The clinical impact of 18F-FDG PET in papillary thyroid carcinoma with a negative 131I whole body scan: a single-center study of 108 patients.
OBJECTIVE
To assess whether FDG PET could localize the recurrent or metastatic lesions in papillary thyroid cancer patients with negative radioiodine scan.


METHODS
Whole body PET was performed after injecting 370-555 MBq of 18F-FDG in 108 patients, who were suspected of having recurrence or metastasis and whose 131I whole body scans were negative. Recurrence or metastasis occurred in 63 patients by pathology or clinical assessment, whereas 45 patients remained in remission.


RESULTS
FDG PET revealed recurrence or metastases in 59 patients (sensitivity 93.7%), whereas thyroglobulin (Tg) levels were elevated in 41 (sensitivity 65.1%). In 35 of 45 patients in remission, FDG PET was negative (specificity 77.8%). When patients positive for antithyroglobulin antibody were excluded, the sensitivity and specificity of serum Tg became 84.8% and 46.9%, respectively. Compared to Tg measurement, FDG PET detected more metastatic lesions in cervical lymph nodes. Of 40 patients with a negative radioiodine scan showing diffuse hepatic uptake, metastases occurred in 23 patients and remission in 17. FDG PET showed 100% sensitivity and 76.5% specificity in the detection of recurrence in these 40 patients.


CONCLUSIONS
FDG PET is useful for localizing recurrent or metastatic lesions in 131I scan-negative thyroid cancer patients. In particular, it is superior to serum Tg measurement for identifying metastases to cervical lymph nodes. We recommend its use in cases of negative radioiodine scan with diffuse hepatic uptake.
Choi
Mi-Yeon
MY
Department of Nuclear Medicine, Seoul National University College of Medicine, Seoul, Korea.
Chung
June-Key
JK
Lee
Ho-Yeong
HY
So
Young
Y
Park
Do Joon
DJ
Jeong
Jae Min
JM
Lee
Dong Soo
DS
Lee
Myung Chul
MC
Cho
Bo Youn
BY
D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D002291:Carcinoma, Papillary / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D049268:Positron-Emission Tomography / Q000379:methods; D013954:Thyroglobulin / Q000737:chemistry; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D051598:Whole Body Imaging
D007457:Iodine Radioisotopes; D019788:Fluorodeoxyglucose F18; D013954:Thyroglobulin