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R Muschter

Publications and source records attributed to R Muschter.

At least 37 records · Page 2Linked to original sources
PubMed1996

Alteration of laser-tissue interaction with the 805 nm diode laser using indocyanine green in the canine prostate.

BACKGROUND AND OBJECTIVE: Research interests in laser prostatectomy continue to evaluate a variety of wavelengths and treatment parameters in an effort to optimize treatment. Recently, a semiconductor diode laser with a wavelength of 805 nm has become available for clinical use; however, free-beam noncontact applications were limited by the low power output (25 W). In this study in the canine prostate, the possible potentiating effects of intravenously administered indocyanine green (ICG) were evaluated with the 805 nm diode laser. STUDY DESIGN/MATERIALS AND METHODS: A total of 16 fixed position, free-beam lasings were performed at 25 W for 60 sec in four dogs with eight lasings before and eight lasings after ICG administration. Endoscopic observations and measurements of lesion volumes were used to evaluate the laser-tissue interactions. RESULTS: Prior to ICG administration, we observed that side fire irradiation produced primarily small coagulative lesions. Following ICG administration, however, immediate and more noticeable tissue vaporization occurred, although total lesion size was not increased. Pathologic review demonstrated less coagulation and hyperemia, but a larger vaporized cavity in the ICG treated tissue. CONCLUSION: These findings suggest intravenous ICG alters laser-tissue interaction with the 805 nm diode laser in the canine prostate. The use of the 805 nm diode laser with enhancing chromophores deserves further investigation.

Animals↗
PubMed1996

[MRI monitoring before, during and after interstitial laser-induced hyperthermia of benign prostatic hyperplasia. Initial clinical experiences].

PURPOSE: To assess the clinical value of MRI in patients with benign prostatic hyperplasia (BPH) before, during, and after interstitial laser-induced thermotherapy (LITT) of the prostate. METHODS: Ten patients with symptomatic BPH had MRI examinations of the prostate 48 h before and after LITT. Online monitoring with MRI at 1.5 T of interstitial Nd:YAG laser energy deposition in the prostate was performed in two patients, repeating a T1-weighted FLASH sequence (TR 100 ms, TE 5 ms, flip angle 90 degrees) every 20 s. Follow-up MRI examinations 2-3 weeks, 6-8 weeks, and 6-12 months after LITT were carried out in eight patients, using T2-weighted FSE images and contrast-enhanced T1-weighted SE images. RESULTS: The prostate was well delineated in all patients on T2-weighted FSE images, with a rather homogeneous peripheral gland and an inhomogeneous central gland. Volume measurements yielded reproducibilities of 3.2%-4.7%. Signal intensity in the FLASH sequence decreased during LITT, both in the prostate in vivo and in specimens of bovine prostate and seminal vesicles in vitro, with signal developments running in parallel. Areas of energy deposition and signal alteration were not sharply delineated. The latter margin of the laser-induced lesions could not be predicted from the FLASH images, while the tip of the laser fibre was easily recognized. Contrast-enhanced T1-weighted MR images immediately after LITT clearly demarcated low signal intensity laser lesions from high signal intensity surrounding prostate tissue. Follow-up examinations showed a decrease of 20% of prostate volume over a period of 6-12 months after LITT. Correlation between prostate volume development and lesion volume alteration was 0.85-0.90 (P = 0.002-0.007) at all follow-up times. CONCLUSIONS: MRI allows rather precise recognition of intraprostatic alterations after LITT, including volume changes over a period of up to 1 year after therapy that can be predicted immediately after LITT. While laser energy deposition in the prostate can be monitored by MRI with T1-weighted FLASH sequences as a function of temperature alteration, it is not possible to determine the lesion margins immediately from the FLASH images. Online temperature development map generation will be necessary to influence on-going LITT procedures with MRI.

Aged↗
PubMed1996

Initial human clinical experience with diode laser interstitial treatment of benign prostatic hyperplasia.

