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Imaging of neuroendocrine tumours (CT/MR/US)

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Neuroendocrine tumours may be broadly divided into pancreatic endocrine tumours (PETs) and carcinoid neuroendocrine tumours (NETs). In both cases, patients may present with a clinical syndrome related to hormone secretion by the tumour. In these cases, cross-sectional imaging plays an important role in the localization of the primary tumour, the detection of metastases, and the assessment of response to treatment. Computed tomography (CT) is established as the primary modality, although following technological advances detection rates on magnetic resonance imaging (MRI) are now challenging those of CT. Endoscopic ultrasound has an important role in the preoperative assessment of the pancreas where a small functioning tumour or the possibility of multiple tumours is suspected. The sensitivity for the detection of small functioning tumours depends upon optimal technique, whichever modality is used. Non-functioning tumours frequently present late with mass effect, as there is no accompanying clinical syndrome. Carcinoid neuroendocrine tumours are most frequently localized on CT. MRI is usually used as a problem-solving tool. As technology evolves, detection rates may continue to improve, and the highest sensitivities may be achieved by a combination of different modalities.

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

References (84)

  • T. Matsumoto et al.

    Endoscopic ultrasonography in rectal carcinoid tumors: contribution to selection of therapy

    Gastrointestinal Endoscopy

    (1991)
  • E.T. Janson et al.

    Carcinoid tumors: analysis of prognostic factors and survival in 301 patients from a referral center

    Annals of Oncology

    (1997)
  • I. Fukai et al.

    Thymic neuroendocrine tumor (thymic carcinoid): a clinicopathologic study in 15 patients

    The Annals of Thoracic Surgery

    (1999)
  • J.H. Khan et al.

    Pulmonary metastases of endocrine origin: the role of surgery

    Chest

    (1998)
  • D.C. Metz

    Diagnosis and treatment of pancreatic neuroendocrine tumors

    Seminars in Gastrointestinal Disease

    (1995)
  • R.B. Kent et al.

    Nonfunctioning islet cell tumors

    Annals of Surgery

    (1981)
  • D.D. Stark et al.

    CT of pancreatic islet cell tumors

    Radiology

    (1984)
  • M.C. Aldridge et al.

    Surgery of endocrine tumours of the pancreas

  • J.A. van Heerden et al.

    Occult functioning insulinomas: which localizing studies are indicated?

    Surgery

    (1992)
  • F.J. Service et al.

    Insulinoma: clinical and diagnostic features of 60 consecutive cases

    Mayo Clinic Proceedings

    (1976)
  • H.R. Alexander et al.

    Pancreatic endocrine tumors

  • F. Yu et al.

    Prospective study of the clinical course, prognostic factors, causes of death, and survival in patients with long-standing Zollinger–Ellison syndrome

    Journal of Clinical Oncology

    (1999)
  • P.J. Hammond et al.

    Localization of pancreatic endocrine tumours

    Clinical Endocrinology

    (1994)
  • A.I. Vinik et al.

    Somatostatinomas, PPomas, neurotensinomas

    Seminars in Oncology

    (1987)
  • T.C. Bottger et al.

    Value of tumor localization in patients with insulinoma

    World Journal of Surgery

    (1990)
  • O. Oshikawa et al.

    Dynamic sonography of pancreatic tumors: comparison with dynamic CT

    AJR. American Journal of Roentgenology

    (2002)
  • N. Ueno et al.

    Utility of endoscopic ultrasonography with color Doppler function for the diagnosis of islet cell tumor

    The American Journal of Gastroenterology

    (1996)
  • T. Rosch et al.

    Localization of pancreatic endocrine tumors by endoscopic ultrasonography

    The New England Journal of Medicine

    (1992)
  • J.A. Norton et al.

    Intraoperative ultrasonographic localization of islet cell tumors. A prospective comparison to palpation

    Annals of Surgery

    (1988)
  • M.K. Kalra et al.

    State-of-the-art imaging of pancreatic neoplasms

    The British Journal of Radiology

    (2003)
  • J.L. Fidler et al.

    Preoperative detection of pancreatic insulinomas on multiphasic helical CT

    AJR. American Journal of Roentgenology

    (2003)
  • A.D. King et al.

    Dual phase spiral CT in the detection of small insulinomas of the pancreas

    The British Journal of Radiology

    (1998)
  • P.C. Buetow et al.

    Islet cell tumors of the pancreas: pathologic-imaging correlation among size, necrosis and cysts, calcification, malignant behavior, and functional status

    AJR. American Journal of Roentgenology

    (1995)
  • D.B. Stafford-Johnson et al.

    Dual-phase helical CT of nonfunctioning islet cell tumors

    Journal of Computer Assisted Tomography

    (1998)
  • L. Van Hoe et al.

    Helical CT for the preoperative localization of islet cell tumors of the pancreas: value of arterial and parenchymal phase images

    AJR. American Journal of Roentgenology

    (1995)
  • M.J. Chung et al.

    Functioning islet cell tumor of the pancreas. Localization with dynamic spiral CT

    Acta Radiologica

    (1997)
  • T. Ichikawa et al.

    Islet cell tumor of the pancreas: biphasic CT versus MR imaging in tumor detection

    Radiology

    (2000)
  • A.C. Pfannenberg et al.

    Dual-phase multidetector thin-section CT in detecting duodenal gastrinoma

    Abdominal Imaging

    (2005)
  • T. Zhang et al.

    The diagnosis and treatment of gastrinoma: report of 17 cases

    Chinese Medical Sciences Journal

    (1999)
  • G.C. Nikou et al.

    VIPomas: an update in diagnosis and management in a series of 11 patients

    Hepatogastroenterology

    (2005)
  • H. Gouya et al.

    CT, endoscopic sonography, and a combined protocol for preoperative evaluation of pancreatic insulinomas

    AJR. American Journal of Roentgenology

    (2003)
  • N.J. Owen et al.

    MRI of pancreatic neuroendocrine tumours

    The British Journal of Radiology

    (2001)
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