The diagnosis of NET of the small bowel is made by

Elevated excretion of 5-hydroxyindoleacetic acid is a probable indicator of the presence of a serotonin-producing tumor (carcinoid)CT scan and MRI may show the primary tumour, mesenteric lymph node and liver metastases.The best method for staging of NET is an octreotide (SRS) scan. This will show all tumour deposits provided that they are large enough and have a high somatostatin receptor densityRef: Bailey and Love 27e pg: 855