G.A. Atkinson, M.L. Smith, L.N. Smith, and R.P. Warr (UK)
Plagiocephaly, 3D reconstruction, data representation andvisualisation, measurement and instrumentation
In this paper, we present a statistical study into skull deformations caused by positional plagiocephaly. We also consider the hardware used for the assessment of both severity
and treatment. State-of-the-art external imaging hardware
is employed to assess the three-dimensional geometry of
the cranium and face of 69 affected babies. The hardware
used for most of this study is based on projected-pattern
range ﬁnding, although we also experiment with photometric stereo techniques.
We then explain how the severity of the condition
can be parameterised, based on the 3D data, using the Extended Gaussian Image (EGI) construction. The EGI is
a method of compactly representing the overall geometry
of surface (unlike existing metrics used in plagiocephaly),
based on its distribution of surface gradients. In this study,
we calculate EGIs for both the face and cranium of each patient. We then deduce metrics to parameterise cranial distortions and facial asymmetries. A clear but ﬂuctuating relationship between facial asymmetry and cranial deformation was found. Our results point towards an improvement
in both metrics through treatment by banding, although a
more detailed study with a control group will be needed in future work.