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Biomedical subjects

C F Hildebolt

Publications and source records attributed to C F Hildebolt.

At least 55 records · Page 3Linked to original sources
PubMed1996

Local staging of endometrial carcinoma: comparison of transvaginal and intraoperative sonography and gross visual inspection.

OBJECTIVE: The purposes of this study were to compare transvaginal sonography (TVS), intraoperative sonography (IOS), and gross visual inspection of the uterus with the histopathologic findings in patients with endometrioid adenocarcinoma, and to compare the accuracies of TVS, IOS, and gross visual inspection in staging of the tumor. SUBJECTS AND METHODS: Sixteen patients with endometriod carcinoma were prospectively evaluated with TVS and IOS. Intraoperative gross visual inspection was also performed. Gray-scale, duplex, and color Doppler findings were used to stage patients. The location and depth of myometrial invasion and the presence of cervical involvement were recorded. At gross visual inspection, only the absence or presence and the depth of myometrial invasion (< or = 50% or >50%) were recorded. The data were analyzed three ways. First, in uterine specimens with myometrial invasion, a site-by-site comparison was made among the TVS and IOS findings and the final histologic results regarding location and depth of tumor invasion. Next, to determine tumor stage, myometrial invasion was defined in two ways: (1) absent, 50% or less, or greater than 50%; and (2) 50% or less or greater than 50%. Then imaging findings, gross visual inspection, and the final histologic results were compared. RESULTS: Of the 16 uterine specimens, eight had myometrial invasion, with 13 separate sites of tumor invasion. IOS correctly identified the location and depth (+/- 10% of the histologic depth) of tumor invasion at four (31%) sites, and TVS at one (8%) site. TVS and IOS overestimated myometrial invasion due to adenomyosis, bulky intraluminal tumor, and lymphovascular invasion. When myometrial invasion was defined as absent, 50% or less, or greater than 50%, TVS was correct in 60% of cases, IOS in 56%, and gross visual inspection in 53%. When myometrial invasion was defined as 50% or less or greater than 50%, TVS was correct in 93% of cases, IOS in 81%, and gross visual inspection in 80%. CONCLUSION: TVS and IOS are inaccurate in predicting the precise location and depth of myometrial tumor invasion. However, when a less rigorous definition of invasion is used, the accuracies of TVS and IOS are comparable to gross visual inspection in staging of the tumor.

Adult↗
PubMed1995

Objective and subjective evaluations of Kodak Ektaspeed Plus dental x-ray film.

A new dental x-ray film, Kodak Ektaspeed Plus (Eastman Kodak Co., Rochester, N.Y.), was compared with Kodak Ektaspeed and Ultraspeed films. The comparison was based on objective measures (film contrast, speed, and fog levels) and subjective appraisals (film graininess and appearance). Ektaspeed Plus had higher contrast than Ektaspeed and in general similar contrast to Ultraspeed. Ektaspeed Plus was faster than Ektaspeed. Films were stored in various locations and base + fog determinations were made during a 16-week period. Ektaspeed Plus and Ultraspeed films were generally stable within this period. There were no meaningful differences in fog buildup based on storage location. Ektaspeed Plus had the least rate of buildup. Ektaspeed demonstrated the greatest rate of buildup and the greatest sensitivity to environmental factors. Periapical exposures were made of the molars of a manikin. These radiographs were subjectively assessed by three observers. The Ektaspeed Plus film was judged to appear less grainy than the Ektaspeed and to have a pleasing appearance. On the basis of the evaluations performed in this initial investigation, it was concluded that Ektaspeed Plus was superior to Ektaspeed film and was superior or equivalent to Ultraspeed film for dental radiography.

Absorptiometry, Photon↗
PubMed1995

A comparison of six intra-oral X-ray films.

