title: Focal airtrapping at expiratory high-resolution CT: comparison with pulmonary function tests.
abstract: This study was undertaken to determine prevalence, extent, and severity of focal airtrapping at expiratory high-resolution CT, and to compare focal airtrapping with age, gender, pulmonary function tests, and blood gas analysis. Two-hundred seventeen patients with and without pulmonary disease underwent paired inspiratory/expiratory high-resolution CT. Six scan pairs with corresponding scan levels were visually assessed for focal--not diffuse--airtrapping using a four-point scale. Pulmonary function tests and blood gas analysis were available for correlation in all patients (mean interval 5 days). Focal airtrapping with lower lung predominance was observed in 80% of patients. Twenty-six of 26 patients with restrictive lung function impairment exhibited focal airtrapping (mean score 2.4), whereas only 72 of 98 (74%) patients with obstruction did (mean score 1.5; p < 0.05). Fifty-eight of 70 (83%) patients with normal lung function (mean score 1.8) and 19 of 23 (83%) patients with mixed impairment (mean score 1.8) had focal airtrapping. Focal airtrapping showed negative correlations with static lung volumes (-0.27 to -0.37; p < 0.001) in all patients and moderate positive correlations with dynamic parameters (0.3-0.4; p < 0.001) in patients with obstruction. No significant correlations were found with age, gender, and blood gas analysis. Visual assessment of focal--not diffuse--airtrapping at expiratory high-resolution CT does not correlate with physiological evidence of obstruction as derived from pulmonary function tests since the perception of focal airtrapping requires an adequate expiratory increase in lung density.
authors.affiliation: Department of Radiology, Johannes Gutenberg-Universität Mainz, Germany.
authors.forename: H U
authors.initials: HU
authors.lastname: Kauczor
authors.forename: J
authors.initials: J
authors.lastname: Hast
authors.forename: C P
authors.initials: CP
authors.lastname: Heussel
authors.forename: J
authors.initials: J
authors.lastname: Schlegel
authors.forename: P
authors.initials: P
authors.lastname: Mildenberger
authors.forename: M
authors.initials: M
authors.lastname: Thelen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D001784:Blood Gas Analysis; D005260:Female; D006801:Humans; D008171:Lung Diseases / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012119:Respiration; D012129:Respiratory Function Tests / Q000379:methods; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed / Q000379:methods*