Validation of HR-pQCT against micro-CT for morphometric and biomechanical analyses: A review

Abstract

High-resolution peripheral quantitative computed-tomography (HR-pQCT) has the potential to become a powerful clinical assessment and diagnostic tool. Given the recent improvements in image resolution, from 82 to 61 μm, this technology may be used to accurately quantify in vivo bone microarchitecture, a key biomarker of degenerative bone diseases. However, computational methods to assess bone microarchitecture were developed for micro computed tomography (micro-CT), a higher-resolution technology only available for ex vivo studies, and validation of these computational analysis techniques against the gold-standard micro-CT has been inconsistent and incomplete. Herein, we review methods for segmentation of bone compartments and microstructure, quantification of bone morphology, and estimation of mechanical strength using finite-element analysis, highlighting the need throughout for improved standardization across the field. Studies have relied on homogenous datasets for validation, which does not allow for robust comparisons between methods. Consequently, the adaptation and validation of novel segmentation approaches has been slow to non-existent, with most studies still using the manufacturer's segmentation for morphometric analysis despite the existence of better performing alternative approaches. The promising accuracy of HR-pQCT for capturing morphometric indices is overshadowed by considerable variability in outcomes between studies. For finite element analysis (FEA) methods, the use of disparate material models and FEA tools has led to a fragmented ability to assess mechanical bone strength with HR-pQCT. Further, the scarcity of studies comparing 62 μm HR-pQCT to the gold standard micro-CT leaves the validation of this imaging modality incomplete. This review revealed that without standardization, the capabilities of HR-pQCT cannot be adequately assessed. The need for a public, extendable, heterogeneous dataset of HR-pQCT and corresponding gold-standard micro-CT images, which would allow HR-pQCT users to benchmark existing and novel methods and select optimal methods depending on the scientific question and data at hand, is now evident. With more recent advancements in HR-pQCT, the community must learn from its past and provide properly validated technologies to ensure that HR-pQCT can truly provide value in patient diagnosis and care.

Novel Therapeutic Strategy for Bacteria‐Contaminated Bone Defects: Reconstruction with Multi‐Biofunctional GO/Cu‐Incorporated 3D Scaffolds

“…Sp is usually defined as the distance between midlines of edges of trabeculae, providing important information about osteoporotic samples. [ 56 ] According to our previous observations, the value of Tb. Sp is positively associated with the degree of osteoporosis or osteolysis, which is characterized by aggravated inflammation and persistent bone infection.…”

Assessment of trabecular and cortical parameters using high-resolution peripheral quantitative computed tomography, histomorphometry and microCT of iliac crest bone core in hemodialysis patients

“…Nevertheless, a significant correlation was found between Ct.Th and BV/TV, especially between the iliac crest and the radius in our study. A review evaluating the validation of HR-pQCT against microCT reinforces the importance of matching anatomical sites when performing such comparisons ( Ohs et al, 2020 ). Maquer et al ( Maquer et al, 2015 ) evaluated radius, iliac crest, femur, and spine fragments by microtomography and observed that the iliac crest BV/TV was greater than the radius BV/TV, as seen in our study.…”

“…However, it depends on expertise in execution, processing, and reading, which can be time consuming ( Moe et al, 2006 ; Dempster et al, 2013 ). MicroCT analyzes the microarchitecture in a three-dimensional manner, but it also requires an invasive biopsy and detects only the mineralized matrix ( Ohs et al, 2020 ). HR-pQCT has characteristics similar to those of microCT in terms of the method used (X-ray attenuation) and the analyzed parameters of microarchitecture in a three-dimensional manner.…”

“…In the assessment of bone microarchitecture, microcomputed tomography (microCT) of bone fragments was used for many years as the gold standard ( Ohs et al, 2020 ). MicroCT allows true volumetric analysis in a three-dimensional approach through X-ray attenuation with high resolution (small voxels), measuring the trabecular and cortical parameters ( Cohen et al, 2010 ).…”

Clinical observation of diminished bone quality and quantity through longitudinal HR-pQCT-derived remodeling and mechanoregulation

“…Note, thresholds greater than 680 mg HA/cm 3 were ignored in the trabecular bone based on the lower mineralized density of trabecular bone and minimal trabecular bone volume measured at higher densities. A threshold of 320 mg HA/cm 3 was defined as a standardized threshold for analysis, based on the use as a trabecular threshold in previous studies 52 . The two images were then compared to determine voxels that had formed, resorbed, or were quiescent at each mineralized density threshold 53 .…”