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Results for “Radiographic Image Interpretation, Computer-Assisted”

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PubMed1992

[Conventional roentgen functional diagnosis--videodensitometry. 1. Densitometric and topometric measurements of roentgen video images: technique and method of measuring].

It is possible to measure movements in the human body with the help of X-ray television systems. A great number of different techniques has been published in the scientific literature. They all based on only two principles with qualitative differences in signal acquisition. The densitometric and topometric measurements are assessed and compared. Neither the densitometric nor the topometric principle seems to be superior. To support the experimental work the videoanalyser VIANA MP was developed on the Ilmenau Institute of Technology.

Computer Systems↗
PubMed1992

[Conventional roentgen functional diagnosis--videodensitometry. 2. Clinical imaging site for noninvasive diagnosis of organ motion].

By means of the described system it is possible to measure and as well analog as digital process the organ movement, needing a X-ray television system for flouroscopy and a videotape for continuously recording. Using the densitometric principle measurements of time and a quantitative form analysis of the curves are performed. After border recognition and using the topometric principle, the local organ motion can be evaluated. The levels of signal and noise in the measured curves are computed by a fourier transformation. In the field of functional cardiology the video signal is recorded and processed synchronously with the electrocardiogram.

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↗
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

Visualization of multimodal image information in medicine.

Radiological and clinical practice can be enhanced by improved access to multimodal image informations. Analysis, visualization, method characteristic image processing and image synthesis is needed not only for the interpretation of the images but also for performing effective consultations with clinical colleagues and computer supported therapy planning and control strategies. The distributed system RADVIS (radiological visualization) is presented which enables the fast display, three dimensional visualization and the modality oriented analysis of multimodal image informations. Based on a unique image format, modality specific evaluation procedures and two- or three dimensional processing tools of image analysis produce the input data for therapy planning programs. The easy use of this multimedia visualisation tool enables radiologists and clinicians to deal with their image data. The description of methods and procedures of the prototype, as well as typical examples of radiologic practice will demonstrate the efficiency of the presented system.

Humans↗
PubMed1992

[Surgery of scoliosis. Decision aid by three-dimensional imaging (3D)].

Scoliosis is a spatial deformations of the spine not reducible to a plan. Usually perception of this phenomena is made from frontal and lateral radiographies and needs a mental process to construct a 3D form. The proposed aid-system consists, firstly, to construct a 3D model from digitalised characteristic points on radiographies, and to visualize this model from any point of view, even the above view. Secondly, corrective bending posture radiographies are used to estimate kinematic spine variables and then to simulate optimal orthopedic correction. Methods and materials are adaptable for other osteo-articular systems.

Decision Support Techniques↗
PubMed1992

[Three-dimensional evaluation of computerized tomography images of pediatric fractures].

Three-dimensional reconstruction from CT was performed in pediatric patients after joint, facial, or spinal injury. Three-dimensional reconstruction proved particularly helpful in children with reduced post-trauma joint mobility. Free fragments, joint dislocations, and articulate surface defects were demonstrated. Here, as well as in facial and spinal injury, three-dimensional CT may facilitate and augment the understanding of two-dimensional displays.

Adolescent↗
PubMed1992

[Densitometry determination of coronary flow rates using digital subtraction angiography (DSA). Methods, multiple examinations and interobserver comparison].