OBJECTIVES: To compare objectively and subjectively national-brand dental X-ray films with widely available and less costly brands. METHODS: A range of dental films, including the recently released Kodak Ektaspeed Plus, was purchased from mail-order suppliers at the lowest published price. Objective measurements (film speed, contrast, fog levels, costs, physical characteristics) and subjective evaluations (ease of use, film graininess, overall appearance) were made. RESULTS: Private-label films were obtained at less cost than those of major vendors. Not all film speeds, sizes and wrapping materials were available from individual manufacturers. Objective measures and subjective appraisals showed that Ektaspeed Plus was the fastest film and had good contrast with the clinically useful density ranges. Agfa Dentus was the next fastest film, but it had rather low contrast and was grainier than the other films. The non-proprietary brands were difficult to open with primary glove barriers, making effective infection control practices arduous. All films were relatively stable over a 16-week period regardless of storage location. CONCLUSIONS: The major manufacturers offered more choices of film sizes and speeds than did private label suppliers. The films from the major manufacturers, although more expensive, were more conducive to effective infection control practices. Ektaspeed Plus had a performance comparable with or better than the other available films. Based on this preliminary study, it is recommended that this new film is considered as an alternative to D-speed films.

Absorptiometry, Photon↗
PubMed1995

Intrafilm controls to standardize grey level variations in digitized radiographs.

OBJECTIVES: Radiometric analysis can be used to identify small changes in grey levels taken from investigator-defined regions of interest (ROIs). To do this, standardization of the radiographic optical densities and image grey scales is considered essential. Rigid standardization is one of the impediments to applying existing radiometric techniques to clinical practice. The purpose of this study was to evaluate the use of grey-level variations from a series of intrafilm control regions of interest (ROIs) to adjust radiometric grey-level data taken from test ROIs. METHODS: After digitization, ROIs were drawn on three locations: the background, anatomical crown, and tooth root. Mean grey levels, histograms and cumulative percent histograms (CPHs) were determined for each group. With the goal of decreasing the distribution of these curves from their unadjusted grey-level positions to zero (superimposing all curves), shifts required to align the control CPHs were applied to test CPHs. Changes between the pre- and post-adjusted CPH distributions were measured. RESULTS: Intrafilm controls provided a combined decrease of 45.3% in the grey-level distribution error. CONCLUSION: While CPHs can be adjusted using intrafilm controls, these adjustments may have limited benefit.

Humans↗
PubMed1994

Splenic volume in children: simplified estimation at CT.

Measurements of splenic length, width, and thickness were obtained from axial computed tomographic (CT) scans in 50 consecutive children (26 male and 24 female patients, aged 8 days to 19 years) referred for abdominal CT. In addition, the outline of the spleen was traced on individual axial CT sections to obtain the splenic volume with use of the software program in the CT computer. The three splenic dimensions correlated well (r = .97) with the splenic volumes obtained with the more accurate technique of tracing the splenic outline on sequential CT sections.

Adolescent↗
PubMed1994

Bitewing-based alveolar bone densitometry: digital imaging resolution requirements.

The resolution requirements were determined for detection of incremental alveolar bone loss from digitized Ektaspeed radiographs. Ten clinical radiographs were examined with a calibrated optical microscope to measure the smallest feature of interest discernible for alveolar bone. Images of trabeculae > 100 microns in diameter could be identified, but smaller ones could not be resolved. The Nyquist Criterion requires sampling with 50 microns (or smaller) pixels to measure such features. Numerous 25 microns Ag aggregates were present. Fifty microns resolution is a practical compromise between noise level and feature resolution. In another example of 10 bitewings digitized at 8 bit grey scale, about half the available range was used for alveolar bone, resulting in uncertainty, over a range of 2 optical density (OD) units, of about 1.42% at the average OD for alveolar bone (1.1). With the same radiographs digitized at 12 bit resolution, over 2000 of 4096 grey scales were used with a corresponding uncertainty of about 0.09%. Twelve-bit precision was also able to resolve smaller increments in an aluminium stepwedge than was 8 bit precision. Twelve-bit grey scale and 50 microns spatial resolution are recommended for alveolar bone densitometry performed with Ektaspeed radiographs.

