Thyroid Cancer—Indications and Opportunities for Positron Emission Tomography/Computed Tomography Imaging

The SNMMI Practice Guideline for Therapy of Thyroid Disease with 131I 3.0

“…The presence of 18 F-FDG-avid disease, especially high-volume 18 F-FDG-avid disease, indicates a relatively poor prognosis compared with patients with no 18 F-FDG uptake in viable tumor (56,57). 124 I PET/CT has a higher spatial resolution and image contrast than planar imaging or SPECT with 131 I but has yet to be shown to make a clinical impact (58). 124 I may have a role in improving lesion dosimetry (59).…”

IMAGING IN ENDOCRINOLOGY: 2-[18F]-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography in differentiated thyroid carcinoma: clinical indications and controversies in diagnosis and follow-up

“…False-negative scans can also result from the negligible accumulation of FDG, especially near regions of physiological FDG uptake (e.g., palatine tonsils, soft palate, lingual tonsils, and tongue) and from small tumors that are below the spatial resolution of PET. Finally, well-differentiated thyroid tumors often exhibit inherently low rates of glycolysis and result in a low FDG uptake (1,3,4).…”

“…Therefore, cytologic or histologic confirmation may be required before one can be certain that an FDG-positive lesion represents metastatic disease (3,4). Although earlier literature suggested that FDG-PET/CT and TxWBS provide complementary information for detecting metastases in the work-up of DTC patients with increased serum Tg levels (12,21), recent studies have seemed to indicate the superiority of FDG-PET/CT and have suggested that empirical RAI therapy be used only in patients with negative or not significant FDG uptake (26,27).…”

“…Since the first report of FDG-PET in patients with differentiated thyroid cancer (DTC) in 1987 (3), FDG-PET alone (i.e., without concurrent CT scanning) and FDG-PET/CT have emerged as important tools for the management of patients affected by DTC with suspected or documented radioiodine (RAI)-negative recurrences (4). Although FDG-PET/CT is most valuable in patients with increasing Tg levels, a negative 131 I whole-body scan (WBS) post-thyroidectomy, and RAI ablation, new uses of FDG-PET/CT for DTC patients have recently been recognized (5).…”

The role of FDG-PET in localization of recurrent lesions of differentiated thyroid cancer (DTC) in patients with asymptomatic hyperthyroglobulinemia in a real clinical practice

“…Early detection of DTC relapse in these patients significantly increases the possibility of an effective treatment, especially in a case of local recurrence or single metastases amendable for surgery. In a patient with elevated serum Tg level, negative WBS and normal results of imaging studies fluorodeoxyglucose-positron emission tomography (FDG-PET) may be considered (6,7,8). It is in fact an examination dedicated for the diagnostics of other types of cancer that, in contrary to DTC, show a high dynamics and rapid cell divisions.…”