Role of 99mTc-Tetrofosmin delayed scintigraphy and color Doppler sonography in characterization of solitary thyroid nodules.
OBJECTIVE
A study was undertaken to evaluate the diagnostic efficiency of Tc-Tetrofosmin scan and color Doppler in the characterization of benign and malignant solitary thyroid nodules.


METHODS
Fifty-two patients found to have a cold solitary thyroid nodule on Tc-pertechnetate scintigraphy were included in this study. All patients underwent a single-injection dual-phase (30 min and 120 min) Tc-Tetrofosmin scan. The intranodular vascularity was measured using color Doppler sonography. Fine-needle aspiration cytology was performed on all the patients. In the following days and weeks all patients underwent surgery.


RESULTS
Thirteen out of 15 patients with thyroid cancer showed delayed retention of radiotracer (on 120 min images as compared to the initial 30 min image). Thirty-six out of 37 patients harboring benign solitary nodules showed significant washout of tracer on delayed images. Sensitivity, specificity, positive predictive value and negative predictive value of delayed Tc-Tetrofosmin scintigraphy were found to be 86.6, 97.2, 92.8 and 94.7%, respectively. The Doppler study was able to demonstrate increased vascularity in the center of 8 of the 15 malignant nodules. Thirty-two patients harboring a benign solitary nodule showed normal or increased peripheral vascularity on Doppler study. Sensitivity, specificity, positive predictive value and negative predictive value of color Doppler were found to be 53.5, 86.4, 61.5 and 82%, respectively.


CONCLUSIONS
Delayed Tc-Tetrofosmin scintigraphy is a highly sensitive and specific method for characterizing solitary thyroid nodules, while color Doppler has a low sensitivity but relatively high specificity in differentiating benign from malignant thyroid lesions.
Sharma
Rajnish
R
Department of Nuclear Medicine, Institute of Nuclear Medicine and Allied Sciences (INMAS), Delhi, India. drrsms@rediffmail.com
Chakravarty
Kanti Lal
KL
Tripathi
Madhvi
M
Kaushik
Aruna
A
Bharti
Pooja
P
Sahoo
Maheswar
M
Chopra
Mahender Kumar
MK
Rawat
Harish
H
Misra
Anil
A
Mondal
Anupam
A
Kashyap
Ravi
R
D000293:Adolescent; D000328:Adult; D000368:Aged; D044963:Biopsy, Fine-Needle; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000000981:diagnostic imaging; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D016606:Thyroid Nodule / Q000000981:diagnostic imaging* / Q000473:pathology; D018615:Ultrasonography, Doppler, Color
D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C078700:technetium tc-99m tetrofosmin