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At least 721 records · Page 40Linked to original sources
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↗
PubMed1994

Neurophysiological assessment of peripheral neuropathy in primary Sjögren's syndrome.

Peripheral nervous system complications are rare in patients with primary Sjögren's syndrome. We investigated a group of six women aged 43-64 years who complained of pain and sensory symptoms. Conventional neurophysiological tests reflecting large nerve fiber function revealed normal motor conduction in all patients, whereas sensory nerve action potentials were absent in two. On the other hand, quantitative thermometry and autonomic nerve function tests indicating small nerve fiber function were more sensitive in the assessment of nerve dysfunction; these showed abnormalities in all cases. Vibrametry showed dysfunctions in four patients. The latter methods possess great sensitivity in discovering sensory disturbances. Neurophysiological assessment of the sensory and autonomic nervous system demonstrating sensory neuropathy contributes to early diagnosis of primary Sjögren's syndrome.

Adult↗
PubMed1980

Minimum phototoxicity dose (MPD). Comparison of conventional light sources and different lasers.

A pilot study was performed on groups of 5-7 volunteers to evaluate the minimum phototoxicity dose (MPD) of several light sources with different UVA qualities to optimise photochemotherapy. Visual observation was more suitable than reflection photometry in determining the threshold and gradation of erythema reactions; thermometry gave poor results. There were no individual differences between the MPD of a PUVA 4000 box and a continuously emitting argon-ion laser with 40 and 400 mW, respectively. The pulsed radiation of a nitrogen laser was the most effective. The limited validity of the Bunsen-Roscoe law for high peak power could thus be tested for a secondary photochemical reaction of the skin. The nitrogen laser (337.1 nm) proved that a repetition rate of 20 Hz was superior to 10 and 40 Hz. The MPD was intraindividually higher at 25 Hz than at 10 and 16.7 Hz for the dye laser tested (325 and 330 nm, respectively).

Dose-Response Relationship, Radiation↗
PubMed1988

Hyperthermia in cancer therapy.

Tumor hyperthermia is a rediscovered technique of oncotherapy which has confirmed value in many studies on cell cultures, rodent and mammalian tumors as well as first investigations on patients with tumors. The biological basis for using heat in the treatment of cancer is well established. Various direct and indirect mechanisms are significant for the effect of hyperthermia on tumor tissue. Whereas there are already extensive studies on the direct effects of hyperthermia on DNA, RNA, and protein synthesis, energy metabolism, and the membrane properties of tumor cells, the indirect effects have only been investigated more closely in recent years. These are likewise important for the damage to the tumor tissue and are mediated above all via alterations in the microcirculation and the environment. The recently gained increasing significance of this new technique in combination with other treatment modalities is well documented. Technical problems of heat application must be overcome, especially in deeper tumors and problems of thermometry must be solved in order to be able to apply tumor hyperthermia not only to selected advanced or recurrent tumors, but in order to use it as the fourth pillar of tumor therapy besides surgery, radiotherapy and chemotherapy. This article considers the biological basis and important aspects of hyperthermia therapy in combination with radiotherapy and chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1980

Clinical requirements for localized hyperthermia in the patient.

The physical and mechanical parameters to be considered when contemplating hyperthermia as a cancer treatment modality are discussed. These parameters include heat field size, uniformity of heating, method of hyperthermic production, selection of energy, heat flow, warm-up period and thermometry.

Hot Temperature↗
PubMed1991

Improvement of local control by regional hyperthermia combined with systemic chemotherapy (ifosfamide plus etoposide) in advanced sarcomas: updated report on 65 patients.

