99mTc-depreotide scintigraphy versus 18F-FDG-PET in the diagnosis of radioiodine-negative thyroid cancer.
BACKGROUND
Papillary and follicular thyroid cancer were found recently to express somatostatin receptors (SSTRs). (99m)Tc-depreotide binds with high affinity to SSTRs 2, 3, and 5.


OBJECTIVE
The aim of this study was to evaluate the feasibility of applying (99m)Tc-depreotide scintigraphy to search for radioiodine-negative thyroid cancer; comparison is made to a standard approach using (18)F-fluorodeoxyglucose-positron emission tomography ((18)F-FDG-PET).


METHODS
Ten radioiodine-negative patients with suspicion of recurrent or metastatic thyroid cancer were investigated with (99m)Tc-depreotide scintigraphy and (18)F-FDG-PET, performed with a time interval that ranged from 1-8 wk. Locoregional recurrence and metastases were confirmed by ultrasonography and/or computed tomography, together with cytology or histological examination in selected cases.


RESULTS
True-positive results were obtained in nine patients (90%) with (99m)Tc-depreotide scintigraphy and in seven patients (70%) with (18)F-FDG-PET. (99m)Tc-depreotide scintigraphy gave better results in terms of detection of recurrent or metastatic disease compared with (18)F-FDG-PET in three patients, whereas (18)F-FDG-PET identified metastatic disease that was not seen with (99m)Tc-depreotide in only one patient. (99m)Tc-depreotide scintigraphy portrayed lesions in three patients with negative morphological imaging.


CONCLUSIONS
Results indicate a potential value of (99m)Tc-depreotide scintigraphy for the diagnosis of thyroid cancer in the setting of detectable thyroglobulin and negative radioiodine scan. Furthermore, (99m)Tc-depreotide adds complementary information regarding the SSTR status of lesions, which may be helpful for individual therapy planning in this group of patients, which is hard to manage clinically.
Rodrigues
Margarida
M
University Clinic for Nuclear Medicine, Anichstrasse 35, A-6020 Innsbruck, Austria. rodriguesradischat@hotmail.com
Li
Shuren
S
Gabriel
Michael
M
Heute
Dirk
D
Greifeneder
Michaela
M
Virgolini
Irene
I
D000368:Aged; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007457:Iodine Radioisotopes / Q000032:analysis; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds; D049268:Positron-Emission Tomography; D013004:Somatostatin / Q000031:analogs & derivatives*; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging*
D007457:Iodine Radioisotopes; D015609:Organotechnetium Compounds; D019788:Fluorodeoxyglucose F18; D013004:Somatostatin; C444119:technetium Tc 99m depreotide