Biomedical subjects

C J Valeri

Publications and source records attributed to C J Valeri.

2 recordsLinked to original sources

PubMed1998

Capturing data from three-dimensional surfaces using fuzzy landmarks.

Anatomical landmarks are defined as biologically meaningful loci that can be unambiguously defined and repeatedly located with a high degree of accuracy and precision. The neurocranial surface is characteristically void of such loci. We define a new class of landmarks, termed fuzzy landmarks, that will allow us to represent the form of the neurocranium. A fuzzy landmark represents the position of a biological structure that is precisely delineated, but occupies an area that is larger than a single point in the observer's reference system. In this study, we present a test case in which the cranial bosses are evaluated as fuzzy landmarks. Five fuzzy landmarks (the cranial bosses) and three traditional landmarks were placed repeatedly by a single observer on three-dimensional (3D) computed tomography (CT) surface reconstructions of pediatric dry skulls and skulls of pediatric patients, and directly on four of the same dry skulls using a 3Space digitizer. Thirty landmark digitizing trials from CT scans show an average error of 1.15 mm local to each fuzzy landmark, while the average error for the last ten trials was 0.75 mm, suggesting a learning curve. Data collected with the 3Space digitizer was comparable. Measurement error of fuzzy landmarks is larger than that of traditional landmarks, but is acceptable, especially since fuzzy landmarks allow inclusion of areas that would otherwise go unsampled. The information obtained is valuable in growth studies, clinical evaluation, and volume measurements. Our method of fuzzy landmarking is not limited to cranial bosses, and can be applied to any other anatomical features with fuzzy boundaries.

Child↗

PubMedDate not supplied

Preoperative morphology and development in sagittal synostosis.

The goal of this study is to characterize the differences between normal cranial morphology and that of patients diagnosed with isolated sagittal synostosis, using three-dimensional (3D) landmark coordinate data collected from computed tomography (CT) scans. This retrospective study uses pre-operative CT images of a sample of children diagnosed with isolated sagittal synostosis (N = 23) and of dry skulls of unaffected children (N = 10). In order to be included in the study, patients had to have a confirmed diagnosis of sagittal synostosis and a pre-operative CT scan of acceptable quality available in digital format. Separation of normal and synostosed individuals on the basis of craniofacial morphology was achieved by applying a principal coordinates analysis to a dissimilarity matrix calculated from the landmark coordinate data. Direct comparison of age-graded samples of normal and synostosed individuals using Euclidean Distance Matrix Analysis enabled localization of the morphological differences between samples. This method was also used to characterize growth patterns of the two samples using cross-sectional data. The parietal bosses were found to be the features that were most influential in separating sagittal synostosis patients from their age-matched normal counterparts. A cross-sectional analysis of growth showed that the specifics of the growth differences between normal and sagittal synostosis individuals changed with the age interval considered. We present direct evidence that the parietal bosses are critical in the differentiation of normal and sagittal synostosis morphology, and indirect evidence of the possible role of the parietal tubers in the etiology of sagittal synostosis.

Child↗