Pediatric Pulmonology 41:1129–1137 (2006) High Resolution Computerized Tomography of the Chest and Pulmonary Function Testing in Evaluating the Effect of Tobramycin Solution for Inhalation in Cystic Fibrosis Patients

To evaluate the sensitivity of high-resolution computerized tomography (HRCT) of the chest compared to spirometry measures in evaluating the effects of tobramycin solution for inhalation (TSI) in cystic fibrosis (CF) patients.Thirty-two subjects 6 years old with mild to moderate CF lung disease were enrolled in a randomized, double-blind, placebo-controlled pilot study. Durationwas 28days; 31 subjects completed the study.HRCTscoresdecreased 4.06 3.20 (mean SD) for TSI and decreased 0.17 1.78 for placebo subjects (P1⁄40.13). Mean forced expiratory flow during middle half of forced vital capacity (FEF25%–75%) predicted increased 6.08 4.86 for TSI and decreased 0.60 2.34 for placebo (P1⁄4 0.23). Percentage forced expiratory volume in 1 s (FEV1) predicted increased slightly for both TSI and placebo (1.29 3.33 for TSI and 1.17 1.4 for placebo) (P1⁄40.97). Two of eight HRCTcomponent scores (atelectasis and inhomogeneity)wereobserved tobehighlydiscordantwith observedHRCTglobal total score and other HRCTcomponent scores. A modified total score was calculated by dropping them from the global total score. The modified HRCT total scores decreased 6.68 3.09 for TSI subjects and increased 0.02 2.0 for the placebo subjects (P1⁄4 0.07). Sample sizes were calculated to showstatistical significance by differences inmodified total HRCTscores, global total HRCTscores, FEF25%–75% predicted or FEV1 % predicted. A total of 60, 100, 200, and over 800 patients would be necessary respectively.HRCT can be a useful measure of change in CF pulmonary disease, requiring a smaller sample size than that required to show treatment effect by pulmonary function testing (PFT) alone. Pediatr Pulmonol. 2006; 41:1129–1137.