Biomedical subjects

K Doi

Publications and source records attributed to K Doi.

At least 973 records · Page 54Linked to original sources

PubMedDate not supplied

Comparison of imaging properties of a computed radiography system and screen-film systems.

To compare the diagnostic quality of images obtained with a computed radiography (CR) system based on storage phosphor technology with that obtained with conventional screen-film systems, a dual-image recording technique was devised. With this technique, a CR imaging plate is placed behind a screen-film system in a conventional cassette. This makes it possible to obtain two images simultaneously, one from each system, in a clinical examination with the same patient positioning, the same degree of patient motion, the same geometric unsharpness, and no additional exposure. The modulation transfer functions (MTFs) of the CR system with and without the dual-image recording technique were greater at low frequencies, but lower at high frequencies, that the MTFs of the screen-film systems used. The noise Wiener spectra of the CR images at the plane of the imaging plate were greater than those of the screen-film systems, but were comparable to those of the screen-film systems at the plane of the printed film due to the reduction in image size. Clinical chest images obtained with the dual-image recording technique appeared comparable, probably because of the image size reduction and the use of mild unsharp mask processing.

Humans↗

PubMedDate not supplied

The nature and subtlety of abnormal findings in chest radiographs.

All detected abnormal findings were recorded for 1085 consecutive chest x-ray examinations. Each finding was classified by descriptive criteria and graded for subtlety. Accuracy of interpretation was evaluated in a randomized sample of 100 cases using follow-up or multiple readers. Seventy percent of standard examinations and 93% of bedside examinations revealed abnormal findings. Pulmonary infiltrates were the most commonly detected abnormality, being present in 55% of abnormal cases. Noncalcified pulmonary nodules and pneumothoraces were each present in approximately 5% of abnormal cases. The most commonly encountered subtle findings were due to intravenous catheters, pulmonary infiltrates, pneumothoraces, rib lesions, and pulmonary nodules in descending order of frequency. It is concluded that it is reasonable to use selected examples of these findings in observer tests when evaluating new imaging modalities such as digital radiography.

Data Interpretation, Statistical↗

PubMedDate not supplied

Image feature analysis and computer-aided diagnosis in digital radiography: automated detection of pneumothorax in chest images.

In order to aid radiologists in the diagnosis of pneumothorax from chest radiographs, an automated method for detection of subtle pneumothorax is being developed. The computerized method is based on the detection of a fine curved-line pattern, which is a unique feature of radiographic findings of pneumothorax. Initially, regions of interest (ROIs) are determined in each upper lung area, where subtle pneumothoraces commonly appear. The pneumothorax pattern is enhanced by the selection of edge gradients within a limited range of orientations. Rib edges included in this edge-enhanced image are removed, based on the locations of posterior ribs that are determined separately. A subtle curved line due to pneumothorax is then detected by means of the Hough transform. The detected pneumothorax pattern is marked on the chest image displayed on a CRT monitor. With the present computer method applied to 50 chest images (28 normals and 22 abnormals with pneumothorax), we were able to detect 77% of pneumothoraces, with 0.44 false-positives per image.

Humans↗

PubMedDate not supplied

Computerized detection of clustered microcalcifications in digital mammograms: applications of artificial neural networks.

Artificial neural networks have been applied to the differentiation of actual "true" clusters from normal parenchymal patterns and also to the differentiation of actual clusters from false-positive clusters as reported by a computerized scheme for the detection of microcalcifications in digital mammograms. The differentiation was carried out in both the spatial and frequency domains. The performance of the neural networks was evaluated quantitatively by means of receiver operating characteristic (ROC) analysis. It was found that the networks could distinguish clustered microcalcifications from normal nonclustered areas in the frequency domain, and that they could eliminate approximately 50% of false-positive clusters of microcalcifications while preserving 95% of the positive clusters, when applied to the results of the automated detection scheme. A large, comprehensive training database is needed for neural networks to perform reliably in clinical situations.

Breast Diseases↗

PubMedDate not supplied

Computer-aided detection of clustered microcalcifications: an improved method for grouping detected signals.

