Biomedical subjects

Kunio Doi

Publications and source records attributed to Kunio Doi.

161 records · Page 9Linked to original sources

PubMed2002

Development of a computerized method for identifying the posteroanterior and lateral views of chest radiographs by use of a template matching technique.

In picture archiving and communications systems (PACS) or digital archiving systems, the information on the posteroanterior (PA) and lateral views for chest radiographs is often not recorded or is recorded incorrectly. However, it is necessary to identify the PA or lateral view correctly and automatically for quantitative analysis of chest images for computer-aided diagnosis. Our purpose in this study was to develop a computerized method for correctly identifying either PA or lateral views of chest radiographs. Our approach is to examine the similarity of a chest image with templates that represent the average chest images of the PA or lateral view for various types of patients. By use of a template matching technique with nine template images for patients of different size in two steps, correlation values were obtained for determining whether a chest image is either a PA or a lateral view. The templates for PA and lateral views were prepared from 447 PA and 200 lateral chest images. For a validation test, this scheme was applied to 1,000 test images consisting of 500 PA and 500 lateral chest radiographs, which are different from training cases. In the first step, 924 (92.4%) of the cases were correctly identified by comparison of the correlation values obtained with the three templates for medium-size patients. In the second step, the correlation values with the six templates for small and large patients were compared, and all of the remaining unidentifiable cases were identified correctly.

Databases as Topic↗

PubMed2002

Detection of lung nodules on digital chest radiographs: potential usefulness of a new contralateral subtraction technique.

PURPOSE: To evaluate the potential usefulness of a contralateral subtraction technique developed for radiologists' performance in the detection of subtle lung nodules on chest radiographs. MATERIALS AND METHODS: Fifty chest radiographs (25 normal and 25 abnormal with a subtle lung nodule) that were digitized with a 0.175-mm pixel size and 4,096 gray levels were used. Twelve radiologists (10 attending and two residents) participated in observer tests and read both original and contralateral subtraction images with a sequential testing method. Radiologists' performance was evaluated by means of receiver operating characteristic analysis with use of a continuous rating scale. The beneficial and detrimental effects of the contralateral subtraction technique on the radiologists' performance were also evaluated. RESULTS: The area under the receiver operating characteristic curve values obtained without and with contralateral subtraction images were 0.926 and 0.962, respectively. Results indicated that the contralateral subtraction images significantly (P <.05) improved diagnostic accuracy, particularly for radiologists with limited experience. CONCLUSION: The contralateral subtraction technique can assist radiologists in the correct identification of subtle lung nodules on chest radiographs.

Humans↗

PubMed2002

Improved detection of lung nodules by using a temporal subtraction technique.

PURPOSE: To evaluate the effect of a temporal subtraction technique for digital chest radiography with regard to the accuracy of detection of lung nodules. MATERIALS AND METHODS: Twenty solitary lung nodules smaller than 30 mm in diameter, including 10 lung cancers and 10 benign nodules, were used. The nodules were grouped subjectively according to their subtlety. For non-nodular cases, 20 nodules without perceptible interval changes were selected. All chest radiographs were obtained by using a computed radiographic system, and temporal subtraction images were produced by using a program developed at the University of Chicago. The effect of the temporal subtraction image was evaluated by using an observer performance study, with use of receiver operating characteristic analysis. RESULTS: Observer performance with temporal subtraction images was substantially improved (A(z) = 0.980 and 0.958), as compared with that without temporal subtraction images (A(z) = 0.920 and 0.825) for the certified radiologists and radiology residents, respectively. The temporal subtraction technique clearly improved diagnostic accuracy for detecting lung nodules, especially subtle cases. CONCLUSION: The temporal subtraction technique is useful for improving detection accuracy for peripheral lung nodules on digital chest radiographs.

Adult↗

PubMed2002

Lung cancers missed at low-dose helical CT screening in a general population: comparison of clinical, histopathologic, and imaging findings.

