Jonathan P. Heldt

Effect of Low Dose Radiation Computerized Tomography Protocols on Distal Ureteral Calculus Detection

PURPOSE Unenhanced multidetector computerized tomography is the imaging modality of choice for urinary calculi but exposes patients to substantial radiation doses with a subsequent risk of radiation induced secondary malignancy. We compared ultra low dose and conventional computerized tomography protocols for detecting distal ureteral calculi in a cadaveric model. MATERIALS AND METHODS A total of 85 calcium oxalate stones 3 to 7 mm long were prospectively placed in 14 human cadaveric distal ureters in 56 random configurations. The intact kidneys, ureters and bladders were placed in a human cadaveric vehicle and computerized tomography was performed at 140, 100, 60, 30, 15 and 7.5 mA seconds while keeping other imaging parameters constant. Images were independently reviewed in random order by 2 blinded radiologists to determine the sensitivity and specificity of each mA second setting. RESULTS Overall sensitivity and specificity were 98% and 83%, respectively. Imaging using 140, 100, 60, 30, 15 and 7.5 mA second settings resulted in 98%, 97%, 97%, 96%, 98% and 97% sensitivity, and 83%, 83%, 83%, 86%, 80% and 84% specificity, respectively. Interobserver agreement was excellent (kappa >0.87). There was no significant difference in sensitivity or specificity at any mA second settings. All false-negative results were noted for 3 mm calculi at a similar frequency at each mA second setting. CONCLUSIONS Ultra low dose computerized tomography protocols detected distal ureteral calculi in a fashion similar to that of conventional computerized tomography protocols in a cadaveric model. These protocols may decrease the radiation dose up to 95%, reducing the risk of secondary malignancies.

Radiation Exposure During Continuous and Pulsed Fluoroscopy

UNLABELLED Abstract Background and Purpose: Previous studies using pulsed fluoroscopy have shown variable effects on radiation exposure because of the ramp and trail effect in older C-arm systems. This study compares radiation delivered in pulsed and continuous modalities using a modern C-arm system. MATERIALS AND METHODS Thermoluminescent dosimeters (TLDs) positioned in three body locations directly measured radiation dose during simulated ureteroscopy. Thirty pedal activations were administered using a pulsed or continuous mode to visualize an implanted guidewire and a radiopaque stone. TLD absorbed radiation and image quality were compared between imaging modes. RESULTS Pulsed fluoroscopy delivered less radiation compared with continuous fluoroscopy at each site: Anterior skin (0.10 vs 0.26 mGy, P<0.001), kidney (0.15 vs 0.40 mGy, P<0.001), and posterior skin (0.92 vs 2.62 mGy, P<0.001). Mean fluoroscopy time differed between continuous and pulsed modes (12.5 vs 3.0 seconds; P<0.001). Fluoroscopy time positively correlated with radiation exposure at all sites: Anterior skin (0.017 mGy/s, R(2)=0.90), left kidney (0.026 mGy/s, R(2)=0.96), and posterior skin (0.18 mGy/sec, R(2)=0.98). When evaluated by blinded urologists, 100% of reviewers felt pulsed images were adequate to identify guidewire position and 90.5% felt pulsed images were adequate for stone localization. CONCLUSION Pulsed fluoroscopy reduced fluoroscopy time by 76% and radiation dose by 64% compared with continuous fluoroscopy. Pulsed fluoroscopy images were adequate for most tasks of ureteroscopy and should be considered for reduction of radiation during ureteroscopy.

Robot-Assisted Radical Prostatectomy in Patients with Previous Renal Transplantation

PURPOSE To evaluate the outcomes of robot-assisted radical prostatectomy (RARP) in patients with previous renal transplantation. PATIENTS AND METHODS We retrospectively identified all patients who had undergone RARP for localized prostate cancer between 2005 and 2008 at a single institution (N=228). Of these, three patients were renal transplant recipients. A four-arm robotic configuration was used in all patients. Port placement was modified in two of the three renal transplant recipients to avoid trauma to the renal allograft. Preoperative demographics, perioperative parameters, and postoperative outcomes were reviewed. RESULTS RARP was completed successfully in all three renal transplant recipients. As expected, the American Society of Anesthesiologists score (3.3 vs 2.4) and Charlson weighted index of comorbidity (4.7 vs 2.4) were greater in previous transplant patients. There were no major differences in mean age, Gleason score, body mass index, estimated blood loss, operative time, complications, or oncologic outcomes between the two groups. Each of the patients with renal allografts had an undetectable prostate-specific antigen level and was continent (needing no pads) at 13 months of follow-up. CONCLUSIONS RARP is feasible in patients with a previous renal transplant. Although technically more challenging, RARP can be performed in previous transplant patients with acceptable morbidity and oncologic outcomes similar to those of other prostate cancer patients.

