Renal Radiofrequency Research Articles

Possible mechanisms of renal denervation long-term cardiac effects

Background.The renin-angiotensin-aldosterone system (RAAS) plays a key role in target organ damage in arterial hypertension (HTN), initiating the development of left ventricular hypertrophy (LVH), as well as the heart and vascular wall fibrosis and remodeling. In addition, one of the mechanisms of the cardiovascular disease progression is the angiotensin II-induced inflammation.Objective.To study the changes in renin, aldosterone and high-sensitive C‑reactive protein (CRP) levels two years after sympathetic renal denervation (RDN), to compare these changes with antihypertensive efficacy of the intervention and LVH regression.Design and methods.We included 77 patients with drug-resistant hypertension in the absence of contraindications to renal denervation. All patients underwent renal radiofrequency ablation. The active renin, aldosterone and a high-sensitive CRP concentrations assessment, 24‑hour blood pressure (BP) measurement and echocardiography were performed before, at 6 months, one and two years after the intervention.Results.There was a gradual decrease in CRP levels (the difference was significant after 6 months), aldosterone (significant two years after surgical treatment), and active renin (the difference was the most pronounced after one year). At all follow-up assessments, plasma renin activity correlated with left ventricular mass. At the same time, there were no significant differences between responders and non-responders.Conclusions.RDN leads to a RAAS activity attenuation, manifested by the decrease in both renin and aldosterone and CRP, probably due to angiotensin II proinflammatory effects reduction. Given these effects are long-term, correlate with LVH degree and unrelated to the BP lowering, a direct cardioprotective effect of renal denervation should be considered.

Volume and Shape Assessment of Renal Radiofrequency Ablation Lesion

To evaluate the microscopic characteristics and quantify the volume of a radiofrequency ablation (RFA) lesion. Ten male pigs were submitted to laparoscopic RFA. An RFA needle was introduced in the lower pole of the left kidney to create a lesion expected to be a sphere of 2.0 cm diameter. The animals were followed up for 21 days. Kidneys were weighed and the volume was assessed using Scherle's method. Cavalieri's principle was used to assess the RFA volume, and sphericity was calculated to assess RFA lesion. One sample t test was used to compare RFA volume with the volume of a sphere of 2.0 cm diameter, and sphericity to hypothetical values of a sphere and an icosahedron. Fragments of RFA region were histologically evaluated. Three animals developed postoperative complications and were excluded from the analyses. There was no difference in the mean weight and volume between right and left kidneys following RFA. The mean total volume of RFA injury was 3.44 cm3. There was no difference in the RFA volume in comparison with hypothetical volumes of a sphere and an icosahedron of 2.0 cm diameter. Sphericity of the RFA injury was not similar with a sphere; however, it was similar to an icosahedron. Histology revealed areas of coagulation necrosis, fibrosis, and inflammatory mononuclear infiltration. Areas with normal tissue were also observed. The volume of injury caused by RFA was as expected and its shape was comparable with an icosahedron. Microscopic evaluation revealed areas of normal-appearing tissue.

Abstract No. 684 Imaging surveillance following radiofrequency ablation of renal cell carcinoma

