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PubMed1991

Effect of heart-size parameters computed from digital chest radiographs on detection of cardiomegaly. Potential usefulness for computer-aided diagnosis.

Heart size is an important and useful diagnostic parameter in chest radiographs. However, there is a large variation in the subjective judgment of cardiac enlargement (cardiomegaly). To reduce this subjective element, the authors are developing an automated system for quantitative analysis of heart size in digital chest radiographs. Four hundred chest radiographs were reviewed initially by two radiologists and were classified into two groups: those with and those without cardiomegaly. Another radiologist reviewed 47 images which were not classified consistently in the initial review. The authors used these radiographs to construct a database for determination of cardiomegaly. Numerous parameters related to heart size were obtained in a semiautomated analysis of these radiographs, and the use of each parameter for detection of cardiomegaly was evaluated by means of receiver operating characteristic analysis. The authors also examined whether the accuracy would be improved when they applied multivariate analysis to a pair of parameters. From the analyses of the individual parameters, the automatically determined cardiothoracic ratio was found to be the single most effective measure for detecting cardiomegaly in chest radiographs. However, multivariate analysis provided results superior to those with an individual parameter.

Cardiomegaly↗
PubMed1990

Computation of digitally reconstructed radiographs for use in radiotherapy treatment design.

The increasing use of 3-dimensional radiotherapy treatment design has created greater reliance on methods for computing images from CT data which correspond to the conventional simulation film. These images, known as computed or digitally reconstructed radiographs, serve as reference images for verification of computer-designed treatments. Used with software that registers graphic overlays of target and anatomic structures, digitally reconstructed radiographs are also valuable tools for designing portal shape. We have developed radiograph reconstruction software that takes full advantage of the contrast and spatial detail inherent in the original CT data. This goal has been achieved by using a ray casting algorithm which explicitly takes into account every intersected voxel, and a heuristic approach for approximating the images that would result from purely photoelectric or Compton interactions. The software also offers utilities to superimpose outlines of anatomic structures, field edges, beam crosshairs, and linear scales on digitally reconstructed radiographs. The pixel size of the computed image can be controlled, and several methods of interslice interpolation are offered. The software is written in modular format in the C language, and can stand alone or interface with other treatment planning software.

Humans↗
PubMed1986

Computer implemented digital filtering, scaling and addition for analysing the structure of early somatosensory evoked responses.

Computer-implemented digital filters are used to separate the fast wave complexes which are superimposed on slower background waves in human short latency somatosensory evoked responses (SSERs). The choice of filter for picking out the fine structure of the fast wave is shown to be not critical. After scaling and adding digitally filtered SSERs from two electrode montages, the peaks believed to be of cortical origin are cancelled, leaving visible a repetitive wave which must be presumed to be generated subcortically. From this, a new interpretation of the origins of peaks in short latency SSERs is made.

Adolescent↗
PubMedDate not supplied

Quantitative digital fluorography. Computer vs. human estimation of vascular stenoses.

Digital subtracted images of iodinated rods, incorporating accurately measured areas of eccentric stenosis were obtained. The average subjective estimations of fractional area reduction (211 readings each) by three experienced angiographers were compared with values obtained using an interactive computer algorithm using the densitometric data. Results were analyzed to identify major influences on accuracy, including iodine concentration, vessel width, absolute severity of the stenosis, and vessel orientation. While no single factor appeared to seriously affect human accuracy, computer readings were significantly influenced by the tilt of the vessel in relation to the x-ray beam. Various potential sources of error including beam hardening, stenosis geometry, and scattering are discussed and appropriate algorithm corrections suggested. The importance of the availability of a reliable and accurate method to quantify vascular stenosis and volume of stenotic material is stressed.

Absorptiometry, Photon↗
PubMed1982

Computer-enhanced digital angiography: correlation of clinical assessment of left ventricular ejection fraction and regional wall motion.

