Positive predictive values of sonographic features of solid thyroid nodule.
OBJECTIVE
The purpose of this study was to assess the positive predictive value of the suspicious sonographic features of solid nodules of the thyroid.


METHODS
After approval by our institutional review board, we evaluated 594 sonographically detected nodules on which fine needle aspiration biopsy had been performed from January to December 2005. Among these, pure cystic lesions and inadequate pathologic results were excluded. The remaining 530 solid thyroid nodules were analyzed by two radiologists. Each lesion was classified based on four sonographic features that suggested malignancy: microcalcifications; an irregular or microlobulated margin; marked hypoechogenicity; and a shape that was taller than wide. The sensitivity, specificity, positive predictive value, and negative predictive value of the each sonographic feature were calculated.


RESULTS
Final pathologic results showed that 97 (18.3%) of 530 nodules were malignant. The positive predictive values for malignancy in each sonographic feature were microcalcifications, 38.6% (39/101); an irregular or microlobulated margin, 28.2% (70/248); marked hypoechogenecity, 49.4% (38/77); taller than wide shape, 59.8% (49/82). In terms of relative risk, microcalcification [P<.01, relative risk (RR)=3.115, 95% CI: 1.724-5.628], hypoechogenecity (P<.01, RR=2.510, 95% CI: 1.290-4.881). The shape of nodule which was taller than wide (P<.01, RR=7.624, 95% CI: 4.156-13.986) revealed the highest predictive sonographic finding suggesting malignancy. However, margin is the least significant feature of detection of thyroid malignancy (P=.27, RR=1.395, 95% CI: 0.777-2.505).


CONCLUSIONS
The three sonographic features of solid thyroid nodule, that is, microcalcifications, marked hypoechogenecity, and a taller than wide shape are meaningful findings in the diagnosis of thyroid malignancy. The shape that was taller than wide was the most reliable sonographic feature for predicting malignancy.
Hong
Yoo Jin
YJ
Department of Diagnostic Radiology, The Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, South Korea.
Son
Eun Ju
EJ
Kim
Eun-Kyung
EK
Kwak
Jin Young
JY
Hong
Soon Won
SW
Chang
Hang-Seok
HS
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016606:Thyroid Nodule / Q000000981:diagnostic imaging*; D014463:Ultrasonography / Q000379:methods*; D055815:Young Adult