Absorptiometry, Photon↗
PubMed1993

Periodontal health in free-ranging baboons of Ethiopia and Kenya.

Frontal and lateral intraoral photographs of 19 baboons from the Awash National Park, Ethiopia and 37 baboons from Amboseli National Park, Kenya, were used to assess periodontal health. The Awash baboons, and two groups (Alto's and Hook's) at Amboseli, fed entirely from natural sources, but baboons from the third Amboseli group (Lodge) fed largely on food refuse from one of the park's lodges. Juveniles and adults were evaluated separately. Intraoral photographs were seriated based on visual appraisals of periodontal health. In both age groups, the best periodontal health was seen in Awash animals; Alto's and Hook's animals were intermediate, and the poorest health was seen in the Lodge sample. The periodontal health decreased with age in adult baboons, as reported in humans. Geochemistry, genetics, age, and diet (particularly variations in bacterial flora) were considered as factors contributing to the intergroup differences. Although it is not possible at present to exclude any of these as a contributing cause, we consider that diet in the broad sense (including food, water, and contamination by oral bacteria of human origin) probably plays a major role.

Age Factors↗
PubMed1993

35-mm film scanner as an intraoral dental radiograph digitizer. I: A quantitative evaluation.

A 35-mm slide scanner digital imaging system was tested for its suitability in digitizing intraoral dental radiographic film for quantitative studies. The system (Nikon model LS-3510AF Nikon Electronic Imaging, Nikon, Inc., Melville, N.Y.) uses a charge-coupled device linear photodiode array. The data content in the original film images was evaluated, and the system performance assessed objectively with the use of specially designed test films. Radiometric and geometric performances for the digitizing system were extracted from measurements and observations, and these were compared with published data for two other film digitizing systems (video camera DAGE MTI, Michigan City, Ind. and Barneyscan 35-mm film digitizer Barneyscan, Berkeley, Calif.). The techniques used to evaluate this system are easy and suitable for evaluation of any digitizing system. This scanner system (Nikon) was superior to previously evaluated systems in transforming and recording radiographic film densities across the range (0.3 to 2.0 optical density units) of clinically relevant optical densities. The scanner offers substantial advantage over the other digitizing systems for gray scale information from clinically important optical densities.

Evaluation Studies as Topic↗
PubMed1993

35-mm film scanner as an intraoral dental radiograph digitizer. II: Effects of brightness and contrast adjustments.

Typical 35-mm slide scanners use a photodiode array and software that allows for digital and analog controls that are manually adjustable. The digital controls provide brightness and contrast adjustments, whereas corresponding analog controls adjust the exposure time and black level that determines the clamping level of the charge-coupled device for the maximum black in the image. The objective of this study was to determine the effects of these controls on the radiometric data of intraoral dental radiograph images, to establish recommended settings, and to set specific standard guidelines for the digitization process. Three approaches were used. The results of this study demonstrate that brightness and contrast control alterations on the digitizer produces different optical densities and modulation transfer function values. The impact of these results is unresolved yet must be considered in analysis on quantitative radiometric studies.

Evaluation Studies as Topic↗
PubMed1993

Effects of region of interest outline variations on gray-scale frequency distributions for alveolar bone.

Normalized cumulative percentage gray-scale distributions from digitized radiographs of dry skulls can be used to evaluate alveolar bone health. With this method, manually defined regions of interest are used to identify the area of the image to be analyzed. The purpose of this study was to determine if variations in the dimensions of the regions of interest affect the gray-scale distributions. Two approaches were used. The effect of region of interest outline variations on (1) the ability to differentiate between various sized bone chips and (2) the ability to distinguish between two groups of skulls with the alveolar bone subjectively rates as normal or diseased were investigated. Four different regions of interest, which consisted of outline and area variations to a basic region, were used. Ninety-one percent of the cumulative histograms that represented chips were sufficiently separated from nonchip plots to be distinguished. Bone health was correctly assessed with a numeric classifier for 37 of 44 quadrants, for an accuracy of 84%, a specificity of 79%, and a sensitivity of 90%. Although ROI size and shape consistency in longitudinal studies are important in radiometric analyses, small variations had minimal impact in this study.