From July 1986 to 1990, 65 patients with deep-seated, advanced sarcomas (43 soft-tissue sarcomas, 12 Ewing's sarcomas, 7 chondrosarcomas and 3 osteosarcomas) were entered in a protocol involving regional hyperthermia (RHT) combined with systemic ifosfamide and etoposide. RHT was produced by an electromagnetic deep regional heating device (BSD Medical Corporation, Salt Lake City, Utah). Of these patients, 62% (40 patients) had received ifosfamide-containing drug regimens before entering the RHT study, 26% (17 patients) were pretreated by surgery and/or radiation and 12% (8 patients) were treated primarily. A total of 426 RHT treatments (mean 6.6 RHT/patient) were applied predominantly within the pelvic region (82%) bearing relative large tumours (mean volume 500 cm3). For systemic chemotherapy, all patients received ifosfamide (1.5 g/m2, days 1-5), etoposide (100 mg/m2, days 1, 3, 5) and 2-mercaptoethanesulphonic acid (mesna; 300 mg/m2 x 4, days 1-5) with RHT only given on days 1 and 5 in repeated cycles every 4 weeks. Detailed thermal mapping by invasive thermometry was performed in all patients. In 61 patients evaluable for tumour control the overall objective response rate including 9 complete responders (CR), 4 partial responders (PR) and 8 patients with favourable histological response (FHR) was 34% (95% confidence limits, 23%-46%). Following CR, the patients are alive and remain disease-free (mean disease-free survival 15.6 months). Of the patients with PR and FHR, 3 died from metastatic and/or local disease after 4, 17, and 39 months, and 1 patient died from other disease (acute myelocytic leukemia) after 27 months. The other 8 patients remain stable at 29, 25, 17, 11, 10, 8, 7, and 6 months. Twenty-two patients revealed no change and 18 patients showed local tumour progression (PD). Side-effects of RHT were tolerable and there was no indication of enhanced bone marrow toxicity due to the addition of RHT to the systemic chemotherapy. By analysis of temperature parameters, the time-averaged temperatures of all RHT treatments calculated for 20% (T20), 50% (T50) or 90% (T90) of measured tumour sites differed significantly between responders (CR + PR + FHR) and non-responders (PD), respectively (T20, P = 0.001; T50, P = 0.0005; T90, P = 0.0001). the data further support a strong potential for ifosfamide plus etoposide combined with RHT in pretreated patients with advanced sarcomas.

Adolescent↗
PubMed1993

The esophageal temperature gradient in anesthetized children.

OBJECTIVE: Our objective was to study the effect of the temperature of the anesthetic gas mixture (AGM) on esophageal temperature measurements made in children whose tracheas had been intubated for anesthesia. We also sought to establish the optimal site for the temperature sensor in the esophagus and to find a way to accurately place the sensor. METHODS: Special esophageal temperature probes with thermistors located at 1-cm intervals were used for data collection on a multiplex system. Esophageal temperature measurements were made every 15 minutes for a period of 120 minutes in anesthetized children receiving heated (n = 30) and unheated (n = 30) anesthetic gases. RESULTS: The temperature of the AGM (p < 0.001), the site of measurement (p < 0.001), and the interaction between AGM temperature and site of measurement (p < 0.007) all had a significant effect on esophageal temperature measurements. This effect was greatest at a point 3 cm distal to the level of the tip of the endotracheal tube when AGMs were not heated. CONCLUSION: We conclude that best results are obtained when care is taken to place the thermistor in the lower quarter of the esophagus. (We provide a simple formula for calculating this placement in pediatric patients of varying ages.) Placing the probe by acoustic criteria cannot consistently be relied on to provide good thermometry.

Analysis of Variance↗
PubMed1992

Laser Doppler measurements of skin blood flow before, during, and after lumbar sympathetic blockade in children and young adults with reflex sympathetic dystrophy syndrome.

Changes in the skin capillary blood flow (SBF) and temperature before, during, and 1 hour after unilateral lumbar paravertebral sympathetic blockade (LSB) were studied simultaneously with laser Doppler flowmetry and thermometry in patients with reflex sympathetic dystrophy syndrome. The baseline flow measurements in the toes on the affected limb were significantly lower than in the contralateral limb (p less than 0.01). During LSB, a 10-fold increase in SBF was detected within 4 minutes after injection of a local anesthetic agent when the sympathetic blockade was effective; an increase of more than 1 degrees C in the skin temperature occurred within 11 minutes. Measurements 1 hour after blockade showed an 18-fold (mean) increase in SBF in the toes (p less than 0.0001) and a 2-fold (mean) increase in SBF in the thighs (p less than 0.001). There was a significant decrease in the skin blood flow in the contralateral toes after the sympathetic blockade (p less than 0.01). We conclude that laser Doppler flow measurements can be used to detect immediate onset of sympathetic blockade in patients under general anesthetic or conscious sedation.

Adolescent↗
PubMed1990

A breast pre-cancer test? Preliminary results based on a breast temperature rhythm abnormality during the menstrual cycle.

