Tomofumi Nagareda

Perilobular pulmonary opacities: high-resolution CT findings and pathologic correlation.

This pictorial essay illustrates the high-resolution CT and histologic findings of various disease processes that involve the perilobular interstitium.

In vitro evaluation of normal and abnormal lungs with ultra-high-resolution CT.

Synchrotron radiation microtomography is a new technique with high directionality of a synchrotron radiation beam and a high-resolution detector array. In this study, we estimated the visualization of the peripheral human lung structure with an ultra-high-resolution computed tomography (CT) system, the synchrotron radiation CT. The synchrotron radiation CT system uses the bending magnet beamline emitted from the 8.0 GeV electron storage ring. Six lung specimens were obtained at autopsy: 3 normal, 1 cellular alveolitis, 1 diffuse alveolar damage, and 1 pulmonary hemorrhage. Each specimen was cut down to a cylindrical sample with 6-mm diameter and 15- to 25-mm height. The synchrotron radiation CT images of these lung samples were obtained using the ultra-high-resolution image detector system with a charge coupled device (CCD) array detector (1024 × 1024 pixels with 12 × 12 &mgr;m2 pixel size). After that, the sample specimens were sliced to 200 &mgr;m (micrometer) thickness, and were observed with a stereomicroscope and by contact radiography. Finally, approximately 10-&mgr;m thick microscopic images were obtained and compared with the synchrotron radiation CT images. The synchrotron radiation CT could depict the peripheral lung including peripheral airways, airspaces, and alveolar walls individually. Each finding in the 3 disease processes seen on the synchrotron radiation CT images correlated well with the microscopic findings. The synchrotron radiation CT allows microtomographic imaging of human lung specimens with ultra high-spatial resolution (12 &mgr;m) on a level approaching that of conventional histopathology, without sectioning.

Metastatic pulmonary calcification: early detection by high-resolution CT.

A 41-year-old man with a renal transplant was admitted with cough, fever, and dyspnea. Although chest radiography was normal, high-resolution CT demonstrated small hazy round opacities in the centrilobular regions throughout both lungs. The biopsy specimen revealed metastatic calcification in the alveolar septa and the walls of the bronchioles and arterioles. High-resolution CT may be useful for the early detection of metastatic pulmonary calcification when plain radiography is negative and therapy has the potential to reverse the process.

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.

Fractal analysis for classification of ground-glass opacity on high-resolution CT: an in vitro study.

PURPOSE Fractal analysis based on the fractional Brownian motion model was applied ground-glass opacity on high-resolution CT (HRCT) to investigate its usefulness in distinguishing ground-glass opacity caused by nonfibrotic disease processes and that caused by fibrotic disease processes, confirming pathology. METHOD Twenty-one postmortem lungs inflated and fixed by Heitzmans method were evaluated. By correlating HRCT and pathology, the lungs were classified into nonfibrotic disease processes and fibrotic disease processes. Fractal analysis based on the fractional Brownian motion model provides the parameter H, which is a statistical measure related to the psychophysical perception of roughness. For regions of interest positioned over ground-glass opacities on HRCT, conventional statistics (mean value and SD) and the estimated H values were calculated using a workstation. RESULTS Pathologically, 10 lung specimens were categorized as nonfibrotic disease processes and 11 as fibrotic disease processes. Whereas the conventional statistics had considerable overlap in two disease processes, the overlapping was drastically reduced in the H values. The H values of fibrotic disease processes (mean +/- SD, 0.423 +/- 0.064) were significantly greater than those of nonfibrotic disease processes (0.297 +/- 0.036) (p < 0.001). CONCLUSION Fractal analysis based on the fractional Brownian motion model may provide a new promising scheme for assessing ground-glass opacity on HRCT caused by either nonfibrotic or fibrotic disease processes.

CT and MR appearances of parotid pseudotumors in Sjögren syndrome.

The radiologic findings in eight patients with parotid pseudotumors associated with Sjögren syndrome (CT in eight; MRI in two) were retrospectively analyzed and compared with the findings in three cases with malignant lymphomas. Diagnosis of pseudotumor was obtained by surgery in six cases and by fine-needle aspiration biopsy and radiologic follow-up in the remaining cases. Six cases (75%) had advanced disease and the remaining had early disease. Both solid (75%) and cystic (38%) masses were seen in the patients with pseudotumors. The masses were solitary in 25%, multiple in 75%, unilateral in 25%, and bilateral in 75%. All three lymphomas were solid masses. The lymphomatous masses were not reliably distinguished from the solid pseudotumors.

Synchrotron radiation microtomography of lung specimens

We have applied a synchrotron radiation computed tomography (SRCT) system to the lung specimens and evaluated its resolving power compared with the histopathologic appearances, precisely. An SRCT system has been constructed in the bending magnet beamline at the SPring-8. The system consists of a double-crystal monochromator, a rotating sample stage, a fluorescent screen, and a charge-coupled device (CCD) array detector (1024 X 1024 pixels with 12 X 12 micrometers 2 pixel size). The energy of the x-ray beam was tuned to 9 - 12 keV. The lungs obtained at autopsy were inflated and fixed by Heitzmans method. A cylindrical specimen (diameter, approximately 8 mm; height, 15 - 25 mm) was rotated in the plane parallel to the beam. The detected signal was transferred to a workstation; then, SRCT images (matrix size, 800 X 800 pixels) were reconstructed by a filtered back- projection. Finally, 6 - 12 micrometer-thick microscopic sections were obtained and stained with hematoxylin and eosin for histopathologic examination. SRCT images well depicted the terminal bronchiole, respiratory bronchiole, alveolar duct, alveolar sac, and alveolar septum. Different pathologic processes (alveolar hemorrhage, alveolitis) demonstrated on SRCT images were well correlated with the histopathologic appearances.

Three-dimensional visualization of morphology and ventilation procedure (air flow and diffusion) of a subdivision of the acinus using synchrotron radiation microtomography of the human lung specimens

We have previously reported a synchrotron radiation (SR) microtomography system constructed at the bending magnet beamline at the SPring-8. This system has been applied to the lungs obtained at autopsy and inflated and fixed by Heitzman’s method. Normal lung and lung specimens with two different types of pathologic processes (fibrosis and emphysema) were included. Serial SR microtomographic images were stacked to yield the isotropic volumetric data with high-resolution (12 μm3 in voxel size). Within the air spaces of a subdivision of the acinus, each voxel is segmented three-dimensionally using a region growing algorithm (“rolling ball algorithm”). For each voxel within the segmented air spaces, two types of voxel coding have been performed: single-seeded (SS) coding and boundary-seeded (BS) coding, in which the minimum distance from an initial point as the only seed point and all object boundary voxels as a seed set were calculated and assigned as the code values to each voxel, respectively. With these two codes, combinations of surface rendering and volume rendering techniques were applied to visualize three-dimensional morphology of a subdivision of the acinus. Furthermore, sequentially filling process of air into a subdivision of the acinus was simulated under several conditions to visualize the ventilation procedure (air flow and diffusion). A subdivision of the acinus was reconstructed three-dimensionally, demonstrating the normal architecture of the human lung. Significant differences in appearance of ventilation procedure were observed between normal and two pathologic processes due to the alteration of the lung architecture. Three-dimensional reconstruction of the microstructure of a subdivision of the acinus and visualization of the ventilation procedure (air flow and diffusion) with SR microtomography would offer a new approach to study the morphology, physiology, and pathophysiology of the human respiratory system.