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At least 253 records · Page 14Linked to original sources

PubMed2005

Changes in multifocal electroretinograms induced by transpupillary thermotherapy.

OBJECTIVE: To determine retinal function after transpupillary thermotherapy (TTT) for subfoveal choroidal neovascularization using multifocal electroretinograms (mfERGs). METHODS: Multifocal electroretinograms were recorded before and after TTT (wavelength, 810 nm; diameter, 3 mm; duration, 60 seconds; power, 350 mW) in 9 eyes in 9 patients with subfoveal choroidal neovascularizations. The stimulus consisted of 7 hexagons; the central hexagon covered the laser-irradiated area and the surrounding 6 hexagons covered the nonirradiated area. Each recording was completed within 1 minute, and mfERGs were recorded periodically during the first 60 minutes after TTT and also at 24 hours and 1 week after TTT. RESULTS: The amplitude of mfERGs from irradiated areas was significantly reduced at 1 minute after TTT (P< .01) and then recovered soon. The peak time was prolonged at 15 minutes after TTT (P< .01), recovered to pre-TTT levels at 60 minutes, and then was prolonged again at 24 hours (P< .05) and 1 week (P< .05) after TTT. The mfERGs in nonirradiated areas were unchanged during the observational period. CONCLUSIONS: We found amplitude reduction in central focal ERGs at 1 minute after TTT, transient peak-time delay at 15 minutes, and a delay at 24 hours. Early reduction is probably directly caused by an increase in temperature during TTT as previously reported in focal flicker ERGs. Peak-time delays at 15 minutes and 24 hours may be caused by other factors, such as increased intracellular calcium (Ca(2+)), the release of nitric oxide or heat shock proteins, vasodilation, or change in choroidal neovascularization. Our findings indicate that recording mfERGs may be a useful tool for evaluating TTT procedures.

Adult↗

PubMed1995

Transpupillary thermotherapy in choroidal melanomas.

OBJECTIVE: To determine safety and efficacy of transpupillary thermotherapy (TTT) as a new treatment for choroidal melanoma. METHODS AND PATIENTS: To perform TTT, diode laser energy at 810 nm was used with a beam diameter of 1.5 to 4.5 mm for a 1-minute exposure. All 12 patients had choroidal melanoma. Six had had insufficient response to ruthenium 106 (106Ru) brachytherapy. Three patients with tumors more than 5 mm in height were treated simultaneously with 106Ru and TTT. Three patients with juxtapapillary or macular tumors were treated by TTT only. RESULTS: All but one tumor exhibited a reduction of tumor height in a follow-up period of 3 to 14 months. Side effects were minimal. Severe visual loss occurred in two patients due to radiation retinopathy, in two patients whose foveas were included in the TTT area, and in one patient resulting from a serous retinal detachment that extended over the posterior pole. CONCLUSIONS: Treatment with TTT may be useful as a complementary modality to brachytherapy. A longer follow-up period is required for final evaluation.

Brachytherapy↗

PubMed1996

In vitro studies and computer simulations to assess the use of a diode laser (850 nm) for laser-induced thermotherapy (LITT).

BACKGROUND AND OBJECTIVE: This study investigated the feasibility of 850 nm diode laser-induced thermotherapy (LITT), a new procedure providing local hyperthermia and photocoagulation, a minimally invasive treatment of tumors, and other disorders such as benign prostate hyperplasia. STUDY DESIGN/MATERIAL AND METHODS: An improved fiber optic diffuser inserted through a catheter was used to irradiate prostate, liver, and kidney tissue in-vitro. Experimental results were compared with predictions from mathematical simulations based on measured optical tissue parameters. RESULTS: After 10 minutes of irradiation with 2-4.6 W CW laser power, sizable coagulation diameters had been achieved. In prostate and kidney tissue, temperature rises and coagulation diameters after laser irradiation were found to be smaller than in liver tissue. Those tissues also had a higher threshold for carbonization, thus reducing the risk of damage to the delivery system. CONCLUSION: The data suggest that a low power diode laser can be recommended for use in LITT to treat prostate and kidney tissue.

