Is there a role for fluorodeoxyglucose positron emission tomography/computed tomography in cytologically indeterminate thyroid nodules?
OBJECTIVE
The aim of this study was to determine the accuracy of the fluorine 18 ((18)F)-labeled fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scan in the evaluation of thyroid nodules in which the cytopathology of fine-needle aspiration (FNA) biopsies are classified as "indeterminate," ie, either follicular or Hürthle cell lesion.


METHODS
At an academic medical center, we conducted a prospective pilot study of 15 patients with thyroid nodules in whom adequate FNA was diagnosed as indeterminate. All patients underwent a whole-body FDG-PET/CT scan followed by thyroidectomy. Preoperative FDG-PET/CT results and the histopathology of the surgical specimen were compared and statistically analyzed.


RESULTS
The FNA demonstrated follicular cells in 11 (73%) patients, Hürthle cells in 3 (20%) patients, and both types of cells in 1 (7%) patient. The histopathology of the surgical specimen revealed thyroid cancer in 7 (47%) patients. The FDG-PET/CT scan was positive in 8 patients; 4 (50%) patients were found to have cancer. The FDG-PET/CT scan was negative in 7 patients. Four of these patients had benign lesions and 3 had thyroid carcinoma. Thus, 4 (27%) patients had false-positive FDG-PET/CT scans and 3 (20%) patients had false-negative studies. The sensitivity of FDG-PET/CT to detect a malignant focus was 57% with a specificity of 50%. The positive predictive value was 50% and the negative predictive value was 57%.


CONCLUSIONS
In this pilot study of patients with cytologically indeterminate thyroid nodules, FDG-PET/CT was not a predictable indicator of benign or malignant disease. Although a larger series may elucidate a role for FDG-PET/CT, the relatively low predictability shown in this study should caution clinicians about using FDG-PET/CT to consider foregoing thyroidectomy for cytologically indeterminate nodules.
Hales
Nathan W
NW
Department of Otorhinolaryngology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA. nathan-hales@ouhsc.edu
Krempl
Greg A
GA
Medina
Jesus E
JE
D000328:Adult; D000368:Aged; D044963:Biopsy, Fine-Needle; D002277:Carcinoma / Q000473:pathology / Q000601:surgery; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000473:pathology / Q000601:surgery; D016606:Thyroid Nodule / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy; D014057:Tomography, X-Ray Computed; D051598:Whole Body Imaging
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18