弥漫性泛细支气管炎

探讨弥漫性泛细支气管炎（ＤＰＢ）的临床与影像学表现,以提高对本病的认识。材料与方法,对２例经病理证实并有完整的临床,实验室及肺功能检查,以及胸片及高辨率ＣＴ（ＨＲＣＴ）检查的弥漫性泛细支气 进行回顾分析。结果２例临床表现为咳嗽,咯痰及活动后气短。胸片示两肺弥漫性分布的小结节影及肺过度充气膨胀并两下支气管扩张,ＨＲＣＴ像上;①肺小叶中心性小结中节影;②小支气管和细支气管扩张;③支气管壁增厚。同时伴有     

Radiology of epidemic adenovirus 21 infection of the lower respiratory tract in infants and young children.

The radiologic features of 18 children admitted to Princess Mary Hospital, Auckland, New Zealand, in the winter and spring of 1977 with adenovirus 21 infection are reported. Attention is drawn to the severity of the disease in the respiratory tract, manifest radiologically as widespread patchy or confluent pulmonary opacification, extensive bronchial wall thickening, or peribronchial linear opacities. No hilar adenopathy was present. Prominent residual bronchopulmonary abnormalities were present in 13 of 15 patients 6--12 months after epidemic. High kilovoltage chester radiography or bronchography demonstrated bronchiectasis in five patients. These findings emphasize the role of adenovirus as a cause of chronic pulmonary disease and bronchiectasis in children.     

High-resolution CT quantification of bronchiectasis: clinical and functional correlation

PURPOSE: To evaluate clinical relevance of high-resolution computed tomographic (CT) findings in patients with bronchiectasis by using a quantitative high-resolution CT protocol to assess extent of bronchiectasis, severity of bronchial wall thickening, and presence of small-airway abnormalities and mosaic pattern. MATERIALS AND METHODS: Sixty Chinese patients with steady-state bronchiectasis underwent thoracic high-resolution CT and lung function tests. Exacerbation frequency per year and 24-hour sputum volume were determined. Extent of bronchiectasis, severity of bronchial wall thickening, and presence of small-airway abnormalities and mosaic attenuation were evaluated in each lobe, including the lingula. Differences between sex and smoking status with respect to high-resolution CT, lung function, and clinical parameters were tested with either the independent sample t test or the Mann-Whitney test. Spearman rank correlation was used to evaluate associations between clinical, lung function, and high-resolution CT scores. Multiple regression analyses were performed to determine which high-resolution CT parameters would best predict lung function and clinical parameters, adjusted for smoking. RESULTS: Exacerbation frequency was associated with bronchial wall thickening (r = 0.32, P =.03); 24-hour sputum volume with bronchial wall thickening and small-airway abnormalities (r = 0.30 and 0.39, respectively; P <.05); and forced expiratory volume in 1 second (FEV(1)), ratio of FEV(1) to forced vital capacity (FVC), and midexpiratory phase of forced expiratory flow (FEF(25%-75%)) (r = -0.33, -0.29, and -0.32, respectively; P <.05). Extent of bronchiectasis, bronchial wall thickening, and mosaic attenuation, respectively, were related to FEV(1) (r = -0.43 to -0.60, P <.001), FEF(25%-75%) (r = -0.38 to -0.57, P <.001), FVC (r = -0.36 to -0.46, P <.01), and FEV(1)/FVC ratio (r = -0.31 to -0.49, P <.01). After multiple regression analysis, bronchial wall thickening remained a significant determinant of airflow obstruction, whereas small-airway abnormalities remained associated with 24-hour sputum volume. Women had milder disease than men but showed more high-resolution CT functional correlations. CONCLUSION: Findings of this study establish a link between morphologic high-resolution CT parameters and clinical activity and emphasize the role of bronchial wall thickening in patients with bronchiectasis. Copyright RSNA, 2002     

Kartagener syndrome

Kartagener syndrome (KS), an autosomal recessively inherited disease, is characterized by the triad of situs inversus, bronchiectasis and sinusitis. This disorder affects the activity of proteins important to the movement of cilia, especially in the respiratory tract and the spermatozoa, developing a series of systemic alterations, which can be diagnosed through radiographic examination. The aim of this paper is to describe a clinical case of this unusual pathology, including a brief literature review, emphasising the radiographic aspects of this pathology and stressing the importance of early diagnosis, which could be determined by an oral radiologist.     

