Date of Award

8-2015

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Food, Nutrition, and Culinary Science

Committee Member

Elliot D. Jesch, Ph.D, Committee Chair

Committee Member

Michelle M. Bohan Brown, Ph.D

Committee Member

Tenly Murphy, MD

Abstract

Introduction: Dual energy X-ray absorptiometry (DXA) scans are the gold standard method for measuring bone mineral density (BMD) calculations for the assessment and measurement of bone health. More recently, DXA scans have become the common method for body composition assessments among clinicians and researchers alike, particularly for its ability to separate soft tissue into and lean mass. This study was designed to calculate the percent coefficient variation (%CV) to determine the least significant change (LSC), or the variability considered significant when measuring BMD, fat mass, and lean mass with a DXA scan. Methods: Thirty-six female and 6 male, aged 50.07 ± 15.70 years, volunteered in the AP Lumbar Spine scan. Thirty-five female and 7 male, aged 49.81 ± 15.12 volunteered in the whole body scan. Any participant who was pregnant or trying to become pregnant was excluded from the study. Height and weight were measured, and date of birth and race was recorded. Body composition and BMD were measured using a Hologic Discovery QDR Series (Hologic, Inc, Bedford, MA) DXA densitometer. Each participant was scanned three times for each type of scan they volunteered for. Scans were taken consecutively by the same technician, and participants were removed from the table and repositioned immediately thereafter for the next scan. Results were calculated with the International Society of Clinical Densitometry’s (ISCD) calculator. Results: Overall average %CV came within a 1% error as reported by the manufacturer and individual %CV recommendations according to ISCD reports, with the exception of WB Visceral Adipose Tissue (VAT) with a 15.95% error. Of the variables measured, only WB fat mass and lean mass had no outliers or measurements outside the recommended %CV as noted by either the manufacturer or ISCD. Conclusions: Although the average %CV met the manufacturers’ and ISCD recommendations many participants did not fall within the %CV distribution and or contained outliers within the distribution despite meeting the recommendations. In addition, WB VAT mass had the highest percent error. Regardless the cause of such variation in measurements is unclear, and requires further investigation.

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