Search PubMed⌕ Search

Biomedical subjects

F L Bookstein

Publications and source records attributed to F L Bookstein.

At least 73 records · Page 4Linked to original sources
PubMed1986

Mediastinal lymph node detection and sizing at CT and autopsy.

Although CT has assumed a major role in the preoperative evaluation of the mediastinum in patients with lung carcinoma, there is no consensus as to its accuracy or efficacy in this setting. A potential source of CT error is inaccurate detection or sizing of lymph nodes in particular mediastinal locations because of inadequate contrast with surrounding tissue or partial volume effects. We imaged five cadavers with CT and then meticulously dissected the mediastinal nodes. The nodes were measured and categorized by using the lymph node mapping scheme of the American Thoracic Society. The short axis nodal diameter was the best CT predictor of nodal volume. Excellent correlation was found between CT and autopsy for lymph node detection in right-sided mediastinal lymph nodes; poorer CT/autopsy correlation was found for left-sided lymph nodes, especially in the lower left peribronchial region. These findings suggest that CT may be less accurate in identifying left-sided mediastinal metastases.

Adult↗
PubMed1986

Cell distribution during mouse secondary palate closure. II. Mesenchymal cells.

The patterns of distribution of both total mesenchymal cells and the ratios of [3H]thymidine-labelled to total cells were mapped during secondary palatal shelf reorientation in vivo and in vitro. Smoothed spatial averaging, a computer-assisted method which takes into account the positions of all cells across an entire histological section of the shelf, was employed. Changes in shelf cross-sectional area and cell size were also measured. Three shelf regions, anterior and posterior presumptive hard and presumptive soft palate, were studied at developmental stages which were 30, 24 and 18 h prior to expected in vivo elevation, after in vivo reorientation and during the course of in vitro reorientation. Region-specific patterns of cell distribution change with shelf reorientation. These changes were observable within 6 h. Increases in cell number by cell division may enhance some high local cell densities, but cannot account for decreases in cell density. Increase in cell size is not a factor in decreasing cell density, nor is cell death. Displacement of cells by expansion of the extracellular matrix may be involved.

Animals↗
PubMed1985

Skeletal and dental changes following functional regulator therapy on class II patients.

Craniofacial growth in 100 patients treated with the functional regulator of Fränkel for about 24 months was compared with craniofacial growth seen in a matched group of untreated persons with Class II malocclusion. Both conventional and geometric cephalometric analyses were used to evaluate the skeletal and dental adaptations. This study shows several clear effects of treatment in either of two age ranges considered. The principal skeletal effect was advancement of the mandible along the direction of the facial axis. This advancement resulted in increases in mandibular length and in vertical facial dimensions. There was little effect of treatment upon maxillary skeletal structures with the exception of point A, which moved slightly posteriorly. Dentoalveolar adaptations due to treatment included a decrease in the normal forward movement of the upper molar and an increase in the normal vertical movement of the lower molar. There was a 2-mm posterior movement of the tip of the upper incisor but minimal anterior tipping of the lower incisor.

Activator Appliances↗
PubMed1985

Cellular behavior in the anteroposterior axis of the regenerating forelimb of the axolotl, Ambystoma mexicanum.

Cellular behavior along the anteroposterior axis of the regenerating axolotl forelimb was studied by use of triploid (3N) tissue grafted into diploid (2N) hosts and three-dimensional computer reconstructions. Asymmetrical upper forelimbs were surgically constructed with one half (anterior or posterior) 3N and the other half 2N. Limbs were amputated immediately after grafting or were permitted to heal for 5 or 30 days prior to amputation. When regenerates had attained the stage of digital outgrowth, the limbs were harvested and sectioned in the transverse axis for histological analysis. When all limbs bearing anterior grafts were considered as a group, 77% of the 3N mesodermal cells were observed in the anterior side of the regenerates and 23% were located in the posterior side of the regenerates. When all limbs bearing posterior grafts were considered as a group, 76% of the 3N mesodermal cells were found in the posterior side of the regenerate and 24% had crossed into the anterior side. Healing times of 0, 5, or 30 days prior to amputation had no effect on the experimental outcome. Three-dimensional computer reconstructions revealed that most 3N cells of mesodermal origin underwent short-distance migration from anterior to posterior or from posterior to anterior and intermixed with diploid mesodermal cells near the midpoint of the regenerated anteroposterior axis. Some 3N cells were observed at greater distances from the graft-host interface. By contrast, labeled epidermal cells from both anterior and posterior grafts exhibited long-distance migration across all surfaces of regenerated limbs. Details of a computer-assisted reconstructive method for studying the three-dimensional distribution of labeled cells in tissues are presented.

