Image processing for the evaluation of dental implants.
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Absorptiometry, Photon↗
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Results for “Radiographic Image Interpretation, Computer-Assisted”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
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The diagnosis of dental caries: 3. Rationale and overview of present and possible future techniques.
A number of changes have taken place recently which may influence a practitioners choice of diagnostic methods for detecting and monitoring dental caries. The first two articles described the use of current diagnostic methods at various specific sites. This third paper discusses the rationale behind the use of these techniques and provides an overview of present techniques and those which may be useful in the future.
Dental Caries↗
Digital radiology for implant treatment planning and evaluation.
Digital radiology has provided the clinician with the ability to store and manipulate radiographic information. The purpose of this paper is to present two applications of digital imaging to implantology. The first application is a personal computer-based imaging technique which can be used to plan the placement of endosseous dental implants using three-dimensional computed tomography images obtained with commercial software. The second application uses digital subtraction radiography to assess longitudinal bony change around dental implants.
Dental Implantation↗
Radiographic evaluation of crestal bone levels adjacent to nonsubmerged titanium implants.
Several parameters have been described to determine success or failure in long-term evaluations of dental implants. One of these parameters is the observation of changes in peri-implant bone levels. Studies on submerged implants have analyzed the bone level changes in the pre- and post-loading phases. No such data exist for intentionally nonsubmerged implants. The purposes of this study were: (1) to test the applicability and reproducibility of a simple computer-assisted method in the evaluation of changes in peri-implant bone levels; (2) to establish a baseline for the longterm radiographic follow-up; and (3) to evaluate changes in crestal bone levels adjacent to nonsubmerged ITI implants between the 1-year and 2-year examination. Standardized periapical radiographs were obtained from 80 implants at the 1-year and 2-year follow-up examinations after their placement. The implants were located in different jaw areas of 55 patients and supported single crowns or short-span fixed partial dentures. For each implant, the distance from implant shoulder to first crestal bone contact (DIB) was measured at the proximal surfaces with a digitizer/computer assembly. Statistically significant greater mean DIB were found at the 1-year (baseline) evaluation for: (1) maxillary sites overall (4.10 x 1.02 mm (SD)) compared with mandibular sites overall (3.61 +/- 1.03 mm); (2) maxillary anterior sites (4.08 +/- 0.97 mm) compared with mandibular posterior sites (3.60 +/- 1.05 mm); and (3) maxillary posterior sites (4.13 +/- 1.12 mm) compared with mandibular posterior sites. No statistically significant changes in DIB occurred in any of the jaw locations between the 1-year and 2-year evaluations.(ABSTRACT TRUNCATED AT 250 WORDS)
Alveolar Bone Loss↗
Reproducibility of measurements of coronary narrowings by videodensitometry and by digital calipers.
Computer-assisted videodensitometry has been shown to be a reliable and reproducible method of measuring absolute and relative coronary narrowings. Using a commercially available analyzer (Vanguard XR70) we confirmed intra- and interobserver reproducibilities in 34 narrowings in 9 patients. Analyses were performed on normal area and diameter, stenotic area and diameter, percent area stenosis and percent diameter stenosis. For all 6 analyses, excellent intra- and interobserver correlations were found (r = 0.93-0.98), with slopes close to 1 and intercepts close to zero. Caliper measurements (Mitutoyo Digimatic) of the same lesions by the same observers showed good inter- and intraobserver reproducibility for percent diameter stenosis (r = 0.90 and 0.86), with mean interobserver difference of 1.67 +/- (SD) 6.4% and intraobserver difference of 2.97 +/- (SD) 7.9%. However, less good correlations were found between caliper and videodensitometric measurements of percent diameter stenosis; r = 0.61 and 0.76 for the two observers. These data suggest that videodensitometry is a highly reproducible quantitative angiographic method, suitable for documenting changes in the severity of coronary artery lesions, both spontaneous or related to interventions. Caliper measurements do not provide the same degree of accuracy, but they have acceptable reproducibility in measuring diameter stenosis. As such, they are also suitable for assessing changes in severity of coronary artery lesions in individual patients.
