Towards computer assisted evaluation of plagiocephaly

Plagiocephaly is a common asymmetry of the skull giving the impression that the subject, usually a neonate, has suffered a compressive force acting unilaterally. Normally innocuous, it is a postural deformity that can be suggestive of other significant abnormalities, e.g. joint dysplasia. Although intuitive measurements of plagiocephaly appear in the literature there is little evidence of analytical evaluation. This paper describes a measurement methodology based on black and white photography. A flat-bed scanner and a personal computer facilitated the transformation of the prepared photograph to standard tagged image file format at 256 grey scale. A utility was used to convert the file scan to a monochrome bitmap image which was displayed on the screen and subjected to an algorithm to compute the centroid of the cranial profile. Radials that emerge from the centroid to the cranial circumference at five degree intervals map to a signal display that represents the plagiocephaly.