Relapsing Polychondritis: Prevalence of Expiratory CT Airway Abnormalities

Abstract

To retrospectively determine the prevalence of expiratory computed tomographic (CT) abnormalities, including malacia and air trapping, in patients with relapsing polychondritis and to retrospectively determine the frequency with which expiratory abnormalities are accompanied by inspiratory abnormalities on CT scans. Institutional review board approval was obtained, and informed consent was not required for this retrospective HIPAA-compliant study. A computerized hospital information system was used to identify all patients with clinically diagnosed or biopsy-proved relapsing polychondritis who were referred for CT airway imaging during a 17-month period. The study cohort comprised 18 patients (15 women, three men; mean age, 47 years; age range, 20-71 years). Multidetector helical CT was performed in all patients by using a standard protocol, which included end-inspiratory and dynamic expiratory volumetric imaging. Two observers who were blinded to the original scan interpretations simultaneously reviewed CT scans. Findings were recorded in consensus. Dynamic expiratory CT scans were assessed for malacia that involved the trachea and main bronchi (reduction in cross-sectional area of more than 50%) and for air trapping (failure of lung parenchyma to increase in attenuation during expiration). Air trapping was visually classified according to pattern and extent (lobular, segmental, lobar, or whole lung). Inspiratory CT scans were evaluated for tracheal and bronchial stenosis (>25% luminal diameter narrowing compared with a corresponding uninvolved segment), wall thickening (>2 mm), and calcification. Expiratory CT abnormalities were present in 17 (94%) of 18 patients and included malacia in 13 patients (72%) and air trapping in 17 patients (94%). Inspiratory CT abnormalities were found in eight (47%) of 17 patients who had expiratory CT abnormalities. Calcification of the airway walls was present in seven (39%) of 18 patients. All patients who had inspiratory CT abnormalities demonstrated expiratory CT abnormalities. Expiratory CT abnormalities were present in the majority of patients with relapsing polychondritis who were referred for airway imaging, yet only half of these patients demonstrated abnormalities on routine inspiratory CT scans. Thus, dynamic expiratory CT should be a standard component of imaging assessment in patients with relapsing polychondritis.