EFFECTS OF ACUTE POSTURAL CHANGE ON MID-THIGH CROSS-SECTIONAL AREA AS MEASURED BY COMPUTED TOMOGRAPHY

Abstract

Fluid shifts resulting from postural change present a potential source of error when assessing the CSA of limb tissue using CT. In the present study mid-thigh axial scans of 13 older women were obtained at 5, 10, and 15 minutes of supine rest. Scans were analyzed for changes in CSA of subcutaneous fat(SF), low density muscle(LDM) and normal density muscle(NDM) tissue. A significant decrease was found in NDM CSA at 15 minutes (2.3 ± 0.8, 1.6%, P<0.05) with no change in LDM or SF CSA between any time interval The current study suggests that the potential measurement error associated with fluid shifting out of the tissues can be minimized when baseline and follow-up CT-derived images of mid-thigh CSA are obtained within the first 10 minutes the subject assumes the supine position and that the CSA of NDM and LDM may be affected differently by loss of hydrostatic pressure.