A computerized scheme for the automated detection of clustered microcalcifications from digital mammograms is being developed. This scheme is one part of an overall package for computer-aided diagnosis (CAD), the purpose of which is to assist radiologists in detecting and diagnosing breast cancer. One important step in the computer detection scheme is to group or cluster microcalcifications, since clustered microcalcifications are more clinically significant than are isolated microcalcifications. Previously a "growing" technique in which signals (possible microcalcifications) were clustered by grouping those that were within some predefined distance from the center of the growing cluster was used. In this paper, a new technique for grouping signals, which consists of two steps, is introduced. First, signals that may be several pixels in area are reduced to single pixels by means of a recursive transformation. Second, the number of signals (nonzero pixels) within a small region, typically 3.2 x 3.2 mm, are counted. Only if three or more signals are present within such a region are they preserved in the output image. In this way, isolated signals are eliminated. Furthermore, this method can eliminate falsely detected clusters, which were identified by a previous detection scheme, based on the spatial distribution of signals within the cluster. The differences in performance of the CAD scheme for detecting clustered microcalcifications using the old and new clustering techniques was measured using 78 mammograms, containing 41 clusters.(ABSTRACT TRUNCATED AT 250 WORDS)

Breast Diseases↗

PubMedDate not supplied

Automated selection of regions of interest for quantitative analysis of lung textures in digital chest radiographs.

In order to implement a computerized scheme for quantitative analysis of interstitial lung disease in chest radiographs in clinical situations, a fully automated method of selecting many square regions of interest (ROIs) in peripheral lung areas are developed. First, the peripheral lung regions are identified, based on the automated detection of lung apices, ribcage edges, and diaphragm. Then a large number of ROIs are selected sequentially by filling in the identified peripheral regions. Finally, those ROIs containing sharp edges are removed based on an edge gradient analysis, for which a gradient-weighted edge orientation histogram is employed. Approximately 200-400 ROIs were automatically selected for each case with this method. The evaluation of using ROC analysis indicated that the automated ROI selection method was effective in quantitative analysis of lung textures in digital chest radiographs.

Biophysical Phenomena↗

PubMedDate not supplied

Development of a high quality film duplication system using a laser digitizer: comparison with computed radiography.

A high quality film-duplication system was developed in order to improve the image quality of duplicated radiographs and to recover improperly exposed films. The system consists of a laser film digitizer, a laser film printer, a workstation, and a magneto-optical disk. Radiographs are digitized by the laser digitizer, processed by the computer for image enhancement, and then printed on a film by the laser printer. A nonlinear density-correction technique is employed in recovering improperly exposed radiographs using the H&D curve of the screen-film system. Using the new duplication system in our department, the average recovery rate was over 80% for chest and abdominal films rejected due to over- or underexposed. The basic imaging properties of the duplication system were compared with those of a Computed Radiography (CR) system and a conventional screen-film system. For low spatial frequencies, the MTF of the CR system is superior to that of the digital duplication system; however, for high spatial frequencies, the MTF of the duplication system is superior. The noise in the duplication system is about half of that in the CR system.

Biophysical Phenomena↗

PubMedDate not supplied

Computerized detection of pulmonary nodules on CT scans.

Helical computed tomography (CT) is the most sensitive imaging modality for detection of pulmonary nodules. However, a single CT examination produces a large quantity of image data. Therefore, a computerized scheme has been developed to automatically detect pulmonary nodules on CT images. This scheme includes both two- and three-dimensional analyses. Within each section, gray-level thresholding methods are used to segment the thorax from the background and then the lungs from the thorax. A rolling ball algorithm is applied to the lung segmentation contours to avoid the loss of juxtapleural nodules. Multiple gray-level thresholds are applied to the volumetric lung regions to identify nodule candidates. These candidates represent both nodules and normal pulmonary structures. For each candidate, two- and three-dimensional geometric and gray-level features are computed. These features are merged with linear discriminant analysis to reduce the number of candidates that correspond to normal structures. This method was applied to a 17-case database. Receiver operating characteristic (ROC) analysis was used to evaluate the automated classifier. Results yielded an area under the ROC curve of 0.93 in the task of classifying candidates detected during thresholding as nodules or nonnodules.

Algorithms↗

PubMedDate not supplied

Expression of cytokines and proteases in mast cells in the lesion of subcapsular cell hyperplasia in mouse adrenal glands.

