The purpose of this study was to evaluate the usefulness of a radiolabeled analog of
somatostatin (iodine-123 octreotide) in the detection and localization of known
carcinoid and
islet cell tumors and to correlate
tumor uptake with the presence or absence of
somatostatin receptors. I-123
octreotide studies were performed in 28 patients. Whole-body and tomographic studies were performed over a 2-day period after injection. Twenty-two of the 28 patients underwent
tumor biopsy, and samples were analyzed for the presence of
somatostatin receptors.
Tumors were best seen on scans obtained 1-4 hours after injection. Of the 28 patients, 22 had positive scans with uptake in
tumors, three showed photon-deficient uptake in regions of known
tumor, and three had negative scans. Seventeen patients in whom results of
tumor biopsy were positive for
somatostatin receptors had positive scans, and one patient in whom results of biopsy were negative for
somatostatin receptors had a negative scan. Previously unsuspected lesions were detected on the I-123
octreotide scans in four of the 28 patients. I-123
octreotide appears to be a useful tracer for the localization of
neuroendocrine tumors and, most likely, other soft-tissue
tumors as well.