Factor analysis of dynamic series (FADS) in somatostatin receptor imaging

The aim of this article was to study the physiopathology of tumoral uptake of In-111-pentetreotide using factorial analysis of dynamic series (FADS) a nd to assess the usefulness of this analysis in somatostatin receptor scint igraphy. Methods: Forty-one patients were included, 24 women and 17 men. Af ter intravenous injection of 111 MBq In-111-pentetreotide, dynamic image ac quisition (68 images of 30 s) began in front of the suspected tumoral site: thoracic in 10 patients with medullary carcinoma of the thyroid and 2 pati ents with bronchogenic carcinoid, and abdominal in 12 cases of midgut carci noid and 17 cases of other gastroenteropancreatic neuroendocrine tumors. FA DS was performed with FAMIS software. Static images were obtained 4 h and 2 4 h later. For every patient, surgery and/or clinical follow-up (4 y) was u sed to classify results as true (T) or false (F) positive (P) or negative ( N) and to evaluate both the sensitivity of static images and the usefulness of FADS, Results: Of the 14 cases of carcinoid tumor, 5 patients were TN; 9 patients were TP with static images but only 8 were TP with FADS (a bronc hogenic carcinoid of 6 mm was missed). Of the 17 cases of gastroenteropancr eatic neuroendocrine tumor, static images were TP in 9 patients, and FADS w ere TP in 5 of these patients (and 4 FN). Static images and FADS were FN in 4 patients and TN in 3 patients, and in the 2 last patients static images were FP, but FADS were TN. Of the 10 cases of medullary carcinoma of the th yroid, static images and FADS were TN in I patient, static images were TP i n 3 patients and FADS were TP in 2 of these patients (and 1 FN), In the six last cases, static images were FN, but FADS were FN in 3 patients and TP i n 3 patients, showing an infiltrate. Conclusion: FADS demonstrates that tum oral kinetics are similar to those of the spleen. FADS can show a diffuse t umoral uptake corresponding to tumoral infiltrate in medullary carcinoma of the thyroid or in hepatic miliaria, whereas static images were normal or d oubtful.