Primary Skeletal Sites
Lumbar Spine | Proximal Femur (Total Hip And Femoral Neck) | Distal Radius | Total Body When Indicated
Supporting Anatomy
Trabecular And Cortical Bone | Vertebral Bodies | Femoral Neck Geometry | Forearm Cortical Thickness
Clinical Landmarks
Iliac Crests | Greater Trochanter | Ulnar Styloid | Midline Spine
AP Projection
Patient Supine | Legs Elevated To Reduce Lordosis | CR Centered To L1 L4 Region | Include L1 Through L4 Vertebrae When Possible
AP Projection
Patient Supine | Internally Rotate Leg 15 To 20 Degrees | CR To Femoral Neck | Scan Total Hip And Femoral Neck
AP Projection
Patient Seated | Forearm Flat On Table | CR To 1 3 Distal To Ulnar Styloid | Used When Hip Or Spine Not Measurable
Whole Body Composition
Patient Supine | Arms At Sides Slightly Away From Body | Used For Lean Mass Fat Mass And Bone Mineral Content
Low Dose Lateral
Lateral Spine Acquisition | Evaluate Vertebral Compression Fractures | Often Performed On Same DEXA Unit
Clothing And Artifacts
Remove Metal Jewelry And Clothing With Metal | Empty Pockets | Avoid Calcium Supplements Immediately Before Scan
Immobilization And Alignment
Use Positioning Aids To Keep Legs And Arms Still | Center Anatomy In Field Of View | Document Any Prior Surgery Or Hardware
Pregnancy And Recent Contrast
Avoid Routine DEXA During Pregnancy | Defer If Recent High Dose Contrast Or Nuclear Tracer Could Affect Results
Osteoporosis Thresholds
Comparison To Young Adult Peak Bone Mass | T Score ? -2.5 Indicates Osteoporosis | T Score Between -1.0 And -2.5 Indicates Low Bone Mass
Age Matched Comparison
Comparison To Age And Sex Matched Population | Z Score ? -2.0 Suggests Secondary Causes Of Low Bone Density
Least Significant Change
Report Precision Error For Device | Use Least Significant Change To Determine True Bone Loss Or Gain | Recommend Repeat Scans On Same Machine When Possible
Bone Mineral Density BMD
Amount Of Mineral Per Unit Area | Measured In g cm 2
T Score
Standard Deviations From Young Adult Mean | Used For Diagnosis Of Osteoporosis
Z Score
Standard Deviations From Age Matched Mean | Useful In Secondary Osteoporosis Evaluation
Least Significant Change LSC
Minimum Change Required To Be Statistically Significant | Depends On Device Precision
Vertebral Fracture Assessment VFA
Low Dose Lateral Spine Image | Screens For Compression Fractures