The purpose of this study is to review our institution's ten-year experience with imaging surveillance following percutaneous radiofrequency ablation for spontaneous stage T1a renal cell carcinoma, and apply risk stratification based upon the post-procedure CT scan, modified renal nephrometry score, and tumor histology. All renal radiofrequency ablation procedures performed at our institution from 1/1/2005 through 7/31/2015 were reviewed, including pathology and follow-up imaging. Inclusion criteria were all cases of T1a biopsy-proven renal cell carcinoma with at least one follow-up imaging study after the post-ablation scan. Exclusion criteria were benign or indeterminate pathology, Von Hippel Lindau syndrome (VHL), no imaging follow-up available, prior thermal ablation on the same lesion, or RFA discontinued due to technical factors. Cases meeting inclusion criteria were evaluated with mRENAL Nephrometry score, tumor histology, and post-therapy CT scan. Time lag to detection was calculated for each instance of recurrence. 52 cases (in 49 patients) of T1a biopsy-proven renal cell carcinoma status post radiofrequency ablation with at least one follow-up imaging study met the criteria for inclusion. 7 cases of RCC recurrence were identified. Cases of disease recurrence had a statistically significantly higher mRENAL score (7.3 versus 6.0, two-tailed T-test p-value .0087). Recurrence was more likely in tumors with clear cell histology (5/18 versus 2/34 for other histology, Fisher exact test statistic value .0409). There were no cases of disease recurrence if the post-therapy CT scan was definitively negative. The mRENAL Nephrometry score, tumor histology, and post-therapy CT scan inform the rate of tumor recurrence following radiofrequency ablation of T1a renal cell carcinoma. These data may be incorporated into the development of surveillance strategies to yield cost savings and decrease patient radiation exposure, while maintaining surveillance effectiveness.Tabled 1Imaging Surveillance Following Radiofrequency Ablation of Renal Cell CarcinomaCharacteristics of RCC RecurrenceCase#Tumor size (cm)mRENAL scoreRCC histologyPost-RFA CTRFA to detection (days)Lag to detection (days)Size at detection (cm)Recurrence strategy13.58Clear cellIndeterminate11382433.5Surveillance23.18Clear cellNot performed76763.2Nephrectomy32.97Clear cellNot performed4584060.9Repeat RFA43.19Clear cellIndeterminate2382381.7Surveillance52.57Clear cellPositive110.3Surveillance62.77RCC NOSNot performed1861861.9Repeat RFA72.14PapillaryNot performed2712711.6Surveillance Open table in a new tab

Glomerular Loss After Renal Radiofrequency Ablation Are Comparable to 30 Minutes of Warm Ischemia.

To compare, with stereological methods, the glomerular loss in kidneys submitted to radiofrequency ablation (RFA) or warm ischemia. Twenty-six male pigs were divided into three groups. Eight animals were allocated in the sham group, which was submitted to laparoscopic dissection of the left renal hilum, without renal ischemia. Eight animals were allocated in the ischemia group, which had the left renal hilum clamped for 30 minutes under laparoscopic access. Ten animals were submitted to RFA of the left kidney lower pole, under laparoscopic visualization. Animals were euthanized 21 days after surgery, when kidneys were collected. Fragments of the upper pole of the left kidney were processed for morphometric analysis. Right kidney was used as self-controls for each animal. Glomerular volumetric density (Vv[glom]); volume-weighted glomerular volume (VWGV); and glomerular density were quantified by stereological methods and compared by Student's t-test and one-way-analysis of variance with Dunnett's post-test. Three animals in the RFA group developed postoperative complications (Urinoma/Hydronephrosis) and were excluded from the analysis. No difference was found among the kidneys submitted to RFA and warm ischemia for all parameters. However, these kidneys showed lower Vv[glom] and glomerular density when compared to its self-controls (right kidneys), and when compared to sham-operated animals (p < 0.05). No difference was observed in regards to VWGV among the groups. RFA in pigs determines a significant reduction of glomerular density in the remaining parenchyma. This alteration was comparable to that observed in kidneys submitted to 30 minutes of warm ischemia.

Pakartotinė inkstų navikų krioabliacija ir radijo dažnio abliacija esant vieninteliam inkstui: dviejų klinikinių atvejų aprašymas

Įžanga Perkutaninė inkstų navikų krioabliacija ir radijo dažnio abliacija yra minimaliai invazyvūs gydymo metodai, leidžiantys mak­simaliai išsaugoti inkstų funkciją. Jie vis dažniau naudojami pacientams, sergantiems sunkiomis gretutinėmis ligomis, esant daugybiniams inkstų navikams, pacientams, turintiems tik vieną inkstą ir (ar) turintiems didelį genetinį polinkį susiformuoti dauginiams inkstų navikams, ypač tais atvejais, kai labai svarbu išsaugoti inkstų funkciją. Straipsnyje siekta įvertinti šių mini­maliai invazyvių gydymo metodųnaudą (efektyvumą ir saugumą) pacientams, turintiems vienintelį inkstą. Klinikiniai atvejai Aprašome ir aptariame du klinikinius atvejus pacientų, kuriems buvo diagnozuoti maži inkstųnavikai (&lt;4 cm) vieninteliame likusiame inkste ir kurie buvo pakartotinai gydyti krioabliacijos bei radijo dažnio abliacijos metodais Nacionaliniame vėžio institute. Kontrolinė kompiuterinė tomografija buvo atlikta kitą dieną po procedūros, po 3, 6 ir 12 mėnesių po procedūros ir toliau kas 6 mėnesius, kartu buvo atliekamas fizinis ištyrimas, šlapimo tyrimas ir nustatoma kreatinino koncentracija se­rume. Abu pacientai inkstų navikų krioabliaciją ir radijo dažnio abliaciją toleravo gerai, pooperacinių komplikacijų, ryškesnių inkstų funkcijos pokyčių nebuvo. Serumo kreatinino koncentracija mažai skyrėsi nuo priešoperacinių verčių. Abiem ligoniams pasiekta visiška / radikali naviko abliacija po vienos gydymo procedūros. Išvada Nors neįmanoma daryti tikslių galutinių išvadų apie navikų vieninteliame inkste gydymo minimaliai invaziniais metodais veiksmingumą ir saugumą tik iš dviejų sėkmingų atvejų, tačiau jie parodo, jog inkstų navikų krioabliacija ir radijo dažnio abli­acija leidžia minimaliai invazyviu būdu gydyti inkstų navikus ir siekti gerų onkologinių rezultatų.

