Imaging of neuroendocrine gastroenteropancreatic tumours

Abstract

The role of imaging in functioning endocrine tumours (FETs) is primarily to detect the tumour, that is, to verify lesion number and location. Radiological detection of carcinoid tumours is limited by typical tumour location throughout the gastrointestinal tract or appendix and is therefore dependent on the tumour being large enough to make it recognisable in that site. The most common FET is insulinoma, which is commonly characterised by the typical appearance of a hypervascular lesion at multidetector-row computed tomography and magnetic resonance imaging. A particularly important role is played by intraoperative ultrasound in defining the exact number of lesions, their relationship with adjacent vascular structures and the pancreatic duct for the purposes of correct surgical planning (enucleation or resection). In the setting of nonfunctioning endocrine tumours (NFETs), which manifest late as large masses causing compression symptoms or as incidental findings, imaging is not primarily aimed at tumour detection, as this is relatively easy given the large size of the lesions. Rather, its role is to characterise the tumour and, in particular, to differentiate pancreatic NFET from ductal adenocarcinoma, as in comparison, malignant NFETs have a more favourable prognosis (5-year survival rate 40% compared with 3%-5% for adenocarcinoma) and therefore require different treatment approaches. As NFET are often malignant, they also require accurate staging and appropriate follow-up. In 80% of cases, NFETs have a "typical" imaging appearance: location in the pancreatic head, large dimensions (diameter between 5 and 15 cm, >10 cm in 30% of cases), capsule, sharp and regular margins owing to the expansile and noninfiltrative growth pattern, solid density and arterial hypervascularity. Some 20% of NFETs display different imaging characteristics ("atypical" appearance) as a result of arterial hypovascularity due to the presence of abundant fibrous stroma. Lastly, a small percentage of NFETs has yet a different appearance ("unusual") due to the cystic nature and/or diffuse location throughout the pancreatic parenchyma.

Screening of pancreaticoduodenal endocrine tumours in patients with MEN 1: multidetector-row computed tomography vs. endoscopic ultrasound

“…L'eco-endoscopia è stata effettuata con strumento radiale (7,(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) MHz, olympus GIF-UM130Q) in sedazione cosciente (Midazolam). Una volta introdotto lo strumento nel lume gastrico si è provveduto ad aspirare l'aria ed il liquido eventualmente presente e si è condotta l'esplorazione ultrasonografi ca del corpo e della coda del pancreas ponendo il trasduttore a contatto con la parete gastrica.…”

Secretin-enhanced MR Imaging of the Pancreas

“…Ductal stenosis is a secondary sign of pancreatic neoplasms, both adenocarcinoma and neuroendocrine neoplasms (74)(75)(76); however, a ductal stenosis may occur also in patients with chronic pancreatitis or autoimmune pancreatitis and as a late complication of abdominal trauma. In some patients, the differential diagnosis between a neoplastic and a benign cause of ductal stenosis is complicated by the coexistence in benign disease of a focal pancreatic enlargement due to inflammation, granulation tissue or lymphocytes, and plasma cell in a periductal infiltrate.…”

Neuroendocrine Neoplasms

“…A well-encapsulated rounded lesion characterized by a wide central cystic area can be demonstrated at US, CT, and MRI. After the administration of contrast agent, a typical rapid enhancement of the solid, usually thick, components is easily documented around the central unehancing portion [1,[50][51][52][53][54].…”

“…Neuroendocrine cystic tumors usually present a unilocular central cyst, with solid complex components, such as irregular thick wall, septa, and nodules; this aspect can also be found in some other cystic pancreatic tumors (e.g., mucinous cystic neoplasms, IPMNs) and in other solid pancreatic neoplasms with cystic component or cystic degeneration, such as solid pseudopapillary tumor, adenocarcinoma, and metastases [1,[50][51][52][53][54]. On the contrary, as previously stated, in case of cystic presentation with thin wall and septa, no possible definitive differential diagnosis in respect to mucinous cystadenoma can be made at imaging.…”