Fumihito Toshima MD, Presenter: Nothing to Disclose

Dai Inoue, Abstract Co-Author: Nothing to Disclose

Toshifumi Gabata MD, Abstract Co-Author: Nothing to Disclose

Tetsuya Minami MD, Abstract Co-Author: Nothing to Disclose

Satoshi Kobayashi MD, Abstract Co-Author: Nothing to Disclose

Osamu Matsui MD, Abstract Co-Author: Research Consultant, Kowa Company, Ltd Research Consultant, Otsuka Holdings Co, Ltd Research Consultant, Eisai Co, Ltd Speakers Bureau, Bayer AG Speakers Bureau, Eisai Co, Ltd

Kotaro Yoshida MD, Abstract Co-Author: Nothing to Disclose

Norihide Yoneda, Abstract Co-Author: Nothing to Disclose

To retrospectively determine the CT and MR imaging findings, distinguishing the histological malignancies of pancreatic neuroendocrine neoplasms (PNENs) defined by World Health Organization (WHO) 2010 classification.

Institutional ethics committee approval and informed consent were obtained. 118 lesions in 109 patients (60 men and 49 women; mean age, 60 years) were histopathologically diagnosed as PNENs in our institutions and 89 resected lesions in 80 patients were included in this study. All lesions were classified into two groups based on the tumor grade, G1 group (including G1 lesions, n=55) and G2 + G3 group (including G2 lesions, n=32 and G3 lesions, n=2), respectively. Various imaging findings such as lesion location, diameter, shape, border, attenuation at non-enhanced CT, homogeneity, enhancement pattern on dynamic multiphase CT, presence of calcification, cystic portion, hemorrhagic change, vascular invasion, and main pancreatic duct (MPD) dilatation, signal intensity of MR images (T1, T2, and diffusion weighted images) and ADC values were evaluated. All imaging findings were compared for each group. Moreover, sensitivity, specificity, PPVs and NPVs in the prediction of G2 + G3 group were also calculated. Mann-Whitney or X2-test was used adequately for evaluating these correlations and a value of p < 0.05 was considered as significant.

Diameter, homogeneity, enhancement pattern, vascular invasion and ADC value were significant differences between G1 group and G2 + G3 group. The rate of lesions with calcification, cystic portion and MPD dilatation tended to be greater in G2 + G3 group than G1 group, however there was no significant difference. All lesions appeared as round or lobulated masses and 84 lesions were well-defined regardless of the tumor grade. Hemorrhagic changes were not found in any lesions. PPVs and NPVs for each imaging findings were 46.9-80.0% and 61.4-90.9%, respectively. Highly PPV and NPV for combined diameter, enhancement pattern and ADC value were observed.

Several imaging findings of CT and MRI are correlated with the tumor grade defined by WHO classification and considered as useful modalities for evaluating histological malignancy.

Several imaging findings of non-invasive modalities such as CT and MR are useful for evaluating histological malignancy defined by WHO 2010 classification and determining the treatment strategy.

Toshima, F, Inoue, D, Gabata, T, Minami, T, Kobayashi, S, Matsui, O, Yoshida, K, Yoneda, N, Pancreatic Neuroendocrine Neoplasms—Imaging features for Distinguishing the Histological Malignancy Defined by World Health Organization 2010 Classification.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14017476.html