Thermo-sensitive hydrogel for preventing bowel injury in percutaneous renal radiofrequency ablation.

Percutaneous radiofrequency ablation (PRFA) has been used to ablate renal neoplasms with good outcome. However, if bowel lies adjacent to a tumor, ablation increases the risk of thermal bowel injury, and the consequences could be fatal. We describe the technique, effectiveness and safety of using thermo-sensitive hydrogel as insulation to displace the bowel away during PRFA. The study was divided into two main parts: the in vitro and in vivo studies. In in vitro study, to explore the heat insulation of hydrogel, the rabbit kidney was entirely embedded in hydrogel, and then radiofrequency ablation was performed; the temperature on the gel-air and gel-kidney interfaces was measured. In in vivo study, hydrogel of poloxamer 407, 25% concentration (w/v), was instilled into the perinephric space of 10 rabbits under CT guidance to separate the kidney from adjacent bowel before PRFA performed in the targeted parenchyma in the gel group. For the control group, PRFA was performed in similar portions of 10 rabbits without instillation of hydrogel. Some parameters were recorded such as kidney-to-bowel and electrode-to-bowel distance. Immediately after PRFA, distribution of hydrogel was evaluated and the dimension of radiofrequency ablation zone was measured; bowel thermal injury was compared between the gel and control groups by gross anatomy and histopathological examination. To assess safety, two additional follow-up groups with 10 rabbits in each were set; after PRFA, CT scan was performed every 2days; gel absorption, thermal damage and some other complications were evaluated during the period. In in vitro study, temperature was significantly lower at the gel-air than gel-kidney interface (P<.05), and the temperature gradient was positively associated with gel thickness. In in vivo study, hydrogel was instilled successfully in all rabbits in the gel group. The kidney-to-bowel and electrode-to-bowel distances were larger in the gel than control group [(1.1±0.6cm vs 0.1±0.0cm, P<.01), (1.8±0.4cm vs 0.5±0.1cm, P<.01), respectively]. The gel and control groups did not differ in size of the ablation zones (0.80±0.2cm vs 0.75±0.3cm, P>.05). Thermal injury in adjacent bowel was more serious in the control than gel group (P<.01). As for the follow-up, rabbits with gel instillation showed good condition and gel was absorbed gradually within 5days. Those rabbits with no bowel displacement by gel got significantly lower survival rate and high complication rate (P<.01). Hydrogel-dissection by means of thermo-sensitive hydrogel instillation is valuable for protecting the bowel adjacent to ablation area against thermal injury during PRFA.

1090 Glomerular volumetric density is reduced after renal radio-frequency ablation as well as after warm ischemia

1090 Glomerular volumetric density is reduced after renal radio-frequency ablation as well as after warm ischemia

Renal radiofrequency ablation with pyeloperfusion.