Ambystoma mexicanum↗
PubMed1985

Normal mediastinal lymph nodes: number and size according to American Thoracic Society mapping.

CT was used to investigate the number and size of normal mediastinal lymph nodes at 11 intrathoracic nodal stations defined by the American Thoracic Society lymph-node mapping scheme. Nodal size was measured both as short- and long-axis diameters in the transverse plane. Findings for 56 patients show the largest normal mediastinal nodes to be in the subcarinal and right tracheobronchial regions. Upper paratracheal nodes were smaller than lower paratracheal or tracheobronchial nodes, and right-sided tracheobronchial nodes were larger than left-sided ones. From the distributions of node sizes, thresholds were set above which nodes in any region might be considered enlarged. These thresholds, in agreement with a prior investigation of patients with lung cancer, suggest 1.0 cm as the upper limit of normal for the short axis of a mediastinal node in the transverse plane.

Adult↗
PubMed1985

The thymus: reexamination of age-related changes in size and shape.

The computed tomographic appearance of the normal and abnormal thymus and its age-related changes have been described. However, there is little quantitative data regarding thymic morphology at the extremes of age and the value of thymic measurements, in particular thickness, to recognize thymic abnormality. Using computed tomography the thymic morphology in 309 normal patients was analyzed retrospectively, examining its appearance at the extremes of age and measuring its dimensions for comparison with similar data in 23 patients with clinically or surgically proven thymic abnormality. The study confirmed the previously reported age-related growth and subsequent involution of the normal thymus. In more than half the patients beyond the age of 40, total fatty involution of the gland occurred. When present, residual thymic tissue usually assumed a small, linear, oval, or round shape and did not produce focal alterations in the lateral mediastinal contour. Comparison of normal and abnormal glands suggests that thymic shape reliably separates normal from abnormal glands. In particular, multilobularity was never a feature of the normal gland at any age but was seen only in patients with thymic abnormality. Logarithms of the anteroposterior, craniocaudal, and transverse dimensions as well as thymic thickness were plotted against age to determine the value of quantitative measurements in detecting thymic abnormality. While thymic thickness and the logarithm of the product of transverse dimension and thickness were sensitive indicators of thymic abnormality, these were not necessary for accurate recognition of abnormality.

Adolescent↗
PubMed1985

Sonographic standards for normal infant kidney length.

Standards for kidney length in relation to size were derived from measures of 34 normal, full-term, healthy infants aged 2-56 weeks. Of six general size variables (age, weight, length, head circumference, abdominal circumference, and C7 to coccyx length), net kidney length correlated best with a combination of infant length and weight. A nomogram has been generated from these data for use by the radiologist.

Female↗
PubMed1985

A comparative cephalometric study of the cranial base in craniofacial anomalies: Part I: Tensor analysis.

The method of mean tensor analysis was used to study the cranial base in six craniofacial anomalies: Crouzon's disease, Apert's syndrome, Pfeiffer's syndrome, craniofacial microsomia (CFM), Treacher Collins (TC) syndrome, and frontonasal dysplasia (FND). The form was represented by five landmarks: the nasion (N), basion (Ba), sella (S), frontomaxillonasal suture (FMN), and sphenoethmoidal registration point (SE), and the deformities were computed as mean deformations from age- and sex-matched normal mean forms. The cranial base in CFM is normal in shape. The other five syndromes manifest four distinct patterns of shape variation. Only in TC and Pfeiffer's syndrome is the cranial-base angle distinctive. In Apert's and Crouzon's syndromes, point SE is displaced anteriorly upon a cranial base, small in size but otherwise normal in shape. In TC syndrome and FND, point SE is displaced posteriorly toward the sella.

Acrocephalosyndactylia↗
PubMed1985

Estimation of patient age based on plain chest radiographs.