PURPOSE: To compare clinical, histopathologic, and imaging features of lung cancers missed at low-radiation-dose helical computed tomography (CT). MATERIALS AND METHODS: Eighty-three primary lung cancers were found during an annual low-dose CT screening program and confirmed histopathologically at either surgery or biopsy. Thirty-two of these lung cancers were missed on 39 CT scans: on 23 scans owing to detection errors and on 16 owing to interpretation errors. The clinical characteristics, CT features, and histopathologic findings of these missed lung cancers were correlated. RESULTS: All missed cancers were intrapulmonary, and 28 (88%) were stage IA. All 20 detection errors occurred in cases of adenocarcinoma, 17 (85%) of which were well-differentiated tumors and 11 (55%) of which were in nonsmoking women. The mean size of cancers missed owing to detection error, 9.8 mm, was smaller than that of cancers missed owing to interpretation error, 15.9 mm (P <.001). In the detection error group, the percentages of nodules with ground-glass opacity (91%) or judged to be subtle (91%) were greater than those of nodules in the interpretation error group (38% and 25%, respectively) (P <.001). In the detection error group, 83% (19/23) of cancers were overlapped with, obscured by, or similar in appearance to normal structures such as pulmonary vessels. On 14 of the 16 CT scans with which there were interpretation errors, the CT findings mimicked benign disease, and the patients also had underlying lung disease, such as tuberculosis, emphysema, or lung fibrosis. CONCLUSION: The lung cancers missed at low-dose CT screening in this series generally were very subtle and appeared as small faint nodules, overlapping normal structures, or opacities in a complex background of other disease.

Adenocarcinoma↗

PubMed2002

Lung cancer: performance of automated lung nodule detection applied to cancers missed in a CT screening program.

PURPOSE: To evaluate the performance of a fully automated computerized method for the detection of lung nodules in computed tomographic (CT) scans in the identification of lung cancers that may be missed during visual interpretation. MATERIALS AND METHODS: A database of 38 low-dose CT scans with 50 lung nodules was obtained from a lung cancer screening program. Thirty-eight of the nodules represented biopsy-confirmed lung cancers that had not been reported during initial clinical interpretation. A computer detection method that involved the use of gray-level thresholding techniques to identify three-dimensionally contiguous structures within the lungs was applied to the CT data. Computer-extracted volume was used to determine whether a structure became a nodule candidate. A rule-based scheme and a cascaded automated classifier were applied to the set of nodule candidates to distinguish actual nodules from areas of normal anatomy. Overall performance of the computer detection method was evaluated with free-response receiver operating characteristic (FROC) analysis. RESULTS: At a specific operating point on the FROC curve, the method achieved a sensitivity of 80% (40 of 50 nodules), with an average of 1.0 false-positive detection per section. Missed cancers were detected by the computerized method with a sensitivity of 84% (32 of 38 nodules) and a false-positive rate of 1.0 per section. CONCLUSION: With an automated lung nodule detection method, a large fraction (84%, 32 of 38) of missed cancers in a database of low-dose CT scans were detected correctly.

Aged↗

PubMed2002

Residues of aflatoxins in the liver, muscle and eggs of domestic fowls.

The residue of aflatoxins in the liver, muscle and eggs of laying ducks, hens and quails and in broiler chickens was examined by conducting 7-day feeding experiments with a diet containing 3 ppm Aflatoxin B1 (AFB1). Birds were sacrificed on the 8th or 11th day of AFB1 feeding. AFB1 and its metabolites in the tissues and eggs were determined by HPLC. The tissue levels of AFB1 and its metabolites were higher in quail than in the other birds. The levels of AFB1 and its metabolites, including acid-hydrolyzable metabolites, were more than 10-fold higher in the liver than in the muscle in all the species. The ratio of AFB1 in the feed to the residual level in the liver was 383 in quail, but was > or = 5769 in the other birds. The corresponding ratios in the egg yolk and albumen of AFB1 were 4615 and 3846, respectively, in chicken hens, and these values were higher than those in the other birds.

Aflatoxin B1↗

PubMed2002

Cerebellar myxoid type meningioma in a Shih Tzu dog.