This study documents the menstrual thermal cycle of 16 breasts considered at normal risk for breast (8 women) and 15 breasts considered at high risk for breast cancer (i.e. ipsilateral N = 7 or contralateral N = 8 to a previously [locally] excised carcinoma). The surface thermometry studies were carried out for 1 1/2 hours each evening for one menstrual cycle using a special automated instrumentation, the 'Chronobra', with the subject at home. The surface temperatures were adjusted to remove the fluctuations in arterial blood temperature during the menstrual cycle, so that they are thought to represent a breast-specific menstrual rhythm. Across subjects, the cycles were synchronised by the day of the progesterone peak obtained by radioimmunoassay of saliva collected daily. Following ovulation, the normal risk breasts exhibited a steady rise of temperature for 14 days to a well defined peak. In contrast the 'high-risk' breasts exhibited a continuous hyperthermia with smaller peaks. Linear discrimination analysis by multiple regression achieved a complete separation of the individual normal and 'high-risk' data sets. The method shows promise for the development of a non-invasive screening test for breast pre-cancer in premenopausal women.

Adult↗
PubMed1999

Thermal distribution of radio-frequency inductive hyperthermia using an inductive aperture-type applicator: evaluation of the effect of tumour size and depth.

A new radio-frequency (RF) inductive hyperthermia device using an inductive aperture-type applicator (IATA) is proposed. This paper reports the evaluation of the heating characteristics of the IATA using a computer simulation and clinical thermal parameters obtained during treatment of superficial and subsurface-seated tumours. The configuration of the IATA is a one-turn square column-like coil whose bottom plate is set to face the heating target. The IATA has advantages over RF capacitive-type heating, such as: generating less heat in the subcutaneous fat layer; less convergency of electric line of force at the edge of the applicator; and no physical contact with the target lesion. The induced magnetic fields and electrical currents within the heating substance are simulated using computer-assisted design software for electro-magnetic analysis. A total of 40 superficial and subsurface tumours are treated with the IATA. Invasive thermometry is performed continuously for 110 sessions using multi-sensor probes of an optical thermometer. Thermal parameters (Tmax, Tmin, Tave) are assessed based on the tumour size and depth. The treated tumours are categorised into three groups according to tumour depth: group 1 (< 3 cm, n = 28), group 2 (3-5 cm, n = 35) and group 3 (> 5 cm, n = 47). The computer simulation shows that induced electrical currents run without convergency, parallel to the surface of the heating material. All thermal parameters of group 3 are significantly higher than those of group 1 and 2 (p < 0.05), indicating that the larger lesions tend to abtain a higher temperature distribution. In conclusion, RF inductive hyperthermia using the IATA results in effective temperature distributions in superficial and subsurface tumours, with large tumours being most effectively heated.

Aged↗
PubMed1990

Does forehead liquid crystal temperature accurately reflect "core" temperature?

Liquid crystal thermometry (LCT) is a non-invasive alternative to temperature monitoring. We evaluated the ability of forehead LCT, rectal temperature, and axillary skin temperature to trend distal oesophageal temperature during rapid warming on cardiopulmonary bypass. In 24 patients undergoing open heart surgery, temperatures were measured during the rapid warming phase on bypass (12-35 min). Scattergrams of temperature vs time for the four temperature sites each contained 150 data points. Polynomial regression analysis revealed that LCT, but not axillary or rectal temperatures, correlated with oesophageal temperature. We conclude that forehead LCT may be useful to monitor temperature trends and to detect rapid elevations in body temperature when more invasive temperature monitoring is inappropriate or unavailable.

Analysis of Variance↗
PubMed2005

The accuracy of a new infrared ear thermometer in patients undergoing cardiac surgery.

PURPOSE: To evaluate the equivalency of the prototype of a new infrared ear thermometer (IRT 4000) in comparison to the temperature measurements of a pulmonary artery catheter (PAC) and a continual contact probe on the tympanic membrane. METHODS: After approval by the local Ethics Committee, 26 (six female and 20 male) patients undergoing elective cardiac surgery were included in a single center open trial. During surgery, temperature measurements were recorded with the IRT 4000 in the left ear, and with a tympanic contact probe in the right ear, as well as with a PAC as reference. Measurements with the infrared ear thermometers and continual PAC values were recorded every six minutes. RESULTS: The average temperature measured with the IRT 4000 was 0.08 degrees C above the temperature of the PAC (95% confidence interval from -0.44-0.61 degrees C). CONCLUSION: Infrared ear thermometers 4000 temperature readings accurately reflect body core temperature and correlate well with the invasive PAC. Infrared ear thermometers may present a clinically useful alternative to the pulmonary artery thermometry for the measurement of core temperature in the perioperative setting or in the intensive care unit.

