See JAX Pipeline on the IMPC website for order of tasks for all mice tested
Project protocol: Dual Energy X-ray Absorptiometry (DXA)
Introduction
DXA is used to measure bone mineral content and density as well as to assess body composition. DXA uses an X-ray generator of high stability to produce photons over a broad spectrum of energy levels. Its photon output is filtered to produce the two distinct peaks necessary to distinguish bone from soft tissue.
Study design
Paradigm: Baseline study
Panel: Collaborative Cross
Number of strains: 18
Sex: Both
Age: 13-15 wks
Sample size: Seven mice per sex from at least two litters
Number of cohorts: 1
Workflow
Step |
Description |
Equipment |
Data collected |
1 |
Anesthetize mice |
- |
- |
2 |
Weigh mice, measure length |
Balance, ruler |
Body weight, body length |
3 |
Measure bone mineral content and density, and determine body composition |
DXA |
Bone mineral content, bone mineral density, fat mass, lean mass, bone area |
Equipment, software and supplies
Procedure
- The volume of anesthetic solution (Avertin) required for i.p. injection is calculated and recorded.
- Mice are anesthetized.
- Mice are weighed and length is measured (nose to beginning of tail).
- Each unconscious mouse is placed in the DXA analyzer.
- A scout-scan is performed.
- The area of interest is optimized and a measure-scan performed.
- The standard analysis is a whole body analysis, excluding the head.
- Remove mouse once image is captured. Place on heated mat set at 37°C, in a cage and monitor closely until consciousness is regained.
Data QC: Calibration of the system is done in daily intervals using the phantoms provided by the manufacturer.
Formulas and derivations: Fat mass = TTM x percent fat / 100. Lean mass = TTM - fat mass.
Measurements
LIMS field name |
MPD variable name |
Description |
Units |
Series |
Primary measurement |
Series order |
MPD computed |
Calculation |
Method |
Data type |
Body weight |
body_weight |
body weight |
g |
|
|
|
|
|
DXA |
Float |
Fat mass |
fat |
fat tissue mass of whole body scan, head excluded |
g |
|
|
|
|
|
DXA |
Float |
Lean mass |
lean |
lean tissue mass of whole body scan, head excluded |
g |
|
|
|
|
|
DXA |
Float |
Bone mineral density |
BMD |
bone mineral density of whole body scan, head excluded |
g/cm2 |
|
|
|
|
|
DXA |
Float |
Bone mineral content |
BMC |
bone mineral content of whole body scan, head excluded |
g |
|
|
|
|
|
DXA |
Float |
Body length |
body_length |
body length |
cm |
|
|
|
|
|
DXA |
Float |
BMC/Body weight |
BMC_adj |
bone mineral content to body weight ratio |
ratio |
|
|
|
|
|
DXA |
Float |
Lean/Body weight |
lean_adj |
lean tissue mass to body weight ratio |
ratio |
|
|
|
|
|
DXA |
Float |
Fat/Body weight |
fat_adj |
fat tissue mass to body weight ratio |
ratio |
|
|
|
|
|
DXA |
Float |
Bone area |
bone_area |
bone area, whole body scan, head excluded |
cm2 |
|
|
|
|
|
DXA |
Float |
% fat |
pct_fat |
percent fat, whole body scan, head excluded |
% |
|
|
|
|
|
DXA |
Float |
TTM |
TTM |
total tissue mass, whole body scan, head excluded |
g |
|
|
|
|
|
DXA |
Float |
Experimental and technical parameters
Equipment name |
Dual Energy X-ray Absorptiometry Analyzer |
Equipment manufacturer |
GE Medical Systems |
Equipment model |
Lunar Piximus II |
Anesthesia |
Avertin |
|