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At least 19 recordsLinked to original sources
PubMed1992

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↗
PubMed1992

[The use of digital techniques with storage phosphors for orthopantomography. Preliminary note].

Digital panoramic tomographies with light-emitting phosphors were obtained in 39 patients, during a study on the clinical applications of digital imaging. Performing digital panoramic radiographies required the preliminary adaptation of the imaging plates to the cassette holder of the radiographic equipment. The digital images were post-processed according to two different protocols, both of which were recorded for each patient. The former image was quite similar to standard X-ray films and was called "analogic-like". The latter, called "xeroradiographic-like", featured a flattening of the overall contrast together with detail contrast enhancement due to the presence of an edge effect, as it occurs in xeroradiography. Digital panoramic tomography allows a marked reduction in patient's exposure to X-rays. In addition, this technique offers constant high-quality results, due to the possibility of recovering over- or under-exposed images during post-processing. Xeroradiographic-like digital films may reduce the sharp contrast that is often present between the anterior and the lateral portions of the maxillary and mandibular arches, thus improving the diagnostic reliability of the examination. Other modalities of digital post-processing may be helpful to depict gingival soft tissues, with obvious advantages for the study of periodontal diseases.

Adolescent↗
PubMed1992

Comparison of four different methods of evaluation on axially corrected tomograms of the condyle/fossa relationship.

One hundred temporomandibular joints of 50 dry skulls were used to determine whether there was a statistically significantly difference among four different techniques that were employed to assess the condyle/fossa relationship on axially corrected tomograms. A two-way analysis of variance was performed and the results indicated that: (1) a highly significant difference in the condyle/fossa relationship existed (p = 0.002) among the various skulls and (2) no significant difference existed between the four techniques employed to assess the condyle/fossa relationship (p = 1).

Analysis of Variance↗
PubMed1992

Direct digital radiography for the detection of periodontal bone lesions.

In this study the diagnostic accuracy of D-speed and E-speed film in the detection of simulated periodontal bone lesions was compared with that of an electronic direct digital image receptor. Lesions of increasing depth were created in 11 human hemimandibles at the buccal cortical plate in the interproximal marginal bone area by means of 1.4 mm diameter round bursa. Specimens were imaged at each lesion stage with the use of all three receptors. Nine viewers used a 5-point rating scale to evaluate whether lesions were present or absent in the resulting images. Receiver operating characteristic curves were generated, and maximum-likelihood curve areas were calculated. The area under the curve was used as the index of diagnostic accuracy. The mean receiver operating characteristic areas for D-speed film, E-speed film, and the direct digital system were 0.745 +/- 0.038, 0.740 +/- 0.038, and 0.741 +/- 0.037, respectively. Critical ratio analysis was used to compare the means. No statistical difference was found between any of the three image receptors (p > 0.05) for the detection of simulated periodontal lesions 1.0 to 3.0 mm in depth, which suggested that the digital system performed comparably with conventional film systems.

Alveolar Bone Loss↗
PubMed1992

Image feature analysis of false-positive diagnoses produced by automated detection of lung nodules.

RATIONALE AND OBJECTIVES: To reduce the number of false-negative diagnoses by radiologists, the authors are developing a computer-aided diagnosis scheme for detection of lung nodules in digital chest images. In this study, the authors attempted to reduce the number of false-positive diagnoses obtained with a previous computer scheme by incorporating additional knowledge from experienced chest radiologists into the computer scheme. METHODS: The authors applied their previous computer scheme, using less-strict criteria, to 60 clinical chest radiographs; this yielded 735 candidate nodules (23 true nodules and 712 false-positive diagnoses). These candidates were analyzed using region-growing, trend-correction, and edge-gradient techniques to determine measures by which to quantify image features of candidate nodules. RESULTS: The 712 false-positive diagnoses represented various anatomic structures that were located throughout the chest image. From this analysis, we were able to decrease the number of false-positive errors from an average of 12 to approximately 5 per image without eliminating any true nodules. CONCLUSION: Our results show that incorporating knowledge from experienced chest radiologists into the computer algorithm will play an important role in the development of computerized schemes for the detection of pulmonary nodules.

