Visual and Quantitative Analysis by Gallium-67 Single-photon Emission Computed Tomography/Computed Tomography in the Management of Malignant Otitis Externa

Objective: To evaluate the value of Gallium-67 single-photon emission computed tomography/computed tomography in the diagnosis and monitoring treatment response of malignant otitis externa. Methods: Eight patients underwent 12 Gallium-67 single-photon emission computed tomography/computed tomography scintigraphy for eight suspected malignant otitis externa and were subsequently subjected to visual and quantitative analysis. Relevant patient clinical data and other investigation results were also retrieved for correlation. Results: Gallium-67 single-photon emission computed tomography/computed tomography improved anatomical localisation of lesion uptake. All patients (7/7) with active malignant otitis externa achieved a statistically significant higher Gallium-67 uptake on the side of the lesion than the contralateral side (p < 0.05). All patients (5 out of 5) without active malignant otitis externa had no significant difference in Gallium-67 uptake between the two sides. Serum inflammatory markers (white cell count, erythrocyte sedimentation rate, and C-reactive protein) did not correlate with disease activity. Conclusion: Gallium-67 single-photon emission computed tomography, when combined with computed tomography, improves anatomical localisation of lesional uptake. It is also accurate in reflecting active infection and hence can confirm or exclude active malignant otitis externa.