Peripheral quantitative computed tomography (pQCT) for the assessment of bone strength in most of bone affecting conditions in developmental age: a review

Abstract

Peripheral quantitative computed tomography provides an automatical scan analysis of trabecular and cortical bone compartments, calculating not only their bone mineral density (BMD), but also bone geometrical parameters, such as marrow and cortical Cross-Sectional Area (CSA), Cortical Thickness (CoTh), both periosteal and endosteal circumference, as well as biomechanical parameters like Cross-Sectional Moment of Inertia (CSMI), a measure of bending, polar moment of inertia, indicating bone strength in torsion, and Strength Strain Index (SSI). Also CSA of muscle and fat can be extracted. Muscles, which are thought to stimulate bones to adapt their geometry and mineral content, are determinant to preserve or increase bone strength; thus, pQCT provides an evaluation of the functional ‘muscle-bone unit’, defined as BMC/muscle CSA ratio. This functional approach to bone densitometry can establish if bone strength is normally adapted to the muscle force, and if muscle force is adequate for body size, providing more detailed insights to targeted strategies for the prevention and treatment of bone fragility. The present paper offers an extensive review of technical features of pQCT and its possible clinical application in the diagnostic of bone status as well as in the monitoring of the skeleton’s health follow-up.

Impact of target joint and FVIII inhibitor οn bone properties in children with haemophilia A: A peripheral quantitative computed tomography study

“…The availability of pQCT in our country is limited to two University metabolic bone disease centres and is provided at no cost to PWH. The radiation exposure dose for a single pQCT examination is 0.01 mSv, slightly higher in comparison with DXA (0.004‐0.005 mSv) . Given that each patient is examined for each extremity separately, the resulting exposure dose for a given patient must be multiplied by a factor of 4 (four).…”

“…The total time taken to perform each scan was between 6 and 8 minutes per extremity, a total of 20 minutes to half hour . During examination subject must be still for optimal scans, which is difficult to obtain in young children . Thus, we did not use a control group because it was judged unethical to investigate children with repeated analyses by ionizing radiation only for methodological purposes.…”

“…Although DXA is a handy and reliable tool for assessing BMD in everyday practice, it has a major limitation; as a two‐dimensional method, it is affected by bone size and underestimates BMD of growing skeleton during childhood. Most recently, peripheral quantitative computed tomography (pQCT) has been advocated as a more specific and sensitive method in detecting deteriorations in bone micro‐architecture, geometry and strength compared to DXA since it can provide three‐dimensional evaluation of volumetric trabecular and cortical bone density along with bone strength …”

Quantitative imaging techniques for the assessment of osteoporosis and sarcopenia

“…Dedicated pQCT scanners (peripheral scanners, smaller and less expensive that whole body CT scanners) are used to evaluate v-BMD and bone microarchitecture at the distal radius and tibia: the 4% and 66% of the length of the radius and the 4%, 38%, 50% and 66% of the length of the tibia are the peripheral sites most commonly evaluated. Using pQCT, v-BMD can be derived and trabecular and cortical bone parameters can be assessed separately, allowing the examination of architectural and geometrical parameters such as Ct.Th, marrow and cortical CSA, both periosteal and endosteal circumference, as well as biomechanical parameters like CSMI (104,109).…”

“…When the standard evaluation protocol was repeated on the 3D registered data, repositioning error was reduced on average by 23% and 8% at distal radius and tibia, respectively (181). Similarly to QCT, daily and weekly QC programs should be conducted to identify drift, which can result as a consequence of decreased X-ray emission (109).…”