Body Composition Analysis

Two basic and well tested technologies currently available for measurement of body composition are dual energy X-ray absorbance (DEXA) and, more recently added, nuclear magnetic resonance imaging (MRI) analysis. Each system offers relative advantages and disadvantages. MRI measurements can quantify fat mass, lean mass, and water; an MRI scan is conducted in less than 50 seconds and can therefore be carried out on mice that are not sedated; and by our measures MRI analyses provide more precisely reproducible results. However, the MRI instrument is not readily portable and requires a 45 minute “cool” down period during which the MRI magnets are cooled but data cannot be collected. DEXA measurements include fat mass, lean mass, and bone density, and the DEXA scanner is smaller and mobile, but it requires ~5 minutes to scan a single mouse and therefore requires mice be anesthetized.

Equipment and Location

The Body Composition Facility currently operates a PIXImus II DEXA scanner (GE Lunar, Fitchburg WI) and a miniSpec NMR analyzer (Buker, Woodlands TX). The DEXA scanner is housed in Room 643 Berrie Pavilion on a mobile cart that allows transport of the machine. Disinfection of the machine can be conducted in cooperation with the Institute of Comparative Medicine staff so that the DEXA scanner can be moved into the mouse barrier facility. The miniSpec MRI scanner is located in Room 738 within the mouse barrier facility of the Berrie Pavilion.

Users are charged based on time (see price schedule below and on website), but Diabetes Research Center users are not charged for training with either piece of equipment.

PRICE LIST DRC Member Non-Member

NMR scan per hour

$ 40.00 $ 60.00
DEXA scanner $ 40.00 $ 60.00

Staff

The staff of the Body Composition Facility includes Charles Le Duc, PhD, who oversees the maintenance and upgrades of both systems, and a senior technician who is responsible for training members of Diabetes Research Center laboratories to use both pieces of equipment. He is also responsible for quality control assessment and record keeping.

Quality Control

There are three methods of quality control employed by the Mouse Phenotyping Core. First, a quality assessment query is sent by email to users who have operated the machine on any given day. These are quick and simple and are reviewed by the facility staff. Second, a senior technician runs weekly calibrations protocols for each machine and measures standards/phantoms. If proper calibration cannot be achieved or measurement of the standards/phantoms is outside the acceptable accuracy, the machine is scheduled for maintenance. Third, we compare the body composition data obtained for one lean and one obese mouse measured using the DEXA scanner and MRI on a bimonthly basis. This provides cross validation of each platform with actual mice.