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Biomedical subjects

N Mihara

Publications and source records attributed to N Mihara.

29 records · Page 2Linked to original sources
PubMedDate not supplied

Respiratory change in size of honeycombing: inspiratory and expiratory spiral volumetric CT analysis of 97 cases.

PURPOSE: The purpose of this study was twofold: to evaluate the change in size of honeycomb cysts with respiration using inspiratory-expiratory spiral volumetric CT (I-E SVCT) and to establish the pathologic basis of this change. METHOD: Ninety-seven patients, who had honeycombing associated with end-stage pulmonary fibrosis on end-inspiratory 1 to 2 mm collimation high-resolution CT (HRCT), underwent I-E SVCT (3 mm collimation, pitch 1, breath-hold time 20 s, reconstruction interval 1 mm, FOV 16-20 cm, high frequency algorithm). I-E SVCT scans were assessed on images obtained in the transverse plane and volumetric sagittal, coronal, and oblique reformations. The histologic findings were assessed in four inflated and fixed lungs that showed honeycombing at postmortem HRCT. RESULTS: In 63 patients (65%), a small percentage of the cysts did not change in size at end-expiration, while in the remaining patients, all the cysts decreased in size. Assessment of volumetric multiplanar reformations showed that cysts that decreased in size during exhalation communicated with airways and represented bronchiolectasis rather than true cysts, while the other cysts did not communicate with the airways. Similar findings were found in pathologic specimens. CONCLUSION: The majority of, but not all, honeycomb cysts seen on HRCT represent dilated bronchioles that communicate with the proximal airways and change in size with respiration.

Adult↗
PubMedDate not supplied

Comparison of high resolution CT findings of sarcoidosis, lymphoma, and lymphangitic carcinoma: is there any difference of involved interstitium?

PURPOSE: The purpose of this study was to determine distinguishing features of three diseases that are distributed along the lymphatics. METHOD: CT scans of 40 patients with lymphangitic carcinomatosis, 41 with sarcoidosis, and 44 with malignant lymphoma were retrospectively reviewed. We evaluated the degree of involvement of the interlobular septa, bronchovascular structures, subpleural interstitium, and other CT findings. RESULTS: The number of thickened interlobular septa and the extent of involvement of the subpleural interstitium in lymphangitic carcinomatosis were higher than those in sarcoidosis and malignant lymphoma (p<0.0001). Nodules of >1 cm in diameter were more often seen in malignant lymphoma (41.0%) than in the other two diseases (p < 0.001). Bilateral distribution was more common in sarcoidosis (100%) than in the others (p<0.001). CONCLUSION: The major difference among lymphangitic carcinomatosis, sarcoidosis, and malignant lymphoma is the greater involvement of the interlobular septa and subpleural interstitium in lymphangitic carcinomatosis than in either sarcoidosis or malignant lymphoma.

Adult↗
PubMedDate not supplied

Acute respiratory distress syndrome and acute interstitial pneumonia: comparison of thin-section CT findings.

PURPOSE: The purpose of this work was to compare the thin-section CT findings of acute respiratory distress syndrome (ARDS) with those of acute interstitial pneumonia (AIP). METHOD: The thin-section CT scans from 25 patients with ARDS and 25 with AIP were independently assessed by two observers without knowledge of clinical and pathologic data. The presence, extent, and distribution of various CT findings were independently analyzed. RESULTS: Honeycombing was seen more frequently in lobes of patients with AIP (26%) than in lobes with ARDS (8%) (p < 0.001). Compared with patients with ARDS, a greater number of patients with AIP had a predominantly lower lung zone distribution (p < 0.05) and a symmetric distribution (p < 0.05) of the parenchymal abnormalities. CONCLUSION: Patients with AIP have a greater prevalence of honeycombing and are more likely to have a symmetric bilateral distribution and a lower lung zone predominance than patients with ARDS. However, significant overlap exists among the CT findings.

Acute Disease↗
PubMedDate not supplied

Invasive and noninvasive thymoma: distinctive CT features.

