CT differentiation of poorly-differentiated gastric neuroendocrine tumours from well-differentiated neuroendocrine tumours and gastric adenocarcinomas.

Purpose: To evaluate the differential CT features of gastric poorly-differentiated neuroendocrine tumours (PD-NETs) from well-differentiated NETs (WD-NETs) and gastric adenocarcinomas (ADCs) and to suggest differential features of hepatic metastases from gastric NETs and ADCs.

Materials And Methods: Our study population was comprised of 36 patients with gastric NETs (18 WD-NETs, 18 PD-NETs) and 38 patients with gastric ADCs who served as our control group. Multiple CT features were assessed to identify significant differential CT findings of PD-NETs from WD-NETs and ADCs. In addition, CT features of hepatic metastases including the metastasis-to-liver ratio were analyzed to differentiate metastatic NETs from ADCs.

Results: The presence of metastatic lymph nodes was the sole differentiator of PD-NETs from WD-NETs (P = .001, odds ratio = 56.67), while the presence of intact overlying mucosa with mucosal tenting was the sole significant CT feature differentiating PD-NETs from ADCs (P = .047, odds ratio = 15.3) For hepatic metastases, metastases from NETs were more hyper-attenuated than those from ADCs.

Conclusion: The presence of metastatic LNs and intact overlying mucosa with mucosal tenting are useful CT discriminators of PD-NETs from WD-NETs and ADCs, respectively. In addition, a higher metastasis-to-liver ratio may help differentiate hepatic metastases of gastric NETs from those of gastric ADCs with high accuracy.

Key Points: • Presence of metastatic LNs is a useful differentiator of PD-NETs from WD-NETs. • Intact overlying mucosa with mucosal tenting suggests PD-NETs more than gastric ADCs. • Metastatic LNs are larger in size and greater in necrotic volume in PD-NETs. • Hepatic metastases from gastric NETs are more hyper-attenuated than those from ADCs.