INDIUM-111-DTPA-D-PHE-1-OCTREOTIDE AND TECHNETIUM-99M-(V)-DIMERCAPTOSUCCINIC ACID SCANNING IN THE PREOPERATIVE STAGING OF MEDULLARY-THYROIDCARCINOMA

The early detection of all tumor sites in patients with medullary thyr oid carcinoma (MTC) before primary surgery is important, because MTC t ends to metastasize to regional lymph nodes of the neck and mediastinu m early during the course of the disease. Methods: In an approach to l ocalize the primary tumor sites and to detect additional tumor involve ment, we have performed in 22 patients with MTC either Tc-99m(V)-dimer captosuccinic acid (DMSA) and/or In-111-diethylenetriamine pentaacetic acid-D-Phe-1-octreotide scintigraphy. Results: Indium-111-octreotide (150-200 MBq) identified the primary tumor in 10 of 14 patients (71%), whereas the primary tumor was visualized by Tc-99m-DMSA (300-370 MBq) in 10 of 17 patients (58%). In 8 of 22 patients (36%), lymph node met astases were present at the time of diagnosis, as confirmed by histopa thology and histochemistry after surgery tall <2 mm). Preoperatively, neither scan was able to detect lymph node involvement in these patien ts (0/8). Conclusion: Both Tc-99m-DMSA and In-111-octreotide studies h ave similar sensitivity to localize primary MTC; however, these scans are not able to detect small lymph node involvement (micrometastases) before initial surgery. Unfortunately, both scans have no clinical imp lication for preoperative staging in patients with MTC.