Use of scintigraphy for diagnosis of equine paranasal sinus disorders.
Authors: Barakzai Safia, Tremaine Henry, Dixon Paddy
Journal: Veterinary surgery : VS
Summary
# Equine Paranasal Sinus Disorders: What Scintigraphy Can and Cannot Tell Us Nuclear scintigraphy using 99Tc-MDP offers modest advantages over radiography for detecting paranasal sinus pathology, though its clinical utility is more nuanced than straightforward diagnosis suggests. Barakzai and colleagues examined 48 horses with suspected sinus or cheek tooth disease alongside 30 controls, using both scintigraphic imaging and radiographic assessment blindly evaluated by two clinicians; objective analysis involved quantifying radionuclide uptake in regions of interest and calculating uptake ratios between affected and unaffected sides. Twenty-eight horses were confirmed with sinusitis (15 primary, 13 secondary), with nine primary sinusitis cases showing focal areas of moderate to marked increased uptake alongside diffuse sinus involvement—a pattern that could easily be misinterpreted as periapical pathology rather than primary inflammation. Whilst scintigraphy demonstrated marginally superior diagnostic accuracy compared to radiography and can helpfully differentiate dental-origin sinusitis from other causes, quantitative analysis of uptake ratios proved unreliable for identifying specific disorders due to considerable overlap between conditions. For practitioners, this emphasises that scintigraphic findings must be interpreted contextually with three-dimensional lesion localisation and supporting clinical evidence rather than relied upon in isolation, particularly when focal uptake patterns risk false-positive diagnoses of tooth-related disease.
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Practical Takeaways
- •Scintigraphy can help differentiate dental-origin sinusitis from other causes, but should always be interpreted with radiographs, clinical signs, and 3D localization to avoid misdiagnosing primary sinusitis as periapical infection
- •Focal hot spots on scintigraphy don't reliably identify specific sinus pathology — use them as part of a complete diagnostic approach rather than as standalone findings
- •When investigating chronic sinus disease, combine imaging modalities and careful clinical assessment; scintigraphy alone is insufficient for definitive diagnosis
Key Findings
- •Scintigraphy showed marginally higher diagnostic accuracy (kappa) for paranasal sinus disorders compared to radiography
- •28 of 48 horses with suspected sinus disease were diagnosed with sinusitis (15 primary, 13 secondary)
- •Focal areas of moderate to marked radionuclide uptake occurred in 9 primary sinusitis cases alongside diffuse uptake
- •Quantitative ROI analysis showed significant differences between affected and non-affected sides but considerable overlap between different disorders, limiting diagnostic specificity