A 6-year and 9 month-old, male, Shih Tzu dog showed ataxia and trembling. By MRI examination, a mass (1 cm) was found in the right cerebellum. As the dog did not respond to radiation therapy, and showed a rise of intracranial pressure, he was euthanized. The cerebellar mass was soft and hemorrhagic. Histologically, the mass contained vimentin-positive spindle- or polyhedral-shaped cells arranged in a cord-like pattern. Mucinous materials were observed in the intercellular spaces. Ultrastructural examination revealed cell processes, microtubule-like structures and desmosomes. The case was diagnosed as myxoid type meningioma.

Animals↗

PubMed2002

Detection of porcine circovirus 2 (PCV-2) DNA by nested PCR from formalin-fixed tissues of post-weaning multisystemic wasting syndrome (PMWS) pigs in Thailand.

A retrospective study for the detection of porcine circovirus 2 (PCV-2) DNA was conducted by nested PCR method in 16 cases of swine post-weaning multisystemic wasting syndrome (PMWS) in Thailand. Histopathology showed characteristic lesions of PMWS and intracytoplasmic viral inclusion bodies in macrophages infiltrating in lymphoid tissues. PCV-2 DNA was detected from formalin-fixed and/or formalin-fixed paraffin-embedded tissues from all pigs with PMWS. The amplified products were digested with Hae III.

Animals↗

PubMed2002

Psittacine beak and feather disease in three captive sulphur-crested cockatoos (Cacatua galerita) in Thailand.

Three sulphur-crested cockatoos (Cacatua galerita) were diagnosed as psittacine beak and feather disease (PBFD). Histopathology of the feather pulp and follicles showed intracytoplasmic botryoid clusters or granular inclusion bodies in epithelial cells and macrophages. Electron microscopy revealed multiple cytoplasmic clusters of electron dense viral particles corresponding to the inclusions. PBFD virus (circovirus) DNA-specific product was detected from formalin-fixed paraffin-embedded feathers by nested polymerase chain reaction (PCR) method.

Animals↗

PubMed2002

Usefulness of an artificial neural network for differentiating benign from malignant pulmonary nodules on high-resolution CT: evaluation with receiver operating characteristic analysis.

OBJECTIVE: The purpose of our study was to use an artificial neural network to differentiate benign from malignant pulmonary nodules on high-resolution CT findings and to evaluate the effect of artificial neural network output on the performance of radiologists using receiver operating characteristic analysis. MATERIALS AND METHODS: We selected 155 cases with pulmonary nodules less than 3 cm (99 malignant nodules and 56 benign nodules). An artificial neural network was used to distinguish benign from malignant nodules on the basis of seven clinical parameters and 16 radiologic findings that were extracted by attending radiologists using subjective rating scales. In the observer test, 12 radiologists (four attending radiologists, four radiology fellows, and four radiology residents) were presented with high-resolution CT images, first without and then with the artificial neural network output. Observer performance was evaluated by means of receiver operating characteristic analysis using a continuous rating scale. RESULTS: The artificial neural network showed a high performance in differentiating benign from malignant pulmonary nodules (A(z) = 0.951). The average A(z) value for all radiologists increased by a statistically significant level, from 0.831 to 0.959, with the use of the artificial neural network output. CONCLUSION: Our computerized scheme using the artificial neural network can improve the diagnostic accuracy of radiologists who are differentiating benign from malignant pulmonary nodules on high-resolution CT.

Adult↗

PubMed2002

[Development of an image processing scheme for chest radiographs using a dot printer].

The performance of dot printers has recently been improved. Images output by dot printers can provide simple, economical medical reference images if important diagnostic information is not lost. We developed an image processing scheme for chest radiographs that employed a dot printer. We used two types of pixel value conversions, a nonlinear pixel value correction using a lookup table and a linear pixel value conversion using histogram analysis. The density distribution of chest radiographs was analyzed and classified into high-density and low-density images. The two types of pixel value conversions were used depending on the density of chest radiographs. Converted pixel value had density characteristics that were adapted to the output image of the dot printer, and thus the density distributions of the lungs of radiographs became comparable. In addition, an adaptive unsharp masking technique with processing parameters optimized for each of the lungs and mediastinum was applied. An ROC study for the detection of lung nodules was carried out to evaluate the performance of dot printer images. The area under the ROC curve (A(z)) for dot printer images was 0.816, while sensitivity and specificity were 77.6% and 75.2%, respectively. The performance indicated the usefulness of our image processing scheme.