CT findings of pulmonary tuberculosis presenting as segmental consolidation.

PURPOSE: The purpose of our study was to determine specific CT findings of tuberculous pneumonia presenting as segmental or lobar consolidation along with a pathologic review of specimens with similar radiographic patterns. METHOD: CT findings of 45 cases of proven tuberculous pneumonia and 21 proven nontuberculous pneumonia were compared. Pathologic findings of five surgically resected tuberculous pneumonia cases were also investigated. The presence of fluid bronchogram (linear, branching shadow of fluid attenuation) and inner low attenuation/cavitation in the area of consolidation, luminal dilatation, and wall thickening of proximal bronchi were the main points sought on CT scan. In addition, the presence of bronchogenic dissemination, lymph node enlargement, and pleural lesions was also checked for in the unaffected area of both lungs. RESULTS: The following bronchial changes were seen in the tuberculous pneumonia and nontuberculous pneumonia groups, respectively: fluid bronchogram in 68.9 and 23.8% (p < 0.05), bronchial luminal dilatation in 60.0 and 23.8% (p < 0.05), and bronchial wall thickening of the proximal airway leading to the area of consolidation in 52.8 and 7% (p < 0.05). Bronchogenic dissemination outside the consolidation appeared in 88.9 and 52.4% (p < 0.05), respectively. In the tuberculous pneumonia group, lymph node enlargement and pleural reaction were seen in 55.6 and 35.6%, respectively, but in 42.9 and 57.1% in the nontuberculous pneumonia group (p > 0.05). Histologically, tuberculous pneumonia showed either bronchioles containing inflammatory exudates and submucosal granuloma or alveoli containing aggregates of alveolar macrophages or cellular debris. CONCLUSION: Fluid bronchogram in the area of homogeneous consolidation, bronchial luminal dilatation, and bronchial wall thickening of the proximal airway were the bronchial changes more significantly prominent in the tuberculous pneumonia group. We suspect that these findings may represent tuberculous bronchitis in small airways.     

Serial high resolution CT findings in nonspecific interstitial pneumonia/fibrosis

PURPOSE: The purpose of this work was to evaluate the radiographic and serial high resolution CT (HRCT) findings in patients with nonspecific interstitial pneumonia/ fibrosis (NSIP). METHOD: We identified 15 patients with biopsy-proven NSIP. Radiography and initial and follow-up CT findings were reviewed. RESULTS: Predominant radiographic findings were bilateral infiltrates distributing in the middle and lower lung zones and decreased lung volumes. At initial CT, predominant patterns were peribronchovascular interstitial thickening (n = 6), parenchymal bands (n = 8), intralobular interstitial thickening (n = 12), and traction bronchiectasis (n = 14). Mixed pattern of ground-glass opacity and consolidation (n = 11) were predominant findings of increased lung opacity. At follow-up CT in 14 cases, the abnormalities had disappeared completely in 3, improved in 9, persisted in 1, and worsened in 1. CONCLUSION: The pulmonary abnormalities observed in NSIP on HRCT can disappear or be diminished in most cases after corticosteroid therapy. Intralobular interstitial thickening and traction bronchiectasis, which have been considered to be indicators of irreversible fibrosis, also show favorable responses.     

Superficial Endobronchial Lung Cancer: Radiologic-Pathologic Correlation

Objective

To analyze the plain chest radiographic and CT findings of superficial endobronchial lung cancer and to correlate these with the findings of histopathology.

Materials and Methods

This study involved 19 consecutive patients with pathologically proven lung cancer confined to the bronchial wall. Chest radiographs and CT scans were reviewed for the presence of parenchymal abnormalities, endobronchial nodules, bronchial obstruction, and bronchial wall thickening and stenosis. The CT and histopathologic findings were compared.

Results

Sixteen of the 19 patients had abnormal chest radiographic findings, while in 15 (79%), CT revealed bronchial abnormalities: an endobronchial nodule in seven, bronchial obstruction in five, and bronchial wall thickening and stenosis in three. Histopathologically, the lesions appeared as endobronchial nodules in 11 patients, irregular thickening of the bronchial wall in six, elevated mucosa in one, and carcinoma in situ in one.