To examine the possible roles of mast cells in the pathogenesis of subcapsular cell hyperplasia (SCH) in the adrenal glands of mice, we investigated the expression of certain cytokines, including stem cell factor (SCF), tumor necrosis factor-alpha (TNF-alpha), nerve growth factor (NGF), and basic fibroblast growth factor (bFGF), and mast cell-specific proteases, such as mouse mast cell protease (mMCP)-2 and mMCP-7. The mRNAs of c-kit (SCF receptor), bFGF, TNF-alpha, mMCP-2, and mMCP-7 were expressed in both the adrenal glands and the mouse bone marrow-derived mast cells (mBMMCs). Immunoreactivities for cytokines (SCF, NGF, TNF-alpha) and proteases (mMCP-2, mMCP-7) were exclusively located in the mast cells in SCH lesions. The immature mBMMCs did not express the mRNAs of SCF and NGF, whereas the mast cells in the SCH lesions showed the expression of SCF and NGF. These findings suggest that SCH may provide a favorable microenvironment for functional maturation of mast cells to produce SCF and NGF, and the mast cells in SCH lesions synthesize SCF and NGF and may, in part, use them in autocrine fashion for their survival and differentiation. Therefore, mast cells may contribute to SCH pathogenesis by producing a range of multifunctional cytokines and proteases.

Adrenal Glands↗

PubMedDate not supplied

Posterior lens rupture in rats.

Rupture of the posterior lens capsule with extrusion of lens fibers or entire lens cortex and nucleus was found in Sprague-Dawley rats. The lesion was detected during an ophthalmoscopic examination as round shadows that interfered with the view of the fundus. By slit-lamp biomicroscopic and dissecting microscopic examinations, the shadows were related to opaque plaques located on the posterior capsule. By light microscopic examination, the posterior lens capsule was ruptured and lens fibers extruded into the vitreous. Mononuclear and multinucleated giant cells were present at the site of rupture, however, few other inflammatory responses were present. Although the incidence and pathogenesis of the lesion is unknown, the lesion should be considered along with other spontaneous ocular changes when evaluating safety assessment studies.

Animals↗

PubMedDate not supplied

The age-related difference in bone changes in rats induced by recombinant human granulocyte colony-stimulating factor.

We examined the bone changes in recombinant granulocyte colon-stimulating factor (rhG-CSF)-treated young and young adult rats in order to investigate the effect of age-related conditions of bone growth on the bone changes induced by rhG-CSF. Recombinant human G-CSF (100 and 1,000 micrograms/kg/day) was given to rats by daily intravenous injection for 28 days starting at the age of either 6 or 14 wk, and the hindlimb bones were evaluated histopathologically. In the young rats, bone lesions were observed in the 100- and 1,000-micrograms/k groups. In the young adult rats, lesions were found only in the 1,000-micrograms/kg group. The lesions involved accelerated osteoclastic bone resorption and osteogenesis due to intramembranous ossification and there was no age-related difference in these histopathological findings. However, both the incidence of bone involvement and the severity of lesions were greater in the young rats than in the dose-matched young adult rats. The results suggest that the higher dose of rhG-CSF may intrinsically induce bone lesions of a particular histopathological nature in rats regardless of their age, and the action of rhG-CSF on bone may be stronger in young growing rats than in young adults.

Age Factors↗

PubMedDate not supplied

Systemic histopathology of rats treated with 6-sulfanilamidoindazole, a novel arthritogenic sulfonamide.