Angioplasty, Balloon, Coronary↗
Influence of CRT workstation on observer's performance.
The effects of the operability of the prototype CRT workstation and room illumination upon observer's performance were studied. In the experiment of reading CT images as a routine daily work at the CRT workstation, the average time required to analyse one CT image under a room illuminance of 100 lux was longer than that on the film viewbox. Prolongation occurred due mainly to the longer time required to retrieve and to arrange images as observers desired, and the limitation to the number of images simultaneously displayed on two CRT monitors. In the ROC studies to detect small pulmonary nodules on CRT images of computed radiography with imaging plate, illuminance around 170 lux showed the best result and a statistically significant difference (P less than 0.05) as compared with that of 480 lux. In addition to the radiologist's visual performance, room illumination must also be taken into consideration as it influences the observer's performance and diagnostic efficiency.
Computer Systems↗
Cardiac CT fractal analysis of LV noncompaction and common cardiomyopathies.
BACKGROUND: Left ventricular noncompaction (LVNC), or hypertrabeculation, is a myocardial condition that remains challenging to diagnose and differentiate from other cardiomyopathies. This study evaluated the ability of cardiac CT to differentiate between LVNC, hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and controls using fractal analysis of LV trabeculae. METHODS: Subjects with LVNC, HCM, DCM, as well as controls, who underwent coronary CT angiography were included. LV trabecular structure was quantified using fractal analysis on a stack of 15 short-axis CT images. For each subject, maximum (FDmax) and average (FDglobal) fractal dimensions were reported. A subset of subjects also had clinically acquired cardiac MRI (CMR) exams for comparison. One-way ANOVA, Pearson correlation, and Bland-Altman analysis were used for statistical analysis. RESULTS: The study included 313 subjects (median age: 58.8 [48.1-68.0] years, 153 male) categorized into Control (89), LVNC (46), HCM (106), and DCM (72) cohorts. FDmax was significantly higher in LVNC (1.379 ​± ​0.047) than in Control (1.305 ​± ​0.033), HCM (1.321 ​± ​0.040), and DCM (1.344 ​± ​0.054) cohorts; all p ​< ​0.001. Similarly, FDglobal was significantly higher in LVNC (1.279 ​± ​0.041) than in the other cohorts; all p ​< ​0.05. In a subset of 132 subjects with both CT and CMR exams, fractal dimensions from the two modalities were strongly correlated (r ​= ​0.63, p ​< ​0.0001), with CT-derived values being higher (1.337 ​± ​0.049 vs. 1.262 ​± ​0.045, p ​< ​0.0001). CONCLUSIONS: CT-derived fractal dimensions of LV trabecular structure were significantly higher in LVNC compared to control subjects, HCM, and DCM. CT-derived fractal dimensions strongly correlated with, but were higher than, those from cardiac MRI in the same subjects.
Humans↗
Evaluation of a digital workstation for interpreting neonatal examinations. A receiver operating characteristic study.
RATIONALE AND OBJECTIVES: The purpose of this study is to compare the diagnostic accuracy of interpreting clinical neonatal radiographs using a commercially available digital workstation versus conventional radiographic images. METHODS: The case sample consists of 100 chest or abdominal radiographs from the neonatal intensive care unit in which diagnosis was confirmed. Four radiologists served as observers. During two initial reading sessions, half of the studies were viewed on digital radiography monitors and the other half by plain film. Observers indicated whether each patient had normal or abnormal findings and their degree of confidence in this judgment. Six weeks later, observers viewed cases on the alternate presentation system. Two statistical analyses were performed: the data from each observer were treated as a separate experiment in the first analysis; the data from all observers were combined using a new method in the second analysis. RESULTS: No differences between areas under receiver operating characteristic (ROC) curves for viewing on the picture archiving and communication system (PACS) console and plain film were found for any observer (0.86 versus 0.86, 0.89 versus 0.86, 0.88 versus 0.85, 0.83 versus 0.82). CONCLUSIONS: The study suggests that for pediatric plain film images, video images offer diagnostic information comparable with that of conventional radiographs for neonatal examinations.
Evaluation Studies as Topic↗
Image comparison techniques for use with megavoltage imaging systems.
