Tests for Neuroblastoma

Ultrasound uses sound waves and their echoes to look inside the body. This might be one of the first tests done in very young children if a tumor is suspected. It is fairly quick and easy, it does not use radiation, and it can often give the doctor a good view inside the body.

Ultrasound is used most often to look for tumors in the abdomen.

MRI scans provide detailed images of soft tissues in the body. These scans may be slightly better than CT scans for seeing a neuroblastoma tumor, especially around the spine.

MRI scans use radio waves and strong magnets to create the images instead of x-rays, so there is no radiation. A contrast material called gadolinium may be injected into a vein before the scan to better see details.

CT scans combine many x-ray pictures to make detailed cross-sectional images of the inside of the body. These tests are often used to look for neuroblastoma in the abdomen, pelvis, and chest.

Before the test, your child may be asked to drink a contrast solution and/or get an IV (intravenous) injection of a contrast dye. These medicines can be used to get a clearer picture.

CT-guided core needle biopsy: CT scans can also be used to help guide a biopsy needle into a tumor, although this is not often done for children with neuroblastoma.

This test is often an important part of finding out how far a child's neuroblastoma has spread. It may be done after a CT scan or MRI.

For this test, a form of the chemical meta-iodobenzylguanidine (MIBG) that contains a small amount of radioactive iodine is injected into the vein. MIBG is similar to norepinephrine, a hormone made by sympathetic nerve cells. In most children, it will attach to neuroblastoma cells anywhere in the body. Between 1 and 3 days later, the body is scanned with a special camera to look for areas that picked up the radioactivity. This helps doctors know where neuroblastoma is and if it has spread to the bones and/or other parts of the body.

MIBG scans can be repeated after treatment to see if the tumors are responding well. It is also good to know if the tumor takes up the MIBG because in some cases, this radioactive molecule can be used at higher doses to treat the neuroblastoma (see Radiation Therapy for Neuroblastoma).

To protect the thyroid gland, a medicine containing non-radioactive iodine is given before, during, and after the test.

If your child’s doctor thinks neuroblastoma is affecting the bone but an MIBG scan does not show this, sometimes a PET scan can be done to be sure (see below).

For a PET scan, a radioactive substance (usually a type of sugar called FDG) is injected into the blood. The amount of radioactivity used is very low and will pass out of the body within a day or so. Because cancer cells are growing quickly, they absorb large amounts of the radioactive sugar.

After about an hour, your child will be moved onto a table in the PET scanner. They will lie on the table for about 30 minutes while a special camera creates a picture of areas of radioactivity in the body. Younger children may be given medicine to help them stay calm or even sleep during the test.

PET scans are usually not needed if an MIBG scan has been done. But a PET scan might be useful for some neuroblastomas, especially if there is no uptake of MIBG in the neuroblastoma cells.

X-rays can be used to look at the bones, although they are not as good at showing other structures in the body.

The doctor may order an x-ray if a child is having symptoms and it is not clear what might be causing them. But the pictures might not be good enough to spot tumors.

In children with neuroblastoma, a MIBG, PET, or bone scan is usually better than an x-ray for looking at the bones in the rest of the body and to see if neuroblastoma has spread to the bones, but an x-ray test might still be helpful in some situations.

Surgical biopsy is the most common type of biopsy for neuroblastoma. It is done by removing a piece of the tumor through an incision (cut) in the skin. For tumors deep in the body, this may be done laparoscopically using long, thin surgical tools inserted through small cuts in the skin. A surgical biopsy is most often used in the diagnosis of neuroblastoma.

For this type of biopsy, a thin, hollow needle is inserted through the skin and into the tumor to remove a small sample. If the tumor is deep within the body, CT scans or ultrasound can be used to help guide the needle into the tumor. This type of biopsy is less common for children with suspected neuroblastoma.

Neuroblastoma can spread to the bone marrow (the soft inner parts of certain bones). If blood or urine levels of catecholamines are increased, then finding cancer cells in a bone marrow sample is enough to diagnose neuroblastoma (without getting a biopsy of the main tumor). If neuroblastoma has already been diagnosed by a biopsy done elsewhere in the body, bone marrow tests are done to help determine the extent of the disease.

A bone marrow aspiration and biopsy are usually done at the same time. Samples are taken from the hip bones.

Even when the area is numbed with local anesthetic, these tests can be painful, so in most cases, the child is also given other medicines to reduce pain or go to sleep during the procedure.

For a bone marrow aspiration, a thin, hollow needle is inserted into the bone and a syringe is used to suck out a small amount of liquid bone marrow.

For a bone marrow biopsy, small pieces of bone and marrow are removed by placing a slightly larger needle in the bone. Once the biopsy is done, pressure is applied to the site to help stop any bleeding.

Samples from the bone marrow are sent to a lab, where they are looked at and tested for the presence of cancer cells. You can read more about testing tissue samples in Testing Biopsy and Cytology Specimens for Cancer.