Jaime L. Montilla MD, Presenter: Nothing to Disclose

Volkan Adsay, Abstract Co-Author: Nothing to Disclose

David Kooby MD, Abstract Co-Author: Nothing to Disclose

Naomi P. Alazraki MD, Abstract Co-Author: Nothing to Disclose

Malcolm H Squires BS, MD, Abstract Co-Author: Nothing to Disclose

Fidias Eduardo De Leon MD, Abstract Co-Author: Nothing to Disclose

This is a retrospective study, trying to determine which imaging modality, 111-In-Pentetreotide or 18-F-FDG is better suited for accurately staging neuroendocrine tumors.

Records of patients with neuroendocrine tumors (NT) from 1995-2007 were reviewed. Inclusion criteria: Pathology specimen and imaging with 111In-Pentetreotide (SRI) and/or 18F-FDG PET/CT (PET). Variables include primary tumor site/size/number/differentiation/presence/absence of metastatic disease. Group A (N=14): well/moderately-well differentiated. Group B(N=19): poorly differentiated. SRI: 4/24 hrs after 6 mCi 111In-Pentetreotide IV, whole body planar and tomographic (SPECT/CT) images. PET: After fasting (BGS<120 mg/dl), 15 mCi 18F-FDG was administered IV. Skull base to thigh PET/CT exam was performed 1 hr later. PET, CT and fused PET/CT images were reviewed by nuclear medicine physician, blinded to pathology results. Quantification (SUVmax) was performed. All patients had a contrast enhanced CT. A pathologist re-examined the specimens for mitotic number/tumor size/nuclear pleomorphism, blinded to imaging results. Statistical analysis performed with SPSS 15.0 for Windows. Fisher’s exact test analyzed dichotomous variables: sex/tumor stage. SRI and PET imaging results recorded as pos or neg. Unpaired t-test analyzed continuous variables of age and tumor size. Histological findings were considered the true standard of tumor differentiation.

44/140 pts with NT diagnosis had pathology and imaging results, 33 pts with NT, 11 with carcinoid. 21 had SRI and 20 had PET, 8 pts had both. SRI detected well-differentiated NT in 9/13(69%), PET was positive in 4/8(50%). PET detected 16/16(100%) poorly-differentiated NTs, while SRI detected 2/4(50%). In 8 pts who had SRI and PET, PET detected 7/8(88%), including all 5 poorly-differentiated tumors. SIR detected 2/3(67%) of well-differentiated tumors but only in 2/5(40%) of poorly differentiated tumors. 10/11 well-differentiated carcinoids had SIR, 3/10 had PET and 2/10 had both. SIR detected 9/10 while PET detected 3/3.

SRI is more effective at staging well-differentiated neuroendocrine tumors, while PET accurately stages poorly-differentiated neuroendocrine tumors.

There is no consensus in our literature on how to accurately stage patients with neuroendocrine tumors, our study sheds some light on this clinical dilemma and proposes an algorithmic approach.

Montilla, J, Adsay, V, Kooby, D, Alazraki, N, Squires, M, De Leon, F, A Retrospective Comparative Analysis of 18-F-FDG PET/CT versus 111-In-Pentetreotide Imaging Correlated with Histological Differentiation in the Evaluation of Neuroendocrine Tumors.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8002885.html