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Acinar lesions, a pathologist's naming for granulomatous lesions formed in the peripheral air space, that is, in the bronchiole or its adjacent alveolar space, is very characteristic and pathognomonic for tuberculosis on HRCT imaging. As a radiological term, it is equal to centrilobular nodule or branching shadow, or tree-in-bud appearance in the recent trend. It is universally seen in most of tuberculosis cases, irrespective of its stage or extensity. Although thus common, its appearance is not always uniform. Firstly they are not well defined in some cases. Exudative tendency in pathological process may explain for this appearance. Secondarily they are not always arranged in an orderly manner or in other words centrilobular manner on CT, but often in a random fashion. Pathologically this phenomenon can be explained by the randomness of formation site of granulomas or by scarring in spontaneous healing process of the disease. Finally, although rare, an extreme pattern, in which acinar lesions are diffusely disseminated in both lung fields without other type of lesions, is well known as Oka's Classification of Pulmonary Tuberculosis Type IIB. This rare type of tuberculosis could be formed through indolent dissemination of bacilli via the airway or from the hematogenous dissemination. It should also be noted that in tuberculous pneumonia, especially when it develops in emphysematous lung, acinar lesions is not seen, making differential diagnosis difficult.

We examined the chest CT findings in 12 cases of intralobar pulmonary sequestration. We classified 4 subtypes by evaluating bronchial and alveolar structures, thus: type A (3 cases), mild cylindrical dilatation of the bronchial structure and hyperlucent alveolar structure; type B (3 cases), marked cylindrical dilatation of the bronchial structure and hyperlucent alveolar structure; type C (2 cases), multicystic dilatation of the bronchial structure and alveolar structure without hyperlucency; and type D (4 cases), multicystic dilatation of the bronchial structure and absence of any alveolar structure. All 77 cases (present and previously reported cases) with CT-documented intralobar pulmonary sequestration could be classified into 4 subtypes: type A 9%, type B 34%, type C 19%, and type D 38%. We concluded that these 4 types were useful for the radiological diagnosis of intralobar pulmonary sequestration.

To evaluate alveolar epithelial damage in PSS, we studied pulmonary epithelial permeability by measuring the clearance of inhaled 99mTc-DTPA aerosol and performing thin slice CT scan, pulmonary function tests and right heart catheterization in 28 patients with PSS. The 99mTc-DTPA clearance rate (kep value) in PSS was greater than in 11 non-smoking normal subjects (18.2 +/- 7.63 x 10(-3)/min vs. 9.12 +/- 0.77 x 10(-3)/min, p less than 0.01). In PSS, the kep value did not correlate with age, sex, duration of illness, dermal lesions, % vital capacity, or PaO2. In contrast, the kep value showed significant correlations with %DLco (diffusing capacity for carbon monoxide), extent of interstitial lesions evaluated by CT scan (CT score), and mean pulmonary artery pressure. On the other hand, the kep value was high in some patients with normal CT scan and normal %DLco. These findings indicate that pulmonary interstitial lesions in PSS are accompanied by alveolar epithelial damage, and that the clearance of 99mTc-DTPA may be an early predictor of interstitial change.

A 33-year-old male was admitted to our hospital for further investigation of unilateral hyperlucency of the left upper and middle lung fields on chest X-ray. A pulmonary scan showed decreased perfusion of the left upper and middle lung fields. Pulmonary arteriography demonstrated small left pulmonary arteries with diminished peripheral vascular branches. Left bronchogram showed almost normal distribution of main and subsegmental bronchi, but poor filling by contrast in the peripheral bronchi. From these findings, the patient was diagnosed as having Swyer-James syndrome. In order to demonstrate the alveoli in this syndrome, selective alveolobronchography (SAB) was performed. SAB revealed coarse ring shadows of B1+2.

We have measured quantitative regional alveolar volume and specific ventilation in healthy subjects by Nitrogen-13 gas and Positron Emission Tomography. Studies have proceeded in the supine position. Subjects have rebreathed N-13 gas in closed circuit. After radioactivity has reached equilibrium, Scan was carried out. During equilibrium, we have taken radioactive gas from the closed circuit to make quantitative alveolar volume and we have measured the radioactivity by well counter. This value means radioactivity in unit of thoracic volume. Well counts/PET counts denote alveolar volume/thoracic volume. After equilibrium, RI has been washed out by air, during the washout phase we have 3 sequential images. Using these sequential images, we have fitted RI activity in the washout phase monoexponential curve. Index of the monoexponential curve means -V/V, if we do not consider rebreathing from dead space. The data shows a large alveolar volume in the ventral region compared to that in the dorsal region, and also a high V/V in the dorsal region compared to that in the ventral region. It seems that the error of V/V in healthy subjects due to rebreathing from dead space is about 8%.