PubMed Health⌕ Search

SEARCH · PubMed Health

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources
PubMed1990

[Digital bone densitometry. A routine method for evaluating and monitoring bone mineralization].

Digitalized bone densitometry is a simple technique for studying bone mineralization which can be performed during the radiological examination. Digitalized bone densitometry was used to estimate the bone mineral content of the third lumbar vertebra in 30 women and 16 men, the neck of the femur in 27 women and 20 men and the second metacarpal in 27 women and 17 men. The results were compared to the data provided by conventional methods. The appearance of the curves, the index of accuracy and reproducibility of the method suggest that it can be used to detect and monitor bone mineralization of patients for a moderate cost.

Absorptiometry, Photon↗
PubMed1990

New approach to analysis of rotational panoramic radiography by computer simulation.

Computer simulation is an effective method for mathematical analysis of the image of rotational panoramic radiography. Conventional simulation methods have been used only for analysis of imaging factors and prediction of the characteristics of the obtained image. This paper describes a new computer simulation method that analyzes the imaging factors and produces the simulated image itself. The simulation is carried out by reproducing the actual image formation process in the computer. The head phantom for simulation, which represents the human dentomaxillofacial structures as a numerical value from 0 to 4, was constructed by scanning a real head phantom from neck to head with an X-ray CT scanner at a slice thickness of 1 mm and at 1 mm slice intervals. The diverging X-ray beam was expressed as a set of straight lines and was moved according to various parameters. The simulated image obtained was satisfactory for image analysis of rotational panoramic radiography.

Computer Simulation↗
PubMed1990

Diagnosis of foraminal and extraforaminal lumbar disk herniation.

Thanks to the more systematical use of CT scan, more and more foraminal and extraforaminal disk herniations are discovered. Some symptoms and signs can be suggestive. Association of negative myelography with important radicular signs should receive special attention. The extremely lateral herniation can be managed easiest and safest by a combined approach, both interlaminar paramedian and lateral to the facet joint, which should be preserved.

Acute Disease↗
PubMedDate not supplied

[Evaluation of condyle fracture with PA X-rays by computer measurements].

The degrees of dislocation after treatment and reduction of the condylar fractures is empirically evaluated with standard X-rays of the lower jaw. The aim of this paper is to investigate the possibilities a more precise evaluation of the degree of dislocation and reduction of the shorter fragment with PA X-rays of the lower jaw. Forty X-rays of 20 patients with unilateral condylar fracture were used. X-rays were put into the memory of a compatible IBM PC with a graphic table. On the graphical presentation of these X-rays the following parameters were determinated: axis of the individual symmetry and condyle axis; angles between the condyle axis and the horizontal line were measured: D--in dislocated condyle, IR--in "ideally" reduced condyle and SR--actually reduced condyle. The angles between the axis of the undamaged condyles and the horizontal line were measured on the X-rays before and after the completion of the treatment. The difference between them was presented am an X-ray error. The obtained results are encouraging.

Humans↗
PubMed1990

[Development of the computed electroradiography. Trial manufacture of digital imaging system].

The fundamental element of a latent image on a selenium plate of Electroradiography is a electrical charge. Therefore, the spatial resolution which can be expected from Electroradiography is extremely high. Here, the author developed the Pulse Electron Beam Scanner (PEBS) as the technique to obtain digital pictorial information from the latent image and obtained following results; 1. We succeeded in converting the latent image into digital signal with high accuracy by using secondary emitted electron through the apparatus that features pulsed electron beam, summing function for secondary emitted electron and plurally arranged detectors and extraction field applied grid. 2. The spatial resolution which we can enjoy to obtain through this apparatus is greater than 500 Lp/mm and the dynamic range at the time when we obtained 500 Lp/mm in terms of the voltage applied to the electrode was +60V to +110V. 3. We succeed in obtaining the digital X ray picture of the bone trabecular structure of human spongy bone with 50 power magnification without using any enlargement picture taking method. The above results indicate that converting the latent image on the selenium plate into digital signal with very high spatial resolution by using PEBS system was achieved. Therefore, we can conclude that we succeeded in obtaining the high spatial resolution digital image from the electroradiographic latent image which has the spatial resolution as high as electrical charge distribution.

Bone and Bones↗
PubMed1990

[Quantitative analysis of the complete image layer in rotational panoramic radiography].