Animals↗

PubMed1997

Transurethral balloon laser enhanced thermotherapy in the canine prostate.

BACKGROUND AND OBJECTIVE: Hyperthermia is performed for prostate cancer. We examined the selective induction of coagulonecrotic changes in the objective area of the canine prostate in enhancing the effect of hyperthermia and treating the target area with transurethral balloon laser enhanced thermotherapy (TUBAL-ET) using a light absorbent material. STUDY DESIGN/MATERIALS AND METHODS: The heat exchange of ultrafine carbon particles after laser irradiation was observed in a phantom study using thermography. The carbon solution was injected at the right prostatic lobe in dogs and TUBAL-ET was performed. RESULTS: The charcoal absorbed the Nd:YAG laser energy and apparently converted it into thermal energy in the phantom study by thermographic observation. TUBAL-ET induced coagulonecrotic changes only at the area at which carbon had been injected in the prostate gland. The necrotic tissue was almost absorbed at four weeks after treatment. CONCLUSIONS: TUBAL-ET induces tissue damage at the target area in the prostate gland.

Animals↗

PubMed1998

Nd: YAG interstitial laser thermotherapy in the treatment of breast cancer.

BACKGROUND AND OBJECTIVE: "Minimal treatment strategy" is desirable in certain breast cancer patients. The main objective of the present study is to examine the use of interstitial laser thermotherapy (laserthermia) for this purpose. STUDY DESIGN/MATERIALS AND METHODS: Thirty-five patients with primary breast cancer were treated with laserthermia using the Nd:YAG (1,064 nm) pulse-wave laser. In 28 patients, laserthermia was performed before radical resection, and in seven patients it was the only invasive treatment. RESULTS: One gaseous rupture of tumor occurred at 3 Watts. The diameter of single focus of laser-induced damage after 1-2 Watts was less than 1 cm, and after 2.5-6 Watts it reached 1.5-2.5 cm. Of seven patients treated without surgery, local tumor control was achieved in five, and in three stage I-III patients disease-free survival followed for 19-60 months. After laserthermia plus surgery, 3-year disease-free survival was 27% in premenopausal and 92% in menopausal patients. CONCLUSIONS: It seems that laser destruction of relatively small primary breast cancer is possible. Provisionally, laserthermia should not be used in premenopausal patients.

Adult↗

PubMed1999

Simplified treatment planning for interstitial laser thermotherapy by disregarding light transport: a numerical study.

BACKGROUND AND OBJECTIVE: The objective was to investigate the effect of light transport on the temperature distribution and the coagulated volume under conditions relevant to interstitial laser thermotherapy (ILT) of tumors in the human liver. STUDY DESIGN/MATERIALS AND METHODS: Temperature distributions and coagulated volumes produced with a diffusing laser fiber or a conductive heat source, at equal output power, were numerically calculated for tissue with different optical penetration depths. Four irradiation times (5, 10, 20, and 30 min) were studied. A three-dimensional finite-element model was used to calculate the temperature distribution during heating with four conductive heat sources (no light emission). Results were compared with measured temperature distributions during laser irradiation in a gel phantom with known optical properties. RESULTS: Numerical calculations showed that the influence of light transport on the coagulated volume was negligible in tissue with optical penetration depths below 3-4 mm at all studied irradiation times. The phantom experiment indicated good agreement with the calculated temperature distribution, both with a single diffusing laser fiber and with four fibers. CONCLUSION: Light transport influences coagulated volumes only slightly under conditions presented in this work, which is relevant to ILT of tumors in the human liver.

Culture Techniques↗

PubMed1996

Transurethral microwave thermotherapy for benign prostatic hyperplasia: relation between clinical response and prostate histology.