PURPOSE: The purpose of this work was to evaluate the CT features of thymoma and to determine the most helpful findings in differentiating invasive from noninvasive thymoma. METHOD: The CT scans from 27 patients with invasive thymoma and 23 with noninvasive thymoma were independently assessed by two observers without knowledge of their invasiveness. The presence and distribution of various CT findings were independently analyzed. RESULTS: Invasive thymomas were more likely to have lobulated (16/27, 59%) or irregular (6/27, 22%) contours than noninvasive thymomas (8/23, 35% and 1.5/23, 6%, respectively) (p < 0.05). Invasive thymomas had a higher prevalence of low attenuation areas within the tumor (16/27, 60%) than noninvasive thymomas (5/23, 22%) (p < 0.001) as well as foci of calcification (14.5/27, 54% vs. 6/23, 26%; p < 0.01). CONCLUSION: The presence of lobulated or irregular contour, areas of low attenuation, and multifocal calcification is suggestive of invasive thymoma.

Adult↗
PubMedDate not supplied

Can acute interstitial pneumonia be differentiated from bronchiolitis obliterans organizing pneumonia by high-resolution CT?

PURPOSE: In the early stages, clinical and chest radiographic findings of acute interstitial pneumonia (AIP) are often similar to those of bronchiolitis obliterans organizing pneumonia (BOOP). However, patients with AIP have a poor prognosis, while those with BOOP can achieve a complete recovery after corticosteroid therapy. The objective of this study was to identify differences in high-resolution CT (HRCT) findings between the two diseases. METHODS: The study included 27 patients with AIP and 14 with BOOP who were histologically diagnosed [open-lung biopsy (n=7), autopsy (n=17), transbronchial lung biopsy (n=17)]. The frequency and distribution of various HRCT findings for each disease were retrospectively evaluated. RESULTS: Traction bronchiectasis, interlobular septal thickening, and intralobular reticular opacities were significantly more prevalent in AIP (92.6%, 85.2%, and 59.3%, respectively) than in BOOP (42.9%, 35.7%, and 14.3%, respectively) (p<0.01). Parenchymal nodules and peripheral distribution were more prevalent in BOOP (28.6% and 57.1%, respectively) than in AIP (7.4% and 14.8%, respectively) (p<0.01). Areas with ground-glass attenuation, air-space consolidation, and architectural distortion were common in both AIP and BOOP. CONCLUSION: For a differential diagnosis of AIP and BOOP, special attention should be given to the following HRCT findings: traction bronchiectasis, interlobular septal thickening, intralobular reticular opacities, parenchymal nodules, pleural effusion, and peripheral zone predominance.

Acute Disease↗
PubMedDate not supplied

Acute and subacute non-infectious lung diseases: usefulness of HRCT for evaluation of activity especially in follow-up.

PURPOSE: The purpose of this study was to survey the usefulness of high-resolution CT (HRCT) for the evaluation of activity in acute and subacute non-infectious diffuse infiltrative lung diseases before and after corticosteroid treatment. PATIENTS AND METHODS: Sequential HRCT images and chest radiographs obtained before and after treatment were retrospectively evaluated in 33 patients with acute or subacute noninfectious diffuse infiltrative lung diseases. All these patients were histologically confirmed to have pulmonary Inflammation and to have responded to treatment with corticosteroid. Radiographic and CT scores were correlated with the degree of dyspnea and the results of arterial blood gas analysis using Spearman's rank-correlation coefficient. RESULTS: On follow-up HRCT, the profusion score of areas with increased attenuation was significantly correlated with arterial oxygen tension (PaO2) (p=.003, r=-.53) and the alveolar-arterial oxygen tension difference (AaDO2) (p=.001, r=.57). No other correlation was found after treatment. Nodular and linear opacities were more commonly seen on follow-up chest radiographs and HRCT images than on initial ones. CONCLUSION: HRCT is useful for the evaluation of disease activity in acute and subacute noninfectious infiltrative lung diseases before and after treatment if paying special attention to the profusion of ground-glass attenuation. Even if pretreatment HRCT has not been performed, posttreatment HRCT should be examined.

Acute Disease↗
PubMedDate not supplied

Pitfalls in the interpretation of multidetector-row helical CT images at window width and level setting for lung parenchyma.

