Diagnostic and Prognostic Role of 68GA-Dotatate in Patients with Neuroendocrine Tumors

F. Marciello; A. Faggiano; L. Aloj; C. Caraco; V. Ramundo; V. Marotta; Prete M. Del; A. Carratu; A. Colao; Storia S. La

Octreoscan is currently the gold standard for diagnosis of somatostatin receptor positive NET but it is limited by a lower spatial resolution and physiological uptake noises. DOTATATE is a somatostatin analogue, radiolabelled with 68Ga and adapted for PET imaging.

Aim of this study was to evaluate the diagnostic performance of 68Ga-DOTATATE PET compared to Octreoscan in NET.

Fifty-one patients with NET (40 sporadic, 17 MEN1) of different origin were enrolled. 68Ga-DOTATATE PET was performed in all cases by acquiring whole body studies 40–60 min after the radioligand i.v. injection (74–111 MBq). Octreoscan was also performed in 27/51 patients using injection of Indium-111-DTPA-Phe1-Octreoscanreotide (120–200 MBq). Examinations results were rated considering histology, CT/MR examination and clinical follow-up.

The patient based sensitivity and specificity of PET was 77% and 100%,respectively; the lesion based sensitivity was 64% with a specificity of 85%. Positive and negative predictive values were 100% and 65%, respectively. The sensitivity was ~100% in pancreas and gut, ~75% in lung and thyroid, <50% in stomach. In the subgroup undergone both PET and Octreoscan, the result was concordant in 21 and discordant in 6 cases. The discordant cases were 5 PET positive/Octreoscan negative (3 pancreatic NET, 2 medullary thyroid cancer) and 1 PET negative/Octreoscan positive (atypical lung carcinoid). In PET-positive patients, a significant inverse correlation between SUVmax and Ki67 was recordered (P<0.01). At ROC analysis, SUVmax in patients with progressive disease was ≤17 while it was >17 in patients with stable or responsive disease (P<0.01).

In patients with NET 68Ga-DOTATATE PET shows higher diagnostic performance than Octreoscan and is suggested to predict clinical behaviour of the tumor.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.

Endocrine Abstracts

P774