Value of HRCT of the chest in evaluation of ankylosing spondylitis: correlation between pleuro-parenchymal abnormalities and disease activity

Abstract

Background Ankylosing spondylitis (AS) is a chronic inflammatory disorder primarily involving the sacroiliac joints and spine. It is associated with both articular and extra-articular clinical manifestations. Pulmonary involvement is a well-recognized comorbidity of AS, even among patients with early disease. The availability of high-resolution computed tomography (HRCT) has enabled better visualization of the entire lung parenchyma and earlier identification of lung pathologies, ranging from mild to more severe involvement, which were previously missed on X-rays. The aim of the study is to establish the role of HRCT in the detection of pleuro-parenchymal manifestations of AS and to look for correlations between these findings and AS activity. Results Lung CT scans were done for all our patients and 27 patients (90%) had positive HRCT thoracic findings, while the remaining 3 patients (10%) had a normal HRCT thoracic study. Lower lobe fibrotic changes were the most common finding seen in 20 patients (66.7%) followed by bronchial wall thickening in 13 patients (43.3%) and upper and lower fibrotic changes seen in 9 patients (30%). HRCT thoracic findings were more prominent in late AS (disease duration ≥ 10 years) (13 of 13 patients); while 14 of 17 patients with early AS (disease duration < 10 years) had mildly abnormal HRCT findings. The result of statistical analysis showed that there was negative correlation between thoracic findings and disease activity assessed by BASDAI and this correlation was insignificant (p value = 0.5). Conclusion HRCT offers an accurate and safe method of assessment of lung disease in patients with AS and without respiratory symptoms. Although there was no correlation between pulmonary findings and AS activity assessed by BASDAI, a positive correlation, albeit insignificant, between pulmonary involvement and disease duration had been found.