A Prospective Randomized Comparison of Traditional Laparoendoscopic Single-Site Surgery with Needlescopic-Assisted Laparoscopic Nephrectomy in the Porcine Model

BACKGROUND AND PURPOSE Laparoendoscopic single-site (LESS) surgery produces virtually no scar but is technically challenging because of the loss of triangulation. The objective of this study is to compare classic transumbilical LESS nephrectomy with needlescopic-assisted laparoscopy (NAL) surgery. In doing so, we evaluated whether the addition of a single 2-mm subcostal port could restore triangulation while not jeopardizing recovery or cosmetic outcome in the porcine model. MATERIALS AND METHODS Ten female farm pigs were randomized to laparoscopic nephrectomy with either LESS or NAL. In LESS, a TriPort was placed through a single 2.5-cm umbilical incision. In NAL, 5- and 10-mm ports were placed in the umbilicus and a 2-mm port was placed in the midclavicular line. Preoperative, perioperative, and postoperative parameters were compared. Variables were analyzed with the Wilcoxon signed-rank test and two-tailed Fisher exact test. Cosmesis was evaluated objectively using the Vancouver Scar Scale and subjectively by a blinded dermatologist. A cost analysis was performed. RESULTS Estimated blood loss was minimal in both groups (28.8 mL in LESS and 9.4 mL in NAL). Operative time was significantly shorter in NAL (103 vs 150 min; P<0.001). There was no difference in complications (2 vs 1; P=0.500), objective cosmesis (3.9 vs 3.8; P>0.2), or subjective cosmesis (2 vs 3; P=0.500). The NAL protocol had significantly lower disposable equipment costs (

Donor Smoking Negatively Affects Donor and Recipient Renal Function following Living Donor Nephrectomy.

363 vs

Ureteral Calculi Detection Using Low Dose Computerized Tomography Protocols is Compromised in Overweight and Underweight Patients

1696). CONCLUSIONS The addition of a 2-mm subcostal port and the restoration of triangulation in the NAL protocol enable shorter operative times, increased surgeon comfort, improved technical ease, and lower costs while maintaining the scarless cosmesis of the traditional LESS protocol.

Prostate Specific Antigen Levels and Prostate Cancer Detection Rates in Patients With End Stage Renal Disease

Background. While tobacco use by a renal transplant recipient has been shown to negatively affect graft and patient survival, the effect of smoking on the part of the kidney donor remains unknown. Methods. 29 smoking donors (SD) and their recipients (SD-R) as well as 71 non-smoking donors (ND) and their recipients (ND-R) were retrospectively reviewed. Preoperative demographics and perioperative variables including serum creatinine (Cr) and glomerular filtration rate (GFR) were calculated and stratified by amount of tobacco exposure in pack-years. Clinical outcomes were analyzed with a Students t-test, chi-square, and multiple linear regression analysis (α = 0.05). Results. At most recent followup, SD-Rs had a significantly smaller percent decrease in postoperative Cr than ND-Rs (−57% versus −81%; P = 0.015) and lower calculated GFRs (37.0 versus 53.0 mL/min per 1.73 m2; P < 0.001). SDs had a larger percent increase in Cr than NDs at most recent followup (57% versus 40%; P < 0.001), with active smokers having a larger increase than those who quit, although this difference was not statistically significant (68% versus 52%; P = 0.055). Conclusions. Use of tobacco by kidney donors is associated with decreased posttransplant renal function, although smoking cessation can improve outcomes. Kidneys from donors who smoke should be used with caution.

