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Edward D Matsumoto

Publications and source records attributed to Edward D Matsumoto.

At least 19 recordsLinked to original sources
PubMed2026

Standardized visual overlays enhance laparoscopic instruction: A mixed-methods evaluation.

Effective communication during laparoscopic procedures is frequently undermined by spatial disorientation and inconsistent terminology between instructors and trainees. This study examined whether standardized visual overlays on endoscopic monitors could enhance communication and learning. We conducted a three-phase mixed-methods study: qualitative observation of 20 laparoscopic teaching cases; a randomized trial of 63 second-year medical students assigned to control, clock, or alphanumeric grid (AG) overlays during three trials of a standardized transfer task; and intraoperative implementation in 44 cases (30 AG, 14 clock) with post-case surveys and qualitative feedback. In simulation, the clock overlay produced the fastest completion times, whereas the AG yielded the lowest error scores, and both overlays outperformed the control. Intraoperatively, the AG was rated higher than the clock for communication clarity, spatial orientation, perceived operative efficiency, and trainee confidence. Standardized visual overlays, particularly the AG, appear to support intraoperative teaching by providing a shared spatial frame of reference.

Laparoscopy↗
PubMed2006

ATM activation is accompanied with earlier stages of prostate tumorigenesis.

The ATM (ataxia telangiectasia mutated) kinase plays an essential role in maintaining genome integrity by coordinating cell cycle arrest, apoptosis, and DNA damage repair. Phosphorylation of ATM at serine 1981 (ATMpSer1981) by DNA damage activates ATM, which subsequently phosphorylates H2AX Ser139 (gammaH2AX), Chk2 Thr68 (Chk2pThr68), and p53 Ser15 (p53pSer15). To determine the role of the ATM pathway in prostate cancer tumorigenesis, we have analyzed 35 primary prostate cancer specimens for ATMpSer1981 (ATM activation), Chk2pThr68, gammaH2AX, and p53pSer15 by immunohistochemistry (IHC) in normal glands, prostatic intraepithelial neoplasias (PINs), and carcinomas. Increases in the intensities of ATMpSer1981, Chk2pThr68, and gammaH2AX and in the percentage of cells that are positive for ATMpSer1981, Chk2pThr68, or gammaH2AX were observed in PINs (p<0.001) compared to normal prostatic glands and carcinoma. However, this pattern of immunostaining was not seen for p53pSer15. Thus, ATM and Chk2 are specifically activated in PINs. As PINs are generally regarded as precursors of prostatic carcinoma, our results suggest that ATM and Chk2 activation at earlier stages of prostate tumorigenesis suppresses tumor progression, with attenuation of ATM activation leading to cancer progression.

Aged↗
PubMed2006

Assessment of basic human performance resources predicts performance of ureteroscopy.

BACKGROUND: Our objective was to predict endoscopic performance in a cadaver model using basic performance resources (BPRs) measurements. METHODS: Medical students (n = 16) underwent intense ureteroscopic training on a virtual reality ureteroscopy trainer and were rated on performing ureteroscopy on a cadaver. The medical students also underwent 13 validated BPR measurements. Urology residents also performed cadaveric ureteroscopy and BPRs. A predictive model built from urology residents' (n = 16) BPRs and performance assessment was used to predict medical student cadaveric ureteroscopy performance based on their BPRs alone. RESULTS: The predictive model built with urology residents predicted the ureteroscopic performance of 10 of 16 medical students within 15% of their rated ureteroscopic performance on the cadaver. CONCLUSIONS: A predictive model built with urology residents can moderately predict the ureteroscopic performance of medical students from BPRs. Additional in vivo evaluation is required.

Adult↗
PubMed2006

Laparoscopic decision making: impact of preoperative reading and laparoscopic experience.

