Pulmonary nodule size evaluation with chest tomosynthesis and CT: a phantom study.

OBJECTIVE: We compared digital tomosynthesis (TOMO) and chest CT in terms of assessing the sizes of nodules located in zones where evaluation by simple radiography is limited. METHODS: A total of 48 images comprising phantom nodules of four sizes in six different locations were used. Nodule size measurement errors for measurements using TOMO and CT images compared with the actual size from each observer were calculated. The inter- and intraobserver repeatability of the measured values and the agreement between the two techniques were assessed using the method described by Bland and Altman. RESULTS: The mean measurement errors for all of the nodules and four observers were -0.84 mm [standard deviation (SD), 0.60 mm] on TOMO and -0.18 mm (SD, 0.71 mm) on CT images. The mean measurement errors for the different observers ranged from -1.11 to -0.55 mm for TOMO and from -0.39 to 0.08 mm for CT. Assessing the agreement between nodule size measurements using TOMO and CT resulted in mean measurement errors of -0.65 mm, with a 95% limit of agreement of -2.53 to 1.22 mm for comparison of TOMO with CT. CONCLUSION: Our results suggest that nodule sizes obtained using TOMO and chest CT are comparable, even for nodules located in areas where the size measurement is limited on simple radiography. ADVANCES IN KNOWLEDGE: TOMO and CT can be used interchangeably, even for nodules located in a blind area on simple radiography.

Accuracy of lung nodule volumetry in low-dose CT with iterative reconstruction: an anthropomorphic thoracic phantom study.

OBJECTIVE: The purpose of this study was to assess accuracy of lung nodule volumetry in low-dose CT with application of iterative reconstruction (IR) according to nodule size, nodule density and CT tube currents, using artificial lung nodules within an anthropomorphic thoracic phantom. METHODS: Eight artificial nodules (four diameters: 5, 8, 10 and 12 mm; two CT densities: -630 HU that represents ground-glass nodule and +100 HU that represents solid nodule) were randomly placed inside a thoracic phantom. Scans were performed with tube current-time product to 10, 20, 30 and 50 mAs. Images were reconstructed with IR and filtered back projection (FBP). We compared volume estimates to a reference standard and calculated the absolute percentage error (APE). RESULTS: The APE of all nodules was significantly lower when IR was used than with FBP (7.5 ± 4.7% compared with 9.0 ±6.9%; p < 0.001). The effect of IR was more pronounced for smaller nodules (p < 0.001). IR showed a significantly lower APE than FBP in ground-glass nodules (p < 0.0001), and the difference was more pronounced at the lowest tube current (11.8 ± 5.9% compared with 21.3 ± 6.1%; p < 0.0001). The effect of IR was most pronounced for ground-glass nodules in the lowest CT tube current. CONCLUSION: Lung nodule volumetry in low-dose CT by application of IR showed reliable accuracy in a phantom study. Lung nodule volumetry can be reliably applicable to all lung nodules including small, ground-glass nodules even in ultra-low-dose CT with application of IR. ADVANCES IN KNOWLEDGE: IR significantly improved the accuracy of lung nodule volumetry compared with FBP particularly for ground-glass (-630 HU) nodules. Volumetry in low-dose CT can be utilized in patient with lung nodule work-up, and IR has benefit for small, ground-glass lung nodules in low-dose CT.

Paratracheal air cysts on thoracic multidetector CT: incidence, morphological characteristics and relevance to pulmonary emphysema.

OBJECTIVE: To determine the incidence, morphological characteristics and relevance of paratracheal air cysts (PTACs) with pulmonary emphysema, as seen on thoracic multidetector CT (MDCT). METHODS: The CT images of 854 consecutive patients who underwent thoracic MDCT during a period of 2 months at our institution were reviewed. 538 of the patients were male and 316 were female. The incidence, size and shape of the PTACs and their relation to pulmonary emphysema were retrospectively analysed. RESULTS: Among the 854 patients, 69 (8.1%) had PTACs. 37 (6.9%) of the 538 male patients and 32 (10.1%) of the 316 female patients had PTACs. The highest prevalence of PTACs (25 patients, 11.2%) was found in those who were in the sixth decade of life. 48 (69.6%) PTACs measured 3-10 mm at the longest diameter and 33 (47.8%) were elongated on the coronal section images. 12 (17.4%) patients with PTACs had underlying gross morphological emphysema. The relationship between the presence of PTACs and the presence of emphysema and the relationship between the presence of PTACs and the severity of emphysema were not statistically significant. The size of PTACs showed an inverse relation to the severity of emphysema. CONCLUSION: The incidence of PTACs was estimated to be much higher than that of previous studies. There was a slight female predilection for PTACs, most commonly found in the sixth decade of life; PTACs mostly measured 3-10 mm and were elongated in shape. The relation of PTACs to gross morphological emphysema was low. ADVANCES IN KNOWLEDGE: PTACs are not correlated with the presence of emphysema on MDCT.