Conclusion

CT helps detect superficial endobronchial lung cancer in 79% of these patients, though there is some disagreement between the CT findings and the pathologic pattern of bronchial lesions. Although nonspecific, findings of bronchial obstruction or bronchial wall thickening and stenosis should not be overlooked, and if clinically necessary, bronchoscopy should be performed.     

Bronchiectasis in hypogammaglobulinaemia--a computed tomography assessment

To determine the pattern of bronchiectasis in hypogammaglobulinaemia we reviewed the CT scans of 38 hypogammaglobulinaemic patients. Twenty-two had bronchiectasis, seven had bronchial wall thickening without bronchiectasis and the remaining nine were normal. The middle lobe was the most common site of bronchiectatic involvement, followed by the lower lobes and the lingula. There were no cases of isolated upper lobe involvement. In patients who had bronchial wall thickening without bronchiectasis the middle lobe and lower lobes were again most commonly affected. It is postulated that in these hypogammaglobulinaemic patients bronchial wall thickening represents a stage of bronchial inflammation prior to the development of bronchiectasis. Patients with X-linked agammaglobulinaemia (XLA) develop bronchiectasis at a significantly earlier age than those with 'common variable' hypogammaglobulinaemia (CVH) (P = 0.02). No correlation was found between the serum levels of immunoglobulin classes at diagnosis and the subsequent development of bronchiectasis.     

Amyloidosis and lymphoproliferative disease in Sjögren syndrome: thin-section computed tomography findings and histopathologic comparisons

OBJECTIVE: To describe the thin-section computed tomography (CT) findings of Sjogren syndrome accompanying pulmonary amyloidosis and lymphoproliferative disease and to compare these with histopathologic findings. SUBJECTS AND METHODS: The thin-section CT findings of 5 women (age range: 42-59 years, mean age=50 years) with primary Sjogren syndrome accompanying pulmonary amyloidosis and lymphoproliferative disease were reviewed retrospectively by 2 chest radiologists, and decisions on findings were reached by consensus. The pathologic specimens of parenchymal lesions (nodules, dense consolidation, and cystic lesion at CT) obtained using video-assisted thoracoscopic surgery were studied to compare with the thin-section CT findings. RESULTS: Nodules, observed in all 5 patients, were variable in size and ranged from 3 to 24 mm (mean=9.9 mm) in diameter, with lobulated or irregular margins. Nodular calcifications were present in 3 patients. Cysts, which also were observed in all patients, ranged from 4 to 45 mm (mean=18.6 mm) in diameter, with a thin (1-2 mm) or no visible wall. Multiple cysts were observed, especially in the distal portion of narrowed bronchioles. Nodules and cysts showed a random distribution. Mild bronchial wall thickening with bronchial dilatation was seen in all patients, ground-glass opacities were seen in 3, and consolidation was seen in 1. Nodules, consolidation, and bronchial wall thickening at CT were caused histopathologically by the interstitial and peribronchiolar deposition of mixed amyloid and lymphoproliferative cells. Cysts lined with respiratory epithelium contained amyloid deposition and lymphoproliferative cells in their walls. CONCLUSION: Sjogren syndrome accompanying pulmonary amyloidosis and lymphoproliferative disease manifests as multiple, large, thin-walled cysts; multiple nodules; parenchymal opacity; and bronchiectasis. These findings are caused by the interstitial or peribronchial infiltration of mixed amyloid and lymphoproliferative cells.     

High-resolution CT in chronic pulmonary changes after mustard gas exposure

PURPOSE: To identify the findings of high-resolution CT (HRCT) of the lung in patients with previous sulfur mustard gas exposure, and to correlate these findings with clinical and chest X-ray (CXR) results. MATERIAL AND METHODS: 50 consecutive patients were studied prospectively. The clinical data were recorded. Standard p.a. CXR and HRCT of the lung and spirometry were performed. The findings of CXR, HRCT and clinical and spirometry results were scored between 0 and 3 according to the severity of the findings. RESULTS: HRCT abnormality was detected in all 50 patients (100%), while CXR was abnormal in 40 patients (80%). The most common HRCT findings was airway abnormalities (bronchial wall thickening in 100% of cases). Other important findings were suggestive of interstitial lung disease (ILD) (80%), bronchiectasis (26%), and emphysema (24%). A statistically significant correlation was found between the severity of clinical presentation and that of the HCTR scores in patients with bronchiectasis, bronchitis and ILD (p< 0.05), but not with severity scores of HRCT in patients with emphysema. No significant correlation was found between severity scores of CXR findings. HRCT evidence of bronchial wall thickening and with a lower frequency ILD were present despite normal CXR in 20% of the patients. CONCLUSION: The results of this study suggest that bronchial wall thickening, ILD and emphysema are common chronic pulmonary sequelae of sulfur mustard injury. HRCT of the chest should be considered as the imaging modality of choice in chemical war injury.     

