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Results for “Radiographic Image Interpretation, Computer-Assisted”

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PubMedDate not supplied

Clinical evaluation of assistant diagnostic system for mammograms using the auto-analyzing method.

Clinical usefulness of a newly developed auto-analyzing system of mammograms to search the abnormal dense areas such as cancer lesions was studied. 345 breasts including 86 cancers, 52 mastopathies, 18 fibroadenomas, 13 cysts, 4 lipomas and 172 normals were analyzed and compared with final diagnosis. 84 of 86 cancer lesions were correctly pointed out (sensitivity: 97.9%). Based on the gradient of the density, the ranking of the cancer or calcified lesions among suspected regions in a mammogram was decided. 55 lesions of them (64.0%) were ordered at the first rank and 83 (96.5%) were in the upper three ranks. 68 of 74 breasts with calcifications were correctly diagnosed and 48 of them were ranked in the upper three ranks. Although further improvement of the system is needed, this system will be a useful assistance for screening the breast cancer in the analyses of mammograms.

Breast Neoplasms↗

PubMed1991

Computable radiology.

Explore the source record for details and available documents.

Radiographic Image Interpretation, Computer-Assist↗

PubMed1991

Three-dimensional imaging of the musculoskeletal system: an overview.

The clinical applications of three-dimensional computed tomography (3-D CT) reconstruction continue to expand rapidly. Recently, the field of three-dimensional magnetic resonance (3-D MR) reconstruction has also been developing. Three dimensional imaging offers a new approach to the analysis of complex anatomic relationships. The spatial configuration of an object can be directly displayed without observers requiring mental integration of a series of two-dimensional images. The easily interpretable images of 3-D CT have proven to be useful for surgical planning. Three-dimensional CT displays have used widely in the preoperative planning of craniofacial surgery, dysplastic hips in children, and complex fractures of skeletal systems. However, 3-D MR displays are technically more difficult than those of CT scans, and 3-D MR displays of the musculaskeletal system are still in a developing stage. Recently, we explored the feasibility of 3-D MR displays. This article provides an overview of those areas of the musculoskeletal system where the use of 3-D MR has proven valuable. The current techniques and ongoing applications are also presented. We believe that this exciting development will expand our ability to visualize pathologic anatomy in the near future.

Algorithms↗

PubMed1991

Computerized angiographic study of the vascular supply of the pectoralis major muscle.

The pectoralis major muscle or musculocutaneous flap is well suited to repair immediately wide defects following surgical removal of carcinomas or traumas of the cervicofacial and thoracic regions. Microsurgery has recently suggested exciting and successful solutions for the same purposes, but we think it is still important to reassess and perfect the flaps already known in order to achieve a better cost-benefit ratio. We examined the intramuscular vascular anatomy of 22 pectoralis major muscles using an image analyzer and a computerized measuring system to quantify the essential features objectively. The data show the segmentation of the pectoralis major muscle into two subunits, each provided with its own vascular supply. Slight anatomical differences and the presence of a well-developed intramuscular vascular supply makes the pectoralis major muscular and musculocutaneous flap a useful and safe procedure.

Aged↗

PubMed1992

Automated scanning and digitizing of roentgenographs for documentation and research.

A comprehensive system has been developed for analyzing and reporting the results of total hip arthroplasty. The personal-computer-based system links patient demographic data with digital storage, retrieval, and analysis of roentgenographs. The system consists of a roentgenograph scanner for converting sheet film to digital data, an optical mark reader for patient data input, an archiving system with optical storage, and a physician display station for preoperative planning and postoperative evaluation. Once a roentgenograph has been digitized and stored, the image can be retrieved and manipulated in a manner not possible with the original sheet film. A selected roentgenograph can be brought to full or enlarged scale, enhanced, and overlaid with templates for preoperative planning or for postoperative measurement of changes. In addition, an intelligent database system has been developed for linking patient demographic information with the roentgenographic data. The database system employs uniform criteria and terminology and allows the retrospective study and statistical analysis of comparable cases. Three machine-readable code sheets are used: Form A, Replacement of the Hip; Form B, Hip Prosthesis Reoperation; and Form C, Follow-up. Forms A and B contain information concerning anamnesis, diagnosis, treatment, postoperative course, recovery, and discharge of the patient from the hospital. Form C provides information on physical examination, pain, mobility of the hip, walking ability, and evaluation of the results by the surgeon as well as the patient.