Wide spectrum of thoracic neurogenic tumours: a pictorial review of CT and pathological findings.

The purpose of this pictorial essay is to illustrate the radiological and pathological findings of a wide spectrum of neurogenic tumours of the thorax according to their anatomical location and histological subtype. Knowledge of these findings will narrow the differential diagnosis and provide guidance for patient management.

Comparison between coronal reformatted images and direct coronal CT images of the swine lung specimen: assessment of image quality with 64-detector row CT.

The aims of this study were to compare the image quality of coronal multiplanar reconstruction (MPR) images from axial spiral images with that of direct coronal spiral and sequential images, and to estimate and analyse the effect of an incremental change on the image quality using 64-detector row CT. 12 swine lungs were used. Five kinds of images from each lung specimen were obtained using 64-detector row CT. All images were analysed by categories and grades, and the direct coronal sequential images were used as the reference standard for the image quality. Statistical analysis was performed for the following categories: (i) inter-observer reliability, (ii) interaction between the observers and images, (iii) image analysis, (iv) anatomical structural analysis of each observer, (v) stair-step artefact and (vi) background noise. The overall image quality and the image quality of all anatomical structures of coronal MPR images with 0.67 mm slice increments were inferior to the image quality of the other images; this difference was statistically significant (p<0.05). Stair-step artefact was detected on coronal MPR images, and was more prominent on coronal MPR images with 0.67 mm slice increments than on coronal MPR images with 0.34 mm slice increments. The most severe background noise was detected on the direct coronal sequential images, but there was no significant difference between the direct coronal sequential images and the direct coronal spiral images. Background noise was least prominent on coronal MPR images with 0.67 mm slice increments. The increment process is important for improving the image quality of MPR images even when using 64-detector row CT. Coronal MPR images with 0.34 mm slice increments using 64-detector row CT showed a similar image quality to that obtained from the direct coronal images, and can be used instead. This means that the coronal MPR images obtained with 64-detector row CT could be as useful for evaluating the lung parenchyma as the axial high-resolution CT images.

Primary localized amyloidosis manifested as supraclavicular and mediastinal lymphadenopathy.

Thoracic involvement of amyloidosis is relatively rare, but mediastinal lymphadenopathy in the absence of pulmonary parenchymal involvement is extremely rare. The case presented here is of a previously healthy elderly woman who developed a palpable mass in the right supraclavicular area. The chest CT scan showed extensive, contiguous and homogeneous low attenuated lymphadenopathy with stippled calcification in the right supraclavicular area and mediastinum. Amyloidosis was confirmed histopathologically on a biopsy specimen from a right supraclavicular lymph node. Because there were no other sites found to be affected by amyloidosis and there was no underlying chronic disease, we made a final diagnosis of primary localized amyloidosis involving only the supraclavicular and mediastinal lymph nodes.

Pulmonary infections in immunocompromised hosts: the importance of correlating the conventional radiologic appearance with the clinical setting.

The lung is one of the most frequently involved organs in a variety of complications in the immunocompromised host. Among the pulmonary complications that occur in this kind of patient, infection is the most common and is associated with high morbidity and mortality. Although chest radiography and computed tomography (CT) are essential diagnostic tools, radiologists often have difficulty in establishing the correct diagnosis on the basis of radiologic findings alone. The reasons are that the immunocompromised host is potentially susceptible to infection from many different microorganisms and that radiologic findings are seldom specific for the detection of a particular pathogen. Experience has shown that a particular clinical setting predisposes patients to infection by particular pathogens. The setting comprises (a) the specific epidemiologic or environmental exposure, (b) the type of underlying immune defect, (c) the duration and severity of immune compromise, and (d) the progression rate and pattern of the radiologic abnormality. Correlating the radiologic appearance with the clinical setting can expedite diagnosis and appropriate therapy. In this review, the authors describe the clinical settings that are helpful in choosing the radiologic approach to treatment of the immunocompromised host who presents with suspected pulmonary infection.

Thoracic manifestations associated with advanced liver disease.

Advanced liver disease and portal hypertension may produce various intrathoracic complications that involve the pleural space, lung parenchyma, and pulmonary circulation. Dyspnea and arterial hypoxemia are the common clinical symptoms and signs in patients with such complications. In these patients, intrathoracic complications most often develop during the course of hepatic disease, but a few patients may be seen first with respiratory symptoms or radiographic abnormalities. Therefore, radiologists should be made aware of these disorders that occur in patients with chronic liver disease. In this article, the authors describe and illustrate the clinical and imaging spectrum of thoracic abnormalities associated with advanced liver disease and portal hypertension.

