Edward T. Bersu

The effect of computed tomographic scanner parameters and 3-dimensional volume rendering techniques on the accuracy of linear, angular, and volumetric measurements of the mandible

OBJECTIVES This study investigates the effect of scanning parameters on the accuracy of measurements from three-dimensional (3D), multi-detector computed tomography (MDCT) mandible renderings. A broader range of acceptable parameters can increase the availability of computed tomographic (CT) studies for retrospective analysis. STUDY DESIGN Three human mandibles and a phantom object were scanned using 18 combinations of slice thickness, field of view (FOV), and reconstruction algorithm and 3 different threshold-based segmentations. Measurements of 3D computed tomography (3DCT) models and specimens were compared. RESULTS Linear and angular measurements were accurate, irrespective of scanner parameters or rendering technique. Volume measurements were accurate with a slice thickness of 1.25 mm, but not 2.5 mm. Surface area measurements were consistently inflated. CONCLUSIONS Linear, angular, and volumetric measurements of mandible 3D MDCT models can be confidently obtained from a range of parameters and rendering techniques. Slice thickness is the primary factor affecting volume measurements. These findings should also apply to 3D rendering using cone-beam CT (CBCT).

Terminological, diagnostic, nosological, and anatomical-developmental aspects of developmental defects in man.

Man’s experience of congenital malformations antedates recorded history and can be inferred from philology and the most ancient of legends. Indeed, the presence of Down syndrome in the chimpanzee (McClure et al., 1969, 1970) and of various X-linked disorders in other mammals (Ohno, 1967) means that even during phylogeny man lived side by side with mammalian cousins affected with homologous forms of his own genetic aberrations. The history of teratology has been written many times and is astoundingly voluminous (Gruber, 1964). It shows that the accomplishments of the early workers in the field consisted primarily of anatomical and clinical descriptions.

Studies of malformation syndromes of man XXXXIA: anatomical studies in the Hanhart syndrome —A pathogenetic hypothesis

Two infants with the Hanhart syndrome, i.e. micrognathia, microglossia, terminal deficiency of all limbs and imperforate anus in one, were dissected and studied in detail. The interrelationships of the muscular and skeletal defects suggested that they were the result of incomplete rather than abnormal morphogenesis. We speculate that the oral and limb abnormalities resulted from deficient mesodermal proliferation caused by disturbances in the ectodermal-mesodermal interactions beginning about the 4th week of development. The imperforate anus may also relate to the proposed defect.

Cytoplasmic abnormalities in cultured cerebellar neurons from the trisomy 16 mouse

This study represents a first effort to characterize the growth and development of murine trisomy 16 neurons using single-cell neuron culture techniques. Murine trisomy 16 is a model for the human Down syndrome, or trisomy 21. Both show similar nervous system abnormalities including decreases in cerebellar size and in numbers of cerebellar neurons. Trisomy 16 cerebellar neurons cultured from 17-gestational day conceptuses grew less extensive neuritic arbors than normal neurons. Unlike controls, the individual neurites of the trisomic neurons were not clearly distinguishable as axons or dendrites over the 10 day period that they were observed. The trisomic neurons were characterized by diminished levels of microtubules, abnormally shaped mitochondria, and the presence of dense bundles of abnormal filaments that were not observed in any of the normal littermate neurons.

