The Correlation between HRCT Emphysema Score and Exercise Pulmonary Testing Parameters

Choi, Eun Kyoung; Choi, Yong Hee; Kim, Doh Hyung; Kim, Yong Ho; Yoon, Se Young; Park, Jae Seuk; Kim, Keun Youl; Lee, Kye Young

Abstract

BACKGROUND
The correlation between the high resolution computed tomography(HRCT) emphysema score and the physiologic parameters including resting and exercise pulmonary function test was investingated in 14 patients(60.6±10.3 years) with pulmonary emphysema.
METHODS
The patients underwent a HRCT, a resting pulmonary function test, and incremental exercise testing(cycle ergometer, 10 W/min). Computed tomography scans were obtained on a GE highlight at 10 mm intervals using 10 mm collimation, from the apex to the base after a full inspiration. The emphysema scores wer determined by a CT program 'Density mask' outlining the areas with attenuation values less than -900 HU, indicating the emphysema areas, and providing an overall percentage of lung involvement by emphysema.
RESULTS
Among the resing PFT parameters, only the diffusing capacity(r=-0.75) and PaO2 (r=-0.66) correlated with the emphysema score(p<0.05). Among the exercise test parameers, the emphysema score correlated significantly with the maximum power(r=-0.74), maximum oxygen consumption(r=-0.68), anaerobic threshold(V-slope method : r=-0.69), maximal O2-pulse(r=-0.73), and the physiologic dead space ratio at the maximum workload(r=-0.80)(p<0.01).
CONCLUSION
We could find that exercise testing parameters showed a much better correlation with the HRCT emphysema score, which is known to have a good correlation with the pathologic severity than the resting PFT parameters. Therefore it is suggested that exercise testing is superior to resting PFT for estimating in the estimation of the physiologic disturbance in emphysema patients.