Large cell neuroendocrine carcinoma of the lung: radiologic and pathologic findings.

PURPOSE: The purpose of this work was to determine the radiologic and pathologic findings of large cell neuroendocrine carcinoma (LCNEC). METHOD: We retrospectively evaluated chest radiographs, CT scans, and pathologic findings of five patients with pathologically confirmed LCNEC. They were confirmed by percutaneous needle biopsy (n = 2) and by surgery (n = 3). The average age of patients was 60 (51-70) years, and all five were smokers (mean 30 pack-years) and men. Radiologic findings were reviewed for the pattern of lesion, location, and associated findings by two radiologists under consensus. Pathologic findings were reviewed by two pathologists. RESULTS: In all five patients, tumors were represented as a peripherally located nodule or mass without associated secondary pneumonitis or distal atelectasis radiographically. On CT scan, masses were oval or round and well demarcated with lobulated margin in all cases, their sizes ranged from 2 to 5 cm, and they did not show internal calcification and necrosis. On contrast-enhanced CT, three cases showed moderate enhancement more than the chest wall muscle. Lymphadenopathy was observed in ipsilateral hilar and mediastinal areas in three cases. Distant metastasis to liver was noted in one case. One case of LCNEC was Stage IV, two were Stage IIIa, and two were Stage Ia at the time of diagnosis. CONCLUSION: Although the epidemiology of LCNEC is more similar to that of small cell carcinoma than atypical carcinoids, in its strong association with smoking, rapid progression, and poor prognosis, our five cases of LCNEC show peripherally located pulmonary nodule or mass with or without regional lymphadenopathy, which are findings similar to those of atypical carcinoids rather than small cell carcinoma.

CT bronchus sign in malignant solitary pulmonary lesions: value in the prediction of cell type.

The aim of this study was to evaluate differences in the prevalence of patterns of CT bronchus sign in malignant solitary pulmonary lesions (SPLs), according to their histologic cell types and with respect to size, location, and degree of cell differentiation. Computed tomography scans of 78 patients, in whom pathologically confirmed malignant SPLs with CT bronchus sign were present, were randomly selected and reviewed by two radiologists under consensus. All 78 were CT scans done using spiral technique with 10-mm collimation and 10-mm reconstruction intervals with enhancement, and 75 included additional high-resolution CT scans. Lesions were classified into four cell types as squamous cell carcinoma (n = 24), small cell carcinoma (n = 12), adenocarcinoma (n = 23), bronchioloalveolar carcinoma (BAC; n = 9), and others (n = 12), into three degrees of differentiation, into three size groups, and according to location (central or peripheral). Patterns of CT bronchus sign were classified into abruptly obstructing (I), patent (II), displacing (III), or tapered narrowing (IV) types. The relationships between the patterns of CT bronchus sign and cell type and degree of cell differentiation were evaluated. Eighty patterns of CT bronchus sign were observed in 78 patients. According to cell type, squamous cell carcinoma showed most often type-I pattern (45.8%) but no type-II pattern, which was the most common pattern observed in BAC (77.8%) and adenocarcinoma (34.8%; p<0.01). Small cell carcinoma showed a varied distribution among the four patterns of CT bronchus sign. According to location, in central squamous cell carcinomas, type-I pattern was more common(55%; p<0.01). Bronchioloalveolar carcinoma showed more peripheral lesions and in both central and peripheral lesions, type-II pattern was significantly more common (100 and 66.7%; p<0.01). In SPLs with CT bronchus sign of obstructing pattern, especially if central location, squamous cell carcinoma should be suspected, whereas in SPLs with patent CT bronchus sign, regardless of the location, the strong possibility of BAC should be considered.

CT findings in malignant tumors of thymic epithelium.

