(dtpa-phe(1))-octreotide and thallium-chloride

Tumor imaging in nuclear medicine has been improved by imaging instruments and newly developed radiopharmaceuticals. One of the imaging developments is a SPECT system using three-detector system. Its each detector rotates 120 degrees when SPECT projection data are acquired and we can save the scanning time and get a high resolution image which is less than 10 mm FWHM. About radiopharmaceuticals 99mTc MDP and 57Ga-citrate are used most commonly for detecting early metastatic lesions in the body. 201Tl chloride and 99mTc MIBI as used for cardiac imaging are also used for tumor detection. 111In-DTPA-D-Phe-octreotide are developed for detection of somatostatin receptor and will be used for many kinds of tumor such as small cell lung cancer, meningioma, malignant lymphoma and gastrointestinal hormone producing tumor.

Topics: Citric Acid; Gallium Radioisotopes; Gamma Cameras; Humans; Indium Radioisotopes; Neoplasms; Octreotide; Pentetic Acid; Technetium Tc 99m Sestamibi; Thallium; Thallium Radioisotopes; Tomography, Emission-Computed, Single-Photon

Radioiodine scintigraphy is the gold standard exploration for imaging metastases of differentiated thyroid cancer and enables the decision of therapy with 131 radioactive iodine to be made. However, other approaches may be of use for diagnosis when there is no visible uptake after the administration of 131I, while elevated thyroblobulin levels suggest the presence of metastatic tissue in one third of metastatic patients. In order to detect recurrences or metastases, in conjunction with conventional imaging techniques (cervical and hepatic ultrasonography, lung CT scan..), other scintigraphic explorations with various radiopharmaceutics may be used, although none of them has any specificity towards thyroid cancer. Tl201 and MIBI which are used as perfusion tracers for myocardial explorations, are also used for detection of various tumors and for metastatic thyroid cancer. The performances of both radiopharmaceutics in imaging metastases are differently evaluated between investigators with a sensitivity ranging from 45 to 94% while the specificity varies less (82-97%). 18-Fluoro-deoxyglucose is retained in malignant tissue depending on the grade of malignancy. It has been shown to accumulate in thyroid cancer and metastases. Its detection by whole body PETscan represents a limitation for use which will be modified by new techniques. 111In-octreotide which binds to somatostatin receptors located on tumor cell membranes is able to show thyroid cancer metastases in some instances. We report on the very preliminary results of these combined scintigraphic approaches, performed in a limited number of patients who had no radioiodine uptake and elevated Tg levels, in order to determine the most appropriate exploration in terms of performance and cost.

Topics: Adenocarcinoma; Carcinoma, Papillary; Deoxyglucose; Fluorodeoxyglucose F18; Humans; Iodine Radioisotopes; Neoplasm Metastasis; Octreotide; Pentetic Acid; Radionuclide Imaging; Radiopharmaceuticals; Technetium Tc 99m Sestamibi; Thallium; Thyroid Neoplasms