Detection of recurrent nasopharyngeal carcinomas with thallium-201 single-photon emission computed tomography in patients with indeterminate magnetic resonance imaging findings after radiotherapy

Background. The aim of this study was to evaluate the usefulness of thallium-201 (Tl-201) single-photon emission CT (SPECT) to detect recurrent nasopharyngeal carcinomas (NPC) when MRI findings are indeterminate. Methods. After radiotherapy, 26 NPC patients with indeterminate MRI findings were included in this study. MRI, Tl-201, and biopsy were performed at least 4 months after radiotherapy and within 1 week. The final results were based on histopathologic findings and clinical follow-up after at least 6 months. Results. For detecting recurrent NPC in indeterminate MRI findings, the sensitivity, specificity, and accuracy of Tl-201 SPECT were 92.3%, 92.3%, and 92.3%, respectively. Conclusions. On the basis of this result, Tl-201 SPECT seems to be effective in detecting recurrent NPC when MRI findings are indeterminate.