PURPOSE: A competent laparoscopic surgeon requires good technical skills and good surgical judgment. The assessment of technical skills using bench models and simulators has been well studied. However, there has been a paucity of studies examining the cognitive aspects of surgery. We developed a novel tool to assess the procedural knowledge and higher level decision making required for successful laparoscopic nephrectomy. We assessed the effect of laparoscopic experience and the effect of self-preparation or preoperative reading on surgical decision making abilities using a novel assessment tool and methodology. MATERIALS AND METHODS: A total of 17 novice and advanced urology residents were randomized to preoperative reading or no preoperative reading. Subjects viewed laparoscopic nephrectomy clips and verbalized their thought processes. Their performance was transcribed and blindly rated using a new surgical decision making rating scale. RESULTS: The correlation with overall surgical decision making rating scale score was good for years of training and moderate for the number of laparoscopic cases performed (r = 0.7 and 0.54, respectively, p < 0.05). Preoperative reading did not have a significant impact on the overall surgical decision making rating scale score (p > 0.05). However, when stratified by laparoscopic experience level (fewer than 10 cases), preoperative reading had a significant impact on the performance of novices with respect to the knowledge components of the procedure but not the judgment domain (each p > 0.05). CONCLUSIONS: Overall preoperative reading did not improve the surgical decision making rating scale. Novice procedural knowledge benefited from preoperative reading but not surgical judgment. The surgical decision making rating scale appears promising and it may have future implications for assessing surgical competency.

Clinical Competence↗
PubMed2006

A randomized, controlled, prospective study validating the acquisition of percutaneous renal collecting system access skills using a computer based hybrid virtual reality surgical simulator: phase I.

PURPOSE: The need to develop new methods of surgical training combined with advances in computing has led to the development of sophisticated virtual reality surgical simulators. The PERC Mentortrade mark is designed to train the user in percutaneous renal collecting system access puncture. We evaluated and established face, content and construct validation of the simulator in this task. MATERIALS AND METHODS: A total of 63 trainees underwent baseline testing on the simulator, consisting of percutaneous renal puncture followed by the introduction of a guidewire into the collecting system. Subjects were then randomized to an intervention arm, in which they underwent 2, 30-minute training sessions on the simulator, and a control arm, in which no further training was given, followed by repeat testing. Performance was assessed using a global rating scale and by virtual reality derived parameters. RESULTS: There were no significant differences between the 2 groups with respect to baseline measures. Subjects who underwent training with the simulator demonstrated significant improvement in objective and subjective parameters compared to their baseline performance and compared to the untrained control group. Spearman rank correlations demonstrated a significant relationship between multiple parameters of the objective and subjective data. CONCLUSIONS: Training on the simulator improves virtual reality skills. It may allow trainees to develop the basic skills necessary to perform percutaneous renal collecting system access. Face and content validity were demonstrated and construct validity was supported by establishing convergent validity.

Computer Simulation↗
PubMed2006

Serum laboratory values following uncomplicated laparoscopic urological surgery.

PURPOSE: Presentation of complications following laparoscopic surgery can be different from corresponding open surgical complications. While leukopenia has been identified as a common finding in patients with unrecognized bowel injury following laparoscopy, to our knowledge no study has determined if leukopenia or other serum abnormalities are unique to patients with laparoscopic complications. We present an analysis of postoperative laboratory values from patients after uncomplicated urological laparoscopic surgery. MATERIALS AND METHODS: A retrospective review of 50 adult patients who had previously undergone uncomplicated laparoscopic urological procedures was performed. Exclusion criteria were preexisting hematological, immune, liver or pancreatic disorders. Common serum laboratory values were measured on postoperative day 1. RESULTS: All values for bilirubin were within normal limits. Of patients undergoing a right side renal procedure, 10 of 16 (63%) had a postoperative increase in liver function tests. Amylase or lipase was increased in a total of 12 (24%) patients. Patients undergoing laparoscopic prostatectomy accounted for the majority of this group with 9 of 21 (43%) patients having increased amylase or lipase. Finally, there were no patients with immediate postoperative leukopenia. CONCLUSIONS: Following uncomplicated laparoscopic procedures, bilirubin levels are rarely affected, amylase and lipase may be acutely increased following laparoscopic prostatectomy, and white blood count is commonly increased. While 16 (36%) patients had postoperative leukocytosis, leukopenia was not detected after uncomplicated laparoscopic urological surgery and should alert the surgeon to the possibility of an undiagnosed complication.