Trisomy 16 mice: neural, morphological, and immunological studies

The occurrence of trisomy (i.e, the presence of an additional chromosome in the genome) is associated with distinct and deleterious effects on the development and cellular processes of affected individuals. Efforts are now directed toward understanding the mechanisms by which the trisomic condition causes adverse effects. Trisomy for autosome number 21, Down’s syndrome, is of particular interest because of its high frequency (1 in 700 live births), the associated mental retardation, and the observation that individuals with the condition survive to the fourth and fifth decades. The Down syndrome has been the single most extensively investigated entity involving mental retardation since it was first identified in the middle of the 19th century.’,* The discovery of the chromosomal basis of Down’s syndrome in 19593 provided the initial impetus to relate specific phenotypic effects with cellular processes that are altered by the presence of the additional genetic material. Such studies have included: ( 1 ) detailed characterizations of Down’s syndrome morphologic phen~type;~,’ (2) identification of gene dosage phenomena for genes located on chromosome 21 (e.g., superoxide dismutase I); and ( 3 ) observations of possible effects of trisomy on cell proliferation.6 An extension of this work is now possible using trisomic mice that can be generated by using males or females with appropriate Robertsonian translocation ch rom~somes .~ The trisomy for murine autosome 16 is of interest because murine chromosome 16 contains several genes that are present in human chromosome 21. The shared genes include those coding for superoxide dismutase-1 , the alpha and beta interferon receptors, and the response of cells to beta-adrenergic agonist s t im~la t ion .~ .~ Three of these genes code for cell surface receptor linked systems. As with the Down’s syndrome, gene dosage effects also occur for the gene products of these loci in the trisomic mice. A difficulty with the trisomy 16 system is that none of these mice survive beyond term with breeding schemes that have been used so far.I0 Our current investigations include an evaluation of the effects of the additional chromosome 16 on the expression of cell surface markers, (e.g., the major histo-

Relationship between the neural dysgenesis and increased production of class I MHC H-2Kk mRNA and protein in neurons of murine trisomy 16 fetuses.

Neuronal cells from murine trisomy 16 fetuses have increased levels of class I MHC H-2Kk. To determine whether this increased level of H-2Kk protein product resulted from an increased synthesis of mRNA, a 33 base antisense cDNA probe complementary to a region in exon 2 of the H-2Kk sequence (nucleotide 392-424) was synthesized. This probe was used to examine, by in situ hybridization and immunohistochemistry, the neural distribution of H-2Kk mRNA and protein product. A marked elevation of the H-2Kk mRNA and protein were localized in mts16 neuronal populations that were susceptible to dysgenesis. The results implicate the expression of the H-2Kk in the neuropathology of mts16 and its human counterpart, Down syndrome.

Hyoid bone fusion and bone density across the lifespan: prediction of age and sex

The hyoid bone supports the important functions of swallowing and speech. At birth, the hyoid bone consists of a central body and pairs of right and left lesser and greater cornua. Fusion of the greater cornua with the body normally occurs in adulthood, but may not occur at all in some individuals. The aim of this study was to quantify hyoid bone fusion across the lifespan, as well as assess developmental changes in hyoid bone density. Using a computed tomography imaging studies database, 136 hyoid bones (66 male, 70 female, ages 1-to-94) were examined. Fusion was ranked on each side and hyoid bones were classified into one of four fusion categories based on their bilateral ranks: bilateral distant non-fusion, bilateral non-fusion, partial or unilateral fusion, and bilateral fusion. Three-dimensional hyoid bone models were created and used to calculate bone density in Hounsfield units. Results showed a wide range of variability in the timing and degree of hyoid bone fusion, with a trend for bilateral non-fusion to decrease after age 20. Hyoid bone density was significantly lower in adult female scans than adult male scans and decreased with age in adulthood. In sex and age estimation models, bone density was a significant predictor of sex. Both fusion category and bone density were significant predictors of age group for adult females. This study provides a developmental baseline for understanding hyoid bone fusion and bone density in typically developing individuals. Findings have implications for the disciplines of forensics, anatomy, speech pathology, and anthropology.

Hyoid bone development: An assessment of optimal CT scanner parameters and 3D volume rendering techniques

