Intrathoracic Major Vessels, Trachea and Main Bronchi: The Effect of Respiration on Size

PURPOSE: To evaluate the effect of respiration on the sizes of intrathoracic vasculature, and the trachea,and the main bronchus. MATERIALS AND METHODS: Seventeen volunteers (10males aged 20-39 years and 7 females aged20-39 years) underwent spiral CT, between the apex and lowest base of the lung, collimation was 10mm, pitch was 1,and images were obtained at breath hold forced end-inspiration and breath hold forced end-expiration. Crosssecional areas or diameters were measured in each respiration state at the aorta (ascending, descending, lowerthoracic) and great branches, the IVC (thoracic, abdominal), the SVC, pulmonary artery (right main, leftdescending) and the tracheobronchus (trachea, left upper bronchus). Changes in the size of vessels and airwaysbetween the respiration states were evaluated and compared between inspiration and expiration. RESULT: Duringbreath-hold forced end-inspiration CT, the ascending, descending, and lower thoracic aorta and itsbranches(brachiocephalic, left common carotid, left subclavian) as well as the thoracic IVC and SVC and the rightmain and left descending pulmonary arteries decreased in size: during breath-hold forced end-expiration CT, thesize of all these vessels increased. For the trachea, left upper lobe bronchus and abdominal IVC, the situationwas reversed. Statistically significant changes(p<0.05) were noted in the ascending aorta and descending aorta,the lower thoracic aorta, the thoracic and abdominal IVC, the SVC, the right main and left pulmonary arteries, andthe trachea. CONCLUSION: During respiration, changes in the size of the thoracic vasculature and airways isprobably due to changes in intrathoracic pressure. In the measurement and diagnosis of stenosis or dilatation inthe intrathoracic vesculature and airways, respiration states should therefore be considered.

Plugging the Biopsy Tract in Rabbit Liver: Gelfoam, Fibrin Sealant and NBCA

PURPOSE: To evaluate the effect of plugging the biopsy tract in rabbit liver and the pathologic changes caused by plugging materials. MATERIALS AND METHODS: Thirty-two New Zealand White rabbits were divided into four groups(eight rabbits in each) and compared with one another. They were labeled group A(control), B(gelfoam),C(fibrin sealant) or D(NBCA). The liver was exposed and biopsied with an 18G disposible biopsy gun. The inner Tru-cut needle was withdrawn and plugging was undertaken through the outer cannula of the biopsy gun. Bleeding times of each material were compared. The rabbits were sacrificed and pathologically evaluated for 17 days. RESULTS: Mean bleeding times were 46.7+/-34.5 sec in group A, 42.9+/-54.7 sec in group B, 12.6+/-15.0 sec in group C, and 0 sec in group D. In groups C and D, these results were statistically significant(p<0.01). Pathologically, fibrin sealant was lowest in foreign body reaction and fibrosis. NBCA was effective for the prevention of hemorrhage. CONCLUSION: NBCA and fibrin sealant effectively plug the biopsy tract through the outer cannula of an18 G biopsy gun.

Squalene-Induced Lipoid Pneumonia in Rabbits: High-Resolution CT and Pathologic findings

PURPOSE: To describe the HRCT and pathologic findings of squalene-induced lipoid pneumonia in rabbits. MATERIALS AND METHODS: Three ml of squalene was instilled into the trachea between the second and the third tracheal ring in 16 rabbits. Serial HRCT scans were obtained on day 4 (n=8), at 1 week (n=7), 2 weeks (n=1), 4 weeks(n=1), 6 weeks (n=2) and 20 weeks (n=1) after squalene instillation. With sacrifice of the rabbits pathology was reviewed at 1 week (n=3), 4 weeks (n=3), and 6 weeks (n=4) after CT scans. RESULTS: Lipoid pneumonia was induced in 8 rabbits; lesions were distributed mainly in the dependent posterior lung. On serial HRCT scans, airspace consolidation, as seen on an air-bronchogrm, and nodular opacities were early findings; these gradually diminshed and with time were replaced by nodular & linear opacities. Histologically, pulmonary fibrosis appeared one week after squalene instillation and progressed over time. Alveolar septal thickening and cuboidal change of the alveolar lining epithelium were more prominent at week 6. CONCLUSION: The early change of squalene-induced lipoidpneumonia in rabbits is the proliferation of intraalveolar macrophage, which is responsible for air-space consolidation with air-bronchograms on HRCT. Nodular and linear opacities on HRCT are due to the appearance of pulmonary fibrosis one week after squalene instillation, and its subsequent progression.

Three Dimensional Spiral CT of the Tracheobronchial Tree: Determination of the Optimal Window Settings

PURPOSE: To determine optimal window settings for measuring the inner diameter of the trachea and both mainbronchi by spiral CT. MATERIALS AND METHODS: Chest PA radiography and spiral CT scanning were performed in ten healthy adult volunteers. Three dimensional images were reconstructed (minimal threshold value : -1000HU ; maximal threshold value : from -200 to -900HU, of 50HU intervals) to measure the inner diameter of the trachea and both main bronchi. The results of 3D spiral CT were compared with those of chest radiography. RESULTS: The inner diameters of the trachea, right main bronchus, left main bronchus-I (1cm below the tracheal carina) and left mainbronchus-II (2cm below the tracheal carina) measured by chest radiograph and 3D spiral CT were not significantly different at maximal threshold values of -400 ~ -550HU, -450 ~ -550HU, -450 ~ -600HU and -500 ~ -600HU, respectively (p>0.05). The differences in the results of the two series were statistically significant at other threshold values however (p<0.05). CONCLUSION: We determined optimal window settings for measuring the inner diameter of the trachea and both main bronchi by spiral CT. The optimal maximal threshold values were somewhat different according to measured sites of the trachea and both main bronchi.