Adult↗
PubMed2006

Effect of high and low calcium diets on stone forming risk during liberal oxalate intake.

PURPOSE: Recent studies suggest that a high calcium diet protects against calcium oxalate stone formation. We compared the effect of high and low calcium diets on urinary saturation of calcium oxalate during liberal oxalate intake. MATERIALS AND METHODS: A total of 10 healthy subjects (5 male, 5 female) participated in a 2-phase, randomized, crossover study comparing high (1,000 mg daily) and low (400 mg daily) calcium intake on a liberal oxalate diet (200 mg daily). During each phase subjects adhered to an instructed diet for 3 days followed by a controlled, metabolic diet for 4 days. Blood and 24-hour urine specimens collected on the last 2 days of each phase were analyzed for serum biochemistry studies and stone risk factors, respectively. RESULTS: Urinary calcium was higher (mean +/- SD 171 +/- 64 vs 124 +/- 49 mg daily, p = 0.002) and oxalate was lower (25 +/- 4.8 vs 27 +/- 4 mg daily, p = 0.02) on the high vs low calcium diet. Overall, the urinary relative saturation ratio of calcium oxalate was higher on the high compared with the low calcium diet (3.3 vs 2.5, p <0.0001) even after adjusting for confounding variables. CONCLUSIONS: In normal subjects urinary saturation of calcium oxalate was higher on a high calcium diet than a low calcium diet during liberal oxalate intake because the decrease in urinary oxalate did not overcome the effect of increased calcium. A high calcium diet during liberal oxalate intake may pose an increased risk of calcium oxalate stone formation.

Adult↗
PubMed2006

Radiofrequency ablation of renal tumors: intermediate-term results.

BACKGROUND AND PURPOSE: Needle ablative therapies are being offered to patients presenting with small renal masses, but long-term outcomes are currently unavailable. We report our intermediate-term results (1-4 years) after radiofrequency ablation (RFA) of small (<4-cm) renal masses. PATIENTS AND METHODS: At our institution, all renal tumors treated using RFA since May 2001 have been recorded in a prospective database. During this time, 94 tumors (mean size 2.4 cm; range 1-4.2 cm) in 78 patients were treated using a temperature-based RFA generator by either a percutaneous (59%) or a laparoscopic approach. The patients followed with imaging at 6 weeks, 3 and 6 months, and every 6 months thereafter. Only patients with at least 12 months of follow-up were eligible for this analysis; the mean follow-up was 25 months. RESULTS: Of the 89% of masses that were biopsied, 77% were renal-cell carcinomas (RCC), of which 66% were Fuhrman grade 1, 31% were grade 2, and 3% were grade 3. Three recurrences were noted, for an overall recurrence-free rate of 96.8%. In this patient population with numerous comorbid conditions, there were six deaths but only one related to renal cancer, for a cancer-specific survival rate of 98.5% and an overall survival rate of 92.3%. CONCLUSION: In the intermediate term (1-4 years), the oncologic effectiveness of RFA appears comparable to that of traditional treatments offered for small renal masses. Further studies of larger numbers of patients with longer follow-up are needed.

Adult↗
PubMed2006

Virtual reality ureteroscopy simulator as a valid tool for assessing endourological skills.

