy of kidney cancer

Needle ablative therapies for small incidental renal masses are emerging as alternatives to traditional extirpative surgery. Reasons include their associated decreased morbidity, shorter convalescence, and the ability to avert the higher risk of extirpative surgery in an aging patient population. Cryoablation (CA) and radiofrequency ablation are the two most thoroughly studied needle ablative methods used for renal cancer. High-intensity focused ultrasound has also been studied but with limited published human experience at this time. For both radiofrequency ablation and CA, in vitro experiments, animal studies, and (increasingly) human experience have been published, allowing us to define appropriate candidates for such therapies, their oncologic outcomes, and the potential pitfalls. While long-term data is being collected, the current literature suggests that CA and radiofrequency ablation can be safely performed and can effectively eradicate small renal cancers with cancer-specific survival rates similar to those of traditional surgical options.

[Renal cancer: what can we expect from emerging new technologies: radiofrequency and cryoablation?]

Radiofrequency and cryoablation are both minimally invasive techniques applied to the treatment of renal cell carcinoma. These techniques allow in situ destruction of neoplasm. Although cryotherapy is the most studied, radiofrequency is the most currently used technique. Indications mostly accepted as elective indication are the less than 4 cm in diameter exophytic tumors. Radiofrequency and cryoablation can also be proposed in patients with solitary kidney, multiple bilateral tumors and patients with contraindication for surgical resection. The radiofrequency parietal tract can be coagulated at the time of radiofrequency electrode withdrawal reducing the rare risk of parietal tumor dissemination. Preliminary oncological results in exophytic small renal tumors are promising with only few complications. A longer follow-up is however mandatory to better define the place of these two new technologies in the treatment of renal cancer.

Minimally Invasive Nephron-Sparing Surgery (MINSS) for Renal Tumours

OBJECTIVES

To review the evolution and current status of probe ablative methods of minimally invasive nephron-sparing surgery (MINSS) for renal tumours.

METHODS

The English language literature of the past 10 yr was reviewed by using the National Library of Medicine database and the following keywords: chemoablation, cryoablation, high-intensity focused ultrasound, kidney, laser interstitial thermotherapy, microwave thermotherapy, nephron-sparing surgery, radiofrequency ablation, radiosurgery, renal, and tumour. Over 300 papers were identified, 50 of which were selected for this review on the basis of their contribution in advancing the field with regards to (1) evolution of concepts, (2) development and refinement of techniques, and (3) intermediate- and long-term clinical outcomes.

RESULTS

Open partial nephrectomy is the reference standard for nephron-sparing surgery against which all MINSS techniques should be measured. Although the initial outcomes of cryoablation and radiofrequency ablation (RFA) are encouraging, long-term studies are necessary to confirm lasting efficacy. The optimal modality for tumour targeting, monitoring therapy, and follow-up remains to be determined. These ablative techniques should be reserved for carefully selected patients, the data should be prospectively accrued, and the long-term cancer cure rates should be compared with the reference standard.

CONCLUSIONS

Promising long-term data are available for cryoablation. RFA is still considered developmental, and instances of incomplete cell kill, despite nonenhancement, are concerning. Other modalities are still experimental.

Percutaneous Computerized Tomography Guided Cryoablation for Localized Renal Cell Carcinoma: Factors Influencing Success

PURPOSE

We evaluated the factors that influenced the initial success rate and complication rate of percutaneous computerized tomography guided cryoablation of localized renal cell carcinoma of clinical stage T1N0M0.

MATERIALS AND METHODS

A total of 21 patients with a mean age of 71.5 years and a pathological diagnosis of renal cell carcinoma were treated with percutaneous computerized tomography guided cryoablation under conscious sedation on an outpatient basis. We retrospectively reviewed clinical data, tumor characteristics, techniques and results. Tumors with complete loss of contrast enhancement were considered successfully treated.

RESULTS

A total of 21 patients with 23 tumors underwent 25 cryoablation sessions. The mean intraoperative computerized tomography scan tumor size was 2.1 cm (range 0.5 to 4.3) and the mean ice ball size was 4.1 cm (range 2.2 to 7.2). Of the patients 82.6% (19 of 23) had a single treatment. Patients were followed with postoperative scans of 4.6 to 18.3 months (mean 12.3). There were 2 recurrences. The rate of successful complete tumor ablation was influenced by various factors. Tumor location and size were the major determinants for achieving tumor eradication.

