Functional significance of the decreased attenuation sign on expiratory CT in pulmonary sarcoidosis : report of four cases

Radiographic and Histopathologic Features in Sarcoidosis: A Pictorial Display

Sarcoidosis is a multisystemic granulomatous disorder that can affect virtually any organ. However, pulmonary and thoracic lymph node involvement predominates; abnormalities on chest radiographs are present in 80 to 90% of patients with sarcoidosis. High-resolution computed tomographic (HRCT) scans are superior to chest X-rays in assessing extent of disease, and some CT features may discriminate an active inflammatory component (which may be amenable to therapy) from fibrosis (for which therapy is not indicated). Typical findings on HRCT include micronodules, perilymphatic and bronchocentric distribution, perihilar opacities, and varying degrees of fibrosis. Less common findings on CT include mass-like or alveolar opacities, miliary opacities, mosaic attenuation, honeycomb cysts, and cavitation. With progressive disease, fibrosis, architectural distortion, upper lobe volume loss with hilar retraction, coarse linear bands, cysts, and bullae may be observed. We discuss the salient CT findings in patients with sarcoidosis (with a major focus on pulmonary features) and present classical radiographic and histopathological images of a few extrapulmonary sites.

Chest Computed Tomography-Based Scoring of Thoracic Sarcoidosis: Inter-rater Reliability of CT Abnormalities

PURPOSE

To determine inter-rater reliability of sarcoidosis-related computed tomography (CT) findings that can be used for scoring of thoracic sarcoidosis.

MATERIALS AND METHODS

CT images of 51 patients with sarcoidosis were scored by five chest radiologists for various abnormal CT findings (22 in total) encountered in thoracic sarcoidosis. Using intra-class correlation coefficient (ICC) analysis, inter-rater reliability was analysed and reported according to the Guidelines for Reporting Reliability and Agreement Studies (GRRAS) criteria. A pre-specified sub-analysis was performed to investigate the effect of training. Scoring was trained in a distinct set of 15 scans in which all abnormal CT findings were represented.

RESULTS

Median age of the 51 patients (36 men, 70%) was 43 years (range 26 - 64 years). All radiographic stages were present in this group. ICC ranged from 0.91 for honeycombing to 0.11 for nodular margin (sharp versus ill-defined). The ICC was above 0.60 in 13 of the 22 abnormal findings. Sub-analysis for the best-trained observers demonstrated an ICC improvement for all abnormal findings and values above 0.60 for 16 of the 22 abnormalities.

CONCLUSIONS

In our cohort, reliability between raters was acceptable for 16 thoracic sarcoidosis-related abnormal CT findings.

KEY POINTS

• Thoracic sarcoidosis is common; knowledge on reliability of CT scoring is limited. • Scoring CT abnormalities in pulmonary sarcoidosis can achieve good inter-rater agreement. • CT scoring validation in thoracic sarcoidosis is important for diagnostic and prognostic studies.

Pulmonary sarcoidosis: comparison of findings of inspiratory and expiratory high-resolution CT and pulmonary function tests between smokers and nonsmokers

OBJECTIVE

The purpose of our study was to compare the high-resolution CT and pulmonary function test findings of smokers and nonsmokers with pulmonary sarcoidosis.

MATERIALS AND METHODS

Full inspiratory and expiratory high-resolution CT of the thorax and pulmonary function tests were performed in 46 patients (23 smokers and 23 lifelong nonsmokers) with histologically proven sarcoidosis. The median interval between high-resolution CT and pulmonary function tests was 8 days (range, 0-27 days). High-resolution CT findings were categorized into six patterns, and the overall extent of each pattern was scored independently (high-resolution CT score). Correlation between each high-resolution CT score with each pulmonary functional parameter was performed using Spearman's rank correlation and stepwise multiple regression analysis.

RESULTS

Air trapping on expiration (45/46 patients, 98%) and small nodules on inspiration (all 46 patients, 100%) were the most common findings. Smokers had a greater extent of emphysema than nonsmokers (p = 0.002). No significant difference was seen in the extent of air trapping, consolidation, ground-glass attenuation, reticular opacities, or small nodules between smokers and nonsmokers. On Spearman's rank correlation, the extent of air trapping negatively correlated with forced vital capacity in smokers (p < 0.05) but not in nonsmokers. The extent of small nodules negatively correlated with forced vital capacity and positively correlated with the ratio of forced expiratory volume in 1 sec to forced vital capacity in nonsmokers (p < 0.05, both) but not in smokers, respectively. On stepwise multiple regression analysis, the extent of air trapping on CT was independently associated with decreased forced vital capacity (p < 0.05), and cigarette smoking was the main determinant of decrease in maximum midexpiratory flow and forced expiratory flow at 50% of vital capacity (p < 0.01).

CONCLUSION

Cigarette smoking confounds the correlation between the CT and pulmonary function test findings in patients with sarcoidosis. Therefore, smoking history must be taken into account when correlating the extent of parenchymal sarcoidosis on CT with functional impairment.

