Clinical applications of SPECT/CT after first I-131 ablation in patients with differentiated thyroid cancer.
OBJECTIVE
This study aimed to determine which thyroid cancer patients would benefit from SPECT/CT in addition to whole-body planar scintigraphy (RxWBS) for the detection and characterization of I-131 focal uptake after first ablation.


METHODS
Neck and thoracic SPECT/CT was performed in 187 patients with I-131 focal uptake suggestive of remnant thyroid tissue (Rem group, n = 152) or presumed lymph node (LN) metastases (mLN group, n = 35) on RxWBS. Clinical and pathologic parameters were analysed and compared in patients with and without additional SPECT/CT findings.


RESULTS
wIn the Rem group, SPECT/CT revealed additional occult findings on RxWBS in 13 patients (8·6%). The serum thyroglobulin levels at the time of ablation were significantly higher in patients with additional SPECT/CT findings than in patients without additional findings (4·3 ± 3·4 ng/ml vs 1·6 ± 2·7 ng/ml, P = 0·001). In the mLN group, SPECT/CT demonstrated only remnant thyroid tissues without evidence of lymph node metastasis in 14 (40·0%) patients, whereas in the remaining 21 (60·0%) patients, I-131 uptake was confirmed in the corresponding neck and mediastinal lymph nodes on SPECT/CT.


CONCLUSIONS
Even in the Rem group, additional SPECT/CT could provide useful information for detecting hidden metastasis, especially in patients with high serum thyroglobulin levels. SPECT/CT should be recommended for patients with focal uptake lymph node metastasis on RxWBS.
Department of Nuclear Medicine, Kyungpook National University Medical Center and School of Medicine, Daegu, Korea.
Shin Young
SY
Jeong
Sang-Woo
SW
Lee
Hae Won
HW
Kim
Bong-Il
BI
Song
Byeong-Cheol
BC
Ahn
Jaetae
J
Lee
D000328:Adult; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008207:Lymphatic Metastasis / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D013954:Thyroglobulin / Q000097:blood; D013964:Thyroid Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000601:surgery; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
D007457:Iodine Radioisotopes; D013954:Thyroglobulin