Michael G. Miller

Doctoral Dissertation Announcement

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Candidate: Michael G. Miller

Degree of: Doctor of Philosophy

Department: Educational Leadership, Research, and Technology

Title: Comparisons of Absolute and Relative Intramuscular Temperature Changes during Ultrasound Treatment Using Three Analytical Techniques

Committee:
Dr. Brooks Applegate, Chair
Dr. Tim Michael
Dr. Chris Cheatham
Dr. Jessaca Spybrook

Date: Monday, February 21, 2011 2:00 p.m. to 4:00 p.m.
Student Recreation Center, Room 1055

Abstract:
Ultrasound is a thermal modality which utilizes acoustic energy to promote heating. While there are many factors that affect heating of body tissues, the effects of skinfold thickness and skin temperature upon ultrasound heating has not been studied extensively. In addition, while temperature typically follows a linear trend, past research typically uses ANOVA or regression analysis to examine this relationship but these models examine within-subject effects (time) and between effects (usually groups) at the group level, not the individual level. Therefore, the purposes of this study are to determine if skin temperature and skinfold thickness are predictors for intramuscular tissue temperature changes during an ultrasound treatment and to examine different statistical models for this data. Thirty-two subjects had an absolute intramuscular depth measured at 1.5 cm from the surface of the calf and relative intramuscular depth at one-half the skinfold thickness added to the absolute depth. Two temperature probes were inserted at the respective depths and a surface temperature wire was affixed to the middle one-third of the treatment area. An ultrasound treatment consisting of 1.0 W/cm2 using a 3MHz frequency was applied until the absolute temperature reached three degrees above baseline temperature. Data was analyzed with ordinary least squares regression, hierarchical linear modeling (HLM), and mixed methods repeated measures (MMRM) techniques. Based upon the different trends within the data, it was concluded that HLM, because of examining within-person effects and parsing out the error components, was a better fit model for analysis. HLM showed that skin temperature was a significant predictor for absolute and relative intramuscular temperatures while regression MMRM showed that skin temperature to be predictive for relative temperature. HLM also showed that skinfold thickness to be predictive of relative temperature. Total heating rates for absolute and relative intramuscular depths were 0.610C and 0.420C per minute, respectively. In conclusion, it appears that tissue temperatures at the relative intramuscular depth (greater than 1.5 cm) can be better predicted using skin temperature and skinfold thickness and that HLM, with examining within-subject temperature variability during the ultrasound treatment, was an appropriate model.