Tissue harmonic imaging of thyroid nodules: initial experience.

Abstract

To determine the impact of tissue harmonic imaging on visualization of the thyroid and gray scale contrast between thyroid nodules and adjacent thyroid parenchyma. A prospective study was performed on 144 patients (148 lesions) undergoing sonographically guided fine-needle biopsy. The fundamental frequency and tissue harmonic images were obtained on a scanner with a wideband 7.5-MHz linear probe. One hundred forty-two benign nodules, 2 papillary carcinomas, 1 anaplastic carcinoma, and 1 metastatic lesion were found. In 1 case a suggestion of a follicular carcinoma was raised, and in 1 case no diagnostic material was obtained. The gray scale intensity of the lesions and adjacent thyroid tissue was measured with graphics software, and the gray scale contrast between lesions and adjacent thyroid tissue was calculated. Additionally, the overall conspicuity and border definition were evaluated by 2 independent observers. Tissue harmonic imaging improved the gray scale contrast between thyroid nodules and adjacent thyroid parenchyma in 116 lesions (78.4%). The overall conspicuity and border definition were improved or equal in the harmonic mode for most lesions. The tissue harmonic imaging technique used as an adjunct to conventional thyroid sonography may improve lesion detectability and characterization.