Radiography is a fundamental method of examination in clinical dentistry. Rotational panoramic radiography provides comprehensive information on the maxilla and mandible, and is thus a very valuable procedure for dental practitioners. It is impossible for the image layer to be altered to perfectly suit each individual patient, so the closest corresponding image layer is selected from the several layers in the current panoramic x-ray units. Therefore, it is essential for the two-dimensional characteristics of the layers to be accurately understood when performing radiography and diagnosis. There are a number of subjective and objective methods available to evaluate the image layers, but they all have certain disadvantages. Accordingly, an experimental model was used to quantitatively analyze the complete image layer from the anterior to the TMJ region. At first the central plane of the image layer was obtained by analyzing the x-ray beam. Subsequently, the modulation transfer function (MTF) values of the complete image layer from the anterior to the TMJ region were measured using the slit method with digital Fourier transformation. In order to define the image layer, the information transfer factor (ITF) was calculated by integrating the squared MTF from 0 to 10 cycles/mm at each position. The measured image layer was then compared with the layer calculated by the method of McDavid et al. A Veraview apparatus (J. Morita Corp., Japan) with a 1.1 mm primary slit width was used as the panoramic x-ray unit, and DuPont HiPlus/Kodax X-Omat RP was used as the screen/film combination. The results are summarized below. 1. The central plane of the layer, which was obtained by analyzing the x-ray beam, showed a palabolic curve on the right side and a sigmoid curve on the left side, and the forms of the curves differed between the premolar and the molar regions. 2. The average horizontal angle of the beam to the median line on the right and left sides was analyzed using panoramic radiograms. It was 24.2 degrees for the mandibular canine, 58.4 degrees for the surface between the 1st and 2nd molars, and 95.1 degrees for the condyle. 3. When the limit of the image layer was defined as an ITF of 75, the measured image layer thickness was 5.74 mm in the anterior region, 7.4 mm in the canine region, 15.1 mm in the molar region, and 20.7 mm in the TMJ region. The calculated values were 6.16 mm, 8.9 mm, 15.7 mm, and 20.0 mm, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Fourier Analysis↗
PubMed1992

An introduction to model-based imaging.

The purpose of this paper is to clarify the distinction between the recognition of form, i.e. pattern recognition, and the interpretation of visual scenes, i.e. image understanding. Pattern recognition is part of image understanding, but the latter also includes cognitive tasks such as learning and inference. The key to developing image-understanding systems is to concentrate on the representation and use of models. This paper is a brief outline of the components of a model-based image-understanding system. First, the notions of iconic, categorical and symbolic knowledge are described. Although they appear to be disparate, the common notion is that the image understanding is based on recognizing concepts and not recognizing form. Next, the notion of a concept is defined, followed by representation techniques and control strategies for using concepts. Last, an example is given of an image-understanding system that learns to recognize concepts such as radiographic projections of teeth in panoramic radiographs.

Expert Systems↗
PubMedDate not supplied

Combining evidence from multiple imaging modalities: a feature-analysis method.

This study was designed to develop methods to improve radiologists' ability to detect and diagnose breast cancer. We evaluated the ability of a feature-analysis method to help radiologists merge judgements constructively from two rather disparate breast imaging tests. To accomplish these goals, we developed a list of perceptual features and quantitated the importance of each in the diagnosis of patients having both diaphanography (Test 1) and mammography (Test 2). Then, two decision aids were developed: One was a checklist of the critical diagnostic visual features from both tests that also assisted readers in rating these features numerically. The second was a computer-based classifier that assisted readers in merging the assessments of the two tests into one overall diagnostic probability. The value of these aids was assessed by comparing radiologists' accuracy in reading a set of proven cases in their standard fashion with their accuracy when reading in an enhanced mode, utilizing the checklist and computer classifier. When Test 1 was read adjunctively with Test 2, use of the decision aids led to a significant improvement in accuracy (p = .013) over the unenhanced, combined readings. For Test 1 alone, the aids led to a significant improvement over its low level of unenhanced reading (p = .046). For Test 2 alone, the enhancements provided little gain in accuracy over an already high level of performance on the full case set (p = .081), although significant gains were realized on the most difficult ones. We conclude that methods to aid standardization and merging of feature-based judgements can improve radiologists performance on complex diagnostic tasks.

Breast Neoplasms↗
PubMed1992

Image preprocessing for a picture archiving and communication system.