The effectiveness of transurethral microwave thermotherapy (TUMT) for BPH has been confirmed. To identify the characteristics of the ideal candidate, retrospective analysis and morphometric study of prostatic tissue were performed. Forty-two patients with symptomatic BPH were included in the study; these comprised 10 patients treated for more than 3 months with anti-androgen pre-TUMT (group A) and 32 fresh cases (group B). Subjective and objective responses were evaluated at 2 months post TUMT. In 12 fresh cases who underwent pre-TUMT biopsy of the prostate, the stromal-to-epithelial ratio was determined via quantitative image analysis on a computer-assisted morphometry system. No significant differences in baseline patient characteristics were found between the two groups: age, prostate volume, peak flow rate (PFR), or International Prostate Symptom Score (I-PSS). However, significant differences in treatment outcome were found between the two groups (group A vs. group B, respectively): total energy delivered to the prostate: 96 kJ vs. 125 kJ: I-PSS decrease from baseline: 5.9 vs. 11.6; PFR increase from baseline: 1.1 vs. 4.7 ml/sec. There was a positive correlation between the I-PSS change from baseline and the stromal-to-epithelial ratio of the prostatic tissue (r = 0.4857). The results suggest that microwave interacts poorly with the prostate due to the artificially created "lack" of glandular tissue. The morphometric study also supports the contention that the histological composition of the prostatic tissue plays an important role in terms of microwave thermal interactions and treatment outcome.

Aged↗

PubMed1998

Analysis of outcome after thermotherapy using different classifications of bladder outlet obstruction.

The urodynamic profiles of 97 patients with benign prostatic hyperplasia undergoing low-energy transurethral microwave thermotherapy (TUMT) for lower urinary tract symptoms were analysed using the Abrams/Griffiths nomogram, the urethral resistance algorithm, the linPURR, Schäfer nomogram, and the CHESS classification. A significant clinical response was seen for the whole group, as shown by changes in symptom score, free flow rate, and residual urine. The best symptomatic response was identified in patients in whom obstruction was present, whatever the classification used. Only the two-dimensional CHESS classification was found to predict a group of patients with a better response in both symptoms and objective variables. Obviously, a better response from TUMT can only be predicted by a classification system that identifies the independent variables of footpoint and slope of the PURR. The CHESS classification was the only one of those studied that satisfactorily identified these two parameters and could be used as a system of case selection for this minimally invasive treatment.

Aged↗

PubMed2001

Interstitial laser thermotherapy in the treatment of colorectal liver metastases.

Metastatic liver disease is the commonest cause of death in patients with colorectal cancer. A small proportion of these patients (10%) may be treated by surgical resection with five year survival approaching 35-40%. Alternative treatment modalities for localised hepatic disease include in situ ablative techniques that have the advantages of percutaneous application and minimal morbidity. These include Interstitial Laser Thermotherapy (ILT), Radio Frequency Ablation, Percutaneous Microwave therapy, and Focussed Ultrasound Therapy. This article focuses specifically on the development and utilisation of ILT in the treatment of colorectal liver metastases. It provides a review of the pathophysiological factors involved, present status of clinical studies, and future directions. ILT is a safe technique for the treatment of colorectal liver metastases. It may be delivered by minimally invasive techniques to lesions considered unresectable by present criteria. Limitations include the extent and completeness of tumour necrosis achieved as well as imaging techniques. Clinical problems include a lack of controlled studies. Assessment of long-term survival in prospective randomised trials is needed to assess the efficacy of this procedure.

Colorectal Neoplasms↗

PubMed2001

Intra-prostatic vasculature studies: can they predict the outcome of transurethral microwave thermotherapy for the management of bladder outflow obstruction?

