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At least 253 records · Page 14Linked to original sources
PubMed2006

Computed tomographic colonography: assessment of radiologist performance with and without computer-aided detection.

BACKGROUND & AIMS: In isolation, computer-aided detection (CAD) for computed tomographic (CT) colonography is as effective as optical colonoscopy for detection of significant adenomas. However, the unavoidable interaction between CAD and the reader has not been addressed. METHODS: Ten readers trained in CT but without special expertise in colonography interpreted CT colonography images of 107 patients (60 with 142 polyps), first without CAD and then with CAD after temporal separation of 2 months. Per-patient and per-polyp detection were determined by comparing responses with known patient status. RESULTS: With CAD, 41 (68%; 95% confidence interval [CI], 55%-80%) of the 60 patients with polyps were identified more frequently by readers. Per-patient sensitivity increased significantly in 70% of readers, while specificity dropped significantly in only one. Polyp detection increased significantly with CAD; on average, 12 more polyps were detected by each reader (9.1%, 95% CI, 5.2%-12.8%). Small- (< or =5 mm) and medium-sized (6-9 mm) polyps were significantly more likely to be detected when prompted correctly by CAD. However, overall performance was relatively poor; even with CAD, on average readers detected only 10 polyps (51.0%) > or =10 mm and 24 (38.2%) > or =6 mm. Interpretation time was shortened significantly with CAD: by 1.9 minutes (95% CI, 1.4-2.4 minutes) for patients with polyps and by 2.9 minutes (95% CI, 2.5-3.3 minutes) for patients without. Overall, 9 readers (90%) benefited significantly from CAD, either by increased sensitivity and/or by reduced interpretation time. CONCLUSIONS: CAD for CT colonography significantly increases per-patient and per-polyp detection and significantly reduces interpretation times but cannot substitute for adequate training.

Adenoma↗
PubMed2001

Potential uses of computed tomography-SPECT and computed tomography-coincidence fusion images of the chest.

The ability to fuse (or merge) data sets from SPECT and coincidence nuclear medicine scans with computed tomographic images combines physiologic information from the former method with the superior anatomic resolution of the latter technique. In many cases, this allows more definitive diagnosis than can be obtained by simple visual comparison of nuclear medicine images and conventional cross-sectional imaging. The technique may be used in the staging and follow-up of lung carcinoma, pulmonary carcinoid, and lymphoma. It may also aid in the interpretation of perfusion defects in Tc-99m MAA lung scanning, aid in the interpretation of ground-glass opacity in selected cases of chest high-resolution computed tomography, and aid in the diagnosis of some mediastinal masses (e.g., intrathoracic goiters). In this nuclear medicine atlas, the method used to create fusion images in the chest is described, and examples of fusion imaging with radiopharmaceuticals are given that may be of clinical use in chest disease.

Humans↗
PubMedDate not supplied

Real-time 'computer-evaded' pseudo-holography of computed tomography images.

An off-line method of dynamic imaging has been developed to facilitate visualization of three-dimensional tomographic data during real-time manoeuvres. Stereo-pair projection of multiple contiguous cross-sectional images on a conventional 625 line 50 Hz television raster has been investigated and pseudo-holograms have been displayed. A Cartesian stereo-pair projection model incorporating three degrees of rotational freedom and perspective has been developed. Computer simulations of the model have been conducted and the feasibility of adopting a simplified model has been examined. A condensed solution with two degrees of freedom, retaining partial perspective effects, has been simulated and analysed for worst-case errors. Reasonable projection accuracy has been demonstrated for small orientation angles. Specialized display hardware has been developed and a departure has been made from conventional picture-element (pixel) display methodology. Elemental quadrilaterals (rho-pixels), varying in size, shape and screen position, have been considered as an alternative to static square pixels in a rigid matrix. Joystick-controlled rho-pixel arrays have been implemented with parallelogram-shaped rho-pixels incorporated as a simplified case of quadrilateral projection. Dynamic stereo-pair projections of 64 X 64 rho-pixel arrays have been generated from computed tomography (CT) images and the results of phantom studies on a four-plane system are discussed.

Computer Simulation↗
PubMed1988

[Online retrieval of patient information by asynchronous communication between a general purpose computer and a stand-alone personal computer].

Asynchronous communication was made between host (FACOM M-340) and personal computer (OLIBETTIE S-2250) to get patient's information required for RIA test registration. The retrieval system consists of a keyboard input of six numeric codes, patient's ID, and a real time reply containing six parameters for the patient. Their identified parameters are patient's name, sex, date of birth (include area), department, and out- or inpatient. Linking this program to RIA registration program for individual patient, then, operator can input name of RIA test requested. Our simple retrieval program made a useful data network between different types of host and stand-alone personal computers, and enabled us accurate and labor-saving registration for RIA test.