6-Sulfanilamidoindazole (6SAI) is a sulfonamide that induces acute, self-limiting arthritis in rats, and 6SAI-induced arthritis is thought to be a model for testing anti-inflammatory agents. In this study, in order to clarify the location of arthritis and relationships between arthritis and other changes in this model, we have investigated the detailed pathologic changes in rats administered orally with 6SAI (125, 250, 500 mg/kg) daily for 4 wk in a time-course experiment. Moderate to severe arthritis was observed in rats of middle- and high-dose groups. Histologically, in the affected ankle, exudative synovitis and periarthritis were observed at 1 wk, granulation tissue formation with angiogenesis and periosteal new bone formation at 2 wk, and marked fibrosis of affected area at 4 wk, respectively. In addition to these changes, in periarticular and periosteal tissues of affected ankles, subendothelial insudation of small-sized arteries and medial fibrinoid degeneration of medium-sized arteries were observed at 1 and 2 wk and intimal thickening and medial hypertrophy at 4 wk, respectively. No arterial changes were observed in the unaffected ankles. Similar arterial changes were often observed in the liver, thyroid glands, and lungs and rarely in various organs and tissues. Acute inflammation of serous tissues such as mesentery, mediastinum, and capsule of spleen or thymus were also present in 6SAI-treated groups, and it was sometimes accompanied by arteritis. In addition, in 6SAI-treated rats, follicular hyperplasia of thyroid glands and pituitary changes, which are thought to be related to depression of thyroid hormone production by 6SAI, were observed. These results show that 6SAI induces not only arthritis but also arteritis, serositis, and thyroid change, and it is necessary to take the interaction between these changes into consideration when anti-inflammatory agents are tested in this model.

Animals↗

PubMedDate not supplied

Dermatotoxicity of agricultural chemicals in the dorsal skin of hairless dogs.

Dermatotoxicity of agricultural chemicals (ACs) with or without ultraviolet (UV) irradiation was histologically examined using hairless descendants of Mexican hairless dogs. ACs examined were pentachlorophenol sodium salt, 2,4-dichlorophenoxyacetic acid (DCPAA), Maneb, and Zineb. One day after cessation of the 7-day AC treatment, the skin treated with DCPPA and Maneb indicated only slight histological changes. The UV + AC-treated sites had as much pigmentation as the control sites. Fourteen days after cessation of treatment, dogs treated with Maneb showed marked reactions such as epidermal degeneration, vasodilation, and intradermal infiltration of inflammatory cells. These histological changes were more severe in the UV + AC-treated sites. Zineb induced comedones with well-developed pilosebaceous glands. These results suggest that hairless dogs may be useful laboratory animals for the investigation of dermatotoxicity of ACs in conjunction with UV irradiation.

2,4-Dichlorophenoxyacetic Acid↗

PubMedDate not supplied

Effects of all-trans-retinoic acid on the dorsal skin of hairless dogs.

Daily topical treatment with all-trans-retinoic acid (t-RA; 0.1% t-RA solution or 0.05% t-RA cream) was compared with its vehicle with regard to improvement of intrinsically aged skin of hairless descendants of Mexican hairless dogs. After 1 mo of treatment with 0.1% t-RA solution, improvements were noted in skin texture, wrinkling, and pigmentation. Treatment with 0.05% t-RA cream caused an intense adverse effect, retinoid dermatitis. Histologically, 0.1% t-RA solution induced restoration of the skin structure of hairless dogs, resulting in an apparent increase in compaction of the stratum corneum and the epidermal thickness. The epidermis became hyperplastic with definite development of the stratum granulosum. The border between the epidermis and dermis became wavy, and dermal papillae were reconstituted. The 0.1% t-RA solution caused a remarkable decrease in melanin granules. In the dermis, the number of small vessels increased and vasodilation was seen. In sites treated with 0.05% t-RA cream, the stratum corneum became involved in dyskeratotic changes. There was a significantly greater increase in epidermal and granular layer thickness. Necrotic and edematous changes were found in the epidermis, and severe inflammatory reactions were also observed in the dermis. In the t-RA-untreated sites, the structure of the aged skin remained histologically unimproved during the study. The results suggest that hairless dogs are useful laboratory animals for evaluating the effectiveness and side effects of t-RA agents.

Administration, Topical↗

PubMedDate not supplied

T-2 toxin-induced apoptosis in hematopoietic tissues of mice.

