Non-invasive method identifies exact position of rare tumours

Researchers have found a non-invasive way to identify the exact position of rare pancreatic tumours less than 1cm in diameter.

A team from the University Hospital of Bern, Switzerland, combined two types of computed tomography (CT) scan to produce two- and three-dimensional images of tumour cells targeted with a radioactive drug that reacts with receptors on the cells.

Researcher Prof Emanuel Christ said the new technique would make it much easier to remove the tumours — known as insulinomas — because current procedures were not able to localise them.

‘These data suggest that it’s possible to detect very small, life-threatening insulinomas within the pancreas, based on the characteristic receptors on the surface of these tumours,’ he said.

‘This technique avoids the more invasive tests to localise the insulinomas and facilitates the surgical approach. Surgery is still the only method of curing this particular disease.’

Insulinomas are very rare tumours occurring in two to four people per million each year, which secrete insulin in an unregulated way, causing blood glucose to fall lower than normal.

‘In the majority of cases these tumours are benign, but they are life threatening because they can lead to severe hypoglycaemia — low blood glucose,’ said Christ.

The researchers found that although insulinomas don’t have a sufficient number of receptors for them to be detected with the established Octreoscan technique, they do have a high density of a type of another hormone receptor that can be radioactively labelled.

They were then able to image the labelled cells using single-photon emission computed tomography (SPECT) and a conventional CT scan.

Current invasive techniques for detecting insulinomas include inserting catheters into the arteries and veins around the pancreas, injecting calcium gluconate into the arteries supplying the pancreas and taking samples from veins to test for insulin.

The researchers now intend to see if positron emission tomography (PET), another nuclear medicine imaging technique, could improve the quality of tumour localisation even further.

They presented their findings yesterday at the joint International Congress of Endocrinology/European Congress of Endocrinology.