The role of combination of ultrasonography and contrast-enhanced CT in diagnosis of recurrent/residual cancer after thyroidectomy / 中华超声影像学杂志

ABSTRACT

Objective To analyze the findings of recurrent/residual caner after thyroidectomy for thyroid cancer in both ultrasonography (US) and contrast-enhanced CT (CECT),and to assess the diagnostic value of combination of these two modalities.Methods Forty-six patients with recurrence/ residue of thyroid cancer underwent both high-frequency US and CECT examinations and were enrolled in this study.The imaging features on US and CECT were reviewed and diagnostic accuracies for local residual lesions and cervical lymph node metastasis were evaluated according to pathological results.Results In 46 patients,the average period between thyroidectomy and diagnosis of recurrent/residual cancer was (14.6 ± 12.1) months(range,7 days-10 years).Twenty patients had local recurrent tumors at the surgical bed and the average size of tumors was 2.1 cm(range,0.5-4.6 cm).On US finding,the recurrent/residual tumors were hypoechoic in 60 ％ of cases,had microcalcification in 40 ％.Cervical lymph node metastasis were found in 40 patients,and 75％ of them were located in zone V[.The smallest size of abnormal lymph node which can be detected by US was 3 mm.In cases of lymph node metastasis,12 cases (30％) became cystic,10 (25 ％) presented microcalcifications,and 5 (12.5 ％) showed microcalcifications and cystic change within a lymph node.Microcalcifications,cystic change and hyperechoic appearance within a lymph node suggested malignant.The detection rate of US and CECT in the local recurrent/residual cancer were 90％ and 90％,respectively.The detection rate of cervical lymph nodes metastasis were 80 ％ and 72.5 ％,respectively.The diagnostic accuracy of US and CECT in local recurrence,cervical lymph node metastasis and both were 65％,67.5％ and 65.2％ vs 75％,55％ and 65.2％,respectively (P ＞ 0.05 for all comparisons).the diagnostic accuracy of combination of US and CECT were increased to 86.4％,77.5％ and 91.3％,respectively.US combined with CECT significantly improved the diagnostic capability compared with US or CECT alone(P ＜0.05).Conclusions US should be used as the first choice of imaging examination for post-thyroidectomy of thyroid cancer.US combined with CECT could further increase the diagnostic accuracy in recurrent/residual thyroid cancer.