Patients with End-Stage Renal Disease Are Candidates for Robot-Assisted Laparoscopic Radical Prostatectomy

PURPOSE Low dose computerized tomography protocols have demonstrated a reduction in radiation exposure while maintaining excellent sensitivity and specificity in the detection of stones in patients of average size. Low dose computerized tomography protocols have not yet been evaluated in subjects in the extremes of weight. We evaluated the effect of body weight when using low dose protocols to detect ureteral calculi. MATERIALS AND METHODS Three cadavers of increasing weight (55, 85 and 115 kg) were prepared by inserting 721 calcium oxalate stones (range 3 to 7 mm) in 33 random configurations into urinary tracts. Cadavers were then scanned using a GE LightSpeed® at 7 radiation settings. An independent, blinded review by a radiologist was conducted to generate ROC curves, with areas under the curve compared using a 1-way ANOVA (α = 0.05). RESULTS Sensitivity and specificity were significantly lower in the low and high weight cadavers compared to the medium weight cadaver at 5 mAs (p <0.001) and 7.5 mAs (p = 0.048). Differences in sensitivity and specificity at radiation settings of 15 mAs or greater were not significant. CONCLUSIONS The sensitivity and specificity for the detection of ureteral calculi on computerized tomography were decreased for underweight and overweight subjects when using extremely low dose radiation settings (less than 1 mSv). Low dose protocols of 15 mAs (2 mSv) can still be used for these subjects without jeopardizing the ability to identify ureteral stones.

In automated fluoroscopy settings, does shielding affect radiation exposure to surrounding unshielded tissues?

PURPOSE Patients with end stage renal disease plus prostate cancer are ineligible to receive a renal transplant at most centers until an acceptable cancer-free period is demonstrated. To our knowledge previously established prostate specific antigen reference ranges have not been validated in patients with end stage renal disease. We determined age stratified 95th percentile prostate specific antigen reference ranges and the prostate cancer detection rate at specific prostate specific antigen intervals for patients with end stage renal disease. MATERIALS AND METHODS We retrospectively reviewed the records of 775 male patients with end stage renal disease on the waiting list for a renal transplant who had undergone a serum prostate specific antigen test. Prostate specific antigen was stratified by age at the time of the blood test and 95th percentile reference ranges were calculated for each decade. A total of 80 patients underwent prostate biopsy for increased prostate specific antigen and/or abnormal digital rectal examination. The cancer detection rate was calculated for specific prostate specific antigen reference ranges. RESULTS The age specific 95th percentile prostate specific antigen references ranges were 0 to 4.0 ng/ml for ages 40 to 49 in 137 patients, 0 to 5.3 ng/ml for ages 50 to 59 in 257, 0 to 10.5 ng/ml for ages 60 to 69 in 265 and 0 to 16.6 ng/ml for ages 70 to 79 years in 69. The cancer detection rate was 44%, 38% and 67% for prostate specific antigen 2.5 to 4.0, 4 to 10 and greater than 10 ng/ml, respectively. CONCLUSIONS In our study population of patients with end stage renal disease age stratified prostate specific antigen was higher than in the general population. The cancer detection rate was increased in our patients with end stage renal disease compared to that in patients with normal renal function at specific prostate specific antigen intervals. Lower prostate specific antigen cutoffs may be appropriate to recommend prostate biopsy in patients with end stage renal disease.

Ocular Complications After Open and Hand-assisted Laparoscopic Donor Nephrectomy

BACKGROUND AND PURPOSE Patients with end-stage renal disease (ESRD) have multiple comorbidities that place them at increased risk for surgical complications. Consequently, patients with both ESRD and prostate cancer (PCa) have rarely been considered candidates for radical prostatectomy. The objective of this study is to compare ESRD patients who are undergoing robot-assisted laparoscopic prostatectomy (RALP) with a cohort of patients with no history of dialysis. PATIENTS AND METHODS A retrospective review was conducted of 430 patients who were undergoing RALP, including 12 receiving dialysis at the time of surgery. Preoperative demographics, perioperative parameters, and postoperative outcomes were compared using a two-tailed Student t test and a chi-square test, with significance at P<0.05. RESULTS Patient demographics including body mass index, Gleason score, and prostate-specific antigen (PSA) value were similar between the two groups. Patients with ESRD had younger age (55.5 vs 62.9 years; P<0.01), higher American Society of Anesthesiologists scores (3.7 vs 2.5; P<0.01), and higher age-adjusted Charlson Comorbidity Index scores (6.2 vs 4.2; P<0.01). Patient outcomes including operative time, estimated blood loss, complication rate, postoperative stay, and positive margins did not differ significantly between groups. No ESRD patients needed pads or had a detectable PSA level using an ultrasensitive assay. CONCLUSIONS This series represents the largest series of patients with ESRD undergoing RALP. These patients experienced similar outcomes compared with patients with no history of dialysis despite greater preoperative comorbidity. RALP produces minimal fluid shifts, low blood loss, and excellent cancer control, making it an ideal treatment option to prepare patients with both ESRD and PCa for renal transplantation.