Humans↗

PubMed2002

[Development of a computerized method for identifying view position and orientation for chest radiographs by using a template matching technique].

For implementation of computer-aided diagnostic systems for chest radiographs in the clinical environment, it is necessary to correctly identify two view positions [posteroanterior (PA) and lateral views] and four orientations (upward, downward, leftward, and rightward) for chest radiographs. In picture archiving and communication system (PACS), the information on the view position and orientation for chest radiographs is often not recorded or is recorded incorrectly. The purpose of this study was to develop a computerized method for correctly identifying view position and orientation for chest radiographs by using a template matching technique. Our basic approach is to find the most similar template to an unknown chest image by examining the similarity of the unknown chest image with a number of templates for PA and lateral views at the four image orientations, and to determine simultaneously the view position and orientation for the unknown chest image. All upward templates were produced from the PA or lateral images for upward orientation for various patient sizes. By rotating the upward templates, we produced the templates for downward, leftward, and rightward orientations. To evaluate the similarity of a test image with all templates, the cross-correlation values of the test image with all templates were obtained. The view position and image orientation for the unknown image was considered to be identical to those for the template with which the largest cross-correlation value was obtained. Our results indicated that all cases of 200 PA and 200 lateral views were correctly identified in terms of the view position and image orientation.

Diagnosis, Computer-Assisted↗

PubMed2001

Three-dimensional and fractal analyses of assemblies of amyloid beta protein subtypes [Abeta40 and Abeta42(43)] in canine senile plaques.

The three-dimensional (3D) distribution of amyloid beta protein (Abeta) subtypes [Abeta40 and Abeta42(43)] in canine senile plaques (SP) was observed using a confocal laser scanning microscope. In diffuse plaques (DP), Abeta42(43) alone was deposited as an uneven nebula-like assembly of fine granules. The border of the Abeta42(43) assembly was unclear and diffusely merged to the surrounding area. Mature plaques (MP), on the other hand, showed two patterns of Abeta deposition. In some MP, only Abeta40 was deposited as a defined assembly of very short fibrillary structures. Other MP consisted of both Abeta40 and Abeta42(43), and the deposition patterns of the two Abeta species were the same as those in single-positive plaques; fine granular with unclear margin for Abeta42(43), and short fibrillary structures for Abeta40. Additionally, we calculated the fractal dimensions (FD) of both Abeta40 and Abeta42(43) assemblies, and examined the serial change of FD in each SP. The FD of Abeta42(43)-positive DP ranged from 1.05 to 1.27, and those of Abeta40-positive MP ranged from 1.13 to 1.54 in single-positive plaques. In one double-positive MP, FD ranged from 1.02 to 1.36 for Abeta42(43) and from 1.01 to 1.51 for Abeta40. These results showed that the FD of canine Abeta40 assemblies was higher than that of Abeta42(43) assemblies, and the spatial changes of FD values for Abeta40 and Abeta42(43) in double-positive plaques were quite different. These morphological analyses clearly showed that canine DP and MP have completely different 3D structures, suggesting that their processes of formation are different.

Alzheimer Disease↗

PubMedDate not supplied

Involvement of p53 in 1-beta-D-arabinofuranosylcytosine-induced rat fetal brain lesions.

1-beta-D-Arabinofuranosylcytosine (Ara-C), a cytidine analogue cytotoxic to proliferating cells, has a teratogenic effect in the brain of experimental animals and causes neural cell apoptosis in vitro and in vivo. In the present study, pregnant rats were injected with Ara-C on Day 13 of gestation and the fetal brain was collected from 1 to 48 h after treatment. Histopathological examinations revealed marked induction of apoptotic cell death and decrease of mitosis in neuroepithelial cells in the brain of Ara-C-treated fetus, and these changes were most prominent from 9 to 12 h. Expression of p53 protein, which mediates apoptosis and cell cycle arrest after DNA damage, was elevated remarkably and peaked at 3 h. p21, a cyclin-dependent kinase inhibitor responsible for p53-mediated cell cycle arrest, showed intense overexpression in protein and mRNA levels following the increase of p53 protein. The mRNA expressions of other p53 transcriptional target genes, bax, cyclinG1, and fas, also significantly increased and peaked at around 9 h. In conclusion, prenatal treatment of Ara-C is thought to induce apoptosis and inhibition of cell proliferation mediated by p53 and its target genes in the fetal brain.

