In cases of retinoblastoma, stages used for treatment purposes include intraocular (which refers to cancers within the eye) and extraocular (which describes cancers that have spread beyond the eye). Retinoblastoma staging involves tests that are performed to find out if the cancer cells have spread to other parts of the body. Tests used for retinoblastoma staging may include a dilated eye exam, a CT scan, and an ultrasound.
Once a doctor makes a retinoblastoma diagnosis, he or she may order more tests to find out if cancer cells have spread to other parts of the body. This is called retinoblastoma staging. It is important to know the stage of the cancer in order to plan retinoblastoma treatment.
Doctors may use the following tests and procedures in the staging process:
- Eye exam
- CT (computed tomography) scan
- MRI (magnetic resonance imaging)
- Lumbar puncture.
During an eye exam, the doctor dilates the pupil with medicated eyedrops and looks through the lens and pupil to the retina. Then he or she examines the inside of the eye, including the retina and the optic nerve, using a light. Depending on the age of the child, this exam may be done under anesthesia.
An ultrasound is a procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs, like the eye, and make echoes. The echoes form a picture of body tissues called a sonogram.
A CT scan (also called a CAT scan) is a procedure that makes a series of detailed pictures of areas inside the body, such as the eye, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.