CT scan methods compared for lung disease in dogs with breathing

Abstract

OBJECTIVE: To determine the diagnostic accuracy of sedated respiratory-gated (RG) CT as a minimally invasive surrogate for anesthetized, ventilator-assisted inspiratory-expiratory breath-hold (I:E-BH) CT scans by being able to identify CT lung patterns and subpatterns, abnormal and normal lung attenuation scores, and bronchomalacia (BM) in dogs with respiratory disease. METHODS: Sedated RG CT and anesthetized I:E-BH CT images were sequentially acquired in 50 client-owned dogs with respiratory clinical signs. Computed tomography lung patterns and subpatterns, 2 CT severity scores, and the presence of BM were assessed. Agreement was estimated using unweighted and weighted Cohen κ coefficients and Bland-Altman plots. McNemar tests and mixed-effects logistic or ordinal logistic regressions were utilized to evaluate discordant pairs between CT techniques. RESULTS: Both scan types had minimal motion artifact. Nodular pattern and airspace nodules and reticular and subpleural interstitial thickening subpatterns were significantly underestimated in RG CT compared to I:E-BH CT. A fair agreement was estimated between the 2 methods for normal lung scores but not for abnormal lung scores, and for BM. There was a significant difference between the two techniques in diagnosing clinical BM. Inspiratory-expiratory breath-hold CT yielded more BM diagnoses, especially in younger dogs with milder BM scores. CONCLUSIONS: In dogs with respiratory disease, RG CT had good concordance with I:E-BH CT on most major lung patterns but not some nodular and linear subpatterns, underdetecting subtle but clinically relevant lesions. The probability of diagnosing clinical BM is higher with I:E-BH CT, particularly in milder cases. CLINICAL RELEVANCE: Compared to RG CT, anesthetized I:E-BH CT provides superior technique and detail that allows for characterization of some subpatterns, which could have diagnostic implications.