AIM: Virtual reality (VR) simulators are now commercially available for various surgical skills training. The Uro Mentor VR Ureteroscopy Simulator by Symbionix is one system that may revolutionize the way we assess and teach surgical residents. Surgical educators may no longer have to depend on the operating room as the sole venue for teaching residents technical skills. We validated performance on this new system with previously developed assessment tools and compared it to performance on a high fidelity ureteroscopy bench model. METHODS: Urology residents (n = 16) were assessed on their ability to perform cystoscopy, guidewire insertion, semirigid ureteroscopy and basket extraction of a distal ureteric stone on the VR simulator. A blinded examiner assessed subject performance using a checklist, global rating scale and a pass/fail rating. In addition, computer-generated parameters including time to complete task, scope and instrument trauma and the number of attempts to insert a guidewire were analysed. Performance on the VR simulator was compared to performance on a high fidelity ureteroscopy bench model. RESULTS: Senior residents (n = 8) scored significantly higher on their global rating scale (29.4 +/- 2.5 vs 20.8 +/- 0.9, P = 0.005), checklist (19.1 +/- 1.1 vs 15.2 +/- 0.9, P = 0.02), pass/fail rating (chi(2) = 7.3, P = 0.007) and required less time to complete the task (352.9 +/- 55.7 s vs 576.8 +/- 67.4 s., P = 0.02) than the junior residents (n = 8) on the VR simulator. Junior residents also had a significantly higher incidence of scope trauma (4 vs 0.6, P = 0.02). No significant differences were noted in instrument trauma and the number of attempts to insert the guidewire. Global rating scale performance on the VR simulator correlated well to performance on the high fidelity ureteroscopy bench model (r = 0.7, P = 0.002) as did time to complete task (r = 0.7, P = 0.004). CONCLUSIONS: The Uro Mentor VR Ureteroscopy Simulator is a useful tool in assessing resident endourological skills. Performance on the VR simulator is comparable to a validated high fidelity ureteroscopy bench model. Future studies will assess the utility of VR simulators in surgical skills training.

Adult↗
PubMed2005

Short-term efficacy of temperature-based radiofrequency ablation of small renal tumors.

OBJECTIVES: To present our experience using radiofrequency ablation (RFA) for the treatment of small renal tumors. Our objective was to assess the short-term (1 to 3 years) oncologic efficacy of RFA. METHODS: Consecutive renal tumors treated since May 2001 with a minimal follow-up of 6 months were included. Patients were treated with a temperature-based radiofrequency generator and were followed up with serial imaging at 6 weeks, 3 and 6 months, and every 6 months thereafter. RESULTS: A total of 109 small renal tumors (91 patients) were treated with computed tomography-guided percutaneous RFA (n = 63) or laparoscopic RFA (n = 46). The mean tumor size was 2.4 cm (range 0.8 to 4.7). The initial ablation was successful in 107 (98%) of 109 tumors. The two incomplete ablations were successfully re-ablated. Of the 60 patients with at least 1 year of follow-up, 60% had biopsy proven renal cell carcinoma (an additional 24% had no tissue diagnosis). In this group, one local recurrence (1.7%) was detected during a mean follow-up of 19.4 months (range 12 to 33), and in those with known renal cell carcinoma, none had evidence of distant progression (0%). The local recurrence was successfully re-ablated such that all 109 cases had no clinical or radiographic evidence of disease at last follow-up. Three patients died of causes unrelated to cancer. CONCLUSIONS: The results of our study have shown that in the short term, RFA appears to be a reasonable therapeutic nephron-sparing approach for treating select patients with small renal tumors. The cancer control appears adequate to date, but longer follow-up is necessary before widespread application.

Adolescent↗
PubMed2005

Cytokine response to surgical stress: comparison of pure laparoscopic, hand-assisted laparoscopic, and open nephrectomy.

