[Diagnosis of thyroid carcinoma by magnetic resonance imaging (MRI)]

Magnetic resonance imaging (MRI) has been demonstrated to be important for the evaluation of thyroid diseases. Several foreign authors have reported MRI manifestation of thyroid carcinoma; however, there were few reports about this in China. This study was designed to investigate the diagnostic value of MRI in thyroid carcinoma by comparing MRI manifestation with histopathological features of thyroid carcinoma.

Thirty-one cases of thyroid carcinoma were analyzed retrospectively with preoperational MRI and postoperational pathological findings.

Among 31 cases of thyroid carcinoma, 20 cases showed heterogeneous intensity in MRI and liquefied or hemorrhagic or cystic degeneration at histopathological examination. Twenty-two cases showed ill defined. Twenty-two cases showed irregular shapes, of 10 cases showed "the discontinuous capsule-like sign with low signal intensity around the tumor" in MRI and that pseudocapsules have been penetrated and partially destroyed by tumors in histopathological findings. Nineteen cases showed the tumors infiltrated the adjacent structures. Nineteen cases showed metastatic lymphadenopathy on the neck.

"The discontinuous capsule-like sign with low signal intensity around the tumor" is the characteristic manifestation of thyroid carcinoma on MRI. Heterogeneous signal, obscure margin, and irregular shape are the important features for diagnosis of thyroid carcinoma. MRI can demonstrate small lesions, provide the precise morphologic characteristics of lesions, and accurately define the local extension of tumors.