Single Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) of the Skull in Necrotizing Otitis Externa: Comparison with Planar Bone Scintigraphy, SPECT and CT

Abstract

Purpose:Assess the diagnostic performance of single photon emission tomography/computed tomography (SPECT/CT) for identifying necrotizing otitis externa (NOE) and compare this technique with planar bone scintigraphy (BS), SPECT and CT. Methods:Data from 13 patients with suspected NOE were retrospectively studied. Planar BS and SPECT images were interpreted by nuclear medicine physician, CT images by radiologist and SPECT/CT images by both nuclear medicine physician and radiologist. Planar BS, SPECT and SPECT/CT images were taken as positive in the presence of increased skull base uptake and CT images in the presence of periosteal reaction and bone lysis. Clinical evolution, imaging results, microbiology and histopathology were taken into consideration to determine the final diagnosis. Sensitivity, specificity, and predictive values, were calculated for each technique. The McNemar's test chi-squared with Yates correction of 0.5 was used to compare sensitivities and specificities. Results:SPECT/CT had the highest sensitivity (100%), followed by SPECT (90%), planar BS (80%) and CT (60%). Specificity was 100% for all imaging modalities since all reported positive cases were identified as NOE in the final diagnosis. No statistically significant difference was noted when comparing SPECT/CT with planar BS, SPECT and CT. However, borderline statistical significance was found between SPECT/CT and CT (p-value=0.08). SPECT/CT was the best imaging modalities in the accurate location of sites of osteomyelitis. Conclusion:SPECT/CT showed high sensitivity and specificity in the diagnosis of NOE, but was not statistically superior to planar BS, CT or SPECT in this small patient population.