Measurements

The XtremeCT II (Scanco Medical AG, Basserdorf, Switzerland) is a validated, 3-dimensional imaging device using low dose x-rays to assess macro and micro architecture in the radius and tibia. With new enhanced resolution, this system can provide measures of both trabecular and cortical microarchitecture. A new longer gantry allows for measurements along the midshaft in addition to the distal regions. The SAMBA laboratory has developed protocols to assess growing bone in childhood and adolescence, as well as mature bone. Finite Element Analyses (FEA) of bone strength, including failure load and stiffness are available. Measures of muscle density and cross-sectional area, and vascular calcification are currently under development.  Further details are provided in the [equipment document].

DXA and HR-pQCT Radiation Doses

The Horizon A DXA system (Hologic Inc., Bedford, MA, USA) with Apex software v5.5 uses a small amount of x-rays to assess areal bone density and body composition. Scans can be performed for areal BMD and BMC at the forearm, spine, hip and whole body. Single energy scans can be performed at the spine for Vertebral Fracture Assessment (VFA) and in the femur to detect atypical femur fractures. Whole body scans also provide regional (e.g. appendicular lean mass) and total lean mass, and regional (e.g. visceral and subcutaneous adipose tissue) and total fat mass.

DXA and HR-pQCT Radiation Doses

Lower Leg Isometric Strength

This measurement is performed because the tibialis anterior attaches directly to the tibia and causes dorsiflexion of the ankle. This strength measure may correlate with HR-pQCT measures in the tibia.

Upper Leg Isokinetic Strength and Endurance

These measures give us information about upper leg strength and endurance and can be used in conjunction with DXA lean mass to assess muscle quality (muscle -specific force).

The Takei Grip Device (Takei, Tokyo, Japan) measures the strength of the grip in the hands.  This is representative of upper body strength and may correlate with forearm measures of DXA and HR-pQCT bone health.

Further details regarding precision and validation are available [here].