Rate of temperature increase in human muscle during 1 MHz and 3 MHz continuous ultrasound.

To achieve the thermal effects of ultrasound, the tissue temperature must be raised from 1 to > or = 4 degrees C, depending on the desired outcome of the treatment. In the past 25 years, there have been no in vivo studies that have measured rate of change in temperature during 1-MHz ultrasound treatments, and none have ever been performed with the 3-MHz frequency. Thus, we are left to pure speculation regarding how long to administer an ultrasound treatment. We performed this study to plot the rate of temperature increase during ultrasound treatments delivered at various intensities and frequencies. We inserted two 23-gauge thermistors into each subjects' medial triceps surae at the following depths: 1 MHz at depths of 2.5 and 5.0 cm (12 subjects) and 3 MHz at depths of .8 and 1.6 cm (12 subjects). Each subject received a total of four 10-minute treatments, one each at .5, 1.0, 1.5, and 2.0 W/cm2, and temperature was measured every 30 seconds. No significant difference was found in the rate of heating at the two depths (p = .987) within the same frequency and dose levels. The 3-MHz frequency heated significantly faster than the 1-MHz frequency at all doses tested (p < .001). On average, the rate of temperature increased per minute at the two depths of the 1-MHz frequency was: .04 degrees C at .5 W/cm2; .16 degrees C at 1.0 W/cm2; .33 degrees C at 1.5 W/cm2; and .38 degrees C at 2.0 W/cm2. The rate of temperature increase per minute at the two depths of the 3-MHz frequency was: .3 degrees C at .5 W/cm2; .58 degrees C at 1.0 W/cm2; .89 degrees C at 1.5 W/cm2; and 1.4 degrees C at 2.0 W/cm2. The results of this research should enable clinicians to choose the correct frequency, intensity, and treatment time when using thermal ultrasound.

Temperature change in human muscle during and after pulsed short-wave diathermy.

STUDY DESIGN: A time series design was used, with the dependent variable being gastrocnemius muscle temperature at a depth of 3 cm. OBJECTIVES: To determine the rate of temperature rise and the rate of post-treatment temperature decline in skeletal muscle following the application of pulsed short-wave diathermy (PSWD). BACKGROUND: Data on PSWD rate and longevity of heating are 20 years old and outdated. With the recent introduction of advanced diathermy equipment, results of our study would provide clinicians with much needed information regarding treatment duration. METHODS AND MEASURES: A 23-gauge thermistor was inserted into the center of the medial head of the anesthetized gastrocnemius muscle, 3 cm below the skin's surface of 20 subjects. The PSWD (27.12 MHz frequency) was applied using the following parameters: 800 bursts per second; 400 microseconds burst duration; 850 microseconds interburst interval; with a peak root mean square (RMS) amplitude of 150 W per burst and an average RMS output of 48 W. Temperature changes were documented every 5 minutes during the treatment and additionally at 5 and 10 minutes following treatment. RESULTS: The average baseline and peak temperatures were 35.84 +/- 0.93 degrees C and 39.80 +/- 0.83 degrees C, respectively. Mean temperature increases were: 1.36 +/- 0.90 degrees C (5 min); 2.87 +/- 1.44 degrees C (10 min); 3.78 +/- 1.19 degrees C (15 min); 3.49 +/- 1.13 degrees C (20 min). After the treatment terminated, intramuscular temperature dropped 0.97 +/- 0.68 degree C in 5 minutes and 1.78 +/- 0.69 degrees C in 10 minutes. CONCLUSIONS: PSWD is an effective modality if temperature elevation of deep tissue over a large area is the clinical objective.

Imaging of irradiated brain tumours. Value of magnetic resonance imaging.

Until recently, computerized tomography (CT) was the most sensitive and reliable imaging method to follow up patients with an irradiated brain tumour, but it is difficult or impossible with CT to differentiate between radionecrosis, residual tumour or recurrent tumour. Magnetic resonance imaging (MRI) has become the most sensitive examination. It ensures optimal focusing of radiography, thereby increasing its effectiveness and reducing its complications. In one-third of the cases studied, MRI has shown pathological signals that were invisible at CT, making for a better adjustment of treatment and a more accurate diagnosis. As regards specificity, MRI does not seem to provide criteria that would enable a radiation lesion to be distinguished from a tumoral recurrence. However, we found that certain signs may contribute to the aetiological diagnosis: a perilesional high-intensity signal extending to the grey matter and/or the corpus callosum is in favour of a recurrent tumour; a high-intensity signal on T1- and T2-weighted sequences and a disproportionally moderate mass syndrome are in favour of a radionecrosis; a post-irradiation leucoencephalopathy sparing the grey matter and the corpus callosum is in favour of a remission. Injecting a gadolinium complex always gives a better distinction between oedema, tumour and necrosis, it may also improve MRI sensitivity and sensitivity in some cases, and it reduces the time taken by the examination. MRI is now the reference morphological examination; its specificity can be further increased by positron emission tomography and assays of polyamines in red blood cells.

