High Resolution Computed Tomography in Asthma

Abstract

High-resolution computed tomography (HRCT) can detect the structural abnormalities in asthma. This study attempts to correlate these abnormalities with clinical and pulmonary function test (PFT) data. Consecutive stable asthma patients attending Mubarak Al Kabeer Hospital, Kuwait, were subjected to HRCT during a six month period from July 2004 to December 2004, after initial evaluation and PFT. Of the 28 cases, sixteen (57.1%) had moderate, 6 (21.4%) had mild and 6 (21.4%) had severe persistent asthma. Thirteen (46.4%) patients had asthma for 1 to 5 years and 12 (42.9%) were having asthma for >10 years. Bronchial wall thickening (57.1%), bronchiectasis (28.6%), mucoid impaction (17.9%), mosaic attenuation (10.7%), air trapping (78.6%) and plate like atelectasis (21.4%) were noted. Bronchial wall thickening (p=0.044) and bronchiectasis (p=0.063) were most prevalent in males. Ten (35.7%) patients exhibited mild, 9 (32.1%) had moderate and 3 (10.7%) had severe air trapping. The difference in Hounsfield units between expiratory and inspiratory slices (air trapping) when correlated with percent-predicted FEV1 in right upper (r=0.25; p=0.30), left upper (r=0.20; p=0.41), right mid (r=0.15; p=0.53), left mid (r=-0.04; p=0.60), right lower (r=0.04; p=0.86) and left lower zones (r=-0.13; p=0.58) showed no relation. The same when correlated as above with the percent predicted FEF 25-75 did not show any significant association. The presence of air trapping was compared with sex (p=0.640), nationality (p=1.000), disease duration (p=1.000) and severity of symptoms (p=0.581). Abnormal HRCT findings are common in asthma; however, air trapping when present was not related to the duration or severity of the illness or to the FEV1.