Individual craniofacial bone volumes and relative densities in postnatal mice provide valuable phenotypic information

The objective of this study was to develop an efficient method, using Avizo software (VSG), to measure the volume and relative bone mineral density of individual craniofacial bones in early postnatal mice from micro‐computed tomography images. Manually labeled individual bones from representative specimens were expanded to define the theoretical space that a bone would occupy in a standard orientation. These models were transformed into the space of related target specimens and used to identify all voxels above three phantom based on minimum bone density thresholds for each bone of the target specimen. Total bone volumes, medium/high density bone volumes, and ratios of these volumes (relative BMD) were produced for Fgfr2Y394C/+ Beare‐Stevenson cutis gyrata syndrome model mice and unaffected littermates at postnatal day 0 and 8. This provided phenotypic and developmental information unavailable from landmark based morphometrics that can help target regions and developmental times for further analyses. This procedure requires <5% of the time required for manual segmentation. Error levels are acceptable for summary analysis of bone volume and relative density, with higher error for older specimens, smaller bones, and bones surrounding teeth. This work is supported in part by a grant from the National Institute of Dental and Craniofacial Research to JTR (R01‐DE018500, ‐DE18500‐S1, ‐DE18500‐S2). Grant Funding Source : National Institute of Dental and Craniofacial Research