Table S1 Postprocedural complications. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

The Application of R.E.N.A.L. Nephrometry Scoring System in Predicting the Complications After Laparoscopic Renal Radiofrequency Ablation

To investigate the clinical significance of R.E.N.A.L. nephrometry scoring system in evaluating the complications after laparoscopic radiofrequency ablation (LRFA) of renal tumors. We conducted a retrospective review of the records of all patients who underwent LRFA of renal tumors from February 2006 to March 2012 in our institution. Tumors were categorized as low (4-6), moderate (7-9), or high complexity (10-12) according to R.E.N.A.L. nephrometry score (NS), which was determined by analyzing preoperative imaging. Perioperative data were analyzed to determine the presence of complications. LRFA was performed on 170 tumors in 170 selected patients with preoperative imaging available. Mean patient age was 55.9 years (range 26 to 81), and mean tumor size was 2.8 cm (range 0.9 to 4.9). Mean NS was 6.6 (range 4 to 12). Of the total tumors, 105 (61.7%) were categorized as low-, 46 (27.1%) as moderate-, and 19 (11.2%) as high-complexity lesions. Overall, there were 21 (12.4%) complications, including 6 (3.6%) grade IIIa and 15 (8.8%) grade I-II complications. There was a significant difference in complication rates among the low- (105 patients, 0%), moderate- (46 patients, 4.3%), and high-complexity (19 patients, 100%) groups, respectively (p<0.05). NS was independently associated with a higher risk of postoperative complications (odds ratio 2.87, 95% CI 1.17-3.04, p=0.02) on multivariate analysis. The results of patients undergoing LRFA show that the R.E.N.A.L. NS is independently associated with the occurrence of complications. Therefore, the R.E.N.A.L. nephrometry scoring system is useful in predicting the complication risks of patients who undergo LRFA, and may help with surgical decision making.

Renal Denervation – A Flight of Icarus?

Since its introduction in 2008 Renal Denervation (RDN) has garnered enthusiasts among physicians, patients and the medical device industry. In December 2013 a research and consulting firm predicted a growth of the global renal denervation market in the next 6 years from approximately 3,000 procedures in 2012 up to nearly 40,000 by 2019 (representing a value of over $170 million). Even though the optimism was toned down after 5 years of trial applications of RDN (initial expectations mentioned a market on the order of a billion dollars by 2020), the hype surrounding this invasive therapy method for patients with treatment-resistant hypertension was still on the rise. This all changed in January 2014 when Medtronic announced that its pivotal SYMPLICITY HTN-3 trial failed to meet its primary efficacy endpoint. After promising data obtained from SYMPLICITY HTN-2 Medtronic’s this next trial, that included a sham-control group, was supposed to strengthen the position of RDN as an emerging leading therapy in patients with treatment resistant hypertension. Putting aside the discussions about the necessity and usefulness of a control sham treatment (according to some experts the pain caused in a number of patients by denervation reduced the validity of blinding) and differences between using ambulatory BP monitoring, home electronic BP monitoring and repeated office electronic measurement as an endpoint, SYMPLICITY HTN-3’s failure has been widely received as a major blow to the potential future worldwide deployment of RDN in the treatment of hypertension. SYMPLICITY HTN 4, HTN-India und HTN-Japan trials have been consequently called off, while previously, at the end of 2013, the EnligHTN II trial was stopped (apparently due to recruitment difficulties). Many have spelled the demise of RDN at this point even though the actual data from the SYMPLICITY HTN-3 trial still needs to be fully analysed. Some are trying to look at the bright side of recent developments now is the time to take a step back and analyse the underlying principle of this treatment method – interruption of signal transmission in the renal sympathetic nervous system. There are still some contradictory views on the longitudinal distribution of renal sympathetic nerves along renal arteries which may affect the currently advised course of RDN procedure (distal to proximal) [1]. Furthermore the radial distribution of nerves in renal artery walls, which seems to be the most important anatomic factor for intravascular RDN, has only been studied in small groups both in animal models and human cadavers [1-3]. It is widely accepted that most (up to 90%) nerves are situated within 2 mm of the lumen-intima interface [2,3]. To obtain a successful result an ablation depth of 4 mm is targeted but it is well known that some ablation related changes might extend to a depth of up to 6 mm [4], thus introducing a potential risk of irreversible injury to the artery itself. Dissections and vasospasm during ablation have been reported and well documented but there are some new reports of delayed renal artery stenosis related to RDN [5,6]. Templin et al used Optical Coherence Tomography (OCT) to document wall oedema after RDN Procedures but they have also admitted to a limitation of their results as a consequence of limited imaging depth of OCT (0.5 to 2.0 mm) [7]. In vivo monitoring of acute RDN related changes in arterial walls remains challenging. In conclusion transcatheter renal radiofrequency ablation is still not yet ready to be widely introduced into clinical practice and must be further investigated. On the other hand different methods of RDN might come into limelight, such as an intravascular ultrasound based technique, chemical trancatheter denervation with ethanol, MR-based or CT-based perirenal denevation with ethanol or an extracorporal high-intensity focused ultrasound. Despite many concerns, the future of RDN seems to be bright.

