sodium-pertechnetate-tc-99m and Neuroendocrine-Tumors

There is growing interest in the human sodium/iodide symporter (NIS) gene both as a molecular imaging reporter gene and as a therapeutic gene. Here, we show the feasibility of radioisotope therapy of neuroendocrine tumors. As a separate application of NIS gene transfer, we image NIS-expressing tumors with pinhole SPECT in living subjects.. Biodistribution studies and in vivo therapy experiments were performed in nude mice carrying stably NIS-expressing neuroendocrine tumor xenografts following i.v. injection of (131)I and (99m)Tc pertechnetate. To show the usefulness of NIS as an imaging reporter gene, (99m)Tc pertechnetate uptake was imaged in vivo using a clinical gamma camera in combination with a custom-made single pinhole collimator, followed by SPECT/small animal MRI data coregistration.. NIS-expressing neuroendocrine tumors strongly accumulated (131)I and (99m)Tc pertechnetate, as did thyroid, stomach, and salivary gland. The volume of NIS-expressing neuroendocrine tumors decreased significantly after therapeutic administration of (131)I or (99m)Tc pertechnetate, whereas control tumors continued to grow. NIS-mediated uptake of (99m)Tc pertechnetate could be imaged in vivo at high resolution with a clinical gamma camera equipped with a custom-made single pinhole collimator. High-resolution functional and morphologic information could be combined in a single three-dimensional data set by coregistration of SPECT and small animal MRI data. Lastly, we demonstrated a therapeutic effect of (99m)Tc pertechnetate on NIS-expressing neuroendocrine tumors in cell culture and, for the first time, in vivo, thought to be due to emitted Auger and conversion electrons.. NIS-expressing neuroendocrine tumors efficiently concentrate radioisotopes, allowing for in vivo high-resolution small animal SPECT imaging as well as rendering possible successful radioisotope therapy of neuroendocrine tumors.

Topics: Animals; Cell Line, Tumor; Humans; Iodine Radioisotopes; Magnetic Resonance Imaging; Male; Mice; Mice, Nude; Neoplasm Transplantation; Neuroendocrine Tumors; Radioisotopes; Radiopharmaceuticals; Radiotherapy; Sodium Pertechnetate Tc 99m; Symporters; Tomography, Emission-Computed, Single-Photon

After the intravenous administration of a radiolabeled somatostatin analogue (octreotide), normal thyroid and neoplastic and nonneoplastic thyroid lesions can be visualized. The authors present the cases of two patients who underwent somatostatin receptor scintigraphy (SSRS) using In-111 pentetreotide: one for the study of suspected paraneoplastic ACTH hypersecretion, and the other for a restaging of breast carcinoma with neuroendocrine features. In both patients, SSRS revealed increased uptake in the thyroid, corresponding to "cold" nodules on Tc-99m pertechnetate imaging. Cytologic and histologic examinations showed the typical features of thyroid goiters without lymphocytic infiltration.

Topics: Adenoma; Adrenocorticotropic Hormone; Biopsy, Needle; Breast Neoplasms; Carcinoma; Female; Goiter, Nodular; Humans; Indium Radioisotopes; Injections, Intravenous; Middle Aged; Neoplasm Staging; Neuroendocrine Tumors; Paraneoplastic Syndromes; Pituitary Neoplasms; Radionuclide Imaging; Radiopharmaceuticals; Receptors, Somatostatin; Sodium Pertechnetate Tc 99m; Somatostatin; Thyroid Gland; Thyroid Nodule