In this paper we describe software facilities for enabling patient positioning studies using the megavoltage imaging system developed at the Royal Marsden Hospital and Institute of Cancer Research. The study focuses on the use of the system for three purposes: patient position verification (by comparing images taken at treatment simulation with megavoltage images taken at treatment time); reproducibility studies (by analysing a set of megavoltage images); and set-up correction (by adjusting the set-up until the megavoltage image obtained at treatment registers with the simulation image). The need is discussed for suitably presented simulator images, a method of determining field boundaries and the possibility of delineating soft-tissue interfaces. Several algorithms of different types, developed specifically for the purpose of intercomparison of planar projection images, are presented. The techniques employed and their usefulness, in both the qualitative and the quantitative sense, are discussed. The results are presented of a phantom and clinical study, to evaluate the rigour and reproducibility of the algorithms. These results indicate that measurements can be made to an accuracy of about 1-2 mm, with a similar value for interobserver reproducibility for the best image comparison techniques available.
Algorithms↗
Comparison of photodensitometric with high-resolution digital analysis of bone density from serial dental radiographs.
Photodensitometry is known to provide high spatial resolution and continuous measurement of optical density for the analysis of dental radiographs, whereas digitization allows powerful image manipulations but, when using conventional video cameras, gives less spatial resolution and fewer grey levels. The aim of this study was therefore to develop a technique of high-resolution digital analysis for the measurement of bone density following the same principles as those of photodensitometry and based upon the use of a CCD Scanner Camera which provides up to 4096 grey levels and a spatial resolution of 4096 x 4096 pixels. Twenty-four zones were analysed with both techniques in five serial dental radiographs taken before and after periodontal therapy in eight patients. Statistical comparison of the results obtained by digital analysis and photodensitometry shows that the two techniques have the same accuracy.
Absorptiometry, Photon↗
Inference systems for automated image analysis.
The radiodiagnostic process is a complicated activity involving the integration of knowledge from low-level image features into more abstract, higher-order entities. This involves spatial and density information at a lower level and area and features at a higher level. The spatial density distribution in a radiographic image is not uniquely related to the three-dimensional structure of the object. Therefore, more information other than just first-order density characteristics of radiographs must be utilized to improve automated interpretation of the image. Prior knowledge of the size, shape and location of anatomical structures and pathognomic features is very useful for improving the process of computer-aided image analysis. Inference systems as used in expert systems can be applied to facilitate the integration of information obtained from the patient and the radiograph in the diagnostic process.
Expert Systems↗
Application of computer-aided image interpretation to the diagnosis of periapical bone lesions.
An image analysis system was developed for the computer-aided diagnosis of periapical bone lesions in dental radiographs. The system was designed to (1) identify the periapical region, (2) determine the presence of a periapical lesion and (3) estimate the size of the lesion in cases when a lesion had been found. To initiate the procedure, an observer indicates an arbitrary point on the root in a digitized radiograph. From this initial point, the location of the radiographic projection of the apex of the root is automatically computed. Next, the trabecular bone pattern is detected through texture analysis. A local absence of the trabecular bone pattern in the periapical region is marked as a periapical bone lesion. When a lesion has been identified, its size is estimated based on local edge properties. Observer interaction is only allowed to adjust the result of the apex localization procedure if the apex has not correctly been localized. In an experiment with randomly selected radiographs of 111 mandibular roots, the performance of the system was tested against the consensual diagnosis of four expert observers. The sensitivity of the system to identify a lesion was 83.3%, the specificity 75.6% and the diagnostic accuracy 80.2%. The correlation between the size of the lesions as estimated by the system and by the observers was 0.67 (P < 0.01). When the procedure was repeated, the percentage of correctly reproduced lesion sizes by the system was 92.8%. The determination of the presence of a lesion was reproducible in 98.2% of all the cases.
Alveolar Bone Loss↗
Computer-aided quality assurance in oral health care: the image of electronic radiographs.
The concept of a decision-support oriented, interactive, multimedia technique-based dental workstation is presented from the viewpoint of improved quality assurance. Special emphasis is given to the modules for handling and interpretation of radiographs.