The failing effects of renal sympathetic denervation in patients with drug resistant hypertension and untreated obstructive sleep apnea

Introduction: Arterial hypertension (AHT) is a common cause of stroke, myocardial infarction, chronic heart failure and death. For patients refractory to more than 4 antihypertensive drugs renal sympathetic denervation (RDN) offers a new therapeutic approach. Our main aim was to investigate the effects of RDN in patients with and without obstructive sleep apnea (OSA). Methods: After excluding of secondary causes for AHT 40 patients (age 56±6 years; 60% male; 4,3% COPD GOLD≥2, 40% OSA, AHI mean 17/h) with resistant arterial hypertension were treated by renal radiofrequency ablation. During a 3 months follow up period the development of 24 hour means of outpatients blood pressure (BP) were assessed and correlated with patients baseline apnea-hypopnea-index (AHI) measured by polysomnography and classified by 3 cohorts. Results: After 3 months, the overall reduction in BP was 15 mmHg systolic and 9 mmHg diastolic. 30 patients showed significant reduction in 24h blood pressure evaluation (mean -17/-11mmHg). 10 patients did not respond to RDN (mean RR +7/+4mmHg). While patients without OSA (AHI <5) showed significant BP reduction (-21/-14mmHg), the reduction in those with an AHI ranging between 5 und 20 was weak (-4/-2 mmHg; r= 0,35). In contrast, BP in patients with an AHI above 20 remained unchanged or even increased (mean +4/+2 mmHg). Thus, untreated OSA is a strong predictor of RDN failure (Kruskal Wallis test, p<0,05). No intervention related complications occurred. Conclusion: Renal denervation is an effective therapeutic option for patients with arterial hypertension refractory to an extended drug regimen. Our results show, that the success in BP reduction following RDN depends on patients state free of OSA. Thus, RDN is not a tool for managing resistant AHT in untreated OSA patients.

Focal Therapy in Urology: Kidney Cancer

Focal therapy has gained attention in the treatment of small renal masses (SRM). However, its use is limited due to scarce data on long-term outcomes. The availability of such data is significantly lower as compared to the relevant data on surgery outcomes. At the same time, minimally invasive surgery has seen the development of laparoscopic nephron-sparing surgery and, recently, robot-assisted surgery. Our purpose is to review the possibilities of treatment for SMR with particular attention on focal therapy. Clinical series and comprehensive reviews support safety and mid/long-term efficacy of renal cryoablation or radiofrequency ablation. Comparative studies and meta-analysis outlined oncological inferiority against partial nephrectomy in local tumor control. For smaller and more peripheral lesions, radiofrequency ablation showed best indications than cryoablation. There are significant demographic and tumor differences between patients treated by one or another approach. The correct indication for each treatment seems to be of key importance to achieve the best oncological and functional outcome. Open partial nephrectomy remains the gold standard treatment for PMR, but laparoscopic approaches have been showing similar results.

Interventional oncology in the elderly: Complications and early response in liver and kidney malignancies

The complication rate, loco-regional responses and length of hospital stay were analyzed in patients with liver and kidney cancer older than 70years treated with interventional oncology procedures. The findings from the older population were compared with the younger patients (<70years) to detect any difference not related to chance. Prospectively collected data on patients who underwent hepatic artery embolization (with or without radiofrequency ablation) and kidney radiofrequency ablation were retrospectively analyzed. Complication rates, loco-regional responses and length of hospital stay for patients older and younger than 70 were compared. 163 patients were treated, 66 (40.5%) older and 97 (59.5%) younger than 70years. The complication rate in patients older than 70 was 4.5% (3/66 pts) versus 3.1% (3/97 pts) (p=0.69) in the younger age-group. The complication rates for the liver embolization group, liver embolization plus radiofrequency and kidney radiofrequency group were 2/90 pts (2.2%), 2/42 pts (4.8%) and 2/31 pts (6.5%), respectively (p=0.46). Median hospital stay was three nights in both older and younger patients. Response rates were not significantly influenced by age. Liver embolization with or without radiofrequency and renal radiofrequency are safe and effective in older patients. Age alone should not be considered a contraindication to treatment in carefully selected patients.