OBJECTIVES: To report the initial results of treatment of outlet obstruction induced by benign prostatic hyperplasia (BPH) using interstitial laser coagulation performed with the Indigo 830 nm diode laser system. METHODS: A group of 112 men with lower urinary tract symptoms caused by BPH underwent treatment with the Indigo 830 nm laser system between October 1994 and November 1995. Patients were assessed prior to treatment and at specified post-treatment intervals for symptom score, uroflow, postvoid residual, and prostate volume. Adverse events and changes in laboratory parameters were monitored at each post-treatment visit to investigate safety of the procedure. RESULTS: Symptom score decreased from 20.9 at initial measurement to 9.6 at 3 months after procedure and 7.9 at 6 months. Uroflow rate increased from 8.0 mL/s initially to 15.2 and 14.2 mL/s at 3 and 6 months, respectively. Residual bladder volumes decreased from 105 mL initially to 59 and 38 mL at 3 and 6 months, respectively. There were no major complications (impotence, sustained incontinence, significant blood loss). Minor complications occurred in a small number of patients but were generally associated with urinary tract infection in patients with catheters. Three patients (2.7%) required retreatment and underwent transurethral resection of the prostate. CONCLUSIONS: Interstitial laser coagulation using an 830-nm diode laser system appears to be a promising new treatment, with substantial improvements in objective and subjective parameters of obstruction and a favorable side-effect profile.

Aged↗
PubMed1995

The effect of popcorn and carbonization on neodymium: YAG laser dosimetry in the canine model.

Neodymium:YAG laser irradiation of the canine prostate provides an experimental model for the study of the laser-tissue interaction in laser prostatectomy. Prostate irradiation was undertaken using right-angle-firing laser fibers through an open suprapubic cystotomy, and the procedure was monitored by video endoscopy via a perineal urethrostomy. The effects of popcorn and surface carbonization on intraprostatic heating profiles were determined by interstitial thermometry. We found that popcorn reduced intraprostatic temperatures but that continued irradiation resulted in the restoration of heating. Carbonization resulted in the loss of heating ability deep in the prostate. These observations allow the urologist to understand the thermal implications of observed surface change and to modify lasing parameters during surgery to obtain the desired laser-tissue interaction.

Animals↗
PubMed1995

Technique and results of interstitial laser coagulation.

By use of thermal "ablation" techniques to apply heat to the prostate from the urethra, the coagulation volume is limited by the limited penetration depth of suitable radiation sources, e.g., lasers, and by heat conduction. Secondarily, the coagulated tissue is removed by sloughing. Interstitial heat application was expected to overcome these problems. Our initial in vitro and animal studies using different light guides for interstitial Nd:YAG laser radiation showed that small, carbonized lesions were created by bare fibers, whereas large, homogeneous coagulation zones measuring up to 2 cm in diameter were produced by specially designed ITT (interstitial thermotherapy) fibers, which secondarily resulted in marked volume reduction by atrophy. Further experiments using such applicators resulted in an operation technique suitable for clinical routine in the treatment of symptomatic benign prostatic hyperplasia (BPH). These laser applicators are inserted into the prostate either transurethrally through a cystoscope under direct vision or percutaneously from the perineum under transrectal ultrasound guidance. The number of placements depends on the size and configuration of the gland. Radiation parameters were optimized for each system. To avoid charring, relatively low levels of laser power and long radiation periods (e.g., 7 W for 10 min) or power-formatting programs (e.g., stepwise reduction of power from 20 to 7 W for a total radiation time of 3 min) are applied. Beginning in July 1991, more than 350 unselected patients with BPH were treated with interstitial laser coagulation in our department, of whom 239 were followed for at least 1 year.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1995

Electrosurgical vaporization of the prostate in the canine model.

