Spirometry-Assisted HRCT in children: Is it worth the effort?

Publication date: Available online 7 April 2017
Source:Current Problems in Diagnostic Radiology
Author(s): Jeffrey Parke Otjen, Jonathan Ogden Swanson, Assaf Oron, Robert M. DiBlasi, Tim Swortzel, Jade Adriana Marie van Well, Eva Anna Elisabeth Gommers, Margaret Rosenfeld
BackgroundImage quality of high resolution chest CTs (HRCTs) depends on adequate breath holds at end-inspiration and end-expiration. We hypothesized that implementation of spirometry-assisted breath holds in children undergoing HRCTs would improve image quality over that obtained with voluntary breath holds by decreasing motion artifact and atelectasis.MethodsThis is a retrospective case-control study of HRCTs obtained at a tertiary care children′s hospital before and after implementation of a spirometry assisted CT protocol, in which children > 8 years of age are first trained in supine slow vital capacity maneuvers and then repeat the maneuvers in the CT scanner, coached by a respiratory therapist. Spirometry-assisted CT scans (cases) were matched by age, gender and diagnosis (cystic fibrosis vs. other) to CT scans obtained with voluntary breath holds in the 6 years prior to implementation of the spirometry assistance protocol (controls), and evaluated by two blinded pediatric radiologists.ResultsAmong both cases and controls (N=50 each), 10 carried the diagnosis of cystic fibrosis and 40 had other diagnoses. Mean age was 12.9 years (range 7.5, 20.1) among cases and 13.0 (7.1, 19.7) among controls. Mean (SD) inspiratory image density among cases was -852 (37) Hounsfield units (HU) and -828 (43) among controls (p=0.006). Mean (SD) expiratory image density was -629 (95) HU among cases and -688 (83) HU among controls (p=0.002). Mean (SD) change in image density between inspiratory and expiratory images was +222 (85) HU among cases and +140 (76) HU among controls (p<0.001). Motion artifact was present on inspiratory images in 5 cases and 9 controls (p=0.39 by Fisher′s exact test), and on expiratory images in 20 cases and 18 controls (p>0.80). Atelectasis was present on inspiratory images in 8 cases and 9 controls and on expiratory images in 9 cases and 10 controls (p>0.80).ConclusionsSpirometry assisted CTs had a significantly greater difference in lung density between inspiratory and expiratory scans than those performed with voluntary breath holds, likely improving the ability to detect air trapping. No appreciable difference in image quality was detected in terms of presence of motion artifact or atelectasis.



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