BACKGROUND AND PURPOSE: Laparoscopic surgery has been shown to induce less immune suppression than open surgery, presumably because there is less tissue trauma, a factor that may impact oncologic-disease control. The objective of this study was to compare the cytokine and stress response associated with pure laparoscopic, hand-assisted laparoscopic (HAL), and open nephrectomy. MATERIAL AND METHODS: Fifteen female farm pigs (45-50 kg) underwent transperitoneal laparoscopic, handassisted (HAL), or open nephrectomy (N = 5 in each group). At 1, 4, 24, and 48 hours post-nephrectomy, blood and peritoneal fluid samples were collected for measurement of tumor necrosis factor (TNF) alpha, interleukin (IL)-1beta, and IL-6 using enzyme-linked immunosorbent assay (ELISA) techniques. Body temperature and serum glucose and cortisol were also measured. RESULTS: No evidence of perioperative infection was detected in any animal through temperature and glucose monitoring. Operating time and blood loss were comparable among the three groups. Peak serum cortisol concentrations were significantly higher in the HAL group than in the pure laparoscopic group at 24 hours (P = 0.02). Serum TFNalpha concentrations were significantly lower in the pure laparoscopy group (40 +/- 6 pg/mL) than in the HAL and open-nephrectomy groups (81 +/- 6 pg/mL and 83 +/- 17 pg/mL, respectively; P < 0.05), although no differences between groups were found in the serum IL-1beta and IL-6 concentrations. Peritoneal IL-1beta was significantly higher in the HAL than in the open-nephrectomy group (2993 +/- 507 pg/mL and 733 +/- 185 pg/mL, respectively; P = 0.05). Peritoneal IL-6 was significantly lower in the pure laparoscopy group (694 +/- 234 pg/mL) than in the open-surgery group (1668 +/- 312 pg/mL) (P = 0.04). CONCLUSION: Pure laparoscopic surgery in pigs elicits a less-robust cytokine response than HAL or open nephrectomy with respect to serum TNFalpha and peritoneal IL-6 concentrations, perhaps reflecting less impairment of the immune system. Clinical confirmation is required, and the implications with regard to oncologic tumor surveillance in humans require further study.

Animals↗
PubMed2005

Retrograde renal cooling during radio frequency ablation to protect from renal collecting system injury.

PURPOSE: We evaluated the protective effect of continuous retrograde irrigation of ice-cold saline on the renal collecting system during central parenchymal temperature based radio frequency ablation (RFA). MATERIALS AND METHODS: In 10 domestic pigs bilateral, centrally located renal parenchymal RFA lesions (intended 2 cm in diameter) were created that intentionally involved the collecting system. RFA probe placement was guided by fluoroscopy with retrograde collecting system opacification and simultaneous direct laparoscopic visualization. In 1 renal unit RFA was performed while infusing ice-cold saline through a previously placed ureteral access sheath and pigtail stent. RFA without renal cooling was performed in the contralateral renal unit. Kidneys were harvested at 7 days. The renal collecting system was inspected for injury by performing retrograde pyelograms and by histological examination of the collecting system adjacent to the ablation zone. The size of RFA lesions was measured. RESULTS: In retrograde cooling procedures the temperature of saline irrigant was -1.0C and the mean temperature of the effluent was 13C. One of 10 cooled renal units demonstrated contrast material extravasation from the collecting system involved by the ablation zone compared with 7 of 10 noncooled renal units (p = 0.025). Lesion size was comparable between cooled kidneys and controls (2.67 and 2.72 cm, respectively, p = 0.629). CONCLUSIONS: Retrograde renal cooling helps protect the renal collecting system from injury during RFA without a decrease in expected lesion size. Clinically retrograde renal cooling may decrease the risk of collecting system injury and subsequent complications during RFA.

Animals↗
PubMed2005

Application of novel hemostatic agent during laparoscopic partial nephrectomy.