Patient age is an essential part of a clinical history, but it is not always provided by referring physicians. We assessed the ability of four radiologists with different levels of expertise (first-year resident to professor emeritus) to predict patient age based on postero-anterior and lateral chest radiographs from 171 patients. All four were able to predict age with a mean error of less than 15 years, but there were statistically significant differences among them. Surprisingly, observer experience did not correlate with accuracy of patient age estimation. While many factors probably operate, the estimation of patient age relies heavily on "gestalt."

Adolescent↗
PubMed1984

A statistical method for biological shape comparisons.

Biological shape data combine two sorts of information: genometric location and biological homology. The link between these two is the landmark, a set of biologically corresponding points located in all the forms of a series. Analysis of shapes as configurations of landmarks proceeds most effectively by D' Arcy Thompson's (1917, 1942) method of transformations. In this tradition, shape change is not the arithmetical difference of distances, angles, and ratios measured on shapes separately; rather, it is a mensurand in its own right, the geometrical deformation taking the Cartesian coordinate space of one form onto that of another in accord with biological homology. Such a deformation may be displayed, continuously or discretely, as a symmetric tensor field of principal crosses, pairs of directions which start and finish at 90 degrees. At any point, along one of these directions the dilatation, or dimensionless rate of change of length, is largest; along the other, smallest. These are the principal dilatations. All conventional scalar descriptions of the shape change may be deduced from the tensor presentation. This article reviews the statistical description of mean biological form-changes viewed in this way, and introduces linearized significance tests for mean shape change and mean size change. The tests, which make no reference to any set of size or shape variables, are based in a convenient parametric distribution for shape changes in triangles of landmarks. On a suitable null hypothesis, the ratio of the difference of the principal dilatations of the mean deformation to the sum of their standard errors goes as square root of pi/2 approximately 0.88 times an approximate t-ratio for shape change; the sum of the deviations of those dilatations from unity, divided by the sum of their standard errors, goes as square root of 2/2 approximately 0.71 times an approximate t-ratio for size change. The difference between these two constants reflects the divergent selection bias of the pair of principal dilatations. In matched studies, the difference of the principal dilatations of the mean change, divided by the mean difference of the principal dilatations case by case, is square root of 2/pi N times an approximate X2 for shape difference. Examples are presented that test cephalometric data in three scientific contexts: comparison of groups of biological shapes observed once each; characterization of mean difference in a matched design (namely, mean growth in one group observed twice); and description of mean differences in growth between groups of shapes each observed twice.

Adolescent↗
PubMed1984

Estimation of ultrasonic attenuation and mean backscatterer size via digital signal processing.

The backscattered rf signals from the lungs of fetal sheep during their last trimester of development were digitized and processed in an attempt to correlate ultrasonic parameters with measured functional parameters related to lung maturation. The broadband, post- TGC , rf signal of a commercial B-mode ultrasonic scanner was digitized at a sampling rate of 25 MHz. Sorting excluded data from regions of rib shadowing and other nonlung structures from analysis. The sorted data were used to estimate the slope of the ultrasonic attenuation coefficient with respect to frequency via linear regression on the average difference of the logarithm of power spectra from separated data segments. The power spectra were also corrected for attenuation, averaged and used to compute the power cepstrum of the backscattered signal which can be related to mean backscatterer radius. Results are presented for eight fetal sheep.

Animals↗
PubMed1983

Automatic computer processing of digital 2-dimensional echocardiograms.

Quantitative studies of left ventricular function using 2-dimensional echocardiography have been limited because of a lack of computerized methods to automatically analyze the echocardiographic images. Previous computer efforts have been directed at digitizing the video output of the 2-D echocardiogram, but this digitizing method has significant limitations. A direct digitization method that produces improvement in signal-to-noise ratio and, subsequently, improved automatic detection of endocardial and epicardial borders, was developed. With definition of these edges, left ventricular global and regional analysis is possible frame by frame so that dynamic changes in cardiac function may be assessed throughout the cardiac cycle. Further technologic advances in 2-D echocardiographic acquisition and image processing should allow computer processing of 2-D echocardiographic data in real time.

Computers↗
PubMed1983

The geometry of craniofacial growth invariants.

