Gallium-67 imaging in the evaluation of thyroid malignancy

One hundred thirty-six patients with suspected thyroid malignancy were studied prospectively with Ga-67 imaging of the thyroid and whole body. All patients subsequently had diagnoses proven by biopsy or surgical resection. Patients with malignant tumors (anaplastic carcinoma, malignant lymphoma, adenocarcinoma, medullary carcinoma, adenocarcinoma with squamous cell transformation, and metastases to the thyroid from other tumors) were examined serially after appropriate therapy. The authors draw on their own experience and a literature review to propose the following indications for Ga-67 imaging in patients with thyroid disease: 1) suspected anaplastic carcinoma or malignant lymphoma of the thyroid gland, 2) detection of distant metastases of anaplastic thyroid carcinoma and malignant lymphoma, 3) evaluation of efficacy of therapy, 4) suspected metastases to the thyroid gland from other malignancies, and 5) differentiation of malignant lymphoma from chronic thyroiditis. The strengths, limitations, and potential pit-falls of the technique are discussed.