PURPOSE: We determined if QuikClot, a novel hemostatic agent made of a granulated mineral substance, could be used to control renal parenchymal bleeding and collecting system leakage during open and laparoscopic partial nephrectomy. MATERIALS AND METHODS: After obtaining renal hilar vascular control 2 domestic female pigs underwent bilateral open and 4 underwent unilateral laparoscopic partial nephrectomy. After excision of the lower pole without cautery the hemostatic agent was applied to the cut surface of the kidney and hilar vascular control was released. Additional QuikClot was added until complete hemostasis was achieved. One week postoperatively the animals were sacrificed and the operated kidneys were harvested for ex vivo retrograde pyelograms and histopathological analysis. RESULTS: All partial nephrectomies were performed without complication. Mean operative and warm ischemia times were 62 and 16 minutes, respectively. An average of 23% of renal mass by weight was resected with a mean blood loss of 73 ml per procedure. No cautery, additional hemostatic agents or techniques were used. No animal had clinical or radiographic evidence of urinoma or delayed hemorrhage. Histopathological analysis showed preservation of the renal parenchyma immediately beneath the QuikClot layer. CONCLUSIONS: In the porcine model QuikClot allowed the resection of large renal segments, while providing reliable hemostasis and closure of the renal collecting system. No deleterious effect on underlying renal parenchyma or surrounding tissues was observed.

Animals↗
PubMed2005

Effect of warmed, humidified insufflation gas and anti-inflammatory agents on cytokine response to laparoscopic nephrectomy: porcine model.

PURPOSE: We evaluated the effects of warmed, humidified CO2 and anti-inflammatory agents on the local and systemic cytokine response after laparoscopic nephrectomy. MATERIALS AND METHODS: A total of 15 pigs were randomized to undergo standard laparoscopic nephrectomy, laparoscopic nephrectomy with warmed, humidified CO2 gas or laparoscopic nephrectomy with perioperative administration of intravenous dexamethasone and oral rofecoxib. At baseline, and 1, 4, 24 and 48 hours after surgery duplicate blood and peritoneal samples were drawn to analyze cortisol, glucose, tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta and IL-6 via a microassay technique. Body temperature was determined at operation, intraoperatively and 1 hour postoperatively. Surgical parameters, including operative time, gas volume used and blood loss, were recorded. RESULTS: Pigs in the warmed, humidified CO2 and anti-inflammatory arms maintained higher intraoperative and postoperative core body temperatures than controls. Warmed, humidified CO2 did not affect peritoneal or systemic cytokine levels. Peak peritoneal TNF-alpha levels in the anti-inflammatory group were significantly higher than in controls at 4 hours. Considerably higher serum TNF-alpha levels in the anti-inflammatory group were observed at 48 hours. Peritoneal IL-1beta and IL-6 levels in the anti-inflammatory group remained similar to those in controls, while serum levels were noticeably lower. There was no observable difference in serum cortisol or the glucose response to laparoscopic nephrectomy among the groups. CONCLUSIONS: While preserving core body temperature, humidified, warmed CO2 did not affect local or systemic trends of pro-inflammatory mediators. The administration of perioperative anti-inflammatory agents produced conflicting local and systemic cytokine response of uncertain clinical significance.

Animals↗
PubMed2004

Acute histologic effects of temperature-based radiofrequency ablation on renal tumor pathologic interpretation.

OBJECTIVES: To describe the histopathologic changes and evaluate the interpretability of human renal tumor specimens obtained after temperature-based radiofrequency ablation (RFA). METHODS: RFA of 119 solid kidney tumors was performed percutaneously under computed tomography guidance, laparoscopically or during open surgery, using a temperature-based system. Of the 119 tumors, 70 were biopsied (two or more samples) after RFA, 39 immediately before ablation, and 10 were not biopsied. All specimens were pathologically classified, and for those specimens obtained after RFA, analysis of the acute histologic changes secondary to RFA was performed by a single pathologist using standard hematoxylin-eosin staining. RESULTS: Ablated tumor specimens maintained their tissue architecture and had predictable changes (cytoplasmic eosinophilia, nuclear elongation, cytoplasmic dissolution) easily recognizable by our pathologists. The diagnostic rate of renal cell carcinoma after RFA (72%) was comparable to the diagnostic rate reported for tumors less than 4 cm in other non-RFA biopsy series. Only 2.6% of specimens obtained before and 5.7% obtained after RFA were nondiagnostic secondary to the paucity of tissue obtained. In 8.3% of all tumors (regardless of RFA treatment), the distinction between oncocytoma and low-grade oncocytic renal cell carcinoma could not be made because of insufficient tissue. CONCLUSIONS: Acutely, RFA of renal tumors causes predictable histologic changes and preserves the tissue architecture. Obtaining two or more incisional biopsies after RFA provided sufficient tissue for reliable pathologic diagnosis.