Obstructive sarcoidosis

Sarcoidosis is a systemic granulomatous disease that frequently involves the lung. Although classically thought of as a restrictive lung disease, airway obstruction has become a recognized feature of the disease in the past years. Sarcoidosis can affect the airway at any level and when the involvement includes small airways, it can resemble more common obstructive airway diseases, such as asthma and chronic bronchitis. Pulmonary function testing and high-resolution computerized tomography of the chest are two important tools to evaluate the presence and extent of airway obstruction in sarcoidosis. Pharmacologic options for the treatment of obstructive sarcoidosis are, in large part, not supported by large, randomized clinical trials. In severe cases of bronchostenosis owing to sarcoidosis granuloma or extrinsic compression from intrathoracic lymphadenopathy, interventional bronchoscopy has successfully been performed, although repeated procedures are usually required. Lung transplantation is an ultimate option in selected patients with late-stage fibrotic disease.

Pharmacotherapeutic management of pulmonary sarcoidosis

Corticosteroids are the mainstay of treatment for sarcoidosis. Although the indications for medical therapy of sarcoidosis are controversial, standard therapy for symptomatic, progressive disease consists of corticosteroids. The British Thoracic Society concluded, with respect to systemic corticosteroids for the treatment of sarcoidosis, that some patients required no treatment, some required prednisone for control of symptoms, and others, with persistent disease, appeared to benefit from long-term corticosteroid therapy. Inhaled budesonide can be an effective treatment for lung sarcoidosis, with few adverse effects, when used in combination with oral systemic corticosteroids such as deflazacort administered in a tapered regimen for 6 months. A randomized controlled trial has also demonstrated the efficacy of 3 months of treatment with oral prednisolone in a tapered regimen followed by inhaled budesonide for 15 months in patients with early stage pulmonary sarcoidosis.Alternative drugs are required in chronic resistant sarcoidosis and/or in conditions where systemic corticosteroids are contraindicated. Immunosuppressive agents (chlorambucil, cyclophosphamide, methotrexate, cyclosporine, azathioprine), anticytokine agents (thalidomide, pentoxifylline), antimalarials (chloroquine, hydroxychloroquine), melatonin and monoclonal antibody (infliximab) have been used in such situations. Chlorambucil and cyclophosphamide have been used in anecdotal cases of pulmonary sarcoidosis as corticosteroid-sparing agents. However, their toxicity and neoplastic potential recommend prudence in patient selection. A comparison between combination therapy with cyclosporine and prednisone and prednisone alone has shown an increased prevalence of serious adverse effects with combined therapy with no between-group differences in treatment efficacy. The cost and toxicity of cyclosporine limit its use to patients in whom its efficacy has been proven. In patients with chronic or refractory disease, methotrexate, usually administered once a week as a single oral dose for at least 2 years, has resulted in a significant improvement in respiratory function, chest radiographs and extrapulmonary manifestations. In most patients, this treatment enabled discontinuation of corticosteroids. Azathioprine may be effective as a corticosteroid-sparing agent in the long-term treatment of sarcoidosis. The combination of prednisolone and azathioprine over a period of 2 years has induced long-lasting remission in patients with resistant sarcoidosis. Thalidomide at low doses is effective in selected cases of sarcoidosis with cutaneous and mild pulmonary involvement. Pentoxifylline alone or combined with low doses of corticosteroids has achieved significant improvement in respiratory function in patients with pulmonary sarcoidosis. Chloroquine and hydroxychloroquine have been shown to have a specific effect in cutaneous manifestations, neurological involvement and hypercalcemia associated with sarcoidosis. Infliximab has yielded good results in patients with chronic resistant pulmonary and extrapulmonary sarcoidosis resistant to corticosteroid and cytotoxic therapy. The effectiveness of melatonin in cutaneous and pulmonary sarcoidosis has also been confirmed in a single center.

Sarcoidosis: assessment of disease severity using HRCT

The value of high-resolution computed tomography (HRCT) in diagnosing and assessing inflammatory activity in sarcoidosis is well established. The aim of the present study was to address the intra- and inter-observer agreements of the HRCT score by Oberstein et al. [8], and to evaluate the relationship between HRCT findings and disease severity expressed in respiratory functional impairment in sarcoidosis. The clinical records of 80 known sarcoidosis patients visiting the outpatient clinic between January 2000 and August 2001, who underwent a HRCT as well as lung function tests (including exercise testing), were reviewed. Two readers scored the first 60 HRCT images twice. Weighted kappa and intra-class correlation coefficient were used to assess the reliability of the HRCT scoring system. Spearman's rank correlation coefficients and multiple regression analyses were performed to evaluate the relationship between HRCT findings (first reading, reader A) and respiratory functional impairment. Intra- and inter-reader reliability demonstrated good agreement. All HRCT subscores, except enlargement of lymph nodes, were correlated to the FEV(1), FVC, DLco, Pao(2)max (all p<0.05) and A-aPo(2 )max ( p<0.001). Furthermore, HRCT abnormalities, but not the chest radiographic stage, were strongly associated with functional parameters. Abnormal changes of lung parenchyma, established by HRCT features, were associated with respiratory functional impairment in sarcoidosis. Moreover, compared with the radiographic stages, HRCT findings appeared to be much more sensitive in depicting respiratory disability, especially abnormal gas exchange.