OBJECTIVES: To investigate the histopathologic changes and heating patterns caused by electrosurgical vaporization of the prostate in the living canine model. METHODS: Prostate electrosurgical vaporization was undertaken in the canine model. Temperatures within and near the prostate and of the irrigation fluid were measured during a single pass and during the creation of a vaporized cavity. The prostate and adjacent tissues were examined by gross and microscopic pathology. RESULTS: Coagulation occurred deep to the vaporization zone for 1.38 to 1.44 mm for a single pass of the rolling cylinder and up to 2.52 mm for multiple passes. Thermometry revealed temperature increases of only 4 degrees C 5 mm away from the vaporization site. The largest temperature increases were found in the irrigation fluid as it passed through the prostatic fossa. Microscopic pathology revealed no damage to adjacent tissues. CONCLUSIONS: Electrosurgical vaporization creates minimal deep heating and coagulation beyond the vaporized cavity. The majority of the heat is removed by the irrigation fluid.

Animals↗
PubMed1995

Interstitial laser therapy outcomes in benign prostatic hyperplasia.

Two hundred thirty-nine patients with benign prostatic hyperplasia (BPH) were treated using interstitial laser coagulation (ILC or LITT; laser-induced interstitial thermotherapy), and the long-term results were determined. In this minimally invasive procedure, special laser light guides were inserted into the adenoma tissue in order to achieve primary large-volume coagulation necrosis and secondary shrinking, leaving the urethra intact. The AUA Symptom Scores improved markedly, from an average of 25 pretreatment to an average of 6 at 1 year. Peak urine flow rates improved commensurably, from 8 mL/sec pretreatment to 18 mL/sec at 1 year. Postoperative irritative symptoms occurred occasionally, affecting only 12% of patients. Significant complications were rare, with 4% of patients suffering strictures and 7% retrograde ejaculation. No patients suffered impotence or incontinence. Only 9.6% of patients required retreatment for BPH during 12 months of follow-up. Twelve patients were treated with subsequent transurethral laser incision of the bladder neck in order to shorten the time required for improvement of voiding function.

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PubMed1995

[Interstitial laser-induced coagulation of the prostate for therapy of benign hyperplasia].

Interstitial laser-induced coagulation (ILC) is a new, minimally invasive, procedure for the treatment of benign prostatic hyperplasia (BPH). It is based on the placement of special light guides in the prostatic tissue, either transurethrally or perineally. The radiation source is a Nd-YAG laser, which is active for 3 or 5 min per fiber placement, respectively, with the power reduced stepwise. The coagulation necroses caused shrink during follow-up, leading to a decrease in the obstruction. In 239 patients treated in this way the mean I-PSS-Score fell from 25.4 to 8.1 points and the quality of life index from 4.1 to 1.6, the urinary peak flow rate increased from 7.7 to 16.3 ml/s, the residual urine volume fell from 151 to 32 ml, and the mean prostate volume declined from 47.4 to 32.2 ml in the first 3 months of follow up; 9.2% of the patients required further treatment within 1 year because of persistent obstruction. The complication rate was low. Statistical analysis showed no factors allowing prediction of the outcome. ILC is an effective method with few side effects and complications, and it has a wide range of indications for all BPH patients.

Aged↗
PubMed1994

The optimization of laser prostatectomy. Part I: Free beam side fire coagulation.

OBJECTIVES: To study laser-tissue interaction and develop unifying principles for the optimization of free beam side fire neodymium:yttrium-aluminum-garnet (Nd:YAG) laser coagulation prostatectomy. METHODS: The heating patterns and coagulation volumes created by different right angle deflecting fibers were studied at different wattages and times in potato and canine models. RESULTS: In the potato, higher wattage resulted in deeper and more rapid heating. The high power density fibers created lesions of smaller volume which increased less with rising wattage than those fibers of lower power density. In the canine model, carbonization decreased heat penetration, and "popcorn" decreased superficial temperature without altering lesion size as long as it occurred without carbonization. As lasing progressed, smaller incremental increases in coagulation depth were achieved. CONCLUSIONS: To optimize coagulation laser prostatectomy, the surgeon should operate at the highest wattage which does not cause carbonization. The visualized intraoperative laser-tissue interaction allows the adjustment of laser power during the case as needed.