Adenoma, Oxyphilic↗
PubMed2004

Laboratory based training in urological microsurgery with bench model simulators: a randomized controlled trial evaluating the durability of technical skill.

PURPOSE: We evaluated the durability of laboratory based technical skills training in urological microsurgery using bench model simulators. METHODS AND MATERIALS: A total of 50 junior surgery residents (post-graduate years 1 to 3) were recruited to participate in a focused training program in urological microsurgery. Prior to training subjects were randomized to receive hands-on training with bench model simulators (silicone tubing or live rat vas deferens, 40) or didactic training alone (10). Four months following the original training program the technical performance of 18 returning subjects (13 from the bench model and 5 from the didactic training group) was reevaluated using a high fidelity, live animal model (vasovasostomy and rat vas deferens). Outcome measures included blinded, expert assessment of videotaped performance using checklists and global rating scores, and evaluation of anastomotic patency. RESULTS: The retention test checklist (p <0.001), global rating scores (p <0.001) and anastomotic patency rates (p = 0.05) in the live animal model remained significantly higher for subjects who originally received hands-on bench model training compared with those who received didactic training alone. The number of interim practice opportunities with microsurgery correlated significantly with expert global ratings of surgical performance irrespective of the nature of training (r = 0.54, p = 0.02). CONCLUSIONS: Laboratory based technical skills training with bench models can lead to a significant retention of technical skill by novice surgeons. Measured performance improvements appear to be durable with time. However, the opportunity for repeat hands-on practice appears to maximize the retention of technical skill.

Adult↗
PubMed2004

The radiographic evolution of radio frequency ablated renal tumors.

PURPOSE: Radio frequency ablation (RFA) of renal tumors is a relatively new technology. Few groups are familiar with the posttreatment appearance of these lesions and how they differ from cryoablated renal masses. We describe the evolution of the appearance of these lesions on followup contrast enhanced (CE) computerized tomography (CT). METHODS AND MATERIALS: A total of 64 consecutive renal tumors treated with RFA from April 2000 to September 2003 for which posttreatment CE-CT was done were included in this study. CE-CT was reviewed at 6 weeks, 3 months, 6 months and every 6 months thereafter to determine the characteristic features and evolution of these lesions. RESULTS: Renal tumors were treated with CT guided percutaneous (34), laparoscopic (28) or open (2) RFA. At a median followup of 13.7 months (range 6 weeks to 29 months) 62 RFA lesions demonstrated an absence of contrast enhancement on CE-CT. Treated endophytic tumors developed a low density, nonenhancing, wedge-shaped defect with fat infiltration seen between the ablated tissue and normal parenchyma. Treated exophytic tumors retained a configuration similar to that of the original with a lack of contrast enhancement and minimal shrinkage. Percutaneous treated lesions developed a peritumor scar or halo that demarcated ablated and nonablated tissue (perirenal fat). Persistent tumor was marked by contrast enhancement within the ablation borders of the original mass in 1 case, whereas tumor recurred after initial successful ablation with an enhancing nodule in 1. CONCLUSIONS: The radiographic features and evolution of radio frequency ablated renal tumors are unique. Successfully treated tumors demonstrated no contrast enhancement, minimal shrinkage and occasional retraction from normal parenchyma by fat infiltration.

Adenocarcinoma, Clear Cell↗