title: Cortical measurements of the tibia from high resolution peripheral quantitative computed tomography images: a comparison with synchrotron radiation micro-computed tomography.
abstract: High resolution-peripheral quantitative computed tomography (HR-pQCT) measurements are carried out in clinical research protocols to analyze cortical bone. Micro-computed tomography (micro-CT) is a standard tool for ex vivo examination of bone in 3D. The aim of this work was to evaluate cortical measurements derived from HR-pQCT images compared to those from synchrotron radiation (SR) micro-CT in a distal position (4.2 cm from the distal pilon). Twenty-nine tibia specimens were scanned with HR-pQCT using protocols provided by the manufacturer. The standard measured outcomes included volumetric bone density (gHA/cm(3)) of the cortical region (Dcomp), and the cortical thickness (Ct.Th, mm). New features, such as cortical porosity (Ct.Po) and mean pore diameter (Ct.Po.Dm), were measured by an auto-contouring process. All tibias were harvested from the posterior region and imaged with SR micro-CT (voxel size=7.5 μm). The cortical thickness, (Ct.Thmicro-CT), porosity (PoV/TV), pore diameter, pore spacing, pore number, and degree of mineralization of bone (DMB) were obtained for SR micro-CT images. For standard measurements on HR-pQCT images, site matched analyses with micro-CT were completed to obtain Dcomplocal and Ct.Thlocal. Dcomp was highly correlated to PoV/TV (r=-0.84, p<10(-4)) but not to DMB. Dcomplocal was correlated to PoV/TV (r=-0.72, p<10(-4)) and to DMB (r=0.40, p>0.05). Ct.Thlocal and Ct.Thmicro-CT were moderately correlated (r=0.53, p<0.01). Ct.Th and Ct.Po results from the autocontouring process are influenced by the level of trabecularization of the cortical bone and need manual correction of the endosteal contour. Distal tibia is a reliable region to study cortical bone with Dcomp as the best parameter because it reflects both the micro-porosity (Havers canals) and macro-porosity (resorption lacunae) of the cortical bone.
authors.affiliation: INSERM 606 University Paris Diderot, PRES Sorbonne Paris Cité, 75010 Paris France.
authors.forename: Agnès
authors.initials: A
authors.lastname: Ostertag
authors.affiliation: CREATIS, INSERM U1044, CNRS 5220, Université de Lyon, 69621 Villeurbanne Cedex, France; ESRF, X-ray Imaging Group, 38043 Grenoble Cedex, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Peyrin
authors.affiliation: INSERM 606 University Paris Diderot, PRES Sorbonne Paris Cité, 75010 Paris France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Fernandez
authors.affiliation: B2OA, UMR CNRS7052, University Denis Diderot, PRES Sorbonne Paris Cité, 75010 Paris, France.
authors.forename: Jean Denis
authors.initials: JD
authors.lastname: Laredo
authors.affiliation: INSERM 606 University Paris Diderot, PRES Sorbonne Paris Cité, 75010 Paris France.
authors.forename: Marie Christine
authors.initials: MC
authors.lastname: de Vernejoul
authors.affiliation: B2OA, UMR CNRS7052, University Denis Diderot, PRES Sorbonne Paris Cité, 75010 Paris, France. Electronic address: christine.chappard@inserm.fr.
authors.forename: Christine
authors.initials: C
authors.lastname: Chappard
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D017356:Synchrotrons; D013977:Tibia / Q000000981:diagnostic imaging*; D055114:X-Ray Microtomography / Q000379:methods*
keywords: Cortical bone; High resolution peripheral quantitative computed tomography; Synchrotron radiation micro-computed tomography; X-ray