Re: Incidence of Multiple Sporadic Renal Cell Carcinomas in Patients Referred for Renal Radiofrequency Ablation: Implications for Imaging Follow-Up

Re: Incidence of Multiple Sporadic Renal Cell Carcinomas in Patients Referred for Renal Radiofrequency Ablation: Implications for Imaging Follow-Up

Preoperative patient counseling for diagnostic renal biopsy and complications with renal radiofrequency ablation

To identify preoperative factors associated with surgical complications and successful diagnostic renal biopsy in both laparoscopic and percutaneous radiofrequency ablation (RFA) of renal masses in order to help aid in preoperative patient counseling for renal RFA. We reviewed our Institutional Review Board approved database from November 2001 to January 2011, containing 335 tumors treated with either laparoscopic (LRFA) or percutaneous RFA (CTRFA). Preoperative patient demographics, tumor characteristics, and intraoperative surgical data were collected along with biopsy results and clinicopathologic outcomes. RFA was performed on 335 renal tumors (124 LRFA, 211 CTRFA). Non-diagnostic biopsy occurred in 18 (5.5%) tumors. Of the 317 procedures performed, 121 complications occurred in 103 (30.7%) procedures. Multivariate analysis only showed CTRFA (vs LRFA) to increase the likelihood of non-diagnostic biopsy (OR 5.1, 95% CI 1.2-22, p = 0.032). Increased tumor size (p = 0.007) and synchronous ablations (p = 0.019) increased the risk for major complications, while decreased surgeon experience (p = 0.003) and tumors close to the collecting system (p = 0.005) increased the risk of any complication. Preoperative recommendations can be made to patients in the future. We suggest counseling patients that when undergoing RFA, percutaneous approach increases the risk of non-diagnostic biopsy, increased tumor size increases the risk of major complications, having more than 1 tumor ablated increases the risk of a major complication, and tumors close to the collecting system may increase the risk of complications.

Pretreatment Imaging Can Be Used to Select Imaging Guidance, Ultrasound Alone Versus CT Plus Ultrasound, for Percutaneous Renal Radiofrequency Ablation

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. 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. 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. 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.

Occurrence and Value of the Color Doppler “Line Sign” After Radiofrequency Ablation of Solid Abdominal Organs

The purposes of this study were to identify the frequency of the color "line sign" after track coagulation during electrode removal and to evaluate the usefulness of color Doppler sonography in predicting complications after radiofrequency ablation. A total of 104 consecution radiofrequency ablations of either the liver (n = 68) or the kidney (n = 36) were evaluated for hemorrhagic complications by color Doppler sonography. All radiofrequency ablations were performed in a similar fashion, including track coagulation during electrode removal. Follow-up computed tomography of the organ of interest was performed within 24-hours after the procedure. The study included 32 patients with 36 renal radiofrequency ablations and 43 patients with 68 hepatic ablations. There were 1 arterial and 0 venous Doppler signals in the renal ablations and 2 arterial and 2 venous Doppler signals in the hepatic ablations. No major complications were observed, but a moderate hematoma occurred in 1 renal ablation. A statistically significant correlation was noted between the computed tomographic findings of hematomas and the presence of a color line sign (P = .048). We found a lower percentage of the color line sign compared to prior reports that identified this sign after biopsy of the liver or kidney. There is a decreased frequency of the color line sign and hemorrhagic complications after radiofrequency ablation compared to their rates of occurrence with core biopsy. Identification of the color line sign may be useful for predicting hemorrhagic complications.