Animals↗
PubMed1994

The optimization of laser prostatectomy. Part II: Other lasing techniques.

OBJECTIVES: To evaluate the laser-tissue interaction during neodymium:yttrium-aluminum-garnet (Nd:YAG) irradiation using right angle firing fibers in motion, contact vaporization applicators, and interstitial lightguides. METHODS: The heating patterns and coagulation volumes created during right angle firing fiber pulling and painting, contact tip vaporization, and interstitial thermotherapy were studied in potato and canine models. RESULTS: High power density right angle firing fibers can be used in motion to create coagulation lesions at 40 and 60 watts (W). The depth of such lesions was less than that obtained during fixed free beam side fire coagulation. Contact vaporization applicators caused tissue vaporization without creating concurrent coagulation lesions. Interstitial lightguide thermotherapy created coagulation lesions without carbonization using A step power reduction approach during irradiation. CONCLUSIONS: Each of the investigated methods had the ability to destroy prostate tissue, and therefore may have a role in the evolution of laser prostatectomy.

Animals↗
PubMed1994

[Laser treatment of benign prostatic hyperplasia].

This review article describes the different methods of laser treatment of benign prostatic hyperplasia and their development. Published treatment results are compared with our own results obtained with different procedures. The aim of therapy is to reduce the volume of the gland by coagulation, with subsequent secondary ablation or primary vaporization. Due to the desired volume effects Nd:-YAG lasers are used almost exclusively. The technique most frequently used is transurethral laser coagulation of the prostate. Radiation is done in the non-contact mode with beam-detecting applicators, with either direct vision (VLAP) or ultrasound guidance (TULIP). In interstitial laser coagulation of the prostate (ILC) laser energy is applied by light guides inserted into the tissue either transurethrally or transperineally. Contact lasers are used for incision of the prostate or superficial ablation.

Follow-Up Studies↗
PubMed1994

[Laser applications in condylomata acuminata].

Condylomata acuminata are benign epidermal proliferations caused by human papillomavirus (HPV). Recent epidemiological data have shown that HPV infection is the most common sexually transmitted disease. Some HPV types are considered to be potentially oncogenic. Therefore, effective examinations and treatment of both sexual partners are important in all cases. The CO2 laser and the Nd:-YAG laser have gained widespread acceptance in the treatment of HPV efflorescences. CO2 lasers are characterized by surface absorption; the Nd:-YAG laser effect depends on volume absorption; depth of coagulation can be controlled by laser power, spot size and exposure time. Both of these fundamentally different laser effects lead to excellent cosmetic results and high cure rates. Our follow-up examinations revealed recurrences in 22%.

Condylomata Acuminata↗
PubMed1994

[Laser lithotripsy of ureteral calculi].

A total of 149 patients with 152 ureteral stones were treated with intraureteral lithotripsy by Dye-laser (83.55%), Alexandrite-laser (41.27%), electrohydraulic lithotripsy adapted for use in the ureter (25.16%) or neodymium: YAG laser with optomechanic coupling (3.2%). The Dye-laser has an automatic pulse shut-off mechanism with spectral analysis of the reflected laser beam, so that effective laser pulses can only be released by contact with a stone. Most (127 of 83.5%) of the stones could be completely fragmented, so that no further treatment was necessary. In 16 cases (10.5%) the stone was too hard for fragmentation and had to be removed by alternative techniques. Intraureteral lithotripsy is a save and effective method of treating ureteral stones that cannot be reached or have not been treated successfully by shockwave lithotripsy. No significant differences in outcome were found between the different lasers or electrohydraulic lithotripsy. In selected cases endoscopic treatment may be recommended as treatment of first choice.

Adolescent↗
PubMed1993

[Interstitial laser coagulation of benign prostatic hyperplasia].