We compared computer-enhanced digital angiography (CEDA) following pulmonary injection of 20 ml Renografin-76 (5 ml/sec) to conventional directly injected left ventriculography (LV) in 13 patients undergoing routine diagnostic catheterization. Left ventricular ejection fraction (LVEF) was determined by planimetry from end-diastolic and end-systolic images by two independent angiographers. The correlation coefficient for LVEF (CEDA vs. LV) was r = 0.75 (p less than 0.005) for observer 1 and r = 0.85 (p less than 0.0005) for observer 2. The interobserver variability for LVEF was very low, resulting in a high correlation coefficient (r = 0.91, p less than 0.0005). Three angiographers independently reviewed both the conventional and CEDA images in a random order for assessment of anterior, apical, and inferior regional wall motion, using a 6-point subjective grading system (198 determinations). The interobserver correlation for subjective assessment of regional wall motion by both LV and CEDA was poor (49% for LV and 59% for CEDA, p = NS). These poor correlations were not improved by excluding any region or angiographer from the analysis. The agreement of regional motion assessments between the two techniques was only 40%. To improve reproducibility of wall motion interpretation, an automated analysis program was developed. First the range of normal contraction was defined from pooled literature data. The movement of any segment of the left ventricular wall could then be determined in millimeters and referenced to the normal range. This method eliminated interobserver variability. In the absence of an acceptable standard of segmental wall motion to which this measurement can be compared, the accuracy of this objective format could not be determined. We conclude that CEDA images allow accurate determination of ejection fraction and that the large interobserver variability of subjective regional wall motion analysis can be overcome by employing more objective formats.

Adult↗
PubMed1984

Sulpiride pharmacokinetics in humans after intramuscular administration at three dose levels.

Pharmacokinetics of the disinhibitory psychotropic agent sulpiride was investigated in 9 healthy male subjects after intramuscular administrations of 50, 100, and 200 mg in a 3 X 3 Latin square design. Plasma and urine concentrations were measured by HPLC for 36 and 48 h, respectively. The lowest detectable concentration was 10 ng/mL. Plasma concentration versus time and urinary excretion rate versus time curves were consistent with an open two-compartment body model, where mean +/- SD apparent half-lives of the absorption from muscle, lambda 1 distribution, and lambda 2 elimination phases were 6.96 +/- 2.64 min, 0.220 +/- 0.120 h, and 6.74 +/- 2.67 h, respectively. The initial volume of distribution was 0.145 +/- 0.063 L/kg, the steady-state volume of distribution was 0.639 +/- 0.184 L/kg, and the total clearance was 89.8 +/- 22.3 mL/min. The microscopic rate constants were k12 = 2.53 +/- 1.13 h-1, k21 = 0.674 +/- 0.197 h-1, and k10 = 0.635 +/- 0.298 h-1. Comparison of total clearance (89.8 mL/min), renal clearance (83.0 mL/min), and renal clearance of unbound drug (97.6 mL/min, f = 0.15) indicated that sulpiride is mainly excreted unchanged by the renal route, 93.1 +/- 6.6% of the administered dose being recovered unchanged in urine. Statistical evaluation of all the above parameters, determined at the three dosage levels, did not show any variations related to dose; the pharmacokinetics of sulpiride, over the dose range tested, was therefore linear and independent of dose. The two-compartment body model proposed was validated by digital computer simulation on a small digital computer (32K).

Adult↗
PubMed2004

The accuracy and reliability of measurements made on computer-based digital models.

For reasons of convenience and economy, orthodontists who routinely use and maintain pre- and posttreatment plaster casts are beginning to use computer-based digital models. The purpose of this study was to determine the accuracy (validity), reproducibility (reliability), efficacy, and effectiveness of measurements made on computer-based models. A plastic model occlusion ie, dentoform, served as a gold standard to evaluate the systematic errors associated with producing either plaster or computer-based models. Accuracy, reproducibility, efficacy, and effectiveness were tested by comparing the measurements of the computer-based models with the measurements of the plaster models--(1) accuracy: one examiner measuring 10 models made from a dentoform, twice; (2) reproducibility and efficacy: two examiners measuring 50 models made from patients, twice; and (3) effectiveness: 10 examiners measuring 10 models made from patients, twice. Reproducibility (reliability) was tested by using the intraclass correlation coefficient. Repeated measures of analysis of variance for multiple repeated measurements and Student's t-test were used to test for validity. Only measurements of maxillary and mandibular space available made on computer-based models differed from the measurements made on the dentoform gold standard. There was significantly greater variance for measurements made from computer-based models. Reproducibility was high for measurements made on both computer-based and plaster models. In conclusion, measurements made from computer-based models appear to be generally as accurate and reliable as measurements made from plaster models. Efficacy and effectiveness were similar to those of plaster models. Therefore, computer-based models appear to be a clinically acceptable alternative to conventional plaster models.

Analysis of Variance↗
PubMed2004

The impact of technical conditions of X-ray imaging on reproducibility and precision of digital computer-assisted X-ray radiogrammetry (DXR).