Absorptiometry, Photon↗
PubMed1993

Inter-relationships between bone mineral content measures. Dual energy radiography (DER) and bitewing radiographs (BWX).

In vitro periodontal alveolar bone mineral content (BMC) measurements obtained with dual-energy radiography (DER) were compared with assessments based on bitewing radiographs (BWX). In addition, in patients, the relationship between bitewing and several postcranial dual-energy-radiographic measures were evaluated. Dual-energy-radiographic and bitewing measurements were made on 2 cadaver mandibles initially and after 2 incremental bone reductions at 4 sites. Rank-order correlations between dual-energy-radiographic and bitewing measures for the 4 sites ranged from 0.7 to 1.00. Bitewing measures indicated true bone loss with a sensitivity of 1.00. For patients, correlations between bitewing measures and dual-energy-radiographic scans suggested the strongest relationships were in the distal sections of the radius and ulna and in the intertrochanteric and Ward's areas of the femur. Correlations, in the 0.5-0.6 range, were not statistically significant (p > 0.05), but were quite robust considering the small sample size and preliminary nature of this investigation. Results suggest that the bitewing measure is sufficiently sensitive to detect clinically meaningful (5% or greater) changes in alveolar BMC and, further, that alveolar bone mineral content may reflect postcranial BMC. The implications of postcranial bone mineral changes being reflected in alveolar bone would enhance both our understanding and treatment of alveolar bone loss. The use of bitewing measures to facilitate identification of patients with postcranial bone loss is discussed.

Absorptiometry, Photon↗
PubMed1993

Digital radiographic image-based bone level measurements: effect of film density.

Previous studies have demonstrated that accurate alveolar bone-level measurements can be made using digitally enhanced bitewing radiographs. In this study, we determined the effect of exposure variations on bone-level measurement accuracy using digital radiographic images of dry skulls. 6 direct bone-level measurements on the mandibular 1st molars of dry skulls were established by consensus of 2 expert observers. 13 bitewing radiographs were taken on each side of 11 skulls, using a specially designed positioning device. Exposure settings of 70 kVp, 10 mA, and 24 impulses were empirically chosen as the baseline. Kilovoltage and impulses times were individually varied (50 to 100 kVp in 10 kV increments and 15 to 48 impulses in 6 steps) to ensure a wide range of clinically relevant optical densities on the test images. The radiographs were digitized and alveolar bone level measurements, corresponding to those for skulls, were made on the images by 2 observers. Pearson product-moment coefficients between radiographs and criteria measurements were calculated. It was found that dry skull and digital bitewing radiographic measurements were highly correlated, within the limits of exposure parameter variations tested. Accurate measurements of alveolar bone level are possible from bitewing radiographs taken within a wide range of exposures, when digital image processing techniques are employed.

Absorptiometry, Photon↗
PubMed1993

Alignment errors in bitewing radiographs using uncoupled positioning devices.

Errors in X-ray beam alignment account for many of the exposure errors in bitewing radiography. A new method for measuring these alignment errors is described. The alignment accuracy of two different models of inexpensive plastic positioning devices, used for bitewing radiography, were quantified and compared. The technique involves documenting the alignment of an 'ideal' reference radiograph and successive exposures. It permits calculation of X-ray beam-film alignment errors in all subsequent radiographs using the 'ideal' reference. Bitewing radiographs were taken on 61 patients and 19 of these were re-radiographed at 6-month intervals over a 2-year period, providing a total of 156 radiographs for the study. Horizontal and vertical angular deviations were measured and total alignment errors calculated for each radiograph. The average angular alignment error was less than 2 degrees total angular error (1.3-2.4 degrees, 95% confidence intervals). It is concluded that these devices can be used when X-ray beam-film alignment error below 2.5 degrees is acceptable.

Humans↗
PubMed1992

Cephalometrics of anterior open bite: a receiver operating characteristic (ROC) analysis.

