[Value of (99m)Tc tetrofosmin scan in well-differentiated thyroid cancer].
BACKGROUND
Patients with cold thyroid nodules without ultrasound malignant suspicion and with benign/undetermined cytology may be subjected to follow-up surveillance. 99mTc-tetrofosmin scan (99mTc-TS) may identify patients where this observation can be performed with more certainty. Absence of uptake never occurs in carcinoma patients. Our objective was to determine the 99mTc-TS negative predictive value (NPV) in patients with cold thyroid nodules.


METHODS
An evaluation with 99mTc-TS was conducted prior to surgery in patients with thyroid gland tumor who were candidates for surgery. All patients underwent thyroidectomy according to histology; NPV and test sensitivity were evaluated when compared with the histopathological result. Then, 296-370 MBq (8-10 mCi) of 99mTc-tetrofosmin was administered, and scan images were evaluated after 120 min. Scan result was reported as a) with increased metabolic activity (IMA) or b) without increased metabolic activity (WIMA).


RESULTS
Included in the study were 86 consecutive patients. In 60 patients the scan showed IMA, 20/60 (33%) with carcinoma, 67% with benign nodule. In 26 (30.2%) the scan was WIMA. In this group, 3/26 (11.5%) had carcinoma and (88.4%) had a benign neoplasia. Sensitivity = 91.43 (95% CI = 80.73-100), specificity = 45.10 (95% CI = 30.46-59.73), positive predictive value = 53.33 (95% CI = 39.8-66.79) and NPV = 88.46 (95% CI 74.26-100). Negative probability ratio = 0.19.


CONCLUSIONS
IMA-99mTc-TS is less specific in thyroid cancer; nevertheless, in WIMA patients the possibility of carcinoma is 13%. Most patients (70%) showed IMA, 33% with carcinoma. WIMA-NPV = 30%. 99mTc-TS may be useful in the therapeutic decision of patients with thyroid nodule with concerns about surgery. Its usefulness lies in the NPV.
Gallegos-Hernández
José Francisco
JF
Departamento de Tumores de Cabeza y Cuello, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social México, D.F., Mexico. gal61@prodigy.net.mx
Pichardo-Romero
Pablo
P
Esparza-Pérez
Hiram
H
Reséndiz-Colosia
Jaime Alonso
JA
Minauro-Muñoz
Gabriel Gerardo
GG
Hernández-Hernández
Dulce María
DM
D006801:Humans; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D011237:Predictive Value of Tests; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*
D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C078700:technetium tc-99m tetrofosmin