Computer Communication Networks↗
PubMed1986

Computer editing of morphometric data on nerve fibers. An improved computer program.

A short guide is given for the planning of nerve fiber morphometry using computer-assisted methods. A new computer program is introduced which allows, among other factors, correction for myelin sheath shrinkage. If myelin shrinkage is not corrected for, there will be false high values for axon caliber and false low values for sheath thickness. The magnitude of the skew produced by this factor is shown on hand from computer editing.

Animals↗
PubMed1988

CAPA--Computer Aided Pesticide Analysis. Computer program for the automated evaluation of chromatographic data for residue analysis of foods.

Pesticide residue analysis in food by means of gas chromatography with columns of different polarity and several selective detectors provides the analyst with a great number of chromatographic data. The introduction of personal computer based chromatographic data systems into research laboratories increased the efficiency of information management and organization; user designed software packages now have direct access to the stored data. The computer program CAPA (Computer Aided Pesticide Analysis) was developed for the interpretation and evaluation of chromatographic results. The program is written in TURBO PASCAL 3.0 and consists of several subprograms. In the main database all pesticides are filed in a multidimensional structure. The various subprograms have access to this catalog of retention and response data. Using the subprogram INTERPRET, which is the core of CAPA, the analyst is provided with all information necessary to interpret a gas chromatogram: identification of calibrated pesticides and estimation of their concentration. Automated screening analyses can be evaluated with the subprogram AUTOINTERPRET, an automated of INTERPRET that uses all relevant information stored in the data base. A report is produced containing the pesticides found in the sample and proposals how to confirm them best with the equipment and methods available. Finally the analyst has to make the decision about the probable presence and quantity of the indicated pesticides and to project the next confirmatory step by using INTERPRET.

Autoanalysis↗
PubMed1999

The evolution of cellular computing: nature's solution to a computational problem.

How do cells and nature 'compute'? They read and 'rewrite' DNA all the time, by processes that modify sequences at the DNA or RNA level. In 1994, Adleman's elegant solution to a seven-city directed Hamiltonian path problem using DNA launched the new field of DNA computing, which in a few years has grown to international scope. However, unknown to this field, two ciliated protozoans of the genus Oxytricha had solved a potentially harder problem using DNA several million years earlier. The solution to this problem, which occurs during the process of gene unscrambling, represents one of nature's ingenious solutions to the problem of the creation of genes. RNA editing, which can also be viewed as a computational process, offers a second algorithm for the construction of functional genes from encrypted pieces of the genome.

Animals↗
PubMed1996

Stereotactic dose computation and plan optimization using the convolution theorem. I. Dose computation.

With Leksell Gamma Knife stereotactic radiosurgery, the dose distribution delivered by a specific helmet can be assumed to remain as a fixed-dose distribution when the shot is moved to different locations within the predefined dose calculation matrix. The convolution theorem may be implemented to take advantage of this fact for fast dose computation and plan construction. Using this technique, the shot spatial arrangement is formulated as a convolution kernel, which is theoretically a three-dimensional multi-delta function. The dose distribution is computed by the convolution of this single-shot dose distribution with the shot convolution kernel. To determine the shot arrangement, an ideal dose distribution is generated based upon the target structure. Deconvolution is then applied to find the convolution kernel which best fits the proposed ideal dose distribution. The primary task of this presentation is to focus on and describe in detail the dose computation using the convolution theorem.

Algorithms↗
PubMed2000

Ergonomic guidelines for using notebook personal computers. Technical Committee on Human-Computer Interaction, International Ergonomics Association.

In the 1980's, the visual display terminal (VDT) was introduced in workplaces of many countries. Soon thereafter, an upsurge in reported cases of related health problems, such as musculoskeletal disorders and eyestrain, was seen. Recently, the flat panel display or notebook personal computer (PC) became the most remarkable feature in modern workplaces with VDTs and even in homes. A proactive approach must be taken to avert foreseeable ergonomic and occupational health problems from the use of this new technology. Because of its distinct physical and optical characteristics, the ergonomic requirements for notebook PCs in terms of machine layout, workstation design, lighting conditions, among others, should be different from the CRT-based computers. The Japan Ergonomics Society (JES) technical committee came up with a set of guidelines for notebook PC use following exploratory discussions that dwelt on its ergonomic aspects. To keep in stride with this development, the Technical Committee on Human-Computer Interaction under the auspices of the International Ergonomics Association worked towards the international issuance of the guidelines. This paper unveils the result of this collaborative effort.