BACKGROUND: Blood perfusion regulates intraprostatic temperatures during transurethral microwave thermotherapy (TUMT). We evaluated baseline intraprostatic vasculature, as a predictor of efficacy of TUMT. METHODS: Twenty-two patients, with lower urinary tract symptoms (LUTS) suggestive of bladder outflow obstruction, were treated with TUMT (Prostatron). At baseline, three-dimensional contrast-enhanced power-flow-Doppler prostate ultrasonography (3D-CE-PFD) was performed. Assuming that the percentage of perfused area (PPA) is a realistic measure of blood flow, it was used to quantify intraprostatic vasculature. RESULTS: The median (range) age, prostate size, and energy delivered were 66 years (48-80), 47 cm(3) (30-121), 110 kJ (29-136), respectively. The response was 77% (5 failures). The median (range) PPA was 2.76% (0.7-11.3). No difference in PPA among good and poor responders was detected nor was any correlation between PPA and baseline parameters. CONCLUSIONS: The baseline intraprostatic vascularization, documented by CE-PFD studies, has no predictive value for the efficacy of TUMT. It seems that "static" baseline blood flow does not reflect the "dynamic" thermoregulatory role of blood flow during treatment.

Aged↗

PubMed1979

A histopathologic study on the effects of radiofrequency thermotherapy on malignant tumors of the lung.

Malignant cells are thermosensitive but this does not fully explain the wide-spread pathologic changes observed in solid cancers following local therapy with radiofrequency heating. The histopathology of human malignant tumors after radiofrequency thermotherapy reveals not only the expected degeneration of tumor cells, but significant changes in the tumor's stroma as well. Stromal blood capillary walls are massively infiltrated with round cells and undergo degenerative changes leading to necrosis and obliteration of the tumor's vascular supply. Extensive infiltration of the stroma with the host's round cells occurs. Following focal necrosis and rupture of the stroma, pools of lymphocytes establish direct contact with heat damaged malignant cells leading to further destruction of persisting tumor. The histologic signs of the generalized breakdown of lung tumors consequent to radiofrequency heat-therapy bear close resemblance to lesions in acutely rejecting organ allografts.

Adenocarcinoma↗

PubMed1990

Radiofrequency thermotherapy for malignant liver tumors.

Inoperable malignant liver tumors have been treated by radiofrequency hyperthermia at Kyoto University Hospital since 1983. In this study, clinical hyperthermia for malignant liver tumor was evaluated for 67 tumors in which we could measure intratumor temperatures. Of the 67 tumors, 41 were hepatocellular carcinomas (HCC), six cholangiocarcinomas, and 20 metastatic tumors. Cholangiocarcinoma and metastatic tumors were more susceptible to this treatment than HCC. Of the three types of HCC, higher intratumor temperatures were achieved in the diffuse type than in the nodular or massive types. The minimum tumor temperature of HCC stayed below 40 degrees C in 46% of cases, especially in larger tumors. The local response rates (complete remission plus partial remission/all) were 28% and 11% for HCC and non-HCC, respectively, for thermochemotherapy; 86% and 33%, for thermoradiotherapy; and 33% and 89%, for thermotherapy with embolization. No apparent relationship was observed between the intratumor temperatures and local response rate.

Adenoma, Bile Duct↗

PubMed1993

Long-term results of postoperative intrathoracic chemo-thermotherapy for lung cancer with pleural dissemination.

BACKGROUND: To overcome the poor prognosis of lung cancer with pleural dissemination, the authors developed postoperative intrathoracic chemo-thermotherapy (PICT). In this report, they present the long-term results for 31 consecutive patients who underwent resection, followed by PICT for lung cancer with pleural dissemination between April 1985 and December 1991. METHODS: Among the patients, there were 26 cases of adenocarcinoma, 3 cases of squamous cell carcinoma, and 1 case each of large and adenosquamous cell carcinoma. Twenty-four of these patients had an initial diagnosis of pleural involvement at thoracotomy. The other seven patients had massive malignant effusion at the time of the initial diagnosis. PICT was started between days 10 to 14 postoperatively. When possible, three courses of this procedure were administered at intervals of 5-7 days. RESULTS: The 5-year cumulative and 5-year local relapse-free survival rates were 24.6% and 76.3%, respectively. The 3-year and 5-year cumulative survival rates for 14 patients without mediastinal lymph node involvement were 68.4% and 42.7%, respectively. Those rates for 17 patients with mediastinal lymph node involvement were 22.7% and 0%, respectively. The 3-year survival rate in the former group was significantly better than that in the latter group. CONCLUSIONS: These results strongly suggest that in patients with pleural dissemination, PICT may be beneficial for regional disease control and improvement of survival, particularly for patients without mediastinal lymph node involvement.

