How Accurate Are Radiographs for Diagnosing Feline Nasopharyngeal Stenosis? New Multicenter Study Reveals Insights

Radiographic Characteristics of Feline Nasopharyngeal Stenosis

Ayano Masuyama, Masahiro Suematsu, Caroline Fulkerson, Tetsuya Taniguchi, Masaya Nakamori, Kanami Nakao, Masahiro Murakami

Background

Feline nasopharyngeal stenosis (NPS) is a narrowing of the nasopharyngeal passage causing chronic stertor and upper airway obstruction. While rhinoscopy remains the gold standard for diagnosis, radiography is more readily available in clinical practice. However, its diagnostic reliability for detecting NPS is underexplored. This study aimed to evaluate the diagnostic accuracy of lateral nasopharyngeal radiographs for NPS and describe characteristic radiographic findings in comparison to cats with stertor but no stenosis.

Methods

This multicenter retrospective cross-sectional study included 52 cats with stertor who underwent both lateral nasopharyngeal radiography and rhinoscopy between 2019 and 2023 across three referral hospitals in Japan. Based on rhinoscopy, cats were divided into an NPS group (n = 21) and a non-stenotic nasal disease (ND) group (n = 31). Two blinded board-certified radiologists independently reviewed radiographs by consensus, assessing the presence, location (rostral, middle, caudal), and morphology (broad or membranous) of NPS, as well as soft palate morphology and presence of oropharyngeal gas. Diagnostic accuracy metrics (sensitivity, specificity, PPV, NPV, accuracy) were calculated using rhinoscopy as the reference standard.

Results

Radiography demonstrated 100% sensitivity, 83.9% specificity, and 90.4% overall accuracy for diagnosing NPS. All 21 confirmed NPS cases were correctly identified radiographically, though five false positives occurred in the ND group.

Stenosis location: rostral (43%), middle (29%), caudal (29%)

Morphology: broad in 18 cats, membranous in 3 cats
A “bent” soft palate—a dorsal deviation of the palate margin—was observed in 19% of NPS cases and in no ND cases, suggesting a potentially specific radiographic indicator. Oropharyngeal gas was present in roughly half of cats in both groups (~57–58%), indicating that it was not specific for NPS.

Limitations

Limitations include the retrospective design, absence of CT correlation or detailed rhinoscopic measurements, and non-standardized head positioning that may have influenced soft palate appearance. Radiographic diagnoses were determined by consensus between two radiologists, precluding assessment of interobserver variability and potentially overestimating diagnostic accuracy.

Conclusions

Lateral nasopharyngeal radiography offers high sensitivity and negative predictive value for detecting NPS in cats with stertor, making it an excellent initial screening tool. Broad-type stenosis and a “bent” soft palate morphology are characteristic radiographic findings suggestive of NPS. However, due to potential false positives, confirmatory rhinoscopy remains necessary. Standardized imaging protocols and observer-blinded studies incorporating CT are warranted to refine diagnostic accuracy and radiographic interpretation criteria.

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