Positive predictive values of sonographic features of solid thyroid nodule☆
Received 1 August 2008; accepted 10 October 2008. published online 14 September 2009. Corrected Proof
Abstract
Aim
The purpose of this study was to assess the positive predictive value of the suspicious sonographic features of solid nodules of the thyroid.
Materials and 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).
Conclusion
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.
aDepartment of Diagnostic Radiology, The Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, South Korea
bDepartment of Diagnostic Pathology, The Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, South Korea
cDepartment of General Surgery, The Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, South Korea
Corresponding author. Department of Radiology, Yonsei University, College of Medicine, Gangnam Severance Hospital, 146-92 Dogok-Dong, Kangnam-Gu, Seoul 135-270, South Korea. Tel.: +82 2 2019 3510; fax: +82 2 3462 5472.
☆ Presented in part as scientific paper SSE12-03 at the 2006 Radiological Society of North America meeting, Chicago, IL, November 2006.
ABSTRACT