Intramuscular temperature differences between the mid-point and peripheral effective radiating area with ultrasound

Abstract

The purpose of the study was to determine whether uniform intramuscular heating is achieved throughout a treatment area 2 times the transducer head at both 1 and 3 MHz. Seven male and three female subjects (Age: 23.6 ± 1.0 yrs, Weight: 83.8 ± 23.2 kg, Site Skinfold: 13.9 ± 7.3 mm) underwent two ultrasound treatments (1 and 3 MHz) in the triceps surae muscle group. Thermocouples were inserted at the midpoint and periphery of the treatment area. Ten minute baseline temperatures were recorded followed by a ten minute ultrasound treatment. Two (site) X 10 (time) repeated measures ANOVAs were separately used to determine significance for 1 and 3 MHz treatments. Post-hoc testing was performed using the Bonferroni adjustment. A significant site-by-time interaction was observed for both the 1 and 3 MHz treatments. From baseline to the end of the treatment, temperature increased approximately 2.62°C and 1.58°C for the midpoint and periphery of the 1 MHz treatment and 5.88°C and 3.64°C for the 3 MHz treatment. The differences in temperature suggest that uniform heating does not occur throughout the treatment area. Key points3 MHz is more effective in raising intramuscular temperature within ERA.Stroke count/rate of transducer may play a factor in heating tissue.Treatment size may alter uniform heating.

Keywords: Tissue; acoustical.; thermal effects.

Figure 1.

Customized template for measuring depth on the triceps surae muscle group.

Figure 2.

Outline of treatment area template and markings for probe insertions on the triceps surae.

Figure 3.

The response in temperature at the midpoint and the periphery during 1 MHz ultrasound treatment (M ± SD). * denotes significant difference between midpoint and periphery at the respective time point, p < 0.0045.

Figure 4.

The response in temperature at the midpoint and the periphery during 3 MHz ultrasound treatment (M ± SD) denotes significant difference between midpoint and periphery at the respective time point, p < 0.0045.