We report on the new method of interstitial laser coagulation for the treatment of benign prostatic hyperplasia (BPH). The procedure is based on the interstitial application of Nd:YAG laser irradiation, delivered through a new light guide system. Such light applicators coagulate constant tissue volumes in a homogeneous manner, as proven by in vitro studies in different tissues, including surgically removed prostate adenoma. The extent of the coagulation is determined by laser power and irradiation time. At 5 W, for example, and during a 10-min period, this zone reached a diameter of up to 20 mm. Temperatures generated in the process were over 100 degrees C, as measured by time/space resolution. These results were confirmed by in vivo studies in canine prostates. In the course of 7 weeks, the coagulated areas formed scars with degeneration and fibrosis, accompanied by marked shrinking. Neighbouring organs were not affected. The method was successfully transferred to clinical practice. The application of the light guides to the lateral lobes was performed percutaneously from the perineum under transrectal ultrasound guidance. The median lobe was punctured transurethrally under direct vision. Twenty-seven patients with an average age of 67.7 years were treated between July 1991 and March 1992. At the time of evaluation 15 patients had a follow-up of more than 2 months. They experienced a mean increase of peak flow rate from 6.6 to 15.2 ml/s and a mean decrease of residual volume from 206 to 38 ml. This was accompanied by a marked lessening of symptoms. The average prostate weight decreased from 63 to 44 g. Sexually active patients did not experience retrograde ejaculation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

[Laser lithotripsy with automatic shut-off on tissue contact].

A group of 88 patients with 89 ureteral calculi were treated with the pulsed dye-laser. Visual control was carried out through 8.5-F or 9.5-F ureteroscopes. The laser has automatic shut-off via spectrum analysis of back-scatter laser light. Effective laser pulses can therefore only be induced in the case of contact with the stone. Of the 89 stones 58 (65.2%) were completely fragmented by laser lithotripsy, 15 (16.8%) by laser lithotripsy in combination with ESWL and 9 (10.1%) by other ureteroscopic techniques. Ureterolithotomy was necessary only in 1 case (1%). There were 5 calculi (5.6%) that were too hard for fragmentation. The pulsed dye-laser is a safe and effective treatment modality for ureteral calculi that are not accessible for ESWL or in which ESWL has been unsuccessful. Further experimental and clinical trials will have to show whether miniature probes for electrohydraulic lithotripsy, dye-laser with automatic shut-off, or alexandrite laser will be the method of choice for lithotripsy of ureteral calculi.

Endoscopes↗
PubMed1990

[Diverticular calculi of the kidney calices--extracorporeal shockwave lithotripsy, percutaneous extraction or open surgery].

The incidence of caliceal diverticula, mostly found on routine excretory urography, is very low. The indications for treatment include chronic or recurrent pyelonephritis, pain, gross hematuria and renal damage. There is controversy as to which treatment is best: extracorporeal shock-wave lithotripsy (ESWL), percutaneous techniques, or traditional open surgery. Since 1984, 27 patients with 28 caliceal diverticula calculi have been treated. Ten patients underwent ESWL, 13 patients percutaneous treatment, and 4 patients open surgery. The success rates as far as a stone-free status is concerned were: 1 patient (ESWL), 10 (percutaneous), and 4 (open surgery). There were no complications due to ESWL or open surgical treatment. Direct traumata such as severe bleeding in two and hydrothorax in one patient occurred during the training phase of the percutaneous techniques. Due to the low complication rate, non-invasive ESWL treatment should be tried first. The indications for percutaneous removal of calculi in caliceal diverticula depend on two aspects: it should be possible to puncture the caliceal diverticula via by a short parenchymal route coaxial to the axis of the calix and, if the intercostal approach is used, a pleural lesion must be excluded. If these requirements cannot be fulfilled, open surgical treatment should be performed, especially if the diverticula are located in the upper and anterior part of the kidney.

Adolescent↗