The characteristic features of CT and MRI in the pancreatic neuroendocrine tumor / 医学研究生学报

ABSTRACT

Objective Pancreatic neuroendocrine tumor( PNET) is a rare kind of tumor with slow growth for which surgery is the main treatment.The histological grading of PNET was closely related to the choice of operation mode and the comprehensive treat-ment after operation.Imaging examinations such as enhanced CT and MRI are of great value in the preoperative diagnosis of PNET. The aim of this study was to investigate the characteristic features of CT and MRI in the PNET. Methods Preoperative imaging data of 80 patients with PNET confirmed by pathology were reviewed, including CT and MRI, and the image features of each PNET were an-alyzed and the statistical analysis was performed. Results There were significant differences in the lesion morphology between the G1 and G2 levels of PNET.The majority of forms of the G1 stage PNET lesions presented round-like regular shape, but the G2 stage did not show regular shape.CT examination showed that regular morphological lesions accounted for 91.30%(21/23) in the G1 level, and 52.00%(13/25)in the G2 level,χ2 =8.857,P=0.003.MRI examination showed that regular morphological lesions accounted for 88.48%(22/27)in the G1 level, and 55%(11/20) in the G2 level, χ2 =3.862,P=0.050.The difference of scan density in PNET lesions was statistically significant.Low density lesions accounted for 73.91%(17/23)in the G1 level, and 32%(8/25)in the G2 level.Equidensity lesions accounted for 26.09%(6/23)in the G1 level, and 68.00%(17/25)in the G2 level,χ2 =8.842,P=0.004.The difference of bile pancreatic duct expansion in the G1 and G2 level lesions was statistically significant by MRI examination. Lesions with expanded pancreatic duct accounted for 7.41%(2/27)in the G1 level,and 40%(8/20) in the G2 level, χ2 =7.287, P =0.007.There was significant difference in the peak time after en-hanced scanning between the G1 and G2 levels.Lesion enhancement peak at the arterial phase by CT examination of accounted for 21.74%(5/23) in the G1 level,and 64%(16/25) in the G2 level,χ2 =8.694,P=0.003.Lesion enhancement peak at the arterial phase by MRI examination accounted for 29.63% (8/27) in the G1 level, and 70% (14/20) in the G2 level, χ2 =7.521,P=0.006. Conclusion The lesion morphology, density of CT plain scan, CT or MRI enhancement peak time, and expansion of the bile duct and pancreatic duct can provide reliable information to distinguish the G1 and G2 stage in PNET.