PET/CT in the Management of Lymphomas: Staging/Re-Staging and Treatment Response

Lymphomas

Malignant lymphomas, including both Hodgkin lymphoma (HL) and Non-Hodgkin lymphoma (NHL), represent a diverse group of cancer diseases that arise from a clonal proliferation of lymphocytes. These cells are part of the body’s immune system in the lymph nodes, spleen, thymus, bone marrow, and other parts of the body. Lymphoma develops when a change, or mutation, occurs within a lymphocyte causing the abnormal growth.

FDG (Fluorodeoxyglucose) PET/CT

FDG-PET/CT is the current state-of-the-art imaging for lymphoma and plays a central role in treatment decisions. At diagnosis, accurate staging (which part of the body is affected by lymphoma) is crucial for appropriate therapy selection. PET/CT can identify areas of lymphoma missed by CT alone helping to avoid under-treatment of patients with advanced disease who would have been misclassified as having limited-stage disease by CT.

The predictive value of FDG-PET after therapy of B-cell lymphomas (evaluation of treatment response) is higher than that of a CT scan. Obtaining relevant prognostic information through CT alone is not sufficient, which is why PET/CT imaging is an essential tool in lymphoma diagnostic imaging.

The current Lugano Classification recommends routine use of FDG-PET/CT imaging in all FDG-positive lymphomas (essentially all subtypes of lymphomas except low-grade lymphomas as small lymphocytic lymphoma and marginal zone lymphoma).

Case Studