Biomedical subjects

Hajime Nakata

Publications and source records attributed to Hajime Nakata.

14 recordsLinked to original sources

PubMed2005

Investigation of misfiled cases in the PACS environment and a solution to prevent filing errors for chest radiographs.

RATIONALE AND OBJECTIVE: The aim of the study was to survey misfiled cases in a picture archiving and communication system environment at two hospitals and to demonstrate the potential usefulness of an automated patient recognition method for posteroanterior chest radiographs based on a template-matching technique designed to prevent filing errors. MATERIALS AND METHODS: We surveyed misfiled cases obtained from different modalities in one hospital for 25 months, and misfiled cases of chest radiographs in another hospital for 17 months. For investigating the usefulness of an automated patient recognition and identification method for chest radiographs, a prospective study has been completed in clinical settings at the latter hospital. RESULTS: The total numbers of misfiled cases for different modalities in one hospital and for chest radiographs in another hospital were 327 and 22, respectively. The misfiled cases in the two hospitals were mainly the result of human errors (eg, incorrect manual entries of patient information, incorrect usage of identification cards in which an identification card for the previous patient was used for the next patient's image acquisition). The prospective study indicated the usefulness of the computerized method for discovering misfiled cases with a high performance (ie, an 86.4% correct warning rate for different patients and 1.5% incorrect warning rate for the same patients). CONCLUSION: We confirmed the occurrence of misfiled cases in the two hospitals. The automated patient recognition and identification method for chest radiographs would be useful in preventing wrong images from being stored in the picture archiving and communication system environment.

Database Management Systems↗

PubMed2004

Improved detection of lung cancer arising in diffuse lung diseases on chest radiographs using temporal subtraction.

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the usefulness of temporal subtraction for the detection of lung cancer arising in pneumoconiosis, idiopathic pulmonary fibrosis, and pulmonary emphysema. MATERIALS AND METHODS: Fifteen cases of lung cancer arising in diffuse lung diseases, including three cases of pneumoconiosis, six of idiopathic pulmonary fibrosis, and six of pulmonary emphysema, were evaluated. Pathologic proof was obtained by surgery or transbronchial lung biopsy. The average interval between previous and current radiographs was 356 days (range, 31-947 days). All chest radiographs were obtained with a computed radiography system, and temporal subtraction images were produced by subtracting of a previous image from a current one with a nonlinear image-warping technique. The effect of the temporal subtraction image was evaluated by observer performance study with receiver operating characteristic analysis. RESULTS: The average observer performance with temporal subtraction was significantly improved (Az = 0.935) compared with that without temporal subtraction (Az = 0.857, P < .0001). CONCLUSION: The temporal subtraction technique is useful for the detection of lung cancer arising in pneumoconiosis, idiopathic pulmonary fibrosis, and pulmonary emphysema.

Adenocarcinoma↗

PubMed2004

Improved detection of lung nodules on chest radiographs using a commercial computer-aided diagnosis system.

OBJECTIVE: The aim of this study was to evaluate the usefulness of a new commercially available computer-aided diagnosis (CAD) system with an automated method of detecting nodules due to lung cancers on chest radiograph. MATERIALS AND METHODS: For patients with cancer, 45 cases with solitary lung nodules up to 25 mm in diameter (nodule size range, 8-25 mm in diameter; mean, 18 mm; median, 20 mm) were used. For healthy patients, 45 cases were selected on the basis of confirmation on chest CT. All chest radiographs were obtained with a computed radiography system. The CAD output images were produced with a newly developed CAD system, which consisted of an image server including CAD software called EpiSight/XR. Eight radiologists (four board-certified radiologists and four radiology residents) participated in observer performance studies and interpreted both the original radiographs and CAD output images using a sequential testing method. The observers' performance was evaluated with receiver operating characteristic analysis. RESULTS: The average area under the curve value increased significantly from 0.924 without to 0.986 with CAD output images. Individually, the use of CAD output images was more beneficial to radiology residents than to board-certified radiologists. CONCLUSION: This CAD system for digital chest radiographs can assist radiologists and has the potential to improve the detection of lung nodules due to lung cancer.

Adult↗

PubMed2003

Postsurgical change in the tracheal bifurcation angle after upper lobectomy: radiographic evaluation.

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate postsurgical changes in the tracheal bifurcation angle on chest radiographs after upper lobectomy and to determine whether bronchial repositioning after upper lobectomy mimics that in upper lobe collapse. MATERIALS AND METHODS: The authors selected 81 patients who had undergone upper lobectomy with complete mediastinal and subcarinal lymph node dissection and in whom chest radiographs had been obtained before operation and at four postoperative intervals. The interbronchial angle and the subcarinal angle were measured on the preoperative and postoperative radiographs and compared statistically. RESULTS: The average interbronchial angle and subcarinal angle during any postoperative period were significantly smaller than those before lobectomy (P < .001). These average angles decreased gradually during the postoperative periods. CONCLUSION: The tracheal bifurcation angle was decreased on follow-up chest radiographs in most patients who underwent upper lobectomy with mediastinal lymph node dissection. This finding may be useful for establishing a history of this surgical procedure on the basis of chest radiographs.

Adult↗

PubMed2003

Clinical feasibility of noncontrast-enhanced magnetic resonance lymphography of the thoracic duct.

STUDY OBJECTIVE: The dilatation of the thoracic duct was previously demonstrated in liver cirrhosis by lymphangiography, endoscopic ultrasound, and at autopsy. The evaluation of the morphologic change of the thoracic duct may be important in assessing the altered lymphodynamics in liver cirrhosis. The objectives of this study were to determine which combination of posture and breathing phase during noncontrast-enhanced magnetic resonance lymphography (MRL) provided the clearest images, and to evaluate the morphologic changes in the thoracic duct in healthy volunteers and patients with liver disease and malignancy. DESIGN: Prospective study. SETTING: Community general hospital. DESIGN AND SUBJECTS: Twenty-three healthy volunteers and 113 patients underwent the MRL examination using a three-dimensional, half-Fourier, fast spin echo sequence on a 1.5-T, whole-body magnetic resonance system. The appropriate posture and breathing phase of MRL to obtain the best visualization was first determined by trial on 14 healthy volunteers. Morphologic changes of the thoracic ducts were evaluated in 23 healthy volunteers including the 14 healthy volunteers for the first trial and 113 patients using this appropriate method. The width of the thoracic ducts in both patients and volunteers was measured. MEASUREMENTS AND RESULTS: MRL with respiratory gating in the supine position depicted the thoracic duct well and was the most comfortable for the subjects. In 82 of 113 patients (72.6%), the thoracic ducts were entirely visualized from the diaphragm level to the subclavian region. The remaining 31 patients had ducts that could not be entirely visualized due to sections or short lengths that were obscured. The maximum diameter was 3.74 +/- 0.81 mm in all healthy volunteers, 6.98 +/- 2.77 mm in alcoholic cirrhosis, 4.12 +/- 1.51 mm in nonalcoholic cirrhosis, 3.76 +/- 1.10 mm in malignancy, and 3.60 +/- 0.80 mm in chronic hepatitis (mean +/- SD). The diameter in alcoholic cirrhosis was significantly greater than in other groups (p < 0.01). CONCLUSIONS: Respiratory gating in the supine position is the best MRL method for acquiring the clearest images. This may be a good method of detecting morphologic changes in the thoracic duct. The patients with alcoholic cirrhosis showed a greater thoracic duct diameter than other groups.

Adult↗

PubMed2003

Differential diagnosis of benign peripheral lipoma from well-differentiated liposarcoma on MR imaging: is comparison of margins and internal characteristics useful?

OBJECTIVE: Our objective was to evaluate the reliability of MR imaging in distinguishing between benign lipoma and well-differentiated liposarcoma. MATERIALS AND METHODS: The MR images of 35 pathologically proven benign lipomas in 35 patients and 23 well-differentiated liposarcomas in 17 patients were retrospectively reviewed. T1-, T2-, and fat-suppressed T1-weighted images were obtained after administration of gadopentetate dimeglumine. Margins and internal characteristics revealed on the MR images and the degree of contrast enhancement of septa were evaluated. These MR imaging findings were compared for well-differentiated liposarcomas and benign lipomas. RESULTS: Completely irregular margins were recognized only in benign lipomas with a pathologic diagnosis of infiltrating lipoma. All tumors without a recognizable nonadipose component were benign lipomas (p < 0.05). As for the well-differentiated liposarcomas, thick septa and nodular or patchy nonadipose components were present more frequently in deep and retroperitoneal lesions than in subcutaneous lesions (p < 0.01). No cases showed only thin septa in the deep lesions of well-differentiated liposarcoma, and all cases showed thick septa or nodular or patchy nonadipose components. The septa in well-differentiated liposarcomas enhanced more strongly than did those in benign lipomas. The septa showed no enhancement relative to muscle in 11 of 19 benign lipomas, whereas the septa showed moderate or marked enhancement in all well-differentiated liposarcomas (p < 0.01). CONCLUSION: Careful assessment of margins and internal characteristics on MR imaging can be a useful aid in further distinguishing between biologically different benign lipoma and well-differentiated liposarcoma.

Adult↗

PubMed2003

[New evaluation for osteoporosis using calcaneal computed radiographs].

Quantitative analysis of bone mass is a method mainly used for the diagnosis of osteoporosis. However, there are cases of osteoporosis that cannot be diagnosed by this method alone. This study was performed to develop a new quantitative method for the evaluation of osteoporosis using texture analysis and geometric feature analysis of trabecular bone on lateral calcaneal computed radiographs. Thirty-seven cases including 11 normal and 26 abnormal lateral calcaneal radiographs were examined. The patients' ages ranged from 24 to 89 years (average age, 58.3 years). The root mean square (RMS) variation and first moment of power spectrum of trabecular bone patterns were determined as quantitative measures for texture analysis. In addition, the total area and total length of trabecular bone were obtained from geometric feature analysis. The RMS variations in pixel values, total area, and total length of trabecular bone were decreased as bone atrophy progressed. These three quantitative measures corresponded well to radiologists' subjective evaluations of bone atrophy. Moreover, our results indicated that these three quantitative measures had strong correlations with bone mineral density of the femoral neck. Therefore, we consider the computerized method with texture analysis and geometric feature analysis of lateral calcaneal radiographs to be very useful for radiologists in evaluating osteoporosis.

Adult↗

PubMed2003

[Results of combined therapy for maxillary sinus squamous cell carcinoma].

The results of 54 cases of maxillary sinus squamous cell carcinoma treated between 1980 and 2002 were analyzed retrospectively. The T classification according to the 1997 UICC was as follows: 2 with stage T1, 29 with T3, and 23 with T4. Ten patients(18.5%) had lymph node metastases at diagnosis. All patients underwent combined therapy including radiotherapy, surgery, and regional or systemic chemotherapy. Fifteen patients received hyperfractionated twice-daily radiotherapy (1.2 Gy or 1.5 Gy/fraction), and the remaining 39 patients received a conventional once-daily regimen(1.5-2 Gy/fraction). The 5-year overall survival and 5-year disease-free survival for all patients were 56.0% and 46.7%, respectively. The N classification was the only significant prognostic factor for 5-year disease-free survival by univariate analysis (favoring N = 0, p = 0.04). There were no significant differences in other prognostic factors including gender, T classification (T1-3 vs. T4), hyperfractionated radiotherapy (yes vs. no), total dose (BED: < 69 Gy10 vs. > or = 69 Gy10), and intra-arterial chemotherapy(yes vs. no). Although radiation-induced cataract was observed in 9 patients, no other severe late complications developed.

Adult↗

PubMed2002

Flow-weighted MRI of the lungs with the ECG-gated half-Fourier FSE technique: evaluation of the effect of the cardiac cycle.