Adenocarcinoma↗

PubMed2001

MR-guided interstitial laser-induced thermotherapy of hepatic metastasis combined with arterial blood flow reduction: technique and first clinical results in an open MR system.

The feasibility and safety of percutaneous laser-induced thermotherapy (LITT) of liver metastases in an open low-field magnetic resonance imaging (MRI) system combined with microsphere-modulated blood flow reduction were tested. Nd:YAG laser therapy with an internally cooled laser applicator was performed under local anesthesia on 20 patients with 34 liver metastases. To increase the effectiveness of LITT, degradable starch microspheres were injected into the proper hepatic artery through an MR-visible catheter initially inserted under fluoroscopy. Near real-time imaging was used for positioning the laser applicator. A T1-weighted gradient-echo breath-hold sequence was used for catheter localization and temperature monitoring. The volumes of the liver metastases and the thermonecroses were determined. MRI-guided LITT could be performed in all patients with no clinically relevant complications. Intraprocedural imaging underestimated the extent of thermonecrosis. In conclusion, percutaneous LITT of liver metastases after injection of starch microspheres is both technically feasible and safe in an open MRI system. J. Magn. Reson. Imaging 2001;13:31-36.

Aged↗

PubMed2001

Perioperative prediction by MRI of prostate volume six to twelve months after laser-induced thermotherapy of benign prostatic hyperplasia.

The purpose of this study was to predict prostate volume outcome 6-12 months after interstitial, laser-induced thermotherapy (LITT) for benign prostatic hyperplasia (BPH) on the basis of prostate magnetic resonance (MR) images obtained within 48 hours before and after LITT. Twenty patients (age, 64.2 +/- 7.4 years) with symptomatic BPH had LITT of the transitional zone of the prostate. MRI was performed within 48 hours before and after LITT, and 6-12 months after LITT (late follow-up). MRI included axial and sagittal T2-weighted fast spin-echo (FSE) images and contrast-enhanced, axial T1-weighted images. Volumes of different prostatic compartments (total prostate, transitional zone, peripheral zone, LITT lesions) were measured by planimetry. Subtraction of LITT lesion volume less than 48 hours after LITT from total and transitional zone volume before LITT, respectively, predicted respective prostatic volumes at late follow-up. Pearson correlations of predicted and measured total prostate and transitional zone volumes were 0.972 and 0.975, respectively. Total prostate volume at late follow-up was accurately predicted (difference, -0.5 +/- 5.7 cc; P = 0.6981, two-tailed paired t-test). Transitional zone volume was underestimated (difference, -3.1 +/- 4.7 cc; P = 0.0075). Peripheral zone volume was overestimated (difference, 2.6 +/- 3.5 cc; P = 0.0034). Perioperative MRI allows accurate prediction of prostate volume 6-12 months after LITT for BPH. Underestimation of transitional zone volume may be due to ongoing growth of BPH. LITT appears to affect peripheral zone tissue outside the target region. J. Magn. Reson. Imaging 2001;13:64-68.

Follow-Up Studies↗

PubMed2003

Interstitial laser thermotherapy for liver tumours.