Equipment Design↗
PubMed1992

[The physician and personal computers--applications of the personal computer].

Nowadays the personal computer is being used in a broad range of activities. Its user is also its operator, directly controlling the process. The paper describes both hardware and software, the structure of the PC, its input and output equipment, basic principles of work with a PC, programs and programming, as well as computer languages. A classification of personal computers is presented and the most frequently used types are assessed. (Fig. 6, Ref. 15.).

Expert Systems↗
PubMedDate not supplied

[Computer in child psychotherapy--on the use of computer games in child guidance counseling].

The article informs about the implementation and the handling of computer games for children and juveniles in psychotherapy. The games in use and the particular therapeutical techniques are described, combined with a report of special ego-functions, which can be trained by the use of computer games. Some short examples show the computer-aided treatment in context with the developmental and personality problems of juvenile clients.

Adolescent↗
PubMed1991

Right parietal stroke with Gerstmann's syndrome. Appearance on computed tomography, magnetic resonance imaging, and single-photon emission computed tomography.

We examined a patient who exhibited Gerstmann's syndrome (left-right disorientation, finger agnosia, dyscalculia, and dysgraphia) in association with a perioperative stroke in the right parietal lobe. This is the first description of the Gerstmann tetrad occurring in the setting of discrete right hemisphere pathologic findings. A well-localized vascular lesion was demonstrated by computed tomography, magnetic resonance imaging, and single-photon emission computed tomographic studies. The patient had clinical evidence of reversed functional cerebral dominance and radiologic evidence of reversed anatomic cerebral asymmetries.

Cerebrovascular Disorders↗
PubMed2001

Occult primary tumors of the head and neck: accuracy of thallium 201 single-photon emission computed tomography and computed tomography and/or magnetic resonance imaging.

OBJECTIVE: To determine the accuracy of thallium 201 single-photon emission computed tomography (thallium SPECT) and computed tomography and/or magnetic resonance imaging (CT/MRI) in the detection of occult primary tumors of the head and neck. DESIGN: Study of diagnostic tests. SETTING: National Cancer Institute, Amsterdam, the Netherlands. PATIENTS AND METHODS: Thirty-two patients with a neck node metastasis of an epithelial tumor and negative findings by mirror examination at initial presentation were included in the study. Twenty-nine patients underwent thallium SPECT and CT/MRI before examination under general anesthesia (EUA). In 3 patients only thallium SPECT was performed before EUA. Histological confirmation of an occult primary tumor during EUA was used as the gold standard. Negative radiodiagnostic and nuclear findings in the upper aerodigestive tract in the presence of a primary carcinoma other than of the head and neck were interpreted as true-negative findings. RESULTS: For thallium SPECT the following results were recorded: sensitivity, 67%; specificity, 69%; accuracy, 69%; positive predictive value, 33%; and negative predictive value, 90%. In 1 patient, thallium whole body scan indicated a primary carcinoma beyond the mucosal lining of the upper aerodigestive tract. The CT/MRI results were as follows: sensitivity, 71%; specificity, 73%; accuracy, 72%; positive predictive value, 45%; and negative predictive value, 89%. CONCLUSIONS: Thallium SPECT and CT/MRI showed comparable results for detection of occult primary tumors of the head and neck. A potential advantage of thallium SPECT is that it allows total body screening.

Adult↗
PubMed2000

Agreement rates among single photon emission computed tomography using gallium-67, computed axial tomography and lymphangiography for Hodgkin disease and correlation of image findings with clinical outcome.

BACKGROUND: This study was undertaken to systematically evaluate the agreement rates among single photon emission computed tomography using gallium-67 (Ga-67 SPECT), lymphangiography (LAG), and computed axial tomography (CT) scan findings for Hodgkin disease and to correlate radiologic findings with clinical outcome. METHODS: One hundred three previously untreated patients with Hodgkin disease who had Ga-67 SPECT scan between August 1992 and December 1994 at our institution form the basis of this study. The agreement rates among Ga-67 SPECT, LAG, and CT scan findings were calculated by sites from the pretreatment evaluation throughout the courses of chemotherapy. The probabilities of recurrence or progression by sites were correlated with the radiologic findings. RESULTS: The median follow-up was 3 years. The pretreatment agreement ranged from 75% to 100% between Ga-67 SPECT and CT scans, 85-100% between CT scan and LAG, and 74-99% between Ga-67 SPECT and LAG. A greater variation in agreement was observed once chemotherapy was started, the site with the least agreement being the mediastinum. The most common site of the recurrence or progression was also the mediastinum. When the CT scan showed persistent abnormality even after Ga-67 SPECT turned negative after chemotherapy, the chances of mediastinal recurrence or progression were 3 in 34 and 3 in 18 after 1-3 cycles and 4-6 cycles, respectively. CONCLUSIONS: Although there was a relatively high correlation between Ga-67 SPECT and the other modalities, the intrinsic limitation of planar Ga-67 was still observed in Ga-67 SPECT especially in the mediastinum. There was still a moderate risk of mediastinal recurrence or progression even after residual CT scan abnormality lost gallium avidity from chemotherapy.