OBJECTIVE: To evaluate the reproducibility of imaging and analysis for bone mineral density (BMD) determination using digital computer-assisted X-ray radiogrammetry (DXR; Pronosco X-posure, version V.2, Sectra Pronosco, Denmark); to verify potential factors that influence BMD extrapolation such as tube voltage, film-focus distance (FFD), film quality and brand (Kodak T-MAT-Plus, Konika SRH, Agfa Scopix), imaging technology (conventional, digital), imaging system (Kodak, Agfa) and exposure level (mAs); and to clarify whether DXR analysis based on printouts of digital images is comparable to analysis of conventional images. DESIGN AND PATIENTS: The hand of a cadaver was X-rayed using varied parameters: 4-8 mAs, 40-52 kV, 90-130 cm FFD. Radiographs under standardised conditions were performed 10 times using a conventional machine (Philips Super 80 CP) and the printouts of a digital system (Digital Diagnost Philips Optimus) for the analysis of reproducibility. One image was scanned and analysed 10 times additionally for imaging reproducibility. RESULTS: Reliability error of the system for the imaging process using conventional radiographs-rays was 0.49% (standard conditions: 6 mAs, 40 kV, 1 m FFD), using printouts of digital images was 2.89% (4 mAs, 42 kV, 1 m FFD) and regarding the analysis process was 0.22%. BMD calculation is not affected by alterations in FFD (precision error 1.21%), mAs (0.83%) or film quality/brand (0.38%), but differs significantly depending on tube voltage (2.70%). The system was not able to analyse conventional images with tube voltages of 49/52 kV. CONCLUSION: DXR technology is stable with most of the tested parameters. Normative data should exclusively be used for calculations using similar tube voltage or correction factors. All other parameters had no significant influence on the BMD calculation. Reproducibility is high. For technical reasons it is not recommended to use the printouts of digital images for BMD determination.

Bone Density↗
PubMed2026

Digital and computational morphology in hematology: current platforms, clinical evidence, and future requirements.

INTRODUCTION: Morphologic examination of peripheral blood and bone marrow remains central to the diagnosis and classification of hematologic disorders. Conventional optical microscopy, however, is labor-intensive, dependent on operator expertise, and affected by interobserver variability. Digital morphology has developed from automated image acquisition and cell pre-classification into a broader field that includes whole-slide imaging, remote review, quantitative morphometry, and artificial intelligence-based analysis. CONTENT: This review examines current applications of digital morphology in peripheral blood, bone marrow aspirates, malaria detection, and body-fluid analysis. Commercial platforms are evaluated with particular attention to the distinction between raw automated pre-classification, expert digital post-classification, and comparison with independent optical microscopy. Digital systems generally perform well for common mature leukocyte populations but remain less reliable for rare or diagnostically critical cells, including blasts, abnormal lymphoid cells, plasma cells, and intermediate maturation stages. Research systems increasingly extend analysis from individual-cell classification to whole-slide, specimen-level, and patient-level assessment. SUMMARY: Digital morphology can improve standardization, image traceability, remote consultation, education, proficiency testing, quality assurance, and selected aspects of laboratory workflow. Its clinical value depends on appropriate validation, transparent reporting of reference methods, recognition of algorithm-specific failure modes, and clearly defined criteria for expert review and conventional microscopy. Human expertise remains essential not only for validating results but also for adapting cell taxonomies and interpretive rules to evolving classifications of hematologic diseases. OUTLOOK: Future progress will require representative multicenter datasets, harmonized morphologic terminology, external validation, interoperability with laboratory information systems, and continuous monitoring after software or hardware updates. Integration of morphology with quantitative hematology, flow cytometry, cytogenetics, genomics, and clinical data may support more comprehensive computational diagnosis. Digital platforms may also broaden access to specialist expertise, training, and quality programs in resource-limited institutions and regions, provided that infrastructure, governance, and professional competency are adequately supported.

artificial intelligence↗
PubMedDate not supplied

Quantification of UV-induced erythema and pigmentation using computer-assisted digital image evaluation.