Aged↗
PubMed2001

Relationship between thermal parameters and tumor response in hyperthermia combined with radiation therapy.

BACKGROUND: In hyperthermia for cancer therapy, thermal parameters related to tumor response have not yet been clarified. We investigated thermal parameters that could predict tumor response to hyperthermia combined with radiotherapy in locally advanced malignancies. METHODS: Fifty-four patients with locally advanced malignancies who were treated by hyperthermia in combination with radiation therapy were enrolled in this study. Local hyperthermia was induced by ultrasound heating equipment for 60 min, within 30 min after irradiation, twice a week, for a total of six to ten sessions. Radiation therapy was administered with a conventional fractionation regimen, at a total dose of 40-70 Gy. Multi-point thermometry results were obtained with every 10-s temperature data acquisition. An average of seven interstitial sites per tumor was monitored for each treatment. Univariate logistic regression analysis was used to investigate the relationship between tumor response and minimum, maximum, and average intratumor temperature (Tmin, Tmax, Tav); the cumulative minutes of treatment at temperatures exceeded by 90%, 50%, and 10% of the measured intratumoral temperatures (T90, T50, T10); and cumulative minutes of the temperature that achieved above the index temperature value in the tumor center ((Cum min T(center) > T(index)). RESULTS: Complete and partial response rates were 32.6% and 46.2%, respectively. Univariate logistic regression analysis revealed that the temperature parameters with predictive probability were highest for Cum min T(center) > 42.5 degrees C, followed by > 42 degrees C and > 41 degrees C; and T90. Cum min T(center) > 42.5 degrees C was most significantly associated with complete tumor response (P < 0.001). CONCLUSION: These results strongly suggest that hyperthermia is a useful adjunct to radiotherapy for increasing the local control of advanced malignancies, and that Cum min T(center) > 42.5 degrees C could be an important thermal parameter for predicting tumor response.

Adult↗
PubMed1999

[Interventional MR-guided laser induced thermotherapy in oncologic indications. Status and prospects].

MR-guided LITT (laser-induced thermotherapy) is currently being evaluated for its effectiveness in clinical oncology. MR-guided LITT is defined as a minimally invasive technology based on the effects of the applied Nd-YAG laser on tumorous tissue. Due to specific characteristics of the laser-induced coagulative effect, online monitoring via MR thermometry is possible and extremely precise. In a period of 6 years 335 patients suffering from malignant soft tissue tumors were prospectively treated via MR-guided LITT. We evaluated the local tumor control rate, the rate of complications and the survival data from the clinical and MRI follow-up. Our results prove that MR-guided LITT results in a extremely low rate of side effects and an effective tumor control rate higher than 95%, depending on the size of the lesion. It is concluded that this therapeutic concept is of clinical value for patients with primary and secondary liver cancer, malignant lymph node involvement, abdominal recurrent tumors and tumors of the head and neck.

Adult↗
PubMed2001

[Pathomorphology of laser-induced interstitial tumor thermotherapy of the liver].

The aim of this study was to analyse pathomorphological findings after treatment with laser induced tumor thermotherapy (LITT) on liver tissue and to correlate the results with magnetic resonance imaging. LITT was performed ex vivo and in vivo using a Neodym-YAG-Laser. Lesions were monitored by MR-thermometry ex vivo and by contrast-enhanced MRI in vivo. After LITT the lesions were examined macroscopically, histologically, and electronmicroscopically. LITT-induced tissue damage was qualitatively evaluated, classified, and quantified by means of digital image analysis. Four different zones of tissue damage were identified within the lesions. Adjacent to the applicator the tissue was completely ablated while more peripheral lesions exhibited only sublethal cell damages seen by EM. In vivo the pattern of tissue injury followed the lobular architecture of the liver tissue. Ultrastructural examination revealed only in areas of minor tissue injury intact sinusoidal patterns. MRI overestimated the diameter of the core zone of complete tissue ablation both ex vivo and to a lesser extent in vivo.

