Abstract
This thesis focused on the introduction of a novel, objective quantification method for UCS (anterior plagiocephaly) and the volumetric and clinical consequences resulting from this diagnosis.
UCS is a challenging simple suture craniosynostosis, and therefore it is of key importance to have a clear and objective method for establishing severity. However,
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no universally accepted and used quantification method for UCS is present.
A novel technique (Utrecht Cranial Shape Quantificator (UCSQ)) for classification of skull deformities due to the most common forms of craniosynostosis; scaphocephaly, brachycephaly, trigonocephaly, and right- and left- sided UCS, and for control patients is presented. UCSQ is an outline-based classification method, in which subsequently external landmarks (porion and exocanthion) are identified, a base plane and a plan at 4 cm height from base plane are created, outlines are segmented, and sinusoidal curves are plotted. Distinctive features per diagnosis of craniosynostosis in the curves are found. Scaphocephaly has a high forehead peak and low troughs, in contrast to brachycephaly. UCS has asymmetry and shifting of the forehead peak. Trigonocephaly has a high and narrow frontal peak. Control patients have a symmetrical skull shape with low troughs and a high and broader frontal peak. Based on these characteristics a diagnostic flowchart is developed.
As severity of UCS can vary, quantification is important for treatment, expectations of treatment and natural outcome, and education of the patient and parents. UCSQ uses the following distinctive variables for UCS: asymmetry ratio of frontal peak and ratio of frontal peak gradient. UCSQ can quantify UCS according to severity using characteristics, it outperforms traditional methods and captures the geometric skull shape.
Additionally, the volumetric changes in orbital and intracranial volume, and the clinical consequences are discussed.
Furthermore, the UCSQ method is applied on 3D photogrammetry. Unlike conventional imaging techniques, no radiation load is used in 3D photogrammetry and additionally there is no need for sedation. Using UCSQ, sinusoid curves of the included patients with craniosynostosis are analyzed and values are extracted for calculations. Results per patient are run through a diagnostic flowchart in order to determine correctness of the flowchart (initially based on CT scans) when using 3D photogrammetry; all included patients are diagnosed correctly.
UCSQ on 3D photogrammetry is also used for the diagnosis of PPP (positional posterior plagiocephaly) and the differentiation between UCS and PPP. UCS and PPP are differentiated, based on the following distinctive parameters: location of the occiput peak in the curve, ratio of gradient, and calculated asymmetry ratio of frontal peak. Based on the distinctive features of both UCS and PPP, the diagnostic flowchart is adjusted and available for noninvasive 3D photogrammetry.
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