Poster Presentation 33rd ASM of the Australian & New Zealand Bone & Mineral Society 2023

Cortical bone mineralization density distribution in paediatics – can peripheral QCT images act as a pain-free bone biopsy? (#222)

Julie Briody 1 2 , Nicholas Pocock 3 , Craig F Munns 4
  1. Faculty of Medicine and Health, Sydney University, Sydney, NSW, Australia
  2. The Children's Hospital at Westmead, Westmead, NSW, Australia
  3. Nuclear Medicine, St Vincent's Hospital, Darlinghurst , NSW, Australia
  4. The University of Queensland, Brisbane, QLD, Australia

“Bone mineralization density distribution” (BMDD) reports the bone mineral frequency distribution within a biopsy image.  In addition to density, it is purported to describe bone heterogeneity, turnover, mineralization kinetics and average bone matrix age1,2. Unfortunately, bone biopsies are invasive, time consuming and are generally performed at trabecular bone sites.

 

Although BMDD is a type of image analysis, it has had limited uptake in other bone imaging techniques. This may be related to the lack of suitable image-analysis software and normative data.

 

Aims

To generate BMDD data using peripheral QCT (pQCT) images, describe BMDD in a normal paediatric population, and investigate if BMDD may act as a “screening” bone biopsy in clinical subjects.

 

Methods

pQCT images of the Radius 65% and Tibia 66% sites were analysed using ImageJ (Fiji v1.52q) and a modified “pQCT plugin”3. Cortical bone voxels were categorized into one of six density bins (280, 480, 710, 955, 1200 and 1700, as mg/cm3) and bin frequencies calculated. 

Normal bin frequencies (age 4-18 years, N≥316) were described by bone site, gender, and pubertal status.

Spinal cord injury (SCI) subjects, without prior exposure to anti-resorptive therapy, were used to demonstrate possible application.

Results

After minor modifications to the generic pQCT plugin, it was possible to produce BMDD data from pQCT images.

Unlike published histomorphometry data4, gender and pubertal differences were observed in normal paediatric BMDD.

Figure 1 illustrates different BMDD in short-term non-loading (complete neurological status), and loading (incomplete neurological status) SCI subjects (both 14.9 years and 0.4 years follow-up).

 

Conclusions

Results suggest BMDD by pQCT might be used clinically to guide intervention selection. For example, the BMDD bin frequency data of the short term, non-loading SCI subject is suggestive of increased bone remodelling which may justify anti-resorptive therapy.

 

Figure 1. SCI Tibia images and BMDD Z-scores

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  1. Ruffoni et al (2007) Bone 40(5):1308-1319
  2. Roschger et al (2008) Bone 42(3):456-466
  3. Rantalainen et al (2011). Journal of musculoskeletal & neuronal interactions 11(3):243-248.
  4. Fratzl-Zelman et al (2009) Bone 44(6):1043-1048