Detection of bronchiectasis by high-resolution computed tomography in the yellow nail syndrome

High resolution computed tomography of the lungs was performed in three patients with the yellow nail syndrome to detect bronchiectasis. Standard CT was performed in a fourth patient. Evidence of bronchiectasis with bronchial wall thickening and bronchial dilatation was observed in all four patients. High resolution CT is a non-invasive method for detecting and assessing the extent of airway disease in the yellow nail syndrome.     

Congenital bronchial atresia (CBA). A critical review of CBA as a disease entity and presentation of a case series

PURPOSE: To analyse the state of the art of diagnostic imaging in the rare disease entity known as congenital bronchial atresia (CBA) and to suggest new guidelines for diagnosis. MATERIALS AND METHODS: From January 2002 to December 2003 we examined 6 patients, 4 males and 2 females. Four of them complained of relapsing bronchitis; one patient was admitted with a diagnosis of pulmonary abscess. All patients underwent chest X-ray and MDCT. RESULTS: Five patients presented at chest x-ray the typical association of hilar mass and distal parenchymal hyperinflation that raised the suspicion of CBA; the remaining patient presented an area of parenchymal translucency that prompted us to perform MDCT, which showed severe stenosis of the segmental bronchus. CBA involved the left upper lobe (LUL) in 4 patients and the right upper lobe (RUL) in the remaining 2. In 50% of cases there were associated anomalies: distal bronchiectasis, bronchogenic cyst, anomaly of branching of bronchial tree and vascular structure. CONCLUSIONS: CBA is a relatively rare, generally oligosymptomatic malformation. Knowledge of the signs present at chest X-ray can prompt the radiologist to perform a CT scan. MDCT with multiplanar reconstruction is fundamental for the characterisation, localisation and study of the distribution of the lesion, helping to make a precise diagnosis. Surgery is seldom required and at any rate only performed in case of complications.     

弥漫性泛细支气管炎的多层螺旋CT诊断价值

目的:探讨弥漫性泛细支气管炎的临床、病理及多层螺旋CT表现,提高对本病的诊断准确性。方法:回顾性分析17例经临床或病理证实的弥漫性泛细支气管炎患者的临床、病理及多层螺旋CT资料。结果:17例中16例(94.1%)病变呈弥漫性分布,1例(5.9%)呈局限性分布。主要CT表现:①弥漫性小结节影伴树芽征17例(100%);②小支气管扩张16例(94.1%),伴有小支气管壁增厚15例(88.2%),合并有黏液栓3例(17.6%);③炎性斑片状实变影8例(47.0%);④肺间质纤维化3例(17.6%);⑤小空洞2例(11.8%)。有副鼻窦炎病史15例(88.2%),最常累及上颌窦。结论:弥漫性泛细支气管炎的临床表现缺乏特异性,主要MSCT表现为弥漫性小结节影伴树芽征、小支气管扩张及炎性斑片影,结合副鼻窦炎病史有助于鉴别诊断,最终确诊需靠病理学检查。     

High-resolution CT imaging of the lung for patients with primary Sjogren's syndrome