Complications following 573 Percutaneous Renal Radiofrequency and Cryoablation Procedures

Purpose To review complications related to percutaneous renal tumor ablation. Materials and Methods Prospectively collected data related to renal radiofrequency (RF) ablation and cryoablation procedures performed from May 2000 through November 2010 were reviewed. This included 573 renal ablation procedures performed in 533 patients to treat 633 tumors. A total of 254 RF ablation and 311 cryoablation procedures were performed; eight patients underwent simultaneous RF ablation and cryoablation. The mean age of patients at the time of the procedure was 70 years (range, 24–93 y), and 382 of 573 procedures (67%) were performed in male patients. Complications were recorded according to the Clavien–Dindo classification scheme. Duration of hospitalization was also documented. Results Of the 573 procedures, 63 produced complications (11.0% overall complication rate). There were 66 reported complications, of which 38 (6.6% of total procedures) were Clavien–Dindo grade II–IV major complications; there were no deaths. Major complication rates did not differ statistically ( P = .15) between cryoablation (7.7%; 24 of 311) and RF ablation (4.7%; 12 of 254). Of the complications related to cryoablation, bleeding and hematuria were most common. Bleeding during cryoablation was associated with advanced age, increased tumor size, increased number of cryoprobes, and central position ( P < .05). Of those treated with RF ablation, nerve and urothelial injury were most common. Mean hospitalization duration was 1 day for RF ablation and cryoablation. Conclusions Complications related to percutaneous renal ablation are infrequent. Recognition of potential complications and associated risk factors can allow optimization of periprocedural care.

Incidence of Multiple Sporadic Renal Cell Carcinomas in Patients Referred for Renal Radiofrequency Ablation: Implications for Imaging Follow-Up

The objective of our study was to report the incidence of multiple sporadic primary renal cell carcinomas (RCCs) in patients referred for radiofrequency ablation (RFA). A retrospective search identified 162 patients (104 men and 58 women; mean age, 74 years) without a history of von Hippel-Lindau disease with a total of 175 tumors treated with RFA for biopsy-proven primary renal malignancies at our institution from 1998 to 2009. Three groups of patients with multiple RCCs were identified: patients with a history of nephrectomy for RCC who had been referred for RFA of a new renal tumor, patients who presented with multiple renal tumors at the time of referral for RFA, and patients who were shown to have developed a new renal tumor on follow-up imaging after RFA. Twenty-eight patients (17%) had multiple biopsy-proven RCCs. Eighteen patients (11%) had undergone prior nephrectomy for surgically proven RCC. The mean interval between prior nephrectomy and RFA referral was 122 months (range, 12-456 months). Seven patients (4%) without a history of nephrectomy presented with two biopsy-proven RCCs at RFA referral. Three patients (2%) who had not undergone nephrectomy and had a solitary RCC at the time of RFA had developed a new biopsy-proven RCC separate from the original treatment site on follow-up imaging after RFA. The mean time to diagnosis from the initial RFA treatment was 52 months (range, 25-89 months). Imaging surveillance of patients referred for renal RFA may be important not only to assess treatment success but also to detect new RCCs.

An unusual cause of chyluria after radiofrequency ablation of a renal cell carcinoma: a case report.

IntroductionThis report highlights a rare cause of chyluria occurring after radiofrequency ablation of a renal cell carcinoma. The condition requires a high index of suspicion, as it may not be diagnosed routinely on imaging follow-up after treatment. As chyluria can vary from no symptoms to hypoproteinemia, hypolipidemia and impaired immune function, prompt diagnosis will allow timely management of symptoms.Case presentationDuring a routine renal examination, an otherwise fit and well 79-year-old Caucasian man was found to have a peripherally situated tumor. He underwent renal radiofrequency ablation as primary treatment. Periodic imaging follow-up over two years showed no evidence of residual or recurrent disease within the zonal ablation. The routine imaging protocol at St James's Hospital included upper abdomen only for kidney assessment; pelvic examination was not included. However, our patient underwent a computed tomography scan of his abdomen and pelvis at the request of his local urologist, around two and a half years after the renal radiofrequency ablation. A fat-fluid level was seen within the urinary bladder, consistent with chyluria. As our patient was asymptomatic, he was treated conservatively.ConclusionIt is important to be aware of chyluria as a possible complication of renal radiofrequency ablation, and to recognize the fat-fluid level sign within the bladder or collecting system on computed tomography scans. As most institutions do not routinely perform computed tomography scans of the pelvis as part of their follow-up protocol after renal radiofrequency ablation, a high index of suspicion is required for diagnosis. Routine urine analysis for fat should be considered, as prompt diagnosis is crucial to guide management for symptomatic patients.