Bone and Body Composition Laboratory
Bone Densitometry
Dual energy absorptiometry (DXA)
The CPNR owns and operates a Hologic Discovery DXA scanner, which is located in the Center for Clinical and Translational Science (CCTS). It is a flat-bed, C-arm scanner that uses fan-beam technology to acquire an areal image. DXA analyzes bone mass and body composition (fat and lean tissue) and can be used for children as well as adults.
The Hologic Discovery DXA is capable of producing the following scan types:
* Total Body (subregion analysis also available)
* A/P Lumbar Spine
* Supine Lateral Lumbar Spine Pair
* Proximal Femur (Hip)
* Distal Femur
* Forearm
We have software version 12.3 from Hologic, Inc, for scan analysis and an FDA–approved pediatric reference database. The software includes the "auto low density" setting for analyses of spine, hip and whole body scans. This analysis feature uses lowered thresholds at which bone and soft tissue are detected to account for smaller body sizes. The automatic detection of threshold settings based on body size allows for a more accurate and reliable assessment of pediatric bone density and body composition.
The FDA–approved pediatric reference database provides Z-scores for lumbar spine and whole body bone mineral density (BMD) for children ages 3–20 years. Hip BMD Z-scores are provided for children ages 5–20 years. The CPNR offers DXA services in both clinical and research settings.
Frequently Asked Questions:
How long does a DXA take? Depending on what scans are being acquired, a DXA may take anywhere from 5 to 25 minutes.
What is the effective dose of radiation associated with a DXA? Effective dose varies with scan type. The National Council of Radiation Protection and Measurements (NCRP) has recommended the annual effective dose limit for infrequent exposure of the general public, including children, is 5,000 µSv and that an annual effective dose of 10 µSv be considered a Negligible Individual Dose.
| Scan Type | Whole Body | A/P Spine | Proximal Femur | Forearm |
| Effective Dose (μSv) |
2.6 | 4.0 | 1.3 | 0.05 |
Peripheral quantitative computed tomography (pQCT)
The CPNR owns and operates a Norland Stratec XCT 2000 pQCT, housed in the Center for Clinical and Translational Science. pQCT measures bone density at peripheral skeletal sites by acquiring a three dimensional image. Using "CAT" scanner technology, pQCT provides a detailed analysis of both trabecular and cortical bone compartments at the forearm and tibia. Aside from volumetric bone mineral density, other parameters measured include bone mineral content, bone area, thickness and strength, as well as muscle cross-sectional area. pQCT scanning is currently only available to research studies.
Frequently Asked Questions:
How long is the scan time? Scan Time is approximately 2.5 minutes per image.
What is the effective dose of radiation from pQCT? Effective dose is approximately 0.3 μSv per scan.
Quantitative ultrasound (QUS)
The CPNR has a Sunlight Omnisense 8000 to evaluate bone strength via quantitative ultrasound (QUS). QUS operates on the axiom that the speed of sound (SOS) is directly proportional to the density of the material through which it travels. The speed at which the sound propagates through the bone is calculated as the time between sound transmission and receipt.
SOS can be done at the mid-shaft tibia or 1/3 distal radius. Three to five consecutive measurement cycles are performed, after which SOS (m/s) is determined and Z-score is reported. QUS is not associated with ionizing radiation and measurements can be completed on most participants within 15 minutes. QUS is currently only available to research studies.
Body Composition
Dual energy absorptiometry (DXA)
The CPNR owns and operates a Hologic Discovery DXA scanner, which is located in the Center for Clinical and Translational Science (CCTS). It is a flat-bed, C-arm scanner that uses fan-beam technology to acquire an areal image. DXA analyzes bone mass and body composition (fat and lean tissue) and can be used for children as well as adults.
Air displacement (PEA POD)
The CPNR owns and operates the “PEA POD” (Life Measurements Inc.), which utilizes air displacement plethysmography, for determining percent fat and fat-free mass in term and pre-term infants. The test consists of measuring the infant’s mass (weight) and volume, which is determined while the infant lies inside the PEA POD chamber. Once the infant’s volume is determined, body density is calculated and the relative proportions of fat and fat-free mass are estimated.
Infants from 1 kg up to 8 kg can undergo PEA POD testing, and testing takes approximately 5 minutes. PEA POD is currently only available to research studies.
Anthropometry
CPNR Staff have extensive experience acquiring precise anthropometric measurements in pediatric populations. Anthropometry includes head and body segment circumferences, skinfold thickness, weight, and height/length measures.
