[99mTc-OCTREOTIDE in Patients with Neuroendocrine Tumors from the GI Tract]

Introduction: It has been demonstrated that scintigraphy with somatostatin analogues is useful for the diagnosis, staging and follow up of patients with neuroendocrine tumors from the gastrointestinal tract (NET-GIT). Some studies suggest that the use of 99mTc-Hydrazinonicotinyl-Tyr3-octreotide (99mTc-HYNIC-TOC) yields similar diagnostic results than the use of 111In-DTPA-octreotide.

Objective: To determine the clinical value of scintigraphy using 99mTc-HYNIC-TOC for the detection of primary and secondary lesions in patients with NET-GIT.

Methods: From September 2004 to May 2009, 32 patients (17 women, age range 18 to 82 years old) with histologically proven or clinically suspected NET-GIT underwent scintigraphy using 99mTc-HYNIC-TOC Patients underwent a whole body scan, with additional static images of abdomen and pelvis, followed by SPECT at 4-hrs post injection of 925 MBq of the tracer. Patients underwent clinical, imaging and histopathology follow-up during 3 to 18 months.

Results: Histopathology demonstrated carcinoid tumor in 20 patients, insulinoma in 2, gastrinoma in 2 and non-specific NET-GIT in 6. Total sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 87%, 100%, 100%, 89% and 94%, respectively. To detect the primary lesion, the values were 94%, 100% 100%, 94% and 97%, respectively and to detect secondary lesions, 79%, 100%, 100%, 86% and 91%, respectively.

Conclusions: 99mTc-HYNIC-TOC is a specific somatostatin analog, with high affinity to receptor subtype SST-2, widely available and affordable by Latin American countries. It has a good performance to be used for diagnosis, staging and follow-up of patients with NET-GIT.