RESEARCH

As new research is published, MAPU encourages members to read up. This page features concise abstracts on particular subjects of interest.

Books

Atlas of Robotic Urologic Surgery, 2009. Chapter: “Radical Prostatectomy: Transperitoneal Approach” by Stern JM., Lee DI.

Description: The Atlas of Robotic Urologic Surgery provides a unique set of operative steps including figures, intraoperative pictures, and accompanying video that will aid the "beginner" at overcoming the learning curve and accomplishing these complex minimally invasive techniques. This unique technique-specific surgical atlas is unlike Vip Patel's which is more basic in its description of technique and also more comprehensive in its scope in covering things outside of technique like complications and results.

Papers

Magnetic Resonance Spectroscopy Predicts the Histologic Assessment of Radiofrequency Ablated Renal Tissue. European Urology, 2008. by Stern JM., Merritt M., Cadeddu JA.

Abstract
Introduction and Objective
Recent advances in magnetic resonance (MR) technology have allowed for high-resolution ex vivo spectroscopy on small, intact tissue samples. We examined the capability of 1H magnetic resonance magic angle spinning (MR-MAS) to correctly characterize post–radiofrequency ablation (RFA) renal biopsies from human samples, compared with standard histology and cross-sectional imaging.
Methods
A minimum of two, 18G, percutaneous renal biopsies were obtained from ten biopsy-confirmed renal tumors at a mean 26.6 mo (range, 15–48) post-RFA. All patients were considered free of disease by computed tomography criteria. A portion of each sample was immediately frozen at −80 °C for spectroscopy and the remainder used for pathological analysis. 1H MR-MAS was performed blinded with a 14.1-tesla field strength. Prior renal biopsies from nonablated tissue were used as positive controls for the spectral analysis. Concordance between, computed tomography, histology, and MR-MAS was analyzed. All spectroscopy was processed with VNMR software.
Results
Histological analysis of all ten post-RFA biopsies demonstrated no cancer or viable tissue. All MR-MAS spectral peaks for each biopsy were consistent with necrosis and, more importantly, indicated an absence of small molecule metabolites characteristic of both normal and malignant renal tissue. Both MR-MAS and histology confirmed, in each case, the conventional computed tomography determination of complete ablation.
Conclusions
MR spectroscopy can correctly diagnose the molecular absence of disease in post-RFA tissue biopsies. This proof of principle study warrants in vivo evaluation to confirm the clinical correlates of this modality.

Take Home Message
Monitoring the postablation lesion after radiofrequency ablation of the kidney is evolving. MRI spectroscopy may offer a unique view of the postablation lesion that is equivalent to conventional histology. A larger study is needed.

Selective Prostate Cancer Thermal Ablation with Laser Activated Gold Nanoshells. The Journal of Urology, 2008 Feb;179(2):748-53. by Stern JM, Stanfield J., Hsieh Jer-Tosng., Kabbani W., Cadeddu JA.

Purpose
Laser activated gold nanoshell thermal ablation represents a new, minimally invasive technology that offers benign tissue sparing thermal ablation of malignant tumors. We evaluated the efficacy of this technology for eradicating prostate cancer in a subcutaneous tumor model.

Materials and Methods
The 110 nm gold nanoshells with a 10 nm gold shell are designed to act as intense near infrared absorbers. PC-3 cells were injected on the dorsum of nude mice in 3 groups, including 1—gold nanoshell plus near infrared laser, 2—saline alone and 3—near infrared laser alone. Animals received 7.0 ml/gm body weight (low dose) or 8.5 ml/gm body weight (high dose) nanoshells via tail vein injection. Control animals received saline. A 810 nm near infrared laser with a 200 μ laser fiber and an energy setting of 4 W/cm2 was aimed at the tumor bed for 3 minutes. Tumors were measured at days 0, 7, 14 and 21. Tissue temperature was monitored during laser activation. Tumors were harvested at day 21 and stained with hematoxylin and eosin, and for nicotinamide adenine dinucleotide diaphorase activity.

Results
We observed 93% tumor necrosis and regression in the high dose treated group. Nicotinamide adenine dinucleotide staining corroborated this finding. The ablation zone was sharply limited to the laser spot size. There was no difference in the size or tumor histology in control groups, indicating a benign course for near infrared laser treatment alone. Temperatures up to 65.4C were attained in the treated group.

Conclusions
Laser activated gold nanoshell ablation is an effective and selective technique for prostate cancer ablation in an ectopic murine tumor model.

Emerging use of Nanoparticles for the Therapeutic Ablation of Urologic Malignancies. Urologic Oncology. 2008 Jan-Feb;26(1):93-6 by Stern JM, Cadeddu JA.

Abstract
Metal nanoshells are a new class of nanoparticle with highly tunable optical properties. Gold nanoshells (GNS) are particularly suitable for use in the surgical arena as their outer shell is composed of a commonly used reduced inert gold. When activated by near infrared light, GNS can raise surrounding temperatures to levels sufficient for cellular ablation. As such, investigators have established both in vitro and in vivo models to examine the role of GNS as a therapeutic modality for the thermal ablation of solid organ tumors.

Safety and Efficacy of Ureteral Access Sheaths. Journal of Endourology, 21 (2); 119-123. Feb 2007. by Stern JM, Yiee J, Park, S.

The ureteral access sheath (UAS) was introduced as a means of passing a flexible ureteroscope. Although the device was initially lauded for its ability to facilitate ureteroscopic access, passage was difficult and risked ureteral injury, and the UAS fell out of favor until the development of a new generation of devices that was easier to insert. The UAS should be advanced under fluoroscopy over a stiff guidewire, and the surgeon should ensure copious hydration of all inner and outer surfaces. Use of the UAS is purported to improve irrigant flow and visibility. The UAS can induce transient ureteral ischemia and promote an acute inflammatory response, but it also prevents potentially harmful elevations in intrarenal pressure. Unequivocal data are not yet available to suggest that UAS use during ureteroscopy protects or harms the upper urinary tract. The UAS also has the potential to improve stone-free rates by allowing passive egress or active retrieval of fragments. A large prospective study is needed to unequivocally determine if UAS use is superior in terms of stone-free rates. Cost studies reported to favor UAS use, although a formal cost-effectiveness analysis has not been performed. Further study is needed before routine use of the UAS can be recommended.