CONCLUSIONS

Percutaneous renal cryoablation using computerized tomography imaging proved to be a successful technique for guiding probe placement and monitoring ice ball formation. Patient selection based on tumor size and location may aid in improved outcomes. Further study and followup are necessary to determine long-term oncological efficacy.

Percutaneous computerized tomography guided renal cryoablation using local anesthesia: pain assessment

PURPOSE

The administration of intravenous sedation during prone computerized tomography guided, percutaneous procedures has the potential for complications. We assessed the pain associated with computerized tomography guided, percutaneous renal cryoablation using straight local anesthesia.

MATERIALS AND METHODS

Patients were treated with cryoablation probes inserted into the renal tumor under computerized tomography guidance with local anesthesia. Patients were asked to rate the pain experienced during needle placement and cryoablation using a visual 10-degree pain score scale. Sedation was given when pain was greater than 7 or when requested by the patient. Parameters assessed were cardiopulmonary complications, the need for intravenous supplementation, the pain score during the procedure and the postoperative score.

RESULTS

A total of 25 patients (30 tumors) underwent a total of 26 cryoablation sessions with only local anesthesia. Mean patient age +/- SD was 67 +/- 13 years (range 33 to 88). Average tumor and ice ball size was 2.1 +/- 0.7 (range 1.1 to 4.3) and 4.1 +/- 1.0 cm (range 2.6 to 5.9), respectively. The mean dose of 1% lidocaine was 43.89 +/- 24.97 ml (range 10 to 110). All procedures were completed in an average of 68.78 +/- 20.7 minutes (range 40 to 120). Vital signs were not significantly changed during the procedure. Successful completion of percutaneous computerized tomography guided cryoablation using local anesthesia was accomplished in 22 of the 26 sessions (84.62%) without sedation. Four patients required intravenous supplementation.

CONCLUSIONS

Percutaneous computerized tomography guided cryoablation for renal tumors can be performed using local anesthesia with minimal discomfort in most patients.

Percutaneous ultrasound-guided cryoablation of renal tumors using the CIVCO assist positioning system

Cryoablation is emerging as an accepted treatment for small renal tumors. Percutaneous placement of cryoprobes using ultrasound guidance is an attractive option for patients with tumors easily seen with transabdominal ultrasonography; however, the placement of probes using hand-held devices is technically challenging. To improve the accuracy and ease of cryoprobe placement during percutaneous renal cryoablation, we describe the novel application of the CIVCO Assist positioning arm system during these complex procedures.

Review of minimally invasive renal therapies: Needle-based and extracorporeal

Management of the small renal mass (< or = 3 cm) is a topic of significant debate among urologists worldwide. With the advent of needle-based therapies and, less frequently, reports of extracorporeal approaches, along with ongoing refinements in each technology, patients with such masses may have the option of being treated in a truly minimally invasive, or even noninvasive, manner. Herein we review the body of available clinical literature on these modalities with respect to patient selection, success and complication rates, follow-up information, energy delivery devices, and current probe configurations.

Cryotherapy: Clinical end points and their experimental foundations

More renal tumors are now being found at an early stage. Similarly, the treatment of patients with such small tumors is shifting away from radical nephrectomy toward nephron-sparing extirpative surgery or nonextirpative renal tumor ablation. Of the various techniques used for renal tumor ablation, cryotherapy is the most extensively studied and has the longest reported outcomes. In this article, we examine the experimental and clinical evolution of cryotherapy for small renal masses. A literature search was performed with the following key words: cryobiology, cryotherapy, cryoablation, tissue-ice interaction, temperature, monitoring, cryoinjury, renal function, blood pressure, and treatment end point. Articles that dealt with the experimental and clinical bases of current cryoablation principles and techniques were selected for review. Some recent studies representative of current clinical outcomes were also examined. Cryotherapy for the small renal tumor can be performed during open surgery, laparoscopically, or even percutaneously with use of a variety of probes and high-resolution imaging techniques to monitor therapy. In the clinical scenario, the ice ball is usually extended 1 cm beyond the visible tumor margin. Cryotherapy per se does not adversely affect renal function and blood pressure. Inadvertent cryoinjury to the collecting system rarely leads to urinary leakage. To date, only 6-month follow-up biopsy data are available. Absence of contrast enhancement on follow-up computed tomography or magnetic resonance imaging is considered oncologic success. For a sporadic unilateral renal tumor, 98% cancer-specific survival at 3 years has been reported. Cryotherapy has moved beyond the "experimental" stage, and initial outcomes are encouraging. The major criticism of this and other ablative techniques is the associated lack of histologic confirmation of complete tumor ablation. Long-term, diligently performed studies that provide detailed, meticulous, sequential 5-year radiologic and histologic data are necessary to confirm lasting efficacy. In addition, these data must be compared with those related to partial nephrectomy, which remains the reference standard.

