Best Practice & Research Clinical Endocrinology & Metabolism
4Imaging of neuroendocrine tumours (CT/MR/US)
Section snippets
Pancreatic endocrine tumours (PETs)
PETs are rare neoplasms that arise from the islet cells of Langerhans, the majority of which are hyperfunctioning, and are classified according to the hormone secreted. They include insulinoma, gastrinoma, VIPoma, glucagonoma and somatostatinoma1; 15–30% of PETs are non-functioning.2, 3
Insulinomas are by far the most common PET, accounting for up to 50% of all cases.4 They are solitary and intra-pancreatic in over 90% of cases, with an equal distribution in the head, body and tail of the gland4
‘Carcinoids’ (Bronchial and gastrointestinal neuroendocrine tumours)
Carcinoid tumours occur much more frequently than PETs and account for 2% of malignant tumours of the gastrointestinal tract.43, 44 Only 10% of such tumours are associated with the carcinoid syndrome, and delay in diagnosis often occurs due to non-specific presenting features. The tumour cells arise from the diffuse neuroendocrine system and have the potential to secrete a wide variety of amines and peptides, and therefore are now often referred to as neuroendocrine tumours (NETs) to reflect
Metastases from pancreatic and carcinoid neuroendocrine tumours
Metastases are a common finding in all NETs. In a large autopsy series, 29% of patients with a carcinoid NET were found to have metastatic disease, the majority (61%) arising from small bowel carcinoids.44 In this series, 90% of metastases were in lymph nodes, 44% in the liver, 14% in the lungs, 14% in the peritoneum and 7% in the pancreas. The imaging appearances of metastatic disease in both pancreatic and carcinoid NETs is similar and will be considered together.
Follow-up
Surgical resection is the only curative technique in pancreatic and carcinoid neuroendocrine tumours. However, in non-resectable tumours imaging may play a role in treatment follow-up. CT (or MRI) is used to assess the response to therapy both in primary and metastatic disease. MRI is the preferred modality for follow-up in patients with disorders such as MEN1 where repeated imaging may be required for prolonged surveillance due to the often indolent nature of the disease.
Conclusion
The technological advances in CT and MRI have allowed these techniques to play an increasingly important role in the management of patients with neuroendocrine tumours. The development of multidetector CT has improved sensitivities in the detection of pancreatic islet-cell tumours, as has faster gradients and other advances in MRI. Both techniques appear to have similar sensitivities for localization of islet-cell tumours, although evaluation of the literature is difficult as series are small
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2021, Surgical OncologyCitation Excerpt :Pancreatic phase images have superior sensitivity to identify pancreatic lesions and are obtained in the late arterial phase at 40–45 s after contrast injection ([10]). PNETs usually appear as well-defined, isodense or sometimes hypodense lesions on non-enhanced CT scan, and as hypervascular tumors on contrast enhanced imaging ([12,22]) (Fig. 1). Due to their hypervascular nature, the pNET lesions appear enhanced on arterial phase ([9,22]) (Fig. 2) often with a vascular blush, which is better elucidated on narrow window settings ([22]).
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