The aim of the present study was to evaluate the clinical significance of this technique in differentiated thyroid carcinoma and to compare the results with other imaging modalities, particularly with whole-body iodine scintigraphy WBS and hexakis 2-methoxyisobutylisonitrile 99m technetium I scintigraphy MIBI.
There were 39 papillary thyroid cancer extranodal extension with papillary tumors and 15 patients with follicular tumors including 3 Hurthle-cell carcinomas. Primary tumor stage pT was pT1 in 5 cases, pT2 in 19 cases, pT3 in 2 cases, pT4 in 24 cases, and unknown in 4 cases, respectively.
Finally, for each case an overall clinical evaluation was done including histology, cytology, thyroglobulin level, sonography, computed tomography, magnetic resonance imaging, and subsequent clinical course, to allow a comparison with functional imaging results.
MIBI was performed in 44 cases. Papillary thyroid cancer extranodal extension, since spatial resolution with respect to tomographic imaging is inferior with single photon emission computer tomography SPECT using MTBI, the observed higher sensitivity of PET might be due to the higher spatial resolution of this method.
As far as grading could be obtained, FDG-PET seemed to be more sensitive than WBS in high-grade tumors, whereas WBS was positive predominantly in low-grade carcinomas, although statistical significance could not be reached.