[Retroperitoneal teratoma in children. Apropos of 2 cases]. / Les tératomes rétropéritonéaux de l'enfant. A propos de deux cas.

Retroperitoneal teratoma is infrequent (5% of all teratomas). The diagnosis is usually made within the first year of life. Two cases are reported. Case n. 1 is typical of mature benign teratoma with teeth, fat and water densities visible on the plain film of the abdomen. Cases n. 2 a malignant partly ossified immature teratoma. The ossification is in continuity of a congenital block of vertebral bodies L2 and L3; this association has not been reported in the literature. CT in both cases was contributive for delineation of the tumor but did not help to answer the question of malignancy or not; foeto-protein remains the only test to do that discrimination.

Penetration of the brain by nonionic water soluble tri- and hexaiodinated contrast media. Experimental autoradiographic study of two contrast media: Iotrol and Iopamidol labelled with iodine 125.

After suboccipital injection of Iotrol and Iopamidol labelled with iodine 125 in rabbits, we measured residual radioactivity in the whole brain and optical density on autoradiographs of brain sections obtained 2, 8 and 24 h after injection. Residual radioactivity is higher with Iotrol than with Iopamidol after 8 h and 24 h. At densitometry, while the penetration of the cortex is the same with both media at 2 h (although subcortical passage of Iotrol is greater), by 8 h the concentration of Iopamidol is twice that of Iotrol, and at 24 h it is three times as high. A similar pattern was seen in the subcortical region. These densitometric findings are in agreement with previous electrophysiological studies, in which changes were less severe and more transient with Iotrol than with Iohexol. There is nevertheless an apparent lack of agreement between the studies of radioactivity and the electrical findings. The lower neurotoxicity of Iotrol may be explained by: a longer half-life in the subarachnoid space; its larger molecules, which inhibit diffusion in the extracellular fluid, and its more hydrophilic nature, which reduces intracellular penetration.

Biostimulation of wound healing by lasers: experimental approaches in animal models and in fibroblast cultures.

Recent evidence suggests that low-energy lasers, such as an He-Ne laser, might stimulate wound healing. In this review we are summarizing our recent observations indicating that low-energy lasers enhance collagen gene expression both in skin fibroblast cultures in vitro, as well as in animal models of wound healing in vivo.

Biostimulation of wound healing in vivo by a helium-neon laser.

Clinical observations have suggested that low-energy lasers might stimulate wound healing. To understand the mechanism of the biostimulation, we previously examined the effects of low-energy lasers on collagen production by human skin fibroblasts and reported an increase of collagen synthesis in vitro. To examine the effects of low-energy lasers in vivo, hairless mice were experimentally wounded, sutured, and subjected to laser irradiation by a helium-neon laser with a power output of 1.56 mW and an energy fluence of 1.22 Joules/cm2. Experimental wounds were subjected to laser treatment every other day for 2 months; control wounds remained untreated. Specimens from the wounds were then examined for histological findings, tensile strength, and total collagen content. Results demonstrated a considerable improvement in the tensile strength of the laser-irradiated wounds at 1 and 2 weeks. Furthermore, the total collagen content was significantly increased at 2 months when compared with control wounds. These results suggest a beneficial effect of the helium-neon laser on wound healing in vivo.

[External epiphysiolysis with caput valga. Apropos of 2 cases]. / Epiphysiolyse externe avec "caput valga". A propos de 2 observations.

External epiphysiolysis with valgus slip of the femoral epiphysis is rare. The authors report two such chronic cases, one unilateral and the other bilateral. This disorder complicates a coxa valga with a reversed cephalic growth plate, downward and externally. This coxa valga which appears constitutional is sometimes associated with an increase in femoral antetorsion. Treatment is the same as classical varus slip of the femoral epiphysis.

Demonstration of elevated type I and type III procollagen mRNA levels in cutaneous wounds treated with helium-neon laser. Proposed mechanism for enhanced wound healing.

To assess laser modulation of wound healing, full-thickness cutaneous wounds were produced in the backs of pigs, and subjected to treatment with helium-neon laser. For comparison, some wounds were treated with non-laser energy source (a tungsten light) or left untreated as controls. Type I and type III procollagen mRNA levels were determined in the wounds by molecular hybridization with cDNA probes. The results indicated that type I and type III mRNA levels were markedly increased at days 17 and 28 of the healing in wounds treated with He-Ne laser, when compared to control or tungsten light-treated wounds. The results suggest that helium-neon laser stimulates wound healing by enhancing procollagen gene expression. These observations may have relevance to previous clinical studies suggesting that helium-neon laser stimulates wound healing.