FDG PET and Lymphoma

When treating a pervasive cancer like lymphoma, it’s crucial that clinicians and oncologists get the most complete picture of the cancer’s spread within the body as possible.

Fluorodeoxyglucose-positron emission tomography (FDG-PET) is one way of doing this. An imaging technique similar to MRI, FDG-PET can isolate residual cancer cells after treatment and identify whether additional treatment is needed.

Description and Significance

Fluorodeoxyglucose, or FDG, is a sugar-like substance derived from basic glucose. It is injected in the body, where it is absorbed most easily by cancerous cells. This is because such rapidly dividing cells require a steady supply of glucose. Using positron-detecting camera equipment, doctors can then detect the energy given off by that much FDG, mapping their locations onto a 3D representation of the body.

A CT scan is usually conducted concurrently to provide more definitive results. Used in conjunction, FDG-PET and CT can isolate discrete tumors, metastasized cancer cells, and lymph node involvement. Because a physical examination and blood work from only one or several involved lymph nodes cannot paint a comprehensive picture of the spread of the lymphoma throughout the body, doctors depend on FDG-PET and lymphoma tests to provide a full-body analysis for diagnostic, staging, and prognostic purposes.

Side Effects

As a non-invasive procedure, there are no side effects to a FDG-PET scan. The FDG can alter blood chemistry slightly, but this quickly returns to normal. The entire process was developed to mitigate the need for more invasive and time-consuming methods of detecting extranodal cancer involvement.

Administration

You will be asked to fast the night before a FDG-PET test in order to settle your blood glucose levels. A blood glucose test is taken immediately prior to the FDG-PET test to calibrate the findings. You will be asked to rest for an hour after receiving the injection of FDG to allow the compound to be absorbed by any potential tumors. You will then be placed in a machine not unlike a CT scanner (indeed, this is the time any CT scans will also be done), and subjected to the PET scan. This should take about 45 minutes, after which you are free to go.

Your oncologist will analyze the data and then schedule a time for you to come in and discuss any unusual findings. The 3D image that FDG-PET for lymphoma produces can detect even tiny pockets of cancer cells that may have survived treatment, and tests administered during chemotherapy or radiotherapy can help direct treatment to more effectively address each individual case.