Computer Systems↗

PubMed1992

Application of artificial neural network to computer-aided diagnosis of coronary artery disease in myocardial SPECT bull's-eye images.

We have developed a computerized system that can aid in the radiologist's diagnosis in the detection and classification of coronary artery diseases. The technique employs a neural network to analyze 201Tl myocardial SPECT bull's-eye images. This multi-layer feed-forward neural network with a backpropagation algorithm has 256 input units (pattern: compressed 16 x 16-matrix images), 5-140 units in a single hidden layer, and eight output units (diagnosis: one normal and seven different types of abnormalities). The neural network was taught using pairs of training (learning) input data (bull's-eye "EXTENT" image) and desired output data ("correct" diagnosis). The effects of the numbers of hidden units and learning iterations in the network on the recognition performance were examined. In our initial stage, the results show that the recognition performance of the neural network is better than that of the radiology resident but worse than that of the experienced radiologist. Our study also demonstrates that the result produced in the neural network depends on the variety of the training examples used. The preliminary study suggests that the neural network approach is useful for the computer-aided diagnosis of coronary artery diseases in myocardial SPECT bull's-eye images.

Coronary Disease↗

PubMed1991

[Digital luminescence radiography . 2: Technical implementation and clinical application--future developments].

In the previously published Part 1 of this paper the basic principle of digital luminescence radiography (DLR) was presented and the technical implementation of the data acquisition system with its advantages and disadvantages as compared with conventional radiography were described [3]. Part 2 covers processing, display, archiving and communication of image data; in addition, suggestions for future improvements in the technique are made. Image processing research is directed towards optimal presentation of the detected data by spatial frequency filtering with unsharp masking and by gradation enhancement. Additional information can be acquired by means of dual energy investigations. The image is displayed on either monitor or transparent X-ray film. Picture archiving requires large storage capacities, and picture communication needs fast transfer rates. At present, about 450 installations for digital luminescence radiography are in clinical use worldwide. Routine use can be expected when technical improvements have been implemented.

Humans↗

PubMed1991

[Digital luminescence radiography. Part 1: Basic principle, technical execution and clinical use].

Digital luminescence radiography (DLR) is a new technique in projection radiography, which enables the production of plain X-ray images and motion tomographies with high quality, and is suitable for digital image management. With this procedure the X-ray image produced by conventional roentgen devices is temporarily stored on a reusable photostimulable storage phosphor screen which is characterized by a wide dynamic range. A laser beam scans the exposed phosphor screen and recovers the stored X-ray information as photostimulated luminescence radiation. A photomultiplier converts the emitted light into electrical signals. After normalization and digitization the signals are transmitted to an image processor. The stored digital image can be individually processed and displayed, digitally archived or transferred to any location. The technique is described in two following papers. Part 1 covers the basic principle of the system and the technical implementation of the data acquisition with its advantages and disadvantages as compared with conventional film/screen radiography.

Equipment Design↗

PubMed1991

[Roentgen diagnosis of pulmonary complications following allogeneic bone marrow transplantation--application of and experience with digital luminescence radiography].