PURPOSE: To assess pulmonary abnormalities in patients with primary Sjogren's syndrome (PSS) using high-resolution computed tomography (HRCT). MATERIAL AND METHODS: The HRCT scans of 24 patients with the diagnosis PSS were retrospectively reviewed regarding the presence, extension and distribution of 16 pathological findings. RESULTS: Nineteen patients (79.2%) showed pathological findings and in five patients (21.8%) the HRCT scan was judged to be normal. A predominance of abnormalities in the lower lobes and subpleural areas was detected. The following pathologies were found: bronchiectasis, thin-walled cysts and small pulmonary nodules (46.2%), ground-glass attenuation and emphysema (37.8%), interlobular-septal thickening (29.4%), honeycombing (25.2%), bronchial wall thickening, tree-in-bud pattern (21.0%), mosaic perfusion (16.8%), architectural distortion (12.6%). Airspace consolidation, air trapping, large nodules (10-30mm) and masses (>30mm), mediastinal lymph node enlargement (>15mm) and free pleural fluid were seen each in 4.2%. In 7 of the 11 patients with thin-walled cysts areas of ground-glass attenuation were detected. CONCLUSION: HRCT seems is contributive to the characterization of the wide variety of lung abnormalities in PSS. Airway disease alone or in association with the presence of varying degrees of interstitial disease represents the main findings in accordance with earlier reports. Unexpectedly, almost half of the patients had thin-walled cysts on the HRCT scans, which etiology is unclear but could be associated with areas of ground-glass attenuation indicating LIP.     

Computed tomography features of primary pulmonary non-Hodgkin's lymphoma.

AIM: To characterize computed tomography (CT) features of primary pulmonary lymphoma (PPL). METHODS: The CT films of six patients (five men, one woman; 63.2 +/- 14.5 years) with low grade non-Hodgkins PPL were evaluated for alveolar opacities (lobar consolidation, masses or nodules, and ill-defined consolidations), peribronchial disease or bronchial wall thickening, mediastinal nodes and pleural effusion. RESULTS: Multilobar bilateral, multilobar unilateral, and unilobar unilateral involvement were present in three, one and two cases respectively. CT features were: ill-defined mainly subpleural consolidations (n = 4), mass-like consolidation (n = 1), lobar consolidation (n = 1), and pleural effusion (n = 1). Minor peribronchial disease was seen in two patients, heterogeneous enhancement in four patients, and CT-angiogram sign in one patient. There were no lymphadenopathy or lung nodules. Although the pleura were inseparable from subpleural disease, pleural enhancement was noted on magnetic resonance imaging (MRI) of a patient with lobar lymphoma. CONCLUSION: PPL is characterized by ill-defined alveolar opacities that are usually multifocal. Peribronchial disease, proximal bronchiectasis and positive CT-angiogram sign are ancillary features. MRI may be useful in further evaluation with respect to pleural or chest wall involvement.     

Spectrum of pulmonary aspergillosis: histologic, clinical, and radiologic findings.

Aspergillosis is a serious pathologic condition caused by Aspergillus organisms and is frequently seen in immunocompromised patients. At computed tomography (CT), saprophytic aspergillosis (aspergilloma) is characterized by a mass with soft-tissue attenuation within a lung cavity. The mass is typically separated from the cavity wall by an airspace ("air crescent" sign) and is often associated with thickening of the wall and adjacent pleura. CT findings in allergic bronchopulmonary aspergillosis consist primarily of mucoid impaction and bronchiectasis involving predominantly the segmental and subsegmental bronchi of the upper lobes. Aspergillus necrotizing bronchitis may manifest as an endobronchial mass, obstructive pneumonitis or collapse, or a hilar mass. Bronchiolitis is characterized by centrilobular nodules and branching linear or nodular areas of increased attenuation ("tree-in-bud" pattern). Obstructing bronchopulmonary aspergillosis mimics allergic bronchopulmonary aspergillosis at CT and manifests as bilateral bronchial and bronchiolar dilatation, large mucoid impactions, and diffuse lower lobe consolidation caused by postobstructive atelectasis. Characteristic CT findings in angioinvasive aspergillosis consist of nodules surrounded by a halo of ground-glass attenuation ("halo sign") or pleura-based, wedge-shaped areas of consolidation. Although imaging findings in pulmonary aspergillosis may be nonspecific, in the appropriate clinical setting, familiarity with the CT findings may suggest or even help establish the diagnosis.     

