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Pancreatic neuroendocrine neoplasms at magnetic resonance imaging: comparison between grade 3 and grade 1/2 tumors

Authors Guo C, Chen X, Xiao W, Wang Q, Sun K, Wang Z

Received 16 November 2016

Accepted for publication 1 February 2017

Published 7 March 2017 Volume 2017:10 Pages 1465—1474

DOI https://doi.org/10.2147/OTT.S127803

Checked for plagiarism Yes

Review by Single-blind

Peer reviewers approved by Dr Manfred Beleut

Peer reviewer comments 3

Editor who approved publication: Dr William Cho

Chuangen Guo,1,* Xiao Chen,2,* Wenbo Xiao,1 Qidong Wang,1 Ke Sun,3 Zhongqiu Wang2

1Department of Radiology, The First Affiliated Hospital, College of Medicine Zhejiang University, Hangzhou, 2Department of Radiology, The Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, 3Department of Pathology, The First Affiliated Hospital, College of Medicine Zhejiang University, Hangzhou, People’s Republic of China

*These authors contributed equally to this work

Background: The grading of pancreatic neuroendocrine neoplasms (PanNENs) is associated with the choice of treatment strategy. The aim of this study is to identify the magnetic resonance imaging (MRI) features in differentiating pancreatic neuroendocrine tumors (PanNETs) grade 1/2 (G1/G2) and pancreatic neuroendocrine carcinoma grade 3 (PanNEC G3).
Patients and methods: A total of 59 patients with histologically proven PanNENs and who underwent pretreatment MRI were retrospectively analyzed. Tumor location, size, boundary, cystic or solid appearance, enhancement degree, pancreatic duct dilatation, metastases and MRI signal were evaluated. Apparent diffusion coefficients (ADCs) were measured on ADC maps. Receiver operating characteristic curve was used to determine the cut off values and the sensitivity and specificity of prediction. Spearman correlation and logistic regression analysis were adopted to identify the association between MRI features and pathological parameters.
Results: A total of 47 lesions were PanNETs G1/G2 and 12 lesions were PanNEC G3. G1/G2 tumors were more common with well-circumscribed border compared with PanNEC G3. Ill-defined boundary, big size, necrosis, low-moderate enhancement, pancreatic duct dilatation, metastases and high diffusion-weighted imaging (DWI) intensity were more common in PanNEC G3 than in PanNETs G1/G2. The ADC values of PanNEC G3 were also significantly lower compared with the PanNETs G1/G2 and normal pancreatic parenchyma. The cut off value of ADC was 0.95×10-3 mm2/s for differentiating PanNEC G3 from PanNETs G1/G2 with 72.3% sensitivity and 91.6% specificity, respectively. Ki-67 index and mitosis count positively correlated with tumor size, pancreatic duct dilatation and metastases (P<0.05) and negatively correlated with ADC values (P<0.01), respectively. Regression analysis further showed that metastases and ADC value were associated with PanNENs grade.
Conclusion: Metastases and ADC value may have potential for differentiating PanNEC G3 from PanNETs G1/G2.

Keywords: pancreatic neuroendocrine tumors, pancreatic neuroendocrine carcinoma, magnetic resonance imaging, diffusion-weighted imaging, apparent diffusion coefficients

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