Jeong Seon Park MD, Presenter: Nothing to Disclose

To evaluate the diagnostic performance of real-time freehand US elastography in differentiating malignant from benign thyroid nodules, with pathologic diagnosis as the reference standard

Between Oct. 2007 and Feb. 2008, conventional ultrasonography (CUS) and real-time US elastography were performed in 226 thyroid nodules of 128 patients who were scheduled to undergo thyroidectomy. We excluded 23 lesions because of poor quality of strain images. Finally, 203 thyroid nodules (117 malignant; 86 benign) of 114 patients (F: M=101:13, mean age of 47.8 years) were included. According to the findings of grey-scale US, the result of CUS were divided into three categories; benign, indeterminate, and malignancy. The elasticity (E) score was assigned from 1 to 5 according to the degree and distribution of strain induced by light compression. The proportion of no strain (PNS, %) per each nodule was assessed. Mean E scores and PNS were examined by using a Student t-test. We evaluated the diagnostic performance to differentiate malignancy from benign lesions by using a ROC analysis to compare the area under the curve, sensitivity, specificity and accuracy at the optimal cut-off value.

For E score, the mean + standard deviation was 3.7 + 1.0 for malignant lesions and 2.0 + 0.7 for benign lesions (P<.001). For PNS, the mean + standard deviation was 82.3 + 24.4 for malignant lesions and 23.3 + 23.6 for benign lesions (P<.001). The area under the curve of CUS, E score and PNS was 0.864, 0.899, and 0.936, respectively. The AUC of PNS was significantly higher than CUS (p=.004) or E score (p=.004). There was no significant difference of AUC between CUS and E score (p=0.181). Sensitivity, specificity, and accuracy of CUS at the cut-off value between indeterminate and malignancy were 83.6%, 86.0%, and 84.6%, respectively. Those of E score at the cut-off value between 2 and 3 were 88.8%, 79.1%, and 82.5%, respectively. Those of PNS at the cut off value of 50% were 87.1%, 88.4%, and 87.5%, respectively.

For the differential diagnosis of thyroid nodules, the diagnostic performance of elasticity score or the proportion of no strain area had at least equivalent value compared to CUS.

For the differentiation of malignant thyroid nodules from benign lesions, US elastography may be useful as an adjunctive method.

Park, J, Clinical Application of Ultrasound (US) Elastography in Thyroid Nodules.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6016715.html