GreenLightTM procedure is an effective and economical way of treatment of benign prostate hyperplasia (BPH); there are almost a million of patients treated with GreenLightTM worldwide. During the surgical procedure, the surgeon or physician will rely on the monitoring video system to survey and confirm the surgical progress. There are a few obstructions that could greatly affect the image quality of the monitoring video, like laser glare by the tissue and body fluid, air bubbles and debris generated by tissue evaporation, and bleeding, just to name a few. In order to improve the physician’s visual experience of a laser surgical procedure, the system performance parameter related to image quality needs to be well defined. However, since image quality is the integrated set of perceptions of the overall degree of excellence of an image, or in other words, image quality is the perceptually weighted combination of significant attributes (contrast, graininess …) of an image when considered in its marketplace or application, there is no standard definition on overall image or video quality especially for the no-reference case (without a standard chart as reference). In this study, Subjective Quality Factor (SQF) and acutance are used for no-reference image quality evaluation. Basic image quality parameters, like sharpness, color accuracy, size of obstruction and transmission of obstruction, are used as subparameter to define the rating scale for image quality evaluation or comparison. Sample image groups were evaluated by human observers according to the rating scale. Surveys of physician groups were also conducted with lab generated sample videos. The study shows that human subjective perception is a trustworthy way of image quality evaluation. More systematic investigation on the relationship between video quality and image quality of each frame will be conducted as a future study.
A previous in vitro study demonstrated that 180W was the optimal power to reduce photoselective vaporization of the
prostate (PVP) time for larger prostate glands. In this study, we investigated anatomic and histologic outcomes and
ablation parameters of 180W laser performed with a new 750-μm side-firing fiber in a survival study of living canines.
Eight male canines underwent anterograde PVP with the 180W 532-nm laser. Four each animals were euthanized 3
hours or 8 weeks postoperatively. Prostates were measured and histologically analyzed after hematoxylin and eosin
(H&E), triphenyltetrazolium chloride (TTC), or Gomori trichrome (GT) staining. Compared to the previous 120W laser,
PVP with the 180W laser bloodlessly created a 76% larger cavity (mean 11.8 vs. 6.7 cm3; p=0.014) and ablated tissue at
a 77% higher rate (mean 2.3 vs. 1.3 cm3/min; p=0.03) while H&E- and TTC-staining demonstrated its 33% thicker mean
coagulation zone (2.0±0.4 vs. 1.5±0.3 mm). H&E-stained cross-sectional prostatic tissue specimens from the 3-hour
(acute) group showed histologic evolution of concentric non-viable coagulation zone, partially viable hyperemic
transition zone of repair, and viable non-treated zone. H&E- and GT-stained specimens from the 8-week (chronic) group
revealed healed circumferentially epithelialized, non-edematous, prostatic urethral channels with no increase in collagen
in the subjacent prostatic tissue vis-á-vis the normal control. Our canine study demonstrates that 180W 532-nm laser
PVP with its new fiber has a significantly higher ablation rate with a more hemostatic coagulation zone, but equally
favorable tissue interaction and healing, compared with our previous 120W canine study.
Cryoablation is a prostate cancer treatment which uses extreme cold to kill prostate cancer cells. Unfortunately,
cryoablation is not specific to cancer cells and normal cells within and surrounding the ice ball may also die which often
includes those in the neurovascular bundles (NVBs). The NVBs contain neuronal and vascular components essential for
erectile function and continence, and damage can cause impotence and incontinence. Therefore, agents that protect the
NVBs during cryoablative procedures are extremely important for the next generation of this technology. The purpose
of these studies was to analyze various agents for their ability to reduce cellular toxicity upon freezing of fibroblasts and
neuronal cells. The agents were compared against DMSO, a well accepted but toxic cryoprotective agent (CPA).
Various concentrations of trehalose, PVP, PEG, and DMSO were incubated with fibroblast or neuronal cells for 45
minutes at 37°C, frozen in liquid nitrogen for one hour, thawed in a 37°C water bath for 5 minutes, and then plated in 6
well plates. After 18 hours, live cells were counted using the trypan blue exclusion assay. No cells survived in DMEM
alone, however, cell viability was observed in the trehalose and DMSO treated samples in both cell types and in the
fibroblast cells only for PEG treated samples. To mimic the general cryoablation procedure consisting of 2 freeze/thaw
cycles, neuronal cells were frozen and thawed twice. Cell viability was observed in the some trehalose and DMSO
treated cells. Our experiments demonstrate that trehalose is capable of acting as a CPA of both fibroblasts and nerve
cells. Its overall ability to act as a CPA is comparable to DMSO, a widely used and well accepted CPA, thus warranting
further experimentation with this agent.
Laser therapy for obstructive benign prostatic hyperplasia (BPH) has gained broad adoption due to effective tissue removal, immediate hemostasis, and minor complications. The aim of this study is to quantitatively compare ablation characteristics of PV (Photoselective Vaporization) and the newly introduced HPS (High Performance System) 532 nm lasers. Bovine prostatic tissues were ablated in vitro, using a custom-made scanning system. Laser-induced volume produced by two lasers was quantified as a function of applied power, fiber working distance (WD), and treatment speed. Given the same power of 80 W and speed of 4 mm/s, HPS created up to 50 % higher tissue ablation volume than PV did. PV induced a rapid decrease of ablation volume when WD increased from 0.5 mm to 3 mm while HPS yielded almost constant tissue removal up to 3 mm for both 80 W and 120 W. As the treatment speed increased, both lasers reached saturation in tissue ablation volume. Lastly, both PV and HPS lasers exhibited approximately 1 mm thick heat affected zone (HAZ) in this study although HPS created twice deeper ablation channels with a depth of up to 4 mm. Due to a smaller beam size and a higher output power, HPS maximized tissue ablation rate with minimal thermal effects to the adjacent tissue. Furthermore, more collimated beam characteristics provides more spatial flexibility and may even help to decrease the rate of fiber degradation associated with thermal damage from debris reattachment to the tip.
Conference Committee Involvement (5)
Therapeutics and Diagnostics in Urology: Lasers, Robotics, Minimally Invasive, and Advanced Biomedical Devices
21 January 2012 | San Francisco, California, United States
Urology: Diagnostics, Therapeutics, Robotics, Minimally Invasive, and Photodynamic Therapy
22 January 2011 | San Francisco, California, United States
Urology: Diagnostics, Therapeutics, Robotics, Minimally Invasive, and Photodynamic Therapy
23 January 2010 | San Francisco, California, United States
Urology: Diagnostics, Therapeutics, Robotics, Minimally Invasive, and Photodynamic Therapy
24 January 2009 | San Jose, California, United States
Urology: Diagnostics, Therapeutics, Robotics, Minimally Invasive, and Photodynamic Therapy
19 January 2008 | San Jose, California, United States
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