OBJECTIVES AND RATIONALE: In a picture archiving and communication system (PACS), images are acquired from multiple modalities and displayed on an electronic workstation. Each modality has different image characteristics. This variability must be addressed before the image is displayed. METHODS: The authors developed methods to automatically process magnetic resonance (MR), computed tomographic (CT), and computed radiography (CR) images before display and subjectively evaluated their effectiveness. RESULTS: Unwanted background successfully was automatically removed from 89.5% of 615 CR images. Of 803 chest, abdomen, and hand images 93% were automatically rotated to the correct orientation. CONCLUSIONS: Automated preprocessing of PACS images can be performed successfully, improving speed and convenience for the radiologist interpreting images at an electronic workstation.

Image Processing, Computer-Assisted↗
PubMed1992

Bending and fracture of the femoral component in cemented total hip replacement.

A computer method was used to make 41 measurements on the geometry of insertion of the femoral component in 200 Charnley total hip replacements. Surgery had been performed at least 12 years before, giving results which were classified as: success (90); fracture (56); or loose (54), according to rigid selection criteria. Fracture was associated with heavier patients in which there was poor proximal fixation of the femoral component but adequate distal fixation. Stems with a medial disposition proximally were more common in the fracture group than in the successful or loose groups. Sequential measurements of bending and subsequent fracture were made on the follow-up radiographs of 24 of the 200 cases (6 fracture and 18 successful). These measurements allowed bending to be detected at an earlier stage than by simple inspection of the radiographs.

Aged↗
PubMed1991

Computed tomography of asbestos-related pulmonary parenchymal and pleural diseases.

Computed tomography has acquired an increasingly central role in the evaluation of asbestos-exposed individuals. The advantages of increased contrast resolution and axial image display have extended our ability to interrogate areas of the pulmonary parenchyma and pleura that are inadequately seen on chest radiographs. The additional information to be gained from CT evaluation must be balanced by the additional expense and time required, particularly in view of the large numbers of asbestos-exposed individuals who will undergo screening over the coming decades. Ideally, imaging strategies that include CT should emphasize those problematic situations in which additional information will serve a differential or diagnostic function, alter the management or habits of the individuals, modify the working environment, or improve our understanding of asbestos-induced diseases. The chest radiograph is the mainstay in the imaging evaluation of asbestos-exposed individuals, providing an inexpensive and rapid appraisal of the presence of both focal and diffuse abnormalities of the pleura and lung parenchyma. Conventional (whole-thorax) CT may be an important adjunct in the following situations: (1) to clarify the presence of pleural thickening, particularly in distinguishing pleural disease from normal extrapleural soft tissues; (2) to stage and determine tumor extent in malignant pleural mesothelioma; (3) to identify optimal sites for biopsy of suspicious pleural changes; and (4) to detect and characterize lung cancers or other focal masses that may be obscured by extensive pleural or parenchymal fibrosis. Limited HRCT studies are roughly competitive in time and cost with four-view radiographic examinations. There is growing evidence that HRCT can detect interstitial disease in advance of conventional clinical or radiographic studies. However, the application of limited HRCT for large-scale screening is controversial. This issue will be resolved as we gain greater understanding of the specificity of HRCT and establish guidelines for standardizing the technique and image interpretation. At present, limited HRCT scans can supplement the evaluation of subjects in whom there is equivocal parenchymal or pleural disease on radiographs or unexplained abnormalities on pulmonary function tests. In individuals with significant pleural disease, HRCT can effectively define the presence and extent of interstitial fibrosis. In individuals with combined cigarette smoking-asbestos exposure in whom symptoms or functional abnormalities are present, HRCT may play a central role in distinguishing emphysematous lung destruction from the peripheral interstitial changes of asbestosis.

Asbestosis↗
PubMed1991

Digital chest radiography.