Percutaneous renal cryoablation

Percutaneous renal cryoablation (PRC) has been gaining acceptance as a minimally invasive option for the treatment of patients with solid renal masses. Herein, we reviewed the historical development of PRC, relevant contemporary clinical data, and future directions of percutaneous approaches to renal masses. Early experience suggests that PRC has the potential to offer an alternative treatment for patients with small renal masses, with the advantages of decreased treatment-associated morbidity and spared renal function. Ultrasound, computed tomography, magnetic resonance imaging, and positron-emission tomography have all been explored as potential solutions to the challenges of image guidance and follow-up; distinct advantages and disadvantages of each are reviewed here. Encouraging early results regarding oncologic efficacy, rate of complications, and overall costs support the continued evaluation of PRC. Longer-term oncologic follow-up is essential if the potential application of this minimally-invasive technique to a broader spectrum of patients with renal masses is to be determined.

Current Status and Advances in Nephron-Sparing Surgery

Localized renal cell carcinoma (RCC) remains a surgical disease, with excision of the tumor or tumor-bearing kidney offering the only chance of cure for affected patients. After the widespread acceptance of partial nephrectomy as equivalent treatment to radical nephrectomy in appropriately selected cases of RCC, a range of nephron-sparing procedures has become available to patients. These include laparoscopic partial nephrectomy, thermal ablative techniques, as well as open partial nephrectomy. These techniques offer the attraction of being minimally invasive, in some cases as outpatient procedures under sedation. This review attempts to clarify the current status of these nephron-sparing techniques. Case selection criteria, outcomes, and complications are presented with the aim of helping the modern urologist appreciate the benefits of these procedures as well as their limitations and role in the management of patients with RCC.

Computerized Tomography Guided Percutaneous Renal Cryoablation With the Patient Under Conscious Sedation: Initial Clinical Experience

PURPOSE

We report on our initial clinical experience with CT guided percutaneous renal cryoablation.

MATERIALS AND METHODS

CT guided percutaneous renal cryoablation was performed on 27 tumors using conscious sedation in 20 patients. Eligible patients had tumors of 5 cm or less and were poor surgical candidates or otherwise warranted nephron sparing treatment. Tumors were classified as central or noncentral depending on their relationship to the renal sinus fat. During cryoablation intraoperative active ice ball formation was monitored with real-time CT imaging to ensure adequate tumor coverage. Postoperative followup imaging was obtained at regular intervals.

RESULTS

Our method appears technically feasible as of the 27 cryoablations performed, only 1 complication occurred requiring blood transfusion in a patient with a large, centrally located tumor. To date we have 16 tumors in 12 patients with imaging followup of 1 month or more (mean followup 5.9 months). Mean baseline tumor size in this group was 2.5 cm with 11 small (3 cm or less) and 5 large (more than 3 cm) tumors. Of the tumors 5 were centrally located and 11 were noncentrally located. Preliminary data suggest that of the 16 cryoablated tumors 15 showed no signs of enhancement on followup.

CONCLUSIONS

CT guided percutaneous renal cryoablation appears to be a feasible treatment option for small, noncentrally located renal tumors. While early results appear promising, longer followup is needed to more clearly define the role of this treatment method.

Renal tumor ablation

PURPOSE OF REVIEW

The management of small renal tumors is changing from radical nephrectomy to nephron-conserving surgery. The aim of this review is to discuss the currently prevailing methods used for nonextirpative renal tumor ablation. The studies published in English during 2004 to May 2005 have been reviewed in this article.

RECENT FINDINGS

Of the various ablation techniques, cryotherapy and radiofrequency ablation are being increasingly applied clinically. They can be performed either laparoscopically or percutaneously using a combination of fine probes and high-resolution imaging techniques for focusing and monitoring the therapy. Noninvasive tumor ablation by high-intensity focused ultrasound, and other techniques, is still at an experimental stage.

SUMMARY

Although the initial outcomes of cryoablation and radiofrequency ablation are encouraging, long-term studies are necessary to confirm their lasting efficacy. The optimal modality for tumor targeting, monitoring therapy, and follow-up remains to be determined. These ablative techniques should be reserved for carefully selected patients, the data should be prospectively accrued, and the results should be compared to that of the reference standard, open or laparoscopic partial nephrectomy.