We examined T-2 toxin-induced lesions in the bone marrow and splenic red pulp as many as 48 hr after oral inoculation with 10 mg/kg body weight of T-2 toxin in female ICR:CD-1 mice. Histopathologically, the bone marrow and splenic red pulp showed a significant hypocellularity. In the bone marrow, the number of myelocytes significantly decreased due to the loss of immature granulocytes, erythroblasts, and lymphocytes. The nuclei of the remaining cells showing pyknosis or karyorrhexis were positively stained by the TdT-mediated dUTP nick end labeling (TUNEL) method, and these TUNEL-positive cells showed ultrastructural characteristics of apoptosis. With agarose gel electrophoresis, DNA ladders were clearly detected in bone marrow samples. The number of TUNEL-positive cells in splenic red pulp increased earlier than it did in the splenic white pulp. Thus, T-2 toxin induced-lesions in the hematopoietic tissues and in the lymphoid tissues were brought about by apoptosis of component cells. We believe that damage to the hematopoietic microenvironment may also play an indirect role in the induction of apoptosis in the bone marrow.

Animals↗

PubMedDate not supplied

Dorsal skin reactions of hairless dogs to topical treatment with corticosteroids.

Dorsal skin reactions to continuous topical treatment with different types of corticosteroids were histologically investigated in hairless descendants of Mexican hairless dogs. The preparations tested were prednisolone (ST-1; weak), fluocinolone acetonide (ST-2; moderate), diflucortolone valrerate (ST-3; strong), and mometasone furoate (ST-4; very strong). Grossly, the sites treated with ST-3 and ST-4 showed moderate inflammatory reactions. After completion of the corticosteroid treatment, both sites were less pigmented and had a thin texture. The severity of histologic changes in the skin was dependent on the efficacy of the corticosteroids. The epidermis was prominently thinned from 1 wk after treatment with the corticosteroids, resulting in a flat dermis-epidermis junction. By the end of the corticosteroid treatment, these lesions became progressively more severe. At 2 wk after completion of topical treatment, the epidermal thickness in the sites treated with ST-1 and ST-2 began to return to normal values, whereas the epidermis of the skin treated with ST-3 and ST-4 became thinner. At 3-4 wk after topical treatment with ST-3 and ST-4, the dermis showed hyalinization of collagen bundles. These dermatologic findings in hairless dogs are in accordance with steroid-induced skin atrophy of human beings. These results suggest that the skin of hairless dogs responds sensitively to topical corticosteroids and that these animals are a useful model for investigating the efficacy and adverse effects of cutaneous topical corticosteroids.

Administration, Cutaneous↗

PubMedDate not supplied

Low frequency of 5'-flanking insertion of human insulin gene in Japanese non-insulin-dependent diabetic subjects.

Polymorphism in the 5'-flanking region of the human insulin gene in 149 unrelated Japanese subjects [77 with non-insulin-dependent diabetes mellitus (NIDDM), 17 with insulin-dependent diabetes mellitus (IDDM), and 55 controls] was analyzed with Southern blot hybridization. We used the size of the hybridized fragments to classify the locus into three groups according to Bell's method (a short, class 1 allele averaging 570 base pairs; an intermediate-size, class 2 allele averaging 1320 base pairs, and a long, class 3 allele averaging 2470 base pairs in size). The allelic frequency of classes 2 and 3 in 298 alleles was 5.0% and in the 146 alleles of NIDDM, 7.8%. The value is lower than in Caucasians, American Blacks, and Pima Indians, and the results suggest that the 5'-flanking insertion is not a genetic marker in most NIDDM patients who are Japanese. However, the frequency of the 5'-flanking insertion in those who were not obese and had a family history of diabetes was higher than that of other NIDDM patients (P = .013), and the frequency in NIDDM patients with onset of diabetes at age less than or equal to 39 yr was lower than those whose onset was at age greater than or equal to 40 yr (P = .053). As NIDDM is a heterogeneous disorder, further analysis is needed. These results suggest that we cannot completely exclude the meaning of the insertion in NIDDM. On the other hand, the frequency in IDDM was 0%, lower than in NIDDM (P = .094). Because the number of subjects studied was small, this result is speculative.

Adult↗

PubMedDate not supplied

Point, minute and small cancers of the stomach at the early developmental stage detected by improved chymotrypsin lavage method for diagnostic cytology.

The improved selective chymotrypsin lavage method under fluoroscopy for cytologic detection led to the discovery of 12 point or minute gastric cancer lesions of less than one cm maximum diameter among 420 patients. It is reported herein how tiny cancers of the stomach can be found by the method, and how valuable it is to employ morphologic criteria for correct identification of the individual atypical cells in these tiny gastric cancers.

Adult↗