Primary ciliary dyskinesia in the paediatric population: range and severity of radiological findings in a cohort of patients receiving tertiary care

AIM: To investigate the clinical range and severity of radiological findings in a cohort of patients with primary ciliary dyskinesia (PCD) receiving tertiary care. MATERIALS AND METHODS: The case notes and clinical test results of 89 children attending the paediatric respiratory disease clinic at our institution were retrospectively analysed. Demographic details including age at diagnosis and common presenting signs and symptoms were studied. Results of chest radiographs, microscopy, and high-resolution computed tomography (HRCT) for quantification of lung damage were analysed. RESULTS: In a cohort of 89 children with PCD, a presentation chest radiograph was available in 62% of patients (n=55), with all but one demonstrating changes of bronchial wall thickening. HRCT of the lungs, available in 26 patients, were scored using the system described by Brody et al. analysing five specific features of lung disease, including bronchiectasis, mucus plugging, peribronchial thickening, parenchymal changes of consolidation, and ground-glass density, and focal air-trapping in each lobe. Peribronchial thickening was observed using HRCT in 25 patients, while 20 patients had bronchiectasis. Severity scores were highest for the middle and the lingular lobes. CONCLUSION: The radiographic findings of the largest reported cohort of patients with PCD are presented, with associated clinical findings. Dextrocardia remains the commonest finding on chest radiography. HRCT demonstrates peribronchial thickening and bronchiectasis, which is most marked in the lower zones. Radiological scoring techniques developed for assessment of cystic fibrosis can also be applied for the assessment of disease severity in this patient population.     

Lung parenchymal changes in patients with ankylosing spondylitis

AIM: To assess lung parenchymal changes in ankylosing spondylitis (AS) using high resolution computed tomography (HRCT). METHODS: We included 78 AS patients whose average age was 33.87 (18-56) years with a ratio of 53 males to 25 females who were followed up for 3.88 (1-22) years on average. neumonia and tuberculosis were excluded. In a detailed examination of lung HRCT findings, we investigated the presence of parenchymal micronodules,parenchymal bands, subpleural bands, interlobular and intralobular septal thickening, irregularity of interfaces,ground glass opacity, consolidation, mosaic pattern,bronchial wall thickening, bronchial dilatation, tracheal dilatation, pleural thickening, emphysema, thoracic cage asymmetry, honeycomb appearance, structural distortion, apical fibrosis and other additional findings.RESULTS: In detailed HRCT evaluations, lung parenchymal changes were found in 46 (59%) of all patients. We found parenchymal bands in 21 (27%) cases, interlobular septal thickening in 9 (12%), emphysema in 9 (12%), apical fibrosis in 8 (10%), ground-glass opacities in 7 (9%), parenchymal micronodules in 5 (6%), irregularity in interfaces in 3 (4%), bronchial dilatation in 3 (4%), mosaic pattern in 2 (3%), pleural thickening in 2 (3%), consolidation in 1 (1%), bronchial wall thick ening in 1 (1%) and a subpleural band in 1 (1%) case. Furthermore, we detected subsegmental atelectasis in 2 patients and a cavitary lesion in 1 patient. CONCLUSION: Our study had the highest number of AS cases of all previous studies in evaluating lung paren chymal changes. The rate of lung parenchymal changes was slightly lower than that reported in recent literature.     

Mycobacterium avium complex lung disease in immunocompetent patients: radiography-CT correlation

This study aimed to describe and correlate the chest radiography and CT findings of Mycobacterium avium complex (MAC) lung disease in immunocompetent patients. 26 patients fulfilled The American Thoracic Society criteria for MAC lung disease and underwent chest radiography and CT within 6 weeks of positive cultures. All abnormalities and predominant lobar involvement were recorded and abnormalities on chest radiography were correlated with those on CT. The images were evaluated by two chest radiologists and decisions were reached by consensus. 21 females and 5 males, with an overall mean age of 69 years, were included in the study. All chest radiographs and CT scans were abnormal. On chest radiography, overinflation was demonstrated in 18 patients. CT scan abnormalities included atelectasis (n=17), bronchiectasis (n=24), cavities (n=13), consolidation (n=3), emphysema (n=11), ground-glass opacity (n=8), linear opacities (n=26), mediastinal lymphadenopathy (n=3), nodules (n=25) and pleural disease (n=15). CT findings were at variance with chest radiography findings in 15 lobes. A new feature from this study is that the majority of patients with MAC lung disease demonstrate overinflation on chest radiography. 19% of cases had predominant upper lobe disease, indistinguishable from post-primary Mycobacterium tuberculosis infection. 77% of cases demonstrated the major imaging criteria of MAC lung disease. These are ill defined nodules, bronchiectasis, predominant middle lobe and/or lingular abnormalities, with or without overinflation. We believe that these characteristic radiological signs will assist the physician in the diagnostic work-up of patients with MAC lung disease.