A comparison of intramuscular temperatures during ultrasound treatments with coupling gel or gel pads.

Abstract

A repeated-measures design was used. The independent variable was ultrasound coupling medium with 2 levels: gel pad and traditional gel. The dependent variable was peak intramuscular (IM) tissue temperature. To compare changes in IM temperature during similar ultrasound treatments with 2 different coupling media. Gel pads are gaining popularity as an ultrasound coupling medium. Intramuscular temperatures during ultrasound with gel pads and standard gel have not been compared. Subjects were 13 student volunteers (21.3 +/- 1.4 years of age) without lower-extremity pathology. Ultrasound treatments were administered in a laboratory on two separate occasions 48 hours apart, each with a different coupling medium (standard ultrasound gel or gel pad). One-MHz continuous ultrasound was administered for 7 minutes at 1.5 W/cm2 with the transducer head moving 3 to 4 cm/s over an area approximately twice the size of the transducer head. Tissue temperature was measured every 10 seconds using implantable thermocouples inserted at a 3-cm depth to the surface of the right medial calf. Data were analyzed using an ANCOVA with pretreatment temperature as the covariate. Tissue temperatures increased during both treatments, with the mean and standard deviation peak temperature during the gel pad treatment reaching 39.40 +/- 1.5 degrees C compared to 39.20 +/- 2.4 degrees C during the normal gel treatment. Statistical analysis revealed no difference in temperature between ultrasound treatments using gel and those performed using gel pads. Because temperature changes were similar with both treatments, we conclude that these coupling methods are equivalent under the ultrasound application parameters tested.