Role of ultrasound diagnosis in assessing and managing thyroid nodules with inadequate cytology.
OBJECTIVE
This study aimed to assess the diagnostic accuracy of a specific ultrasound classification system in evaluating thyroid nodules with inadequate cytology, defined as a cytologic result that shows insufficient cellularity and does not provide useful information. Ultrasound diagnoses were made in accordance with a specially devised ultrasound classification system.


METHODS
From January 2008 to December 2009, 1036 patients with 1289 thyroid nodules (largest diameter ≥ 5 mm) diagnosed by ultrasound and subsequent ultrasound-guided fine-needle aspiration (FNA) were enrolled in the study. Each thyroid nodule was prospectively classified on the basis of its ultrasound features by a single radiologist into one of five diagnostic categories: benign, probably benign, borderline, possibly malignant, or malignant. Solid nodules were classified using all five categories, whereas partially cystic thyroid nodules were classified using four (borderline was omitted). Repeated ultrasound-guided FNA was performed on all nodules for which the initial ultrasound-guided FNA revealed inadequate cytology.


RESULTS
Of 96 nodules with inadequate cytology (96/1289, 7.4%), 22 were surgically removed, and the ultrasound diagnoses and cytopathology results of all 96 were compared. A borderline ultrasound diagnosis was assigned to 13 nodules. The sensitivity, specificity, positive and negative predictive values, and accuracy were calculated for all nodules excluding all the borderline nodules (100%, 95.1%, 33.3%, 100%, and 95.2%, respectively) and with four borderline nodules reclassified as benign (100%, 95.3%, 33.3%, 100%, and 95.4%, respectively). The values obtained with these approaches were not significantly different (p > 0.05).


CONCLUSIONS
The selective use of repeated ultrasound-guided FNA for nodules with initial inadequate cytology may be preferable to its unconditional use depending on the ultrasound diagnoses of thyroid nodules.
Department of Radiology, Busan Paik Hospital, Inje University College of Medicine, Busanjin-gu, South Korea. dwultra@lycos.co.kr
Dong Wook
DW
Kim
Eun Joo
EJ
Lee
Jun Hyung
JH
Lee
D000328:Adult; D044963:Biopsy, Fine-Needle; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D016606:Thyroid Nodule / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D018084:Ultrasonography, Interventional