Diagnostic Errors↗
PubMed1992

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↗
PubMed1992

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↗
PubMed1992

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↗
PubMed1992

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↗
PubMed1992

Subtraction radiography of interradicular bone lesions.

Subtraction and conventional radiography were evaluated for their diagnostic potential to assess interradicular bone lesions in the mandibular premolar region. Both conventional radiographs and subtraction images were interpreted by 10 observers. The receiver-operating characteristic (ROC) technique was used to compare the two techniques. The diagnostic validity was higher for the subtraction technique, both for lesions confined to cancellous bone and for lesions including the cortical bone, than for the conventional technique. For bone defects confined to cancellous bone the diagnostic accuracy was lower than those reported from periapical bone lesions irrespective of whether subtraction or conventional radiography was used. We conclude that subtraction radiography improves the detectability of bone lesions, shallow ones in particular. Lesions in the interradicular bone are more difficult to detect than those in the periapical bone.

Alveolar Process↗
PubMed1992

[The value of digital luminescence radiography within the scope of traumatologic follow-up examinations].

At the present time we cannot unhesitatingly recommend the general use of digital luminescence radiography in traumatological follow-up examinations. Marked drawbacks of this method are, for example, sudden changes in contrast in the marginal areas of osteosynthesis material, occasional limitations in the detailed assessment of spongious structures and problems in respect of imaging geometry. By modifying the image processing parameters, increasing the image matrix and enlarging the format spectrum, however, these problems should be capable of being resolved in the future. Positive features, on the other hand, are even now the possibility of reducing the dosage to a marked degree in many traumatological follow-up examinations, especially in children and adolescents, and in case of conservatively treated fractures. In the long run we can foresee the routine use of digitalised examination methods on traumatology coupled with the possibility of storage in an image filing and communication system, although this is at present not yet feasible due to lack of requisite experience and the cost of the necessary equipment.

Computer Systems↗
PubMed1992

[Quantitative analysis of pneumoconiosis in standard chest radiographs].

A computerized method to quantify and characterize interstitial diseases by using physical texture measures obtained from an analysis of the power spectrum of lung textures in digital chest radiographs was applied to Japanese standard radiographs of pneumoconiosis. Texture measures were determined from standard radiographs of silicosis, asbestosis, and other types of pneumoconiosis as well as chest radiographs of normal lungs. Our preliminary results indicated that the texture measures obtained from computer analysis corresponded closely with the standard categories of silicosis. However, there was no significant correlation between texture measures and the categories for asbestosis and other types of pneumoconiosis in terms of texture pattern. Japanese standard radiographs of pneumoconiosis are categorized according to the profusion of opacities, without reference to the size and shape of the opacities. Furthermore, in some films the size and shape of the opacities vary considerably within the same category. Therefore, it is considered that these characteristics of the standard films affected the results of our texture measures. It also considered that a large ROI and other texture measures are needed to characterize large opacities and mixed-shaped opacities of pneumoconiosis.

Humans↗
PubMed1979

Quantitation in positron emission computed tomography: 1. Effect of object size.

The effect of object size on the capability of positron emission computed tomography to measure isotope concentrations in a cross section was studied. The relationship between the apparent isotope concentration in an image and the true concentration was measured as a function of object size for three instrument resolutions and four convolution filters. The relationship between image size and object size was also measured under the same conditions. Depression of apparent isotope concentration in an image for objects equal in size to the instrument resolution (FWHM) was significant (50% for a cylinder and 25% for a bar). For objects larger than 1.0 FWHM, accurate object sizes can be estimated from the images. Thus, reasonably accurate and practical schemes of compensation for object size effects can be implemented for objects larger than 1.0 FWHM. Accuracy in quantitating isotope concentrations in smaller objects is seriously compromised by the loss of sensitivity to the object size and the large correction factors required to compensate for instrument response. The results of the measurements were found to be in good agreement with theoretical predictions for ideal systems of comparable resolution.

Copper↗