The use of three dimensional (3D) imaging for measuring morphological structures in a 3D environment is well-known. Examples of such imaging include CT (computer tomography) scans and MRI (magnetic resonance imaging) whereby axial, coronal and sagittal sections may be used to take linear measurements. CBCT (cone beam computer tomography) may provide the additional benefit of enabling sections on high resolution images (voxel size of approximately 500 µm3) in any direction, which is especially beneficial in the field of dentistry. Microfocus X-ray CT scanning delivering more focused images of as small as 50 µm3 is precluded in living individuals, but may also be useful for precise quantitative analyses of inaccessible internal structures on cadaver material. Examples of internal structures include the middle and inner ears, bony tables and vascular foramina. Such findings can then be brought into clinical context by comparison with living references.
Although the use of geometric morphometrics (shape analysis) is not as widely appreciated in the clinical setting, valuable insights in shape changes, variations and associations, applicable in the fields of neuropsychiatry, clinical genetics, orthodontics, maxillo-facial and plastic surgery, anthropometric descriptions and forensic medicine may so be appreciated. It is also ideal for studying growth, ageing or other changes in the shape of structures anticipated because of an identified biomechanical stimulus. A clear example of this would be the change in shape of the mandible when teeth are lost. Techniques applied for 3D structure analysis can also be applied for 2D structure analysis.
3D facial surface analysis by 3D laser scanning and geometric morphometrics allows a more efficient detection of affected children with foetal alcohol syndrome. As the face and the brain develop in strict coordination, abnormalities or differences in facial morphology can be indicative of underlying brain pathology. Statistical analysis of brain shape by geometric morphometrics of the corpus callosum and subcortical structures is specifically relevant for foetal alcohol syndrome. Other developmental abnormalities include schizophrenia. Shape analysis is also useful in plastic and reconstructive surgery for cleft lip and palate patients where detailed images of the facial areas to be corrected are necessary.
Other uses for shape analysis include manufacturing of objects and prostheses.
Bookstein, FL, Sampson, PD, Streissguth, AP & Connor, PD 2001. Geometric morphometrics of corpus callosum and subcortical structures in the fetal‐alcohol‐affected brain. Teratology, 64, 4-32.
Bugaighis, I, O'higgins, P, Tiddeman, B, Mattick, C, Ali, OB & Hobson, R 2010. Three-dimensional geometric morphometrics applied to the study of children with cleft lip and/or palate from the North East of England. The European Journal of Orthodontics, cjp140.
Hennessy, RJ, Mclearie, S, Kinsella, A & Waddington, JL 2005. Facial surface analysis by 3D laser scanning and geometric morphometrics in relation to sexual dimorphism in cerebral–craniofacial morphogenesis and cognitive function. Journal of anatomy, 207, 283-295.
Sforza, C, De Menezes, M & Ferrario, V 2013. Soft-and hard-tissue facial anthropometry in three dimensions: what’s new. J Anthropol Sci, 91, 159-184.