Ultrasound scans use high-frequency sound waves, which people cannot hear, to create a picture of the inside of the body. During an ultrasound test, sound waves are transmitted through body tissues using an instrument called a transducer. This information is then displayed on a computer monitor.


These scans are usually carried out in the radiology department of a hospital. Two types of ultrasound that may be used to help diagnose NETs include:

  • Abdominal ultrasounds: Can be used to examine organs inside the abdomen. However, abdominal ultrasounds are limited in detecting very small tumors. Abdominal ultrasounds are also often used for scanning pregnant women
  • Ultrasound endoscope: Can help pick up smaller tumors that might not be clearly visible on an abdominal ultrasound. These types of ultrasounds are usually carried out under sedation and involve looking at the digestive tract with an endoscope. A flexible fiberoptic tube will be inserted down the back of the throat (gastroscopy) or through your rectum (colonoscopy). Biopsy can also be performed during the endoscopic ultrasound

Computed tomography (CT)

CT and MRI are two imaging techniques used for diagnosing NETs. These techniques can both be used to determine the position and size of tumors.

A CT scanner is a special type of X-ray machine that uses radiation to provide a three-dimensional picture of the inside of the body. The CT scan is usually carried out by a radiologist. Regular CT scans are useful to find out more about the rate of tumor growth and how your NETs are responding to treatment.

See the practical tips section for more advice on preparing for imaging scans.

Magnetic resonance imaging (MRI)

MRI is a type of scan that uses a powerful magnetic field and pulses of radio wave energy to make cross-sectional images of organs, tissues, bones and blood vessels. A computer turns the images into three-dimensional pictures. An MRI scan may be used if an ultrasound scan or CT scan do not provide doctors with enough information to make a diagnosis. Similar to having a CT scan, you will need to lie very still while the machine scans your body.

See the practical tips section for more advice on preparing for imaging scans.


Echocardiography is an imaging test that uses ultrasound to produce moving images of the heart and blood flow through the heart’s valves and chambers.

Some types of NETs that are associated with carcinoid syndrome will release hormones called serotonin and tachykinins into the bloodstream. These hormones can travel to the heart and affect the cardiac valves.

If you have been diagnosed with carcinoid syndrome, your specialist may perform an echocardiography to examine your heart, and/or a blood test called an NT-proBNP, which is used to help detect and evaluate the risk of heart failure.

The echocardiography probe is placed on the thorax and images are taken through the chest wall (transthoracic echocardiography).

Depending on the results of the echocardiography, you may need further investigations, such as transesophageal echocardiography or a cardiac MRI.

See the practical tips section for more advice on preparing for imaging scans.

Positron emission tomography (PET)

A PET scan is a unique type of imaging test that allows doctors to see how the organs and tissues inside your body are actually functioning. This scan involves injecting a very small dose of a radioactive chemical, called a tracer, into the vein of your arm.

PET scans can detect and record the energy given off by the tracer in your cells. Detailed, three-dimensional images from the PET scan are then produced through a computer. A PET scan is usually used in combination with a CT scan to build up a picture of the size, location, and status of NETs.

Certain types of radioactive tracers can be used in PET scans to detect particular types of NETs:

18F-DOPA PET scan

18F-DOPA is an abbreviation for 18F-dihydroxy-phenylalanine, which is the radioactive tracer for this type of PET scan. This tracer is highly sensitive for detecting the primary tumor of a NET, and secondary tumors (metastases), where the disease has spread.

FDG-PET scan

FDG is an abbreviation for fluorodeoxyglucose, which is the tracer injected for this type of PET scan. A PET scan is used to identify the presence of a metabolically active tumor within the body.

Gallium-68 PET scan

Gallium-68 is a radioactive tracer that can be attached to octreotate. It is injected into the body and can be used to identify specific neuroendocrine cancer cells containing somatostatin receptors. Gallium-68 may also be used for other diagnostic tests.

Scintigraphy Scans

Scintigraphy scans, such as a somatostatin-receptor scan, may be performed to determine where the neuroendocrine tumors (NETs, which you may also hear referred to as carcinoid tumors, GI-NETs, GEP-NETs, pancreatic NETs, and lung NETs) started and if the tumors have spread in the body.

Scintigraphy scans are radioactive imaging techniques and also include bone scintigraphy and an MIBG scan, which are discussed below.

Scintigraphy scans are usually performed after a patient has already had another type of scan such as an ultrasound scan, magnetic resonance imaging (MRI) scan, computed tomography (CT) scan, or PET scan.

Somatostatin-receptor scintigraphy (SRS)

A somatostatin-receptor scintigraphy (SRS) is used to detect certain neuroendocrine cancer cells in the body. The test requires multiple scans, usually taken over 2 days.

On the first day, you will receive an injection that contains a very small amount of a radioactive substance called a tracer.

The tracer will attach to neuroendocrine cells with somatostatin receptors on their surface.

Later that day, the first set of scans will be taken to look for areas in the body that have picked up this tracer, which may indicate where certain neuroendocrine cancer cells are located. Further SRS scans will usually be taken over the next 24 to 48 hours to produce more detailed pictures.

Bone scintigraphy scan

A bone scintigraphy scan is an imaging test that uses a very small amount of a radioactive substance to determine if a NET has spread to the bones from another part of the body.

Usually the entire body is scanned during a bone scintigraphy. If the results show bone damage that may be caused by cancer, then more diagnostic NET tests may be necessary. These may include a CT scan, an MRI scan, or taking a biopsy.

MIBG scintigraphy scan

A MIBG scan is another imaging test that can be carried out to find the location of NETs in the body, but it is used less often than an octreotide scan.

It works by injecting a substance called an isotope into your veins. The MIBG scan is named after the chemical “iodine-131-meta-iodobenzylguanidine,” or MIBG for short, to which the isotope is attached.

After it is injected, the isotope travels around the body and can detect NETs. Several hours or days later the body is scanned with a gamma camera to look for areas that have picked up the isotope.

This allows doctors to identify and pinpoint any areas of abnormality, including certain types of NETs.

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The emotional, physical, and social challenges of living with NETs.

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