Computer Communication Networks↗
[Technique for measuring the atheroma volume in men].
The evaluation of the impact of therapy on the evolution of atherosclerotic lesions or restenosis after angioplasty requires the use of techniques of vascular imaging. The reference invasive method is digital angiography although it does not provide data on the arterial wall thickness. This parameter can be approached however by intravascular ultrasound imaging, a technique which has a number of important practical limitations. Of the non-invasive techniques available, Doppler ultrasonography is the only one that can be used in clinical trials. Nuclear magnetic resonance imaging is the object of much research and is without doubt the technique of the future. The choice of model of atherosclerosis influences that of the imaging technique: cineangiography for coronary arteries, digital angiography or Doppler ultra sonography for lower limb arteries and Doppler ultrasonography for the carotid arteries. Interpretation of angiography is now performed quantitatively by videodensitometry. Interpretation of other techniques should be performed by a second independent observer and "blinded" with respect to the order in which the investigations were performed and to the treatment administered. The criteria of judgment may be qualitative (progression, stabilisation, regression) or quantitative, the latter having a number of advantages over the former. Of the quantitative criteria, the percentage stenosis, though widely used, does not fully answer the question posed, and neither does the diameter of the stenosis. The volume of the arterial lumen calculated from videodensitometric data would seem to be the best, by its sensitivity and additivity, current angiographic parameter.(ABSTRACT TRUNCATED AT 250 WORDS)
Angiography, Digital Subtraction↗
Estimating the validity of radiographic measurements of marginal bone height changes around osseointegrated implants.
The accuracy of determining marginal bone height changes around osseointegrated implants depends on the validity of comparing serial films and the reliability of the measurements. X-ray beam orientation changes can alter the validity of serial films. A human dry mandible containing a Brånemark implant was irradiated +/- 12 degrees in the vertical plane at 1-degree intervals to the perpendicular to the long axis of the fixture. The thread width was recorded on both sides of each fixture image using a computer. Twenty-five randomized unclassified images were remeasured and the vertical angle of the x-ray beam was estimated from the previous measurements to test for validity of comparing images. The reliability of measurements with altered image magnification and penumbra were calculated. The reliability of 24 repeated thread width measurements was a SD of 0.01 mm. Of the 25 unknown beam angulations, 32 percent matched correctly, 20 percent +/- 1 degree, 16 percent +/- 2 degrees, or 68 percent < or = +/- 2 degrees. Alteration from a short to a long cone technique was estimated to produce magnification errors similar to the reliability SD of 0.01 mm. Similarly the penumbra varied from 0.057 mm to 0.032 mm with short to long cones using a 1.0-mm focal spot. With a 0.6-mm focal spot, the smallest penumbra of 0.19 mm was twice the measurement reliability. This method demonstrated x-ray beam angulation and validity for comparing serial films can be estimated for the extreme variations but not accurately for +9 to -6 degrees from a tangent to the fixture.(ABSTRACT TRUNCATED AT 250 WORDS)
Alveolar Bone Loss↗
A method to evaluate and compare roentgenograms.
A simple and practical method is suggested to evaluate and compare roentgenograms concerning optical density and contrast. The method is specifically indicated for research in which a metallic stepwedge penetrometer and a photodensitometer are used. A PC computer may be optionally employed for the mathematical and statistical processing of the data.
Contrast Media↗
Computerized image analysis in dentistry: present status and future applications.
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Humans↗
Improved diagnosis with digital radiography.
In radiodiagnosis, much effort is spent in reducing the radiation dose and simultaneously improving the information obtained with radiographs. Computer technology has the potential to significantly impact radiography in medicine and in dentistry to achieve these goals. Advanced digital imaging techniques will be available for the general practitioner within the next decade. Storage and retrieval of images, contrast enhancement, and noise reduction are some examples of basic image manipulation tools. Subtraction radiography and image reconstruction will improve diagnosis and treatment planning. The clinical knowledge of dentists and radiologists will be incorporated into computer programs to perform more sophisticated tasks in the form of automated image analysis and computer-aided image interpretation.
Humans↗