Photography has been used in human skin research for some time. With the advent of digital photography in recent years, its use has increased. However, the focus has now turned from documentation to actual analysis and quantification of skin color changes. The advantages of digital photography outweigh any shortcomings as long as consistent, standardized procedures are followed and quality control is implemented. We present a simple procedure to standardize images and discuss a computer-assisted digital image evaluation (CADIE) technique to quantify skin color changes following UV exposure. The CADIE approach is illustrated with examples from two different studies on UV responses in human skin. Using the Commission Internationale de l'Eclairage L*a*b* color coordinate system in combination with a personal computer and image-editing software, we analyzed digital images obtained in these two studies. We demonstrate the feasibility of using digital photography for objective evaluation of UV erythema in different racial/ethnic groups and for measuring pigmentation changes caused by repeated exposures over a period of several weeks. Our results indicate how objective assessment using CADIE can be an adjunct to visual and optical observation in clinical and scientific evaluations.

Erythema↗
PubMed2005

Comparison of peer assessment rating (PAR) index scores of plaster and computer-based digital models.

INTRODUCTION: The peer assessment rating (PAR) index is a valid and reliable tool for measuring malocclusion on plaster models, but it has not been shown to be valid and reliable when used to score computer-based digital models. The purpose of this study was to determine whether the PAR index is a valid and reliable measure on digital models. METHODS: The study sample consisted of 48 pairs of plaster and digital pretreatment models. One examiner, calibrated in the PAR index, scored the digital and plaster models. The overall PAR scores were examined for reliability and validity by using analysis of variance and the intraclass correlation coefficient (ICC). Reliability of the components of the PAR score was compared with values originally presented by Richmond et al (1992). RESULTS: No significant differences were found between overall PAR scores of plaster and digital models (P = .82), and scores were highly correlated (ICC = 0.95; lower confidence boundary (LCB) = 0.92; upper confidence boundary (UCB) = 0.97). Intraexaminer reliability was excellent for both plaster models (ICC = 0.98; LCB = 0.97; UCB = 0.99) and digital models (ICC = 0.96; LCB = 0.94; UCB = 0.98). Reliability of all components of the PAR score generated on digital models except for buccal occlusion was similar to those of Richmond et al. CONCLUSION: PAR scores derived from digital models are valid and reliable measures of occlusion.

Dental Arch↗
PubMed1985

Histopathological comparison of the effects of hematoporphyrin derivative on two different murine tumors using computer-enhanced digital video fluorescence microscopy.

A comparison study of the effects of hematoporphyrin derivative (HPD) photoradiation therapy on two different mouse sarcoma tumor model systems (RIF-1 + EMT-6) was performed. Twenty-four h after i.v. administration of HPD, the responses to total laser light doses of 50-400 J/cm2 were evaluated by histological examination and the uptake and distribution of HPD using a computer enhanced digital video fluorescence microscopy technique. In response to total laser light dose (630 nm) of 50-400 J/cm2, 40 mice with RIF-1 tumor showed only minimal superficial tumor necrosis upon histological examination and a 9-12% increase in maximal tissue fluorescence. In contrast, 40 mice with EMT-6 tumor showed marked areas of patchy coagulation necrosis and vascular hemorrhage at doses as low as 50 J/cm2 and essentially total tumor destruction at total light doses of 150 J/cm2 or more. A 59-74% increase in maximal tissue fluorescence was observed using digital video fluorescence microscopy. It is concluded that the greater efficacy of treatment in the EMT-6 tumor as compared to the RIF-1 tumor was due to the greater localization of HPD as demonstrated by digital video fluorescence microscopy.

Animals↗
PubMed2007

Hypothesis testing via integrated computer modeling and digital fluorescence microscopy.

Computational modeling has the potential to add an entirely new approach to hypothesis testing in yeast cell biology. Here, we present a method for seamless integration of computational modeling with quantitative digital fluorescence microscopy. This integration is accomplished by developing computational models based on hypotheses for underlying cellular processes that may give rise to experimentally observed fluorescent protein localization patterns. Simulated fluorescence images are generated from the computational models of underlying cellular processes via a "model-convolution" process. These simulated images can then be directly compared to experimental fluorescence images in order to test the model. This method provides a framework for rigorous hypothesis testing in yeast cell biology via integrated mathematical modeling and digital fluorescence microscopy.

Computational Biology↗
PubMed1997

How does computer-assisted digital wall motion analysis influence observer agreement and diagnostic accuracy during stress echocardiography?