In invasive diagnostics of coronary heart disease (CHD), three each DSA examinations of the left coronary artery were performed at 2-minute intervals in ten patients subsequent to conventional examination by means of a left-side cardiac catheter and coronary angiography. While placing the patient in left anterior oblique (60 degrees) position, 6 ml each of ionic contrast medium were injected mechanically with a flow of 4 ml/sec at a pacemaker-induced heart rate of 100/min. Examinations were performed according to a standard mode and were evaluated via the image analysing computer APU of the Philips DVI-DSA system. The purpose of this approach was to analyse the examination conditions and a new improved evaluation algorithm in respect of stability, feasibility and sensitivity. 17 series were evaluated by two examiners who were independent of each other. The interobserver differences obtained were between 5% at the time of maximum density (Tmax) and 25% with exponential downward slope of the curve (lambda), with reference to the median value in each case. Scatter of the individual examinations around the median value of all the three DSA runs is 11 to 17% with the exception of lambda. A significant rise can be proven in the RCX region for the curve slope rise parameters "slope" and "RFL2". We interpret this as a genuine 1.2 to 1.3 fold regional flow increase due to the residual effect of the contrast medium. At the same time, this can be interpreted as an indicator for the good sensitivity of the method.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Percutaneous transhepatic dissolution of gallbladder stones.

The method of percutaneous transhepatic dissolution with methyl tert-butyl ether (MTBE) has been used at the Zagreb Clinical Hospital Department of Medicine since 1989. From December 1989 until December 1991, 69 patients, 51 (74%) females and 18 (26%) males, with symptomatic and cholesterol gallbladder stones were hospitalised at the Department. All patients preferred percutaneous transhepatic dissolution to surgical treatment of gallbladder stones. The gallbladder was successfully punctured and the catheter placed into the gallbladder lumen in 63 (91%) patients, whereas complete dissolution was achieved in 59 (85.5%) patients. In 21 (33.9%) of these 59 patients, after completed dissolution computer-processed roentgenograms and ultrasonic scan of the gallbladder revealed residual particles of debris sized up to 2 mm. Six patients in whom puncture, i.e. the placement of the catheter into the lumen was unsuccessful, were electively operated on the following day without any complications. The mean duration of hospitalisation for 63 patients was 4.5 days.

Adult↗
PubMed1992

Three-dimensional computed tomography image of small pulmonary lesions.

To evaluate diagnostic imaging of small lesions in the peripheral lung, three-dimensional (3D) reconstruction CT images were used to study 36 cases (including which had been 19 resected) of pulmonary nodules less than 3 cm in diameter. Rapid scanning was employed in 17 cases and helical scanning (in which the X-ray tube rotates continuously with simultaneous table sliding) in 19 cases. The rapid scanning could not be evaluated in two cases because respiratory motion resulted in discontinuous image data. We were able to evaluate 34 cases. The addition of 3D images to the conventional images made it possible for us to obtain useful information on visualizing relations between nodules and vascular structures in 32% (11/34) of the cases. The 3D images enabled us to visualize the lesions and pulmonary vessels three-dimensionally. It was, however, difficult to evaluate lesion shape since we were able to obtain useful information in only 3% (1/34) of the cases. In helical scanning, data are acquired from an extensive area within a short time, providing consecutive axial-slice images remain free of any respiratory artifacts. In this regard, helical scanning is suitable for generating 3D images. A diagnostic procedure based on 3D lesion analysis should be developed and standardized.

Aged↗
PubMedDate not supplied

Anatomical macroelements in the study of craniofacial rat growth.

In order to avoid the arbitrary division of biological structures, rational polynomial interpolants are utilized to study growth. The major advantage of this method is the elimination of artificial internal element boundaries through anatomical structures. Since the boundary element methodology is employed in the finite element setting, other benefits, without additional computer coding, include the ability to use elements with any number of sides and reference frame invariance. Longitudinal landmark coordinates from midsagittal X-ray tracings of 22 albino female rat skulls of various ages were averaged. The skull was partitioned into three macroelements: a neural skull and two functionally distinct portions of the facial skull--olfactory and respiratory. The digital computer programming was carried out in the computer mathematics environment of Mathematica. Maximum elongation ratios were calculated for approximately 400 interior points. The elongation ratios in the neural skull compared well with previously documented growth behavior of internal brain structures. The calculated ratios from the facial skull were used to analyze the behavior of macroelement interpolation close to common anatomical boundaries.

Animals↗
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

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↗
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↗
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↗