OBJECTIVE: Differentiation of invasive thymoma from thymic carcinoma is important because of their different clinical behaviors. Retrospectively, we evaluated the CT findings of invasive thymomas and thymic carcinomas to determine the differential points between them. MATERIALS AND METHODS: We reviewed the CT scans of 12 patients with invasive thymoma and 10 patients with thymic carcinoma that were confirmed by surgery or percutaneous needle aspiration. We analyzed CT scans, paying special attention to homogeneity, attenuation, invasion of adjacent mediastinal structures, pleural implants, mediastinal nodes, and extramediastinal metastases. RESULTS: Most of the invasive thymomas and thymic carcinomas were homogeneous and isodense with chest wall muscle. Irregular infiltration into the adjacent organ suggesting invasion was seen in 11 patients (92%) with invasive thymoma and 8 patients (80%) with thymic carcinoma. Pleural implants were observed in four patients (33%) with invasive thymoma and one patient (10%) with thymic carcinoma. Mediastinal lymphadenopathy was seen in one patient (8%) with invasive thymoma and four patients (40%) with thymic carcinoma. Metastases to the lung, adrenal glands, or liver were observed in four patients (40%) with thymic carcinoma but none with invasive thymoma. CONCLUSION: Despite the similarities of CT findings between invasive thymoma and thymic carcinoma, there are some differential points. Thymic carcinomas were infiltrating tumor and were more commonly associated with mediastinal nodes and extrathymic metastases, but less commonly associated with pleural implants than invasive thymoma.

Thoracic manifestations of Behçet syndrome: radiographic and CT findings in nine patients.

PURPOSE: To evaluate the radiographic and computed tomographic (CT) findings of patients with thoracic Behçet syndrome. MATERIALS AND METHODS: Chest radiographs and CT scans of nine patients with thoracic Behçet syndrome were retrospectively reviewed. Findings were compared. RESULTS: Radiographs of the nine patients showed mediastinal widening in five (56%), air-space consolidation in five (56%), and lung mass in three (33%). CT scans of the nine patients showed that mediastinal widening was due to thrombosis in four (44%) or narrowing of the superior vena cava in one [11%], which caused mediastinal edema; that air-space consolidation (seen on both radiographs and CT scans) was due to pulmonary hemorrhage or infarction in five (56%); and that lung mass was due to aneurysm of the right or left pulmonary artery in three (33%). In addition, CT scans showed hyperinflation in one patient. CONCLUSION: Chest radiographic findings of thoracic Behçet syndrome are variable and nonspecific. CT can be helpful in the assessment of the syndrome by showing thrombosis of the superior vena cava and characteristic aneurysms of the pulmonary arteries.

High-resolution CT appearance of miliary tuberculosis.

OBJECTIVE: The purpose of this study was to define the range of abnormalities and to assess the contribution of high-resolution CT (HRCT) in the evaluation of miliary tuberculosis involving the lung parenchyma. MATERIALS AND METHODS: The authors retrospectively reviewed HRCT scans of 11 patients with microbiologically or clinically proved miliary tuberculosis. RESULTS: In 10 patients, the most characteristic HRCT finding of miliary tuberculosis was the presence of small nodules uniformly distributed throughout both lungs. The profusion of nodules was numerous in all 10 patients. High-resolution CT scans showed both sharply and poorly defined, small nodules varying in sizes from 1 to 2 mm (n = 6), 1 to 3 mm (n = 2), and 1 to 4 mm (n = 2) in diameter. These nodules had a diffuse random distribution in the secondary lobule in all 10 patients. In 1 of the 10 patients with small nodules on HRCT, chest radiography had shown no evidence of miliary nodules in the lung. In addition to nodules, HRCT showed diffuse or localized reticular opacities superimposed on nodules in five patients, especially in the lower lung zones. In 1 of all 11 patients, ground-glass attenuation was the predominant abnormality seen on HRCT. CONCLUSION: We believe that in the appropriate clinical situation, miliary tuberculosis may be suggested on HRCT. Moreover, in cases with no evidence of miliary nodules on the chest radiograph, HRCT scan may depict miliary nodules in the lung parenchyma.

Scanning electron microscopic observations of Thelazia callipaeda from human.

Four females and a male nematode isolated from 2 patients who visited eye clinics in Seoul were identified as Thelazia callipaeda and their ultrastructures were observed by scanning electron microscopy (SEM). General features of the worms were slender and attenuated at both ends. Vaginal opening was located at 0.27 mm from the anterior end, and in front of the esophago-intestinal junction. In the body cuticle transverse striations varied characteristically through the body. The number of cuticular transverse striations was 400-650/mm at head portion, 250/mm at middle portion and 300-350/mm at tail portion. The SEM observation of the mouth part of the females showed 6 cord-like cuticular thickenings in hexagonal arrangement and an amphid was observed. A lateral line, a vaginal opening, a pair of phasmids, and an anus were identified in the body portion. A pair of papillae and 6 cord-like cuticular thickenings were on the mouth part of the male. It was difficult to observe structures at the tail of the male except wrinkle-like structures. Most of the larvae isolated from the uterus of a female worm were sheathed and thus cuticular striations were not seen. Others were un-sheathed and revealed cuticular striations. The oval membrane which encysted sheathed larvae was also observed. These are the 18th and 19th record of human thelaziasis in Korea as the literature are concerned.