Pulmonary complications exercise a decisive influence on the prognosis of leukaemia patients after bone marrow transplantation. Very early diagnosis is a mandatory prerequisite to successful therapeutic intervention. Of great importance besides the clinical findings and bronchoalveolar lavage is the analysis of the x-ray morphology of pneumonic infiltrates to narrow down the differential diagnostic spectrum. Since the patients are at high risk of infection, they are under isolated care, so that x-ray examinations can only be performed by means of projection radiography using mobile units. Due to these difficulties in performing relevant radiography the required optimal and constant image quality cannot be achieved by means of conventional x-ray film, so that very early detection of pulmonary complications is not always possible. The use of digital luminescence radiography (DLR) with luminescent storage foils enables a highly constant and hence comparable image quality thanks to increased image dynamics, a larger area of the examined object, and histogram evaluation of the image data for determining the optimal parameters for assessment. In addition, details can be better identified to supply answers to specific questions, because the image can be reprocessed to select relevant image parameters by monitoring. Pulmonary complications in 86 patients were analysed retrospectively. These patients had received an allogeneic bone marrow transplant for acute myeloic leukaemia, after they had been treated with high-dose radio-/chemotherapy. The x-ray morphology, clinical and sometimes autopsy findings were correlated with the occurrence of pulmonary complications subsequent to bone marrow transplant.

Adolescent↗

PubMed1991

[Computer-assisted report generation and image transmission in bedside chest x-rays in intensive therapy units].

Since a few years ago, in our department the bedside chest X-rays of intensive care patients have been reported by means of a computer program which has also storing function. This computer program is a guideline for the radiologist and is organized in pages having a logical sequence. The program has proved very useful in learning the correct reporting of bedside chest X-rays. The nosographic data of the patients, the ventilatory and the technical data are stored for a better clinico-radiological correlation. The last four reports are displayed on the monitor to better understand the patient's history. The other reports become part of a "historical" archive. Most important is the cooperation with the referring physician: to make the most of it, a system has been implemented which sends the images from the Radiology Department to Intensive Care. The images are filmed with a camera and then digitalized on 1024 x 768 matrix with 16 million colors and 256 gray levels. Each workstation is composed of: AT286 computer with 60-MB hard disk, hardware or the digitalization and compression of images, a high-resolution monitor, an intercommunication system, and a modem. It is possible to zoom on the images, but a close-up on the image with the camera is better for improved spatial resolution. The images are stored on the hard disk: each image requires 3M bytes, but it can be compressed down to 25:1 with no detail loss. The images are transmitted via modem in at least 20 seconds/image. More images can be sent out-line. During transmission, it is possible to talk by the intercommunication system, pointing out structures on the monitor or drawing objects on both sides of the system. In our experience, image quality is good. We are therefore considering extending the network to other Departments and making the transmission of images of pathologic specimens possible. The natural evolution of this system is the teleconsult.

Computer Communication Networks↗

PubMed1991

[Digital thoracic radiography--a comparison of digital and analog imaging techniques].

New analog and digital imaging techniques for the chest became available in recent years. In this study conventional film/screen radiography was compared with slit technique ('AMBER'), storage phosphor radiography and digital image intensifier radiography by phantom exposures and patient examinations. Because of its low spatial resolution, quality of digital image intensifier radiography was insufficient for chest imaging. The slit technique demonstrated the highest image quality, especially in the fields of the mediastinum and the thoracic wall. In comparison to conventional film/screen radiography, storage phosphor radiography had advantages in the mediastinal field. Digital techniques are connected to new possibilities of image post-processing, storage and transfer. For difficult conditions of exposure (emergency unit) over- or underexposed images can be avoided by these new digital techniques. The combination of slit- and storage phosphor-technique did not increase image quality.

Analog-Digital Conversion↗

PubMed1991

Automated selection of clinical data to support radiographic interpretation.

Modern computerized hospital information systems can store much of the clinical information required for patient care. In some settings the amount of this information is great enough to interfere with its efficient use. Supplying information in support of radiographic interpretation provides an example of this problem. We describe an automated process that abstracts select data from a clinical database and creates a report recounting salient facts designed to assist the radiologist in interpreting the chest x-ray. The reporting system selects data using a combination of expert systems technology and information theory. It produces a brief summary of relevant clinical data. The original version of this process required run-time use of expert systems techniques that were time-prohibitive in the clinical setting. Through the use of pre-compiled tables of finding specific information contents we have reduced the time requirement to a point where the applications will soon be clinically feasible.

Databases, Factual↗

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↗

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↗