BACKGROUND: Primary hepatocellular carcinoma (HCC) and metastases from colorectal cancer are the most common malignant liver tumours. Surgical resection is the optimum treatment in suitable patients. Interstitial laser thermotherapy (ILT) is gaining acceptance for the treatment of irresectable liver tumours and as a potential alternative to surgery. An understanding of the principles of therapy and review of clinical outcomes may allow better use of this technology. METHOD: An electronic search using the Medline database was performed for studies on the treatment of hepatic malignancy published between January 1983 and February 2003. RESULTS: Current information on the efficacy of ILT is based on prospective studies. ILT appears to be a safe and minimally invasive technique that consistently achieves tumour destruction. The extent of destruction depends on the fibre design, delivery system, tumour size and tumour biology. Real-time magnetic resonance imaging provides the most accurate assessment of laser-induced tumour necrosis. In selected patients with HCC and colorectal cancer liver metastases, ILT achieves complete tumour necrosis, provides long-term local control, and improves survival, compared with the natural history of the disease. In addition, ILT has survival benefits for patients with other tumour types, especially those with isolated liver metastases from a breast cancer primary. CONCLUSION: ILT improves overall survival in specific patients with liver tumours. Advances in laser technology and refinements in technique, and a better understanding of the processes involved in laser-induced tissue injury, may allow ILT to replace surgery as the procedure of choice in selected patients with liver malignancies.

Breast Neoplasms↗

PubMed2003

Laser-induced thermotherapy (LITT) of liver metastases: MR-guided percutaneous insertion of an MRI-compatible irrigated microcatheter system using a closed high-field unit.

PURPOSE: To evaluate the efficacy and safety of a new MRI-compatible irrigated laser microcatheter system for thermal ablation of liver metastases. MATERIAL AND METHODS: The new microcatheter system consists of a titanium needle with a diameter of 1.5 mm and a surrounding Teflon catheter with an outer diameter of 1.8 mm (5.5 F). In vitro laser-induced coagulation of bovine liver tissue was performed to determine the optimal perfusion rate of cooling saline flow, maximum laser energy, and ablation time. Laser-induced thermotherapy using the new microcatheter system, an Nd:YAG laser (Dornier), and a flexible laser light guide (Somatex GmbH, Berlin, Germany) was performed in 28 patients with liver metastases. Percutaneous insertion and positioning of multiple microcatheters in the lesion and monitoring of therapy was performed with a closed high-field MRI scanner using T1-weighted gradient-echo sequences during breath-hold. RESULTS: A perfusion rate of 0.75 mL/minute, a laser energy of 15 W, and an ablation time of 20 minutes were found suitable to achieve safe and sufficient ablation of metastatic tissue. The mean volume of induced coagulation in vitro was 23.9 mL. Ablation of liver metastases in patients was technically and clinically successful. CONCLUSION: The new microcatheter system allows for both catheter placement and monitoring of therapy using a single imaging modality. This shortens the procedure and enables more precise puncture and therapy of liver metastases. Due to the miniaturized design of the catheter and the real-time monitoring, the procedure is minimally invasive and very well tolerated by patients. This new technique seems to be a safe and feasible alternative in treating liver metastases.

Aged↗

PubMed2001

Laser-induced interstitial thermotherapy of liver metastases in an interventional 0.5 Tesla MRI system: technique and first clinical experiences.

Laser-induced interstitial thermotherapy (LITT) surveyed by magnetic resonance imaging (MRI) has been shown to be effective in various applications. The laser treatment of colorectal liver metastases usually requires a separate device (e.g., ultrasound or CT) to position the laser applicator. In this study, we used an interventional 0.5 T MRI system, allowing both the navigation to the target tissue and on-line thermometry. Laser irradiation was performed using a near-infrared laser source combined with a cooled laser light guide. We treated 20 patients exhibiting a total of 58 colorectal liver metastases. Clinically relevant complications did not occur. No residual tumor was observed after laser irradiation in all metastases with a diameter below 2 cm. Metastases with a mean diameter between 2 and 3 cm demonstrated total necrosis in 71%, while in larger tumors this proportion decreased to 46% (diameter, 3-4 cm) and 30% (diameter, >4 cm), respectively. We conclude that LITT, guided by the employed interventional MRI system, is feasible and safe. The results suggest a more aggressive treatment, especially for larger metastases. J. Magn. Reson. Imaging 2001;13:729-737.

Aged↗