We investigated temporal MR signal changes in the peripheral lung and proximal pulmonary vessels during the entire cardiac cycle in order to evaluate the characteristics of the diastolic-systolic subtraction method in the lung. In eight healthy volunteers free of lung diseases, changes in the MR signal during one breath-hold were investigated with the multiple ECG-triggered half-Fourier single-shot fast-spin echo (SS-FSE) technique. The signal intensity-time course curve in the lung showed that biphasic signals decreased 20% to 47% at systole and 5% to 33% at mid-diastole, measured against the maximum signals at late diastole. This signal decrease in the peripheral lung was correlated to that in the proximal pulmonary vessels during an entire cardiac cycle (r=0.667 to 1.000). The best visualization of the lung was obtained at late diastole, when the intra-vascular flow in the lung was expected to be stagnant. Compared with the late diastolic SS-FSE images, the late diastolic-systolic subtracted SS-FSE images improved the signal-to-noise ratio in the lung as well as the signal-intensity ratio of the peripheral lung to surrounding tissues. Although the flow-induced signal dephasing in the lung was completely unavoidable and its amount was unpredictable even at late diastole, the diastolic-systolic subtracted SS-FSE images showed the relative differences in flow alteration during the cardiac cycle between the images at diastole and those at systole. The main characteristic of diastolic-systolic subtracted SS-FSE was the enhancement of visibility of cardiac-dependent signal changes in the lung due to the alteration in pulsatile flow.

Adult↗

PubMed2002

MRI findings including gadolinium-enhanced dynamic studies of malignant, mixed mesodermal tumors of the uterus: differentiation from endometrial carcinomas.

Our objective was to evaluate the usefulness of MRI including dynamic study in differentiating malignant, mixed mesodermal tumor (MMMT) from endometrial carcinoma (EC). The MR images were reviewed in 4 patients with histologically confirmed MMMT and 11 patients with EC. Flow voids inside and/or around the tumors were seen in 2 patients with MMMT but not in any EC cases. In dynamic studies, all 4 patients with MMMT showed areas of early and persistent marked enhancement similar to that of the myometrium, mixed with areas of gradual and delayed marked enhancement. The portions showing early and persistent enhancement histologically corresponded to predominantly sarcomatous components with prominent vascularity. Ten of 11 ECs did not show such enhancement and only one showed a rapid enhancement in the early phase which was diminished in the delayed phase. The MR imaging with a gadolinium-enhanced dynamic study seems to be useful in differentiating MMMT from EC.

Aged↗

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 cancer screening using low-dose spiral CT: results of baseline and 1-year follow-up studies.

STUDY OBJECTIVE: To evaluate the feasibility of lung cancer screening using low-dose spiral CT as a part of annual health examinations. DESIGN: Nonrandomized, screening practice. METHODS: From April 1998 to August 2000, CT screening was performed as a part of annual health examinations on a total of 7,956 individuals who belonged to the Hitachi Employee's Health Insurance Group. Of those participants, 5,568 were rescreened 1 year later. When a noncalcified solitary pulmonary nodule (SPN) >or= 8 mm was detected on CT screening, a detailed CT scan was carried out approximately 1 month later. RESULTS: During the baseline screening, a total of 2,865 noncalcified SPNs were detected among the 7,956 participants. Primary lung cancer was histologically confirmed in 40 patients (41 lesions). The prevalence was 0.44% of all participants from the baseline, and 0.07% from the repeated screening. Thirty-five of 41 tumors were stage I. Current or former smokers represented only 17 of 40 cases. The detection rate was rather high in female participants. CONCLUSION: Low-dose spiral CT seems to be a promising method for screening early lung cancer as a part of annual health examinations. Female and nonsmoking subjects should be included in the baseline screening. However, for yearly repeat screening, the participants may be selected on the basis of gender, smoking history, and results at the baseline screening.

Age Distribution↗

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

[Prevalence of emphysematous changes as shown by low-dose spiral CT screening images in 6144 healthy subjects].

We assessed the prevalence of emphysematous changes among healthy workers and retired persons, using subjective evaluations of low-dose spiral CT images obtained during thoracic CT screenings for lung cancer. Among 6144 male participants (50-69 years old; mean age, 57), we detected 686 cases (11.2%) with emphysematous changes. The majority (95.3%) of CT-detected emphysema cases were in current or former smokers, and 169 cases (24.6%) showed significant obstructive impairment. Of 236 cases with emphysematous changes in the internal region (more than 20 mm from the costal margin), 98(41.5%) had significant obstructive impairment. Smoking was found to be the major risk factor for CT-detected emphysema. Longitudinal observation of the emphysema cases, as well as health care support for cessation of smoking, is very important.

Aged↗