Animals↗

PubMedDate not supplied

Histopathological study on the PTHrP-induced incisor lesions in rats.

Parathyroid hormone related peptide (PTHrP) was discovered as a causative factor of humoral hypercalcemia of malignancy (HHM). The present study elucidates the histopathological characters of incisor lesions in the HHM rat model. Nude rats were implanted with PTHrP-expressing tumor (LC-6) cells, maintained for 12 weeks, after which the mandibular incisors were collected. Incisor fractures were observed grossly. Microscopically, hypercalcified dentin, dentin niche with osteodentin, and thinning of dentin were observed. Hypercalcified dentin was observed as a basophilic line of calcified dentin without associated odontoblastic changes, whereas dentin niche and thinning of dentin occurred with osteodentin and loss of cell height, respectively. In contrast with hypercalcified dentin, which was distributed throughout the dentin, dentin niche and thinning of dentin were localized to the labial area of the apical and middle region, and to the labial and lingual areas of the middle and incisal region, respectively. These results suggest that hypercalcemia affected the entire calcification process resulting in hypercalcified dentin, and that high PTHrP concentrations affected selective populations of odontoblasts resulting in formation of dentin niche and thinning of dentin. The localization of dentin niche and thinning of dentin also suggest that PTHrP may also be involved odontoblastic development in the rat.

Animals↗

PubMedDate not supplied

Effects of granulocyte colony-stimulating factor (G-CSF) on bleomycin-induced lung injury of varying severity.

We evaluated the effects of granulocyte colony-stimulating factor (G-CSF) on bleomycin (BLM)-induced lung injury that developed diffuse alveolar damage and subsequent pulmonary fibrosis (PF) of varying severity. G-CSF (100 microg/kg/day) was administered subcutaneously to BLM (0.2, 20, 2,000 microg)-treated or -untreated rats for 3 or 14 days. In the BLM 0.2 microg group, slight alveolar mononuclear cell infiltration was observed, although PF was not noted. In the BLM 20-microg and 2,000-microg groups, diffuse alveolar damage along with neutrophil infiltration and subsequent PF were observed. In the saline + G-CSF group and BLM 0.2 microg + G-CSF group, a marked increase in the number of alkaline phosphatase (ALP)-positive neutrophils was noted in the alveolar capillaries, although there was neither neutrophil infiltration in alveoli nor exacerbation of lung injury. In the BLM 20 microg + G-CSF and BLM 2,000 microg + G-CSF groups, an exacerbation of lung injury along with an increase in the number of ALP-positive neutrophils in the alveoli was observed. These results indicate that the administration of G-CSF to rats with slight lung injury bearing no PF does not exacerbate the lung injury. The exacerbating effects of G-CSF seem to be associated not only with the marked infiltration of activated neutrophils but also with the severity of underlying lung injury.

Alkaline Phosphatase↗

PubMedDate not supplied

Computer-aided diagnosis in chest radiography: results of large-scale observer tests at the 1996-2001 RSNA scientific assemblies.

Since 1996, computer-aided diagnosis (CAD) schemes have been presented as interactive demonstrations on computer workstations at each scientific assembly of the Radiological Society of North America. The schemes involved (a) detection of pulmonary nodules, (b) temporal subtraction, (c) detection of interstitial lung disease, (d) differential diagnosis of interstitial lung disease, and (e) distinction between benign and malignant pulmonary nodules on chest radiographs. Large-scale observer tests were carried out to examine how radiologists can benefit from CAD systems. Observer performance was evaluated by analysis of receiver operating characteristic (ROC) curves. The statistical significance of the difference between the areas under the ROC curves without and with CAD was analyzed with the Student t test. In all of the tests, the diagnostic accuracy of the radiologists in total improved significantly when CAD was used. This result provides additional evidence that CAD has the potential to improve the performance of radiologists in their decision-making process in interpreting chest radiographs.

Diagnosis, Computer-Assisted↗