In the description of craniofacial growth it is crucial to identify constant geometric relations. The search leads to complex manipulations of coordinate data from cephalograms. In the regularities that he finds, the clinician must be aware of the difference between empirical contingency and geometric necessity. For instance, common procedures for identifying centers away from which growth proceeds radially (the "polar phenomenon") ignore theorems about the indeterminacy of such centers. The scan for growth invariants in configurations of landmarks should be based on the method of tensor analysis. Any shape change may be summarized in terms of two directions in each triangle of landmarks. The directions are at 90 degrees in each triangle both before growth and after; one of them bears the greatest percent rate of change of length of all directions in the triangle, and the other bears the least. From a diagram of these axes one comes immediately to strict invariants of the shape change--specific angles and proportions along segments defined by relations between the triangle and the axes--linked to other specific angles and proportions which change most rapidly. It is simple to adapt this machinery so that it can deal with average shape changes in populations. Included here are two examples of the technique: (1) extracting the statistically most stable definition of "growth axis" (displacement of menton from cranial base) in children aged 6 to 14 years and (2) describing the shape change of the rat calvarium between the ages of 7 days and 150 days. Such descriptions should be the first step in designing any cephalometric analysis.

Adolescent↗
PubMed1983

Growth and development of human adipose tissue during early gestation.

805 normal-for-age human embryos and fetuses were used to study early prenatal fat development. The investigation included observations on stages of fat morphogenesis at the light microscopic level and computerized image analyses of fat lobule size and number. The buccal fat pad was selected as a model system for the analyses. Fat tissue differentiates between the 14th and the 16th weeks: there are five morphogenic phases in adipose tissue formation, strongly associated with the formation of blood vessels. Fat lobules are the earliest structures to be identified before typical vacuolated fat cells appear. Concerning fat lobule size and number, we show that after the 23rd week the total number of fat lobules remains approximately constant, while from the 23rd to 29th week the growth of adipose tissue is determined mainly by an increase in size of the lobules. These results suggest that the 14th through the 23rd week is a sensitive period in fat lobule development, and that disturbances of normal adipogenesis during this period may play a role in the etiology of obesity in later life.

Adipose Tissue↗
PubMed1983

Evaluation of the pulmonary hilum: comparison of conventional radiography, 55 degrees posterior oblique tomography, and dynamic computed tomography.

In 84 patients with suspected intrathoracic neoplasms we compared the accuracy of conventional radiography, 55 degrees posterior oblique tomography, and contrast-enhanced dynamic incremental computed tomography (CT) in evaluation of the pulmonary hilum. We found dynamic incremental CT to be better than either conventional radiography or oblique tomography in hilar evaluation. In addition, significant information was detected in extrahilar and extramediastinal locations by CT in 21% of patients. This study, unlike earlier reports, indicates a role for CT in hilar evaluation.

Adenocarcinoma↗
PubMed1982

On the cephalometrics of skeletal change.

This essay introduces the general tensor analysis of skeletal change for landmark data. Consider first a single triangle of landmarks at two times. Joint changes in the lengths of its sides, or in the positions of its vertices according to some coordinate system, may be taken to specify a uniform deformation of the entire interior. The biorthogonal method expresses this by a pair of principal dilatations--maximum and minimum rates of change in length--along directions lying at 90 degrees in some orientation upon the triangle. No analysis of static form is involved in their calculation, which measures shape change without measuring shape. From this basic biorthogonal decomposition, we pass by a suitable averaging to descriptions of mean change in groups of diverse initial form and subsequently to explicit comparison of two mean changes, such as "treatment effect," all in the same parameters: two dilatations and an orientation. Schemes of more than three landmarks may be analyzed by reduction to triangles. I exemplify the method using data from Sheldon Baumrind's study of Angle Class II treatment effects. With respect to the growth observed in a "control" group of untreated Class II cases, both "cervical" (headgear) and "intraoral" (activator) appliances have the effect of compression a facial polygon horizontally (parallel to S-N) by about 1 percent per year and extending it vertically (perpendicular to S-N) by about 1 percent per day. These effects are slightly larger for the cervical treatment, which also causes an increase in the distance from nasion to the line sella-ANS (that is, "rotates the face downward") by some 1 percent per year relative to the growth observed in the controls.

Activator Appliances↗