Digestive Disease Interventions 2017; 01(S 01): S111-S142
DOI: 10.1055/s-0037-1603715
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The Role of 68Ga-DOTA-NOC PET in the Evaluation of Neuroendocrine Tumors

H. Al Mrad
1   Faculty of Medicine, Lebanese University, Beirut, Lebanon
,
R. Abou Said
2   Paul L Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, Texas
,
M. Haidar
3   American University of Beirut, Beirut, Lebanon
,
M. Haddad
1   Faculty of Medicine, Lebanese University, Beirut, Lebanon
,
M. Greige
4   Nuclear Medicine Department, Mount Lebanon Hospital, Beirut, Lebanon
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Publikationsdatum:
24. Mai 2017 (online)

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Functional imaging is a crucial part of the evaluation of neuroendocrine tumors. The aim of this study was to describe the yield of 68Ga- DOTA-NOC positron emission tomography (PET) in the diagnosis, staging, and follow up of neuroendocrine tumors (NETs).

Materials and Methods: This is a retrospective study, 68Ga-DOTA-NOC PET was reviewed for 180 patients as shown in Fig. 1.

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Fig. 1

Findings were compared with final outcome (follow ups/pathology data). Then, these were classified as true positive, true negative, false positive, or false negative. Sensitivity and specificity of PET were calculated and compared with literature values of dedicated computed tomography (CT) and scintigraphy. Sensitivity and specificity were also calculated based on the reason for PET use.

Results: The most common pathology was pancreatic NETs n = 28 (27.2%) followed by bowel carcinoid n = 14 (13.8%). 68Ga-DOTA-NOC PET was true positive in 74 (57.4%), true negative in 43 (33.3%), false positive in 1 (0.8%), and false negative in 11 (8.5%) patients. The false-positive one was attributed to inflammatory changes. The 11 false negatives included 8 in the staging group due to small lesions obtained by tissue sampling (2 gastroscopy, 1 colonoscopy, 2 transcutaneously) and 3 having high grade tumors hence, the loss of somatostatin receptors. Our study showed excellent performance of 68Ga-DOTA-NOC PET with sensitivity (87.1%) and specificity (97.7%) values comparable to those described in the literature. Further analysis based on the reason for PET scan showed that the highest accuracy (0.952) was in follow-up patients: advanced disease, multiple metastases. Most patients with clinical indication alone had a negative scan (14/17) while patients with radiological indication had a high positive result ratio (6/14). Clinical suspicion alone is not enough to justify a Ga-DOTA scan and other biological/conventional radiological studies should precede Ga-DOTA. Results are summarized in Tables 1 and 2.

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Table 1
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Table 2

Conclusion: In our study, we demonstrate a higher detection rate of NET using 68Ga-DOTA-NOC PET with a high sensitivity of 87.1% and specificity of 97.7%. Considering the superior values to diagnostic CT and scintigraphy in various clinical situations (initial diagnosis, staging, and follow-up), we support the use of 68Ga-DOTA-NOC PET as a primary diagnostic modality when evaluating NETs and we suggest further prospective multicentric studies with both dedicated CT scans and PET/CTs performed in the same set of patients are warranted to further support our study.