Which scans are used in helping to diagnose NET cancers?

There are also a number of scans the patient may be asked to have. The physician will request the specific test that he/she requires and this may change dependent on the stage of disease and reason for scanning.

There are different reasons for different scans to be used, these are:

  • screening
  • detecting the primary tumor in a patient suspected of a NET
  • assessing extent of disease
  • assessing response to treatment
  • follow up after an initial diagnosis and/or treatment

NB: There is no standard group of tests – each patient may need to undergo a different combination of tests. If you have any questions about these tests, please confer with your medical team.

OctreoScan®

This scan uses a body imaging technique. Cells that receive hormonal messages do so through receptors on the surface of the cells. For reasons that are not understood, many neuroendocrine tumor cells possess especially strong receptors; for example, GEP-NETs often have strong receptors for somatostatin, a very common hormone. The OctreoScan® uses a synthetic form of somatostatin, which is chemically bound to a radioactive substance. This is then injected via a vein in the arm and then observed 24 hours later using a radio-sensitive scan. These scans can diagnose and locate around 80-90% of GEP-NETs, although further scans, such as PET scans may still be required.

CT Scan

A CT (Computer Tomography) scanner is a special type of X-ray machine. A CT scan uses ionizing radiation to provide a three-dimensional picture of the inside of the body. It can be used to determine the position and size of tumors, and regular scans are useful to find out more about the rate of tumor growth and how the tumor is responding to treatment. Before the scan, the patient may have an injection or drink a fluid containing a dye that shows up on the scan.

MRI Scan

A Magnetic Resonance Imaging (MRI) scan can be used to locate a tumor. Magnetism is used instead of X-rays to produce soft-tissue images that can distinguish between normal and diseased tissue. If a tumor is identified in this way, further tests may be needed to confirm what type of tumor it is.

PET Scan

A Positive Emission Tomography (PET) scan is a nuclear medicine imaging technique which produces a three-dimensional image of functional processes in the body. When FDG-18 is injected into your body it travels to places where glucose is used for energy. It shows up cancers because they use glucose in a different way from normal tissue. And it will show up changes in tissues that use glucose as their main source of energy – for example, the brain. It is usually used in conjunction with a CT scan to build up a picture of the size, location and status of tumors.

PET scanners are very expensive and a limited number of hospitals have one. This means that a patient may have to travel to another hospital for their scan. Not everybody who has cancer will need to have a PET scan, other types of tests and scans may be more suitable.

MIBG Scan

An MIBG Scan is a nuclear medicine scan which involves an injection of a liquid radioactive material called iodine-123-meta-iodobenzylguanidine – MIBG for short. The radioactive material is injected into a vein on the front of your arm at the level of your elbow, or in the back of your hand.

A special gamma camera (a type of scanner), finds or confirms the presence of tumors. These tumors involve specific types of nerve tissues and most commonly include pheochromocytomas (a rare cancer of the adrenal gland which is located on the surface of the kidneys) and neuroblastomas (cancers which affect nerve tissue). Neuroblastoma tumors usually begin in the adrenal gland but may also be found elsewhere in the body.

Bone Scan

A bone scan looks for changes or abnormalities in the bones. It is also called a radionuclide scan, or a scintigram and is usually done in the medical physics department, nuclear medicine department, or X-ray department of the hospital.

A bone scan can look at a particular joint or bone. In cancer diagnosis, it is more usual to scan the whole body.

Echocardiogram

Carcinoid tumors release chemicals called serotonin and tachykinins into the blood stream which can travel to the heart and affect the cardiac valves. If you have been diagnosed with a midgut carcinoid your doctor may do a blood test called a NT proBNP. If the result of this test is elevated, then he/she will send you for an echocardiogram to examine your heart. This is an ultrasound of your heart and is usually performed by a cardiac technician.

A small amount of sterile water will be injected into a vein and this is pictured as it passes around the heart. Depending on the results you may need two further investigations:

  • Transesophageal echocardiogram
  • Cardiac catheterisation