Comparative Diagnostic Value of Computed Tomography Lung and Bone Window Settings for the Detection of Nasal Foreign Bodies in 47 Dogs Presented to Two UK Referral Hospitals (2015–2023)

Confident diagnosis of nasal foreign bodies (FBs) with computed tomography (CT) is challenging. Plant material FBs may be inconspicuous depending on size and attenuation and may be obscured by secondary nasal changes such as accumulation of mucous. The authors anecdotally observed that the lung window (LW) might improve visualization of some nasal FBs. The aim of this retrospective, multicentre study was to assess the diagnostic utility and interobserver variability of the LW in the diagnosis of nasal FBs. We hypothesized that use of the LW improves detection rate of nasal FBs compared to the bone window (BW), and that interobserver agreement is strong. Computed tomography examinations of 47 dogs with an endoscopically confirmed nasal foreign body (FB) were included, and each study was reviewed independently by two board certified radiologists, resulting in a total of 94 assessments. Pre-contrast CT series were reviewed in the BW and LW. The reviewers were blinded to the final diagnosis and were asked to evaluate the CT studies for presence or absence of a convincing nasal FB. Reviewers confidently detected a nasal FB on 19/94 (20%) assessments in the BW and 20/94 (21%) in the LW, the majority of the FBs were elongated in shape (30%) and were visible in the rostral and mid-portion of the nasal cavity. The interobserver agreement was moderate in the BW (<i>k</i> < 0.53) and in the LW (<i>k</i> < 0.49). Our findings do not support our main hypothesis that the use of the LW significantly increases diagnostic accuracy for the identification of nasal FBs in dogs. However, as the LW enabled correct diagnosis in one assessment, it may occasionally be helpful if no FB is visualized on initial examination.