Automated human skull landmarking with 2D Gabor wavelets.

Landmarking of CT scans is an important step in the alignment of skulls that is key in surgery planning, pre-/post-surgery comparisons, and morphometric studies. We present a novel method for automatically locating anatomical landmarks on the surface of cone beam CT-based image models of human skulls using 2D Gabor wavelets and ensemble learning. The algorithm is validated via human inter- and intra-rater comparisons on a set of 39 scans and a skull superimposition experiment with an established surgery planning software (Maxilim). Automatic landmarking results in an accuracy of 1-2 mm for a subset of landmarks around the nose area as compared to a gold standard derived from human raters. These landmarks are located in eye sockets and lower jaw, which is competitive with or surpasses inter-rater variability. The well-performing landmark subsets allow for the automation of skull superimposition in clinical applications. Our approach delivers accurate results, has modest training requirements (training set size of 30-40 items) and is generic, so that landmark sets can be easily expanded or modified to accommodate shifting landmark interests, which are important requirements for the landmarking of larger cohorts.

Complications in Mandibular Midline Distraction.

Mandibular midline distraction (MMD) is a relatively new surgical technique for correction of transverse discrepancies of the mandible. This study assesses the amount and burden of complications in MMD. A retrospective cohort study was performed on patients who underwent MMD between 2002 and 2014. Patients with congenital deformities or a history of radiation therapy in the area of interest were excluded. Patient records were obtained and individually assessed for any complications. Complications were graded using the Clavien-Dindo classification system (CDS). Seventy-three patients were included of which 33 were males and 40 were females. The mean follow-up was 2.1 years. Twenty-nine patients had minor complications, grades I and II. Two patients had a grade IIIa and three patients had a grade IIIb complication. Common complications were pressure ulcers, dehiscence, and (transient) sensory disturbances of the mental nerve. This study shows that although MMD is a relatively safe method, complications can occur. Mostly the complications are mild, transient, and manageable without the need for any reoperation.