Animals↗
PubMed2001

[Oligonodular hepatocellular carcinoma (HCC): MR-controlled laser-induced thermotherapy].

PURPOSE: To prospectively evaluate the therapeutic potential of MR-guided laser-induced thermotherapy (LITT) in patients with oligonodular hepatocellular carcinoma. MATERIAL AND METHODS: 39 patients with 61 intrahepatic lesions were treated with LITT. The Nd:YAG laser fiber was introduced with a percutaneously positioned irrigated laser application system. Qualitative and quantitative MR parameters and clinical data were evaluated. RESULTS: All patients tolerated the procedure well under local anesthesia. All observed complications were minor and no further treatment was necessary. Online MR thermometry allowed exact visualization. Lesions up to 2 cm in diameter could be efficiently treated with a single laser application, larger lesions were treated simultaneous multiapplication. In 97.5% we achieved a complete necrosis of the tumor and a 5 mm safety margin, resulting in a complete destruction of the tumor without local recurrences. Mean survival was 4.4 years (95% CI: 3.6-5.2 years) after the time of diagnoses of the HCC (Kaplan-Meier-method). CONCLUSION: In intrahepatic oligonodular involvement of hepatocellular carcinoma LITT appears to be an effective therapeutic procedure with a high tumor control rate and better survival data.

Adult↗
PubMed2002

Radiofrequency energy induced heating of bovine capsular tissue: in vitro assessment of newly developed, temperature-controlled monopolar and bipolar radiofrequency electrodes.

This in vitro investigation characterized temperature changes associated with radiofrequency (RF) energy induced heating of bovine capsular tissue using newly developed, temperature-controlled monopolar (Vulcan RF system and Vulcan, TAC-S Electrothermal Probe) and bipolar (VAPR II RF system and VAPR TC RF electrode) RF systems and electrodes. Bovine capsular tissue samples were placed in a saline bath maintained at room temperature. Both RF generators were used at settings of 75 degrees C and 40 W. The RF electrodes were placed in stationary positions on the tissue samples and activated for 1- to 10-s. A fluoroptic thermometry system was utilized to record temperatures at the RF electrode-tissue interface at 1-s intervals. The results indicated that the mean tissue temperatures for the monopolar RF electrode tended to be higher than those produced by the bipolar RF electrode, especially during the 2- to 10-s RF delivery time intervals (P<0.05). Notably, during the 2- to 10-s time intervals the monopolar RF electrode produced mean tissue temperatures that exceeded the set temperature of 75 degrees C (range of differences +1.2 to +15.7 degrees C highest mean temperature 90.7 degrees C). By comparison, the bipolar RF electrode maintained tissue temperatures relatively close to the set temperature(range of differences -3.2 to +2.7 degrees C; highest mean temperature 77.7 degrees C). These findings provide basic temperature profiles for the two new temperature-controlled RF devices.

Animals↗
PubMed2001

Radiofrequency energy induced heating of bovine articular cartilage: comparison between temperature-controlled, monopolar, and bipolar systems.

This in vitro investigation characterized temperature changes associated with radiofrequency (RF) energy induced heating of bovine articular cartilage using temperature-controlled, monopolar (Vulcan RF system and Vulcan, TAC-S Electrothermal Probe) and bipolar (VAPR II RF system and VAPR TC RF electrode) electrosurgical equipment. The RF generators were used at the same setting (set temperature 70 degrees C; 30 W). The cartilage tissue sample was placed in a saline bath maintained at room temperature. Temperatures were recorded using fluoroptic thermometry at the RF electrode-tissue interface at 1-s intervals before, during deliver of RF energy (1- and 2-s), and after (1- to 3-s). For both electrosurgical systems the mean RF electrode-tissue interface temperatures were significantly ( P<0.05) higher than the mean baseline value during delivery of RF energy (monopolar, highest mean temperature, 65.7 degrees C; bipolar, highest mean temperature, 54.1 degrees C). In general, during and after the deliver of RF energy, the monopolar RF system produced tissue temperatures that were significantly ( P<0.05) higher than those produced by the bipolar RF system. Neither electrosurgical system exceeded the set temperature of 70 degrees C. These findings provide basic tissue temperature characteristics for the newly developed, temperature-controlled RF devices applied to articular cartilage.

Animals↗