This study assessed interobserver and intraobserver variation and diagnostic accuracy during 25 dipyridamole stress echocardiography tests interpreted with different analysis systems: a) computer display of high frame rate digital cineloops (47 frames/s); b) computer display of lower frame rate digital cineloops (24 frames/s); and c) videotape recordings. The majority of the patients (84%) had documented coronary artery disease with baseline wall motion abnormalities due to previous myocardial infarctions and/or coronary bypass surgery, thus comprising a population with difficult interpretation of stress echocardiography. Diagnostic accuracy was assessed using coronary angiography as reference method. Interobserver and intraobserver agreement was highest when analysis was performed from computer-displayed cineloops, 96 and 92%, respectively, compared to 84 and 80% respectively, using videotape recordings. Sensitivity for identification of coronary artery stenosis was similar using digital cineloops with high frame rate or videotape recordings (67% to 80% for both systems), and tended to be lower using cineloops with lower frame rate for analysis (53%). Inter- and intraobserver differences for wall motion score index were not significantly influenced by the analysis system. We conclude that computer assisted analysis with high frame rate of the displayed cineloops provides optimal observer agreement and diagnostic accuracy in the same range as videotape analysis in patients undergoing stress echocardiography.

Adult↗
PubMed2004

Quantitative computer-assisted digital-imaging upper airway analysis for obstructive sleep apnoea.

This was a prospective study of a new objective method which quantitatively analyses the upper airways in patients with obstructive sleep apnoea (OSA). Video-nasopharyngoscopic examinations of the upper airways of 45 patients were carried out with an endoscopic calibrator. Images of the upper airway during quiet respiration and Mueller's manoeuvre in erect and supine positions were digitized by computer to generate the actual dimensions of obstructive sites. Measurements by the new method were validated by comparing 90 pairs of videoendoscopic images with upper airway magnetic resonance imaging (MRI) measurements at two identical levels. Quantitative precision is 100% for the retropalatal level and 95.6% for the retrolingual level with a tolerance of 0.5 cm(2) between the two methods. The absolute mean of the difference between the two methods of measurement is 0.08 cm(2) at the retropalatal level and 0.18 cm(2) at the retrolingual level. The agreement between the digital-imaging videoendoscopic and MRI measurements was 93.3% for the retropalatal level and 95.6% for the retrolingual level. Quantitative computer-assisted digital imaging is a reliable, cost-effective clinical method of upper airway evaluation in OSA patients. This method allows us to examine the dynamic and static morphology objectively, measure surgical outcomes of upper airway, opening up new avenues for OSA management.

Body Mass Index↗
PubMed2003

Productivity and cost assessment of computed radiography, digital radiography, and screen-film for outpatient chest examinations.

An objective assessment and comparison of computed radiography (CR) versus digital radiography (DR) and screen-film for performing upright chest examinations on outpatients is presented in terms of workflow, productivity, speed of service, and potential cost justification. Perceived ease of use and workflow of each device is collected via a technologist opinion survey. Productivity is measured as the rate of patient throughput from normalized timing studies. The overall speed of service is calculated from the time of examination ordering as stamped in the radiology information system (RIS), to the time of image availability on the picture archiving and communication system (PACS), to the time of interpretation rendered (from the RIS). A cost comparison is discussed in terms of potential productivity gains and device expenditures. Comparative results of a screen-film (analog) dedicated chest unit versus a CR reader and a DR dedicated chest unit show a higher patient throughput for the digital systems. A mean of 8.2 patients were moved through the analog chest room per hour, versus 9.2 patients per hour using the CR system and 10.7 patients per hour with the DR system. This represents a 12% increase in patient throughput for CR over screen-film; a 30% increase in patient throughput for DR over screen-film, which is statistically significant; and a 16% increase in patient throughput for DR over CR, which is not statistically significant. Measured time to image availability for interpretation is much faster for both CR and DR versus screen-film, with the mean minutes to image availability calculated as 29.2 +/- 14.3 min for screen-film, 6.7 +/- 1.5 min for CR, and 5.7 +/- 2.5 min for DR. This represents an improved time to image availability of 77% for CR over screen-film, 80% for DR over screen-film, and 15% for DR over CR. These results are statistically significant (P <.0001) for both CR over screen-film and DR over screen-film but not statistically significant for DR over CR. A comparison of the digital technology costs illustrates that the high cost of DR may not be justifiable unless a facility has a steady high patient volume to run the device at or near 100% productivity. Both CR and DR can improve workflow and productivity over analog screen-film in a PACS for delivery of projection radiography services in an outpatient environment. Cost justification for DR over CR appears to be tied predominantly to high patient volume and continuous rather than sporadic use patterns.

Ambulatory Care Facilities↗