The hyoid bone anchors and supports the vocal tract. Its complex shape is best studied in three dimensions, but it is difficult to capture on computed tomography (CT) images and three‐dimensional volume renderings. The goal of this study was to determine the optimal CT scanning and rendering parameters to accurately measure the growth and developmental anatomy of the hyoid and to determine whether it is feasible and necessary to use these parameters in the measurement of hyoids from in vivo CT scans. Direct linear and volumetric measurements of skeletonized hyoid bone specimens were compared with corresponding CT images to determine the most accurate scanning parameters and three‐dimensional rendering techniques. A pilot study was undertaken using in vivo scans from a retrospective CT database to determine feasibility of quantifying hyoid growth. Scanning parameters and rendering technique affected accuracy of measurements. Most linear CT measurements were within 10% of direct measurements; however, volume was overestimated when CT scans were acquired with a slice thickness greater than 1.25 mm. Slice‐by‐slice thresholding of hyoid images decreased volume overestimation. The pilot study revealed that the linear measurements tested correlate with age. A fine‐tuned rendering approach applied to small slice thickness CT scans produces the most accurate measurements of hyoid bones. However, linear measurements can be accurately assessed from in vivo CT scans at a larger slice thickness. Such findings imply that investigation into the growth and development of the hyoid bone, and the vocal tract as a whole, can now be performed using these techniques. Anat Rec, 298:1408–1415, 2015.

Hyoid Bone Development: An Assessment Of Optimal CT Scanner Parameters and Three-Dimensional Volume Rendering Techniques

The hyoid bone anchors and supports the vocal tract. Its complex shape is best studied in three dimensions, but it is difficult to capture on computed tomography (CT) images and three‐dimensional volume renderings. The goal of this study was to determine the optimal CT scanning and rendering parameters to accurately measure the growth and developmental anatomy of the hyoid and to determine whether it is feasible and necessary to use these parameters in the measurement of hyoids from in vivo CT scans. Direct linear and volumetric measurements of skeletonized hyoid bone specimens were compared with corresponding CT images to determine the most accurate scanning parameters and three‐dimensional rendering techniques. A pilot study was undertaken using in vivo scans from a retrospective CT database to determine feasibility of quantifying hyoid growth. Scanning parameters and rendering technique affected accuracy of measurements. Most linear CT measurements were within 10% of direct measurements; however, volume was overestimated when CT scans were acquired with a slice thickness greater than 1.25 mm. Slice‐by‐slice thresholding of hyoid images decreased volume overestimation. The pilot study revealed that the linear measurements tested correlate with age. A fine‐tuned rendering approach applied to small slice thickness CT scans produces the most accurate measurements of hyoid bones. However, linear measurements can be accurately assessed from in vivo CT scans at a larger slice thickness. Such findings imply that investigation into the growth and development of the hyoid bone, and the vocal tract as a whole, can now be performed using these techniques. Anat Rec, 298:1408–1415, 2015.

Hyoid Bone Development: An Assessment Of Optimal CT Scanner Parameters and Three-Dimensional Volume Rendering Techniques: HYOID BONE SEGMENTATION FROM CT

The hyoid bone anchors and supports the vocal tract. Its complex shape is best studied in three dimensions, but it is difficult to capture on computed tomography (CT) images and three‐dimensional volume renderings. The goal of this study was to determine the optimal CT scanning and rendering parameters to accurately measure the growth and developmental anatomy of the hyoid and to determine whether it is feasible and necessary to use these parameters in the measurement of hyoids from in vivo CT scans. Direct linear and volumetric measurements of skeletonized hyoid bone specimens were compared with corresponding CT images to determine the most accurate scanning parameters and three‐dimensional rendering techniques. A pilot study was undertaken using in vivo scans from a retrospective CT database to determine feasibility of quantifying hyoid growth. Scanning parameters and rendering technique affected accuracy of measurements. Most linear CT measurements were within 10% of direct measurements; however, volume was overestimated when CT scans were acquired with a slice thickness greater than 1.25 mm. Slice‐by‐slice thresholding of hyoid images decreased volume overestimation. The pilot study revealed that the linear measurements tested correlate with age. A fine‐tuned rendering approach applied to small slice thickness CT scans produces the most accurate measurements of hyoid bones. However, linear measurements can be accurately assessed from in vivo CT scans at a larger slice thickness. Such findings imply that investigation into the growth and development of the hyoid bone, and the vocal tract as a whole, can now be performed using these techniques. Anat Rec, 298:1408–1415, 2015.