This article describes pitfalls in the interpretation of multidetector-row helical CT (MDCT) images at the window width and level settings for lung parenchyma. On MDCT, linear artifacts, which look like black and white linear densities and are called "hurricane artifacts," radiate out from objects that have very different densities from their neighbors. For the evaluation of fine parenchymal details, a low table speed/slice collimation should be used. In fact, axial (step and shoot) scanning may be more effective for the evaluation of fine details. Since artifacts from vessels highly enhanced by contrast medium cause data blackout in the surrounding areas at high table speed/slice collimation, pulmonary parenchyma in such situations should be evaluated with unenhanced CT. Although multidetector-row helical CT is a promising tool for the evaluation of lung parenchyma, it is important to identify its shortcomings due to artifacts when interpreting images at the window width and level settings for lung parenchyma and to apply the appropriate methods for eliminating such artifacts.

Artifacts↗
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Evaluation of image quality and spatial resolution of low-dose high-pitch multidetector-row helical high-resolution CT in 11 autopsy lungs and a wire phantom.

PURPOSE: The aim of this study was to evaluate whether low-dose high-pitch (6:1) multidetector-row helical high-resolution CT is appropriate for the evaluation of various pulmonary abnormalities, including faint opacities. METHODS: Eleven autopsy lungs were scanned with a multidetector-row CT scanner using 2.5 mm x 4 beam collimation, effective slice thickness 3 mm, 6:1 pitch, 0.8 second gantry rotation speed, 20 cm Display FOV, high spatial frequency (bone) algorithm, and various radiation doses (120 kVp; 160, 80, 40, 24, and 8 mAs). The image quality of each CT set was assessed as adequate or inadequate for diagnosis by two independent observers. In addition, a wire phantom was scanned with the same parameters in order to describe the MTF curves. RESULTS: There was excellent agreement between the observers for the evaluation of image quality (kappa statistic, 0.84). The ratio of images evaluated as inadequate for 8 mAs and 24 mAs was significantly higher than that for 160, 80, and 40 mAs (p<0.01: chi-square test). MTF curves of both 8 and 24 mAs were significantly inferior to those of 40, 80, and 160 mAs (p<0.0 1, Friedman test), while the MTF curve of 40 mAs was relatively inferior to that of 160 mAs (p<0.05, Friedman test). CONCLUSION: More than 40 mAs in combination with 120 kVp is preferable for the evaluation of details of lung parenchyma by high-pitch. multidetector-row helical high-resolution CT.

Autopsy↗
PubMedDate not supplied

Evaluation of compressed lung CT image quality using quantitative analysis.

The goals of this study were (1) to evaluate the quality of compressed lung CT images obtained using high resolution CT (HRCT: 2 mm slice thickness) for degree of compression and conventional CT (10 mm slice thickness) images by using physical and subjective evaluations, and (2) to analyze the distortion of density distribution on lung CT images using histogram analysis for each compression ratio. The coding method was performed according to the Joint Photographic Experts Group (JPEG). We physically evaluated the quality of compressed lung CT images using the peak signal-to-noise ratio (PSNR) as given by the square root of the ratio of the peak value of the gray level squared to the mean square error (dB) and subjectively evaluated the CT images using the mean opinion score (MOS). The acceptable compression ratio for diagnosis was about 1:6 to 1:7 for conventional CT images and about 1:4 to 1:5 for HRCT images as determined by MOS. The PSNR corresponding to acceptable compression ratios was about 50 dB. The difference in density distribution between HRCT and conventional CT was statistically significant (Friedman test: p<0.02) in histogram analysis. Results suggested that, in comparison with conventional CT, a high compression ratio was not suitable for HRCT.

Algorithms↗
PubMedDate not supplied

A case of acute interstitial pneumonia indistinguishable from bronchiolitis obliterans organizing pneumonia/cryptogenic organizing pneumonia: high-resolution CT findings and pathologic correlation.

We report a case of histologically proved acute interstitial pneumonia (AIP) with subacute onset whose high-resolution CT (HRCT) findings were indistinguishable from those of bronchiolitis obliterans organizing pneumonia (BOOP)/cryptogenic organizing pneumonia (COP). The HRCT findings were air-space consolidation with air-bronchiologram associated with little ground-glass attenuation, and nodules. Some cases of AIP present HRCT findings indistinguishable from those of BOOP/COP.

Acute Disease↗