A new approach is presented for the evaluation of cephalometric measurements in which a measurement is considered to be a diagnostic test for the presence or the absence of some component of malocclusion. This approach allows cephalometric measurements to be judged by the criteria that are generally used for clinical diagnostic tests, including determination of sensitivities, specificities, positive and negative predictive values, and, most important, receiver operating characteristic (ROC) curves. In this study, ROC curves are generated for the relationship between several skeletal cephalometric measurements and anterior dental open bite in a sample of 1541 orthodontic patients. The overbite depth indicator is found to be a better diagnostic criterion for the presence of dental open bite than any other commonly used skeletal cephalometric measurement or ratio. ROC curves are of substantial value for evaluating the diagnostic information of cephalometric measurements.

Adolescent↗
PubMed1992

Radiometric classification of alveolar bone health.

A radiograph-based classifier for discrimination between normal and diseased alveolar bone was developed. The alveolar bone health of dry mandibles was rated, by consensus of two trained observers, as normal or diseased. Bitewing radiographs of mandibular quadrants were digitized and regions of interest (ROIs) of the alveolar bone between the first and second permanent molars outlined. Gray-scale histograms for the ROIs were computed, and a classifier based on these histograms was developed. Two observers (independently) used only the classifier to rate the bone as being normal or diseased. These ratings were compared with the original ratings of trained observers who viewed and scored the actual alveolar bone. The sensitivity (the ability to detect diseased alveolar bone), specificity (the ability to detect normal alveolar bone), and accuracy were 0.90 or greater, indicating good agreement with subjective visual assessments of dry mandibles. These results suggest that this procedure may be applicable for evaluations of bone health in humans.

Adult↗
PubMed1992

Digital dental image processing of alveolar bone: Macintosh II personal computer software.

Dental radiographs are amenable to digital image processing and analysis for both subjective interpretation and quantification of scene features. Four general-purpose image processing programs for the Apple Macintosh II computer (NIH Image, Enhance, IP Lab and DIP Station) were applied to digital analysis of dental radiographs. These programs can manipulate and quantitatively analyse the gray scale and spatial data of dental images and improve their subjective quality. They can interactively make geometric measurements of features. The programs were evaluated for their versatility and applicability in the quantification of alveolar bone. Overall, NIH Image was judged most suitable for current dental imaging needs. Each of the other programs offered unique features that may be valuable in specific applications.

Alveolar Process↗
PubMed1991

ROC analysis of observer-response subjective rating data--application to periodontal radiograph assessment.

Many physical anthropological studies require that an observer or device discriminate between states that can be easily confused. Receiver operating characteristic (ROC) analysis currently offers the best method for determining the accuracy of such choices, particularly for small sample sizes. Although ROC analysis is widely accepted in psychophysical and biomedical testing, its use in anthropological studies has not been reported. ROC analysis is used here to determine the usefulness of enhanced dental radiographs to assess vertical alveolar bone defects for quantitative studies of human variation with regard to periodontal disease. The presence or absence of vertical-bony defects (truth) for 75 human skulls was established by the consensus of two trained observers. Dental bitewing-radiographs were taken of the alveolar processes, the radiographs digitized, and the brightness and contrast of the digital images enhanced. The two observers who established truth then rated 1) plain bitewing radiographs, 2) unenhanced digital images of bitewings, and 3) enhanced digital images of bitewings for vertical bony defects. The rating scale varied from 1 (vertical defect definitely or almost definitely present) to 5 (definitely or almost definitely absent). ROC analysis was used to compared the diagnostic value of the 3 imaging modalities. All modalities had nearly identical diagnostic performance, measured as Az values (areas beneath ROC curves) that were less than 0.80, which indicates only moderate usefulness. It is concluded that enhancement does not increase success in vertical-bony-defect diagnosis from digital dental radiographs processed in this manner. Moreover, it is suggested that conventional bitewing radiographs may be unsuitable for accurate quantification of such defects.

Alveolar Bone Loss↗