It is apparent that digital radiography holds considerable promise. Although there are some immediate advantages to be gained from using digital technology at present, such as more consistent image quality in portable radiography, most of the benefits have not been fully realized. To do so requires a completely integrated digital radiology department using high-resolution video displays throughout the hospital connected to a large digital image archiving system. This concept, referred to as picture archiving and communication systems (PACS), represents the logical culmination of the extensive research that is continuing in this area. Because of the great expense involved, it is likely that the transition from conventional to digital radiography will be evolutionary in most medical centers, with establishment of local PACS networks initially, such as between the intensive care units and the radiology department. At a more basic level, limited digital radiography systems can function in isolation and address specific needs successfully. Although the science of computer-aided diagnosis is at an early stage, it seems likely that the sensitivity and specificity of these programs will continue to improve. Their eventual utility will depend on their accuracy and ease of use. The ultimate goal would be a relatively "transparent" multifaceted program that would screen all radiographs prior to interpretation to provide the radiologist or clinician with diagnostic suggestions and quantitative data. Given the present rate of progress in this area, such a concept is not unrealistic. However, even the most ardent enthusiasts do not envision totally independent computer-based interpretation of radiographic images for some time. Although digital image processing has not greatly improved diagnostic accuracy merely by enhancing the appearance of the radiographs, there are other potential diagnostic advantages in using digital images, such as rapid retrieval of previous examinations and the ability to correlate chest radiographs with CT or MRI studies rapidly on a video display. Direct image correlation with registration and superimposition has been achieved in the case of positron-emission tomography and MRI studies of the brain. For chest radiograph examinations, superimposition and subtraction of earlier radiographs to enhance the detection of interval change is being studied. The question of when digital chest radiography will replace conventional imaging is controversial. In a recent multiauthored review of this subject, it was estimated that digital chest radiography will replace conventional film radiography in at least 50% of large teaching hospitals by the turn of the century.(ABSTRACT TRUNCATED AT 400 WORDS)

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

Retrospective fusion of radiographic and MR data for localization of subdural electrodes.

Prior to epilepsy surgery, subdural electrodes are often implanted and monitored for a few days to identify the focus of abnormal electrical activity. During the implantation and subsequent brain resection, there may be uncertainty about the exact location of the electrodes with respect to features of brain anatomy such as specific gyral convolutions or lesions. In experiments with a phantom and patients, implanted electrodes were imaged with multiplanar skull radiographs (or CT scans). After retrospective registration with preimplantation MR data, the electrodes were mapped from these studies onto an MR-derived three-dimensional brain model. The resulting multimodality displays showed the relationship of the electrodes to brain anatomy. In one patient the position of each electrode with respect to a metabolic lesion was also displayed by mapping preimplantation PET data onto the same brain model. This new display of electrode positions may strengthen the interpretation of subdural electrical recordings and thereby reduce uncertainty in planning the resection of epileptic tissue.

Adult↗
PubMed1991

Comparison of a PACS workstation with conventional film for interpretation of neonatal examinations: a paired comparison study.

The diagnostic value of neonatal examinations using picture archiving and communication systems (PACS) was compared with that of conventional radiographs. A total of 202 consecutive chest or abdominal radiographs from the newborn intensive care unit were digitized for display on a commercially available PACS console. Experimental design was a paired comparison study. Plain films and PACS images were reviewed alternately in unbiased fashion. After the examination was evaluated using the second modality, any change in diagnosis or confidence in diagnosis was noted. Overall evaluation showed slight preference for the PACS modality. Change of diagnosis or in confidence of diagnosis was more than twice as likely to occur with evaluation of PACS (35%) after hardcopy than with evaluation of conventional radiographs (14%) after PACS. Of the variety of image processing features available on PACS, only window and leveling were judged to be of significant value. These results indicate that PACS and conventional radiographs of the neonatal chest and abdomen are of similar diagnostic value.

Humans↗
PubMedDate not supplied

Image processing in digital chest radiography: effect on diagnostic efficacy.

The usefulness of digital image processing of chest radiographs was evaluated in a clinical study. In 54 patients, chest radiographs in the posteroanterior projection were obtained by both 14 inch digital image intensifier equipment and the conventional screen-film technique. The digital radiographs (512 x 512 image format) viewed on a 625 line monitor were processed in three different ways: (1) standard display; (2) digital edge enhancement for the standard display; and (3) inverse intensity display. The radiographs were interpreted independently by three radiologists. The diagnoses were confirmed by CT, follow-up radiographs and clinical records. Chest abnormalities of the films analyzed included 21 primary lung tumors, 44 pulmonary nodules, 16 cases with mediastinal disease and 17 cases with pneumonia/atelectasis. Interstitial lung disease, pleural plaques, and pulmonary emphysema were found in 30, 18 and 19 cases, respectively. The sensitivity of conventional radiography when averaged overall findings was better than that of the digital techniques (P less than 0.001). The differences in diagnostic accuracy measured by sensitivity and specificity between the three digital display modes were small. Standard image display showed better sensitivity for pulmonary nodules (0.74 vs 0.66; P less than 0.05) but poorer specificity for pulmonary emphysema (0.85 vs. 0.93; P less than 0.05) compared with inverse intensity display. We conclude that when using 512 x 512 image format, the routine use of digital edge enhancement and tone reversal at digital chest radiographs is not warranted.

Adolescent↗