Hua Ren

Computed tomography of inflation-fixed lungs: the beaded septum sign of pulmonary metastases.

Radiographic identification of pulmonary metastases has proved to be a challenging problem. We applied high resolution CT (HRCT) to 180 postmortem lung specimens prepared by a method that allows for direct one-to-one pathologic-radiologic correlation. Of the 180 lungs, 32 had pulmonary metastases. The location, number, size, and interstitial changes were evaluated in 32 cases with pulmonary metastases. The pulmonary metastases were peripheral lesions in 94% of these 32 patients, and multiple tumors were found in 91% of these cases. The metastases were <1 cm in diameter in 78%. Twenty-two of the 32 cases (69%) had obvious interstitial changes. In 19 of these 22 cases the interstitial change was characterized by the appearance of a “beaded septum” on HRCT. This beaded septal change corresponded directly to tumor growth in pulmonary capillaries and lymphatics and the septal interstitium. This sign was not noted in any of the specimens with pulmonary edema or fibrosis or in normal lungs. We believe that detection of the beaded septum sign on HRCT is highly suggestive of pulmonary metastases.

Three-dimensional Ct-volumetric Reconstruction and Display of the Bronchial Tree

We applied a refined version of our volumetric rendering technique for three-dimensional (3-D) computed tomographic (CT) imaging to display the cadaveric lung and the major components of the bronchial tree. We report details of the technical aspects of 3-D imaging of the lung, and four representative case studies of lung specimens from our initial experience.

CT of inflation-fixed lungs: Wedge-shaped density and vascular sign in the diagnosis of infarction

To evaluate the role of high resolution CT (HRCT) in the diagnosis of pulmonary infarcts, we selected 83 postmortem lung specimens with subpleural densities from a collection of 180 lungs that had been prepared by a method which allows for a direct radiologic-pathologic correlation. Twelve of the lungs had pulmonary infarcts and 71 lungs had other disorders that had produced a subpleural shadow on HRCT. Lungs were evaluated for the presence of wedge-shaped pleural-based densities and for the presence of an associated vascular sign. There was no significant difference in the incidence of wedge-shaped densities on HRCT between lungs with pulmonary infarcts and lungs with pulmonary hemorrhage, pneumonia, tumor, or edema (p greater than 0.05). A vascular sign associated with a subpleural density was, however, more common (p less than 0.01) in lungs with pulmonary infarcts. We suggest that the vascular sign associated with a wedge-shaped density may be of importance in diagnosing pulmonary infarcts by HRCT.

CT-pathology correlation of amiodarone lung

Eleven isolated lungs from patients who had received amiodarone therapy and 22 other lungs from age-race-sex-matched controls autopsied at The Johns Hopkins Hospital were inflation fixed, air dried, and examined by high resolution CT (HRCT). The HRCT findings were directly correlated with gross and histologic changes in these lungs. Intralobular septal thickening and visceral pleural thickening on postmortem HRCT were significantly more severe in the lungs from patients who had received amiodarone than in the controls (p < 0.05). These HRCT findings were directly associated with the presence of mural foam cells and intraalveolar foam cells. These results suggest that amiodarone therapy may lead to the accumulation of mural and intraalveolar foam cells, and the accumulation of these foam cells may account for the changes seen on HRCT.

Prevention of syngeneic graft-versus-host disease by recovery of thymic microenvironment after cyclosporine

Immunopathology Unit, Department of Pathology, and The Bone Marrow Transplant Unit of the Oncology Center, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205 Following a course of cyclosporine, syngeneic rat radiation chimeras consistently develop a GVHD-like syndrome. Correlation of the thymic immunopathology with conditions leading to syngeneic graft-versus-host disease (sGVHD) suggested the hypothesis that reconstitu-tion of the normal thymic microenvironment after CsA is necessary for self-tolerance. When thymic regeneration is impaired, as in rats receiving previous mediastinal irradiation, then self-reactive effector cells are not regulated and proceed to damage the target tissues. Alternately, it could be argued that the observed thymic abnormalities are irrelevant to sGVHD. To test the primary hypothesis, post-CsA thymic reconstitution was prevented by total thymectomy in unirradiated rats. These rats consistently developed acute type sGVHD seen at 7 and 21 days post-CsA while rats from the CsA-treated sham thymectomy control group failed to develop sGVHD. Because thymectomy prior to CsA blocks sGVHD, most likely the peripheral effector cells in the post-CsA thymectomy group were derived from the CsA-altered thymus. The absence of sGVHD in the sham group indicates that the thymus led to active regulation of these cells after stopping CsA. If regeneration of the thymus restored only negative selection, then the sham thymectomy group should have also developed sGVHD. Flow cytometry and morphology of the spleen and lymph nodes demonstrated that the thymectomized rats, like CsA-treated radiation chimeras, experienced a significant delay in maturation of T cells following CsA. In contrast to the usual model in radiation chimeras, however, the post-CsA thymectomized rats did not convert to chronic type sGVHD. The importance of an abnormal thymus for this transition was confirmed in syngeneic radiation chimeras. Thymectomy after CsA in these rats also blocked the rapid transition to chronic sGVHD.

Inflation-fixed lungs: pathologic-radiologic (CT) correlation of lung transplantation.

Pulmonary infections and lung rejection are the two major complications of lung transplantation. Although the therapies for these two processes differ greatly, they often cannot be differentiated using standard radiography. We applied high resolution CT (HRCT) to seven lung specimens that were obtained from patients who had received a heart-lung transplant. The lungs were fixed by a method that allows for direct one-to-one pathologic-radiologic correlation. We found: (a) that in contrast to the extensive changes present microscopically, acute lung allograft rejection was characterized by only minor changes on HRCT; (b) that bronchiolitis obliterans, the hallmark of chronic lung allograft rejection, was not reliably identifiable on HRCT; (c) that bronchiectasis with associated peribronchial inflammation and fibrosis, a common finding in lung allograft rejection, was identifiable on HRCT, but that the HRCT appearance of this lesion was not specific for rejection; and (d) that pulmonary infections were often identifiable as a mixed airway-interstitial process on HRCT.

Computed tomography of rounded atelectasis

High resolution CT of a fixed-inflated air-dried lung was obtained from a patient with rounded atelectasis. The dense periphery of the mass was shown to correspond to an invagination of the pleura, and the central lucency to slightly aerated atelectatic lung parenchyma.