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Biomedical subjects

R Muschter

Publications and source records attributed to R Muschter.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1989

[The neodymium:YAG laser in infiltrating bladder tumors].

Over the last 11 years we have treated 47 patients with infiltrating bladder carcinomas with the neodymium:YAG laser alone or in combination with TUR. After a mean observation period of 3 1/2 years (19-133 months) 39 patients (83%) were still alive. Only two of them showed tumor dissemination. Thirteen patients (27.7%) had no recurrent disease after laser therapy. Mostly heterotopic recurrences with no tumor progression were found in 23 patients (48.9%). Six patients (12.8%) developed recurrences with progression, including two cases with pelvic lymph node metastases. Five patients (10.6%) died of their tumor disease and three of myocardial infarction, having shown no signs of tumor recurrence at the last follow-up examination.

Combined Modality Therapy↗
PubMed1987

[Extra-corporal shock wave lithotripsy using the HM3 Dornier lithotripter with a modified shock wave generator. Initial clinical reports of experiences].

We report on the clinical application of a modified shock-wave generator for the Dornier Lithotripter HM 3. Stone fragmentation, complication rate, and frequency of auxiliary measures were unchanged in comparison to the former generator. The new shock-wave generator led to markedly reduced patient discomfort during treatment, with the result that more than 50% of all ESWLs could be done with sedation only or without any medication.

Analgesia↗
PubMed1979

[Gynaecomastia and mammography (author's transl)].

The term gynaecomastia indicates an increase in the mass of the normally rudimentary male breast; morphologically there is hyperplasia and differentiation of the epithelial and mesenchymal breast components. Gynaecomastia is not a disease in itself, but a symptom of some underlying disease or the result of drugs. Of 2895 breast operations performed at the surgical clinic of the University of Göttingen, 2.97% were operations on men with gynaecomastia. Amongst 79222 mammograms in the Radiological Clinic of the University, there were 900 mammograms (1.14%) of 392 men with gynaecomastia. Most benign and malignant conditions in men are retromammary in localisation. For this reason clinical evaluation is frequently wrong. The use of mammography as an additional diagnostic method in men is therefore more important than it is in women. Systematic analysis of the mammograms performed on men has made possible a classification of gynaecomastia according to the radiological appearances: I Septal linear structures (8.5%), II Opacities of varying density and size (26.5%), III Circular, usually inhomogenous shadows (15.5%), IV Homogeneous, demarcated foci of varying size (35.5%), V Soft-tissue hyperplasia-pseudo-gynaecomastia (10%).

Adolescent↗
PubMed1979

[Differential diagnosis of gynaecomastia in the mammogram (author's transl)].

The purely clinical examination of swelling in the region of the male mammary gland involves a high error quota and must, therefore, be supplemented by other methods. Mammography has proved to be a reliable diagnostic method in the differential diagnosis of diseases of the mammary gland in the male; this method is of great importance in a positive sense as well. Gynaecomastia, with its typical criteria, must first of all be excluded. This enables the doctor to differentiate between various forms of gynaecomastia and to classify them into a kind of scheme. In all patients over 25 years of age, a carcinoma must be suspected particularly in case of a unilateral finding.

Adolescent↗
PubMedDate not supplied

Predictability of the size of laser-induced lesions in T1-Weighted MR images obtained during interstitial laser-induced thermotherapy of benign prostatic hyperplasia.

The purpose of this study was to predict diameters of lesions induced by laser-induced thermotherapy (LITT) of benign prostatic hyperplasia (BPH) from MRI signal/tissue temperature correlations during on-line monitoring with a temperature-sensitive fast low-angle shot (FLASH) sequence. Twenty LITT procedures with Nd:YAG (1,064 nm) and diode (830 nm) lasers were monitored on line with a T1-weighted FLASH sequence at 1.5 Tesla. Interstitial prostate temperature (T) was measured on line in 10 LITT procedures and laser energy deposition in 12. Slopes of linear regression curves for signal intensity (SI) over T were applied to determine SI at 60 degrees C to estimate diameters of intraprostatic LITT lesions. Diameters of unperfused LITT lesion cores in contrast-enhanced T1-weighted images served as gold standards. Linear regression curves with an average slope of -.54% SI/degrees C were obtained in 17 LITT procedures. Correlation coefficients were r = .92-.95 for SI/T and SI/energy deposition. Baseline variation of SI at body temperature was +/-3.9%, corresponding to +/-7 degrees C. Prediction of size (13 lesions) from on-line FLASH imaging was correct in 10 of 13, whereas 3 lesions were overestimated. Prediction of LITT lesion diameters from on-line MRI monitoring is possible with a temperature-sensitive FLASH sequence in the prostate. Accuracy may suffice to assign target regions of interest to tissue locations to be protected from coagulation.

Aged↗