Adolescent↗
PubMed2002

Detection of recurrent or persistent nasopharyngeal carcinomas after radiotherapy with technetium-99m methoxyisobutylisonitrile single photon emission computed tomography and computed tomography: comparison with 18-fluoro-2-deoxyglucose positron emission tomography.

BACKGROUND: The diagnostic accuracy of technetium-99m methoxyisobutylisonitrile (Tc-MIBI) single photon emission computed tomography (SPECT) and computed tomography (CT) of the head and neck for differentiating recurrent or residual nasopharyngeal carcinomas (NPC) from benign lesions after radiotherapy was compared with positron emission tomography (PET) with 18-fluoro-2-deoxyglucose (FDG). METHODS: Thirty six NPC patients underwent head and neck CT, Tc-MIBI SPECT, and FDG-PET four months after radiotherapy to differentiate recurrent or residual NPC from benign lesions. Histopathologic examinations of nasopharyngeal biopsies were performed for all 36 patients. No patients had multiple foci of NPC. RESULTS: Based on biopsy results, the sensitivity, specificity, and accuracy of CT for differentiating recurrent or residual NPC from benign lesions were 73%, 88%, and 83%, respectively. The sensitivity, specificity, and accuracy of Tc-MIBI SPECT were 73%, 96%, and 89%, respectively. The sensitivity, specificity, and accuracy of FDG-PET were 100%, 96%, and 97%, respectively. Combination CT and Tc-MIBI SPECT for 28 NPC patients with congruent results showed the same sensitivity, specificity, and accuracy of 100%, 96%, and 96%, respectively, as FDG-PET for differentiating recurrent or residual NPC from benign lesions. In eight patients with incongruent results between CT and Tc-MIBI SPECT, FDG-PET correctly differentiated two benign lesions and six recurrent or residual NPCs. CONCLUSIONS: In detecting recurrent or residual NPC, FDG-PET is the best tool. However, combined use of CT and Tc-MIBI SPECT can result in the same accuracy as FDG-PET.

Adolescent↗
PubMed2002

Femoral anatomy, computed tomography and computer-aided design of prosthetic implants.

Precise digital data of the internal femoral anatomy are necessary to develop new prosthetic implants with computer-aided design (CAD) techniques. Thirty human cadaveric femurs of central European origin were analysed by high precision computed tomography (CT) using thin slice and high resolution imaging. The CT data were image processed with thresholding to obtain a reconstruction of the cortical bone geometry. The CT threshold for cortical bone was optimized by comparison with saw cuts of macerated femurs. For each specimen a three-dimensional (3D) model of the cortical femur was calculated by the CAD system based on the processed CT data. Virtual 3D models of the 30 femurs were used to adjust a hypothetical stem to the proximal femur anatomy by repeated virtual implantations. The CAD system allowed for evaluation of anatomical parameters after hip reconstruction, amount of bone removal, and cortical bone contact. The fit and fill of the stem could be tested before clinical application and implant-related problems could be corrected.

Aged↗
PubMed1987

A computer-aided three-dimensional reconstruction of brain structures using high level computer graphics.

This paper describes how line drawings and continuous tone shaded images of a three-dimensional solid model of a brain structure are generated using a powerful general purpose computer graphics package. The model is built from a series of serial sections. We developed a software interface to convert the data entered by a section oriented way into a brain structure oriented file. We point out particularly the modular approach which consists of separating the tasks on small microcomputers or on bigger machines according to their computing cost. An example of a thalamic structure in a stereotaxic referential is presented.

Animals↗
PubMed1988

Computer graphics and computer animation of the electric heart field.

The authors present in their paper the possibilities of the application of computer graphics and computer animation for visualization of the electric heart field (EHF). They describe the construction of three-dimensional potential maps by the methods of interpolation, perspective projection, hidden line elimination and text generation. They also present a method for making of animation films showing the electric activity of the heart by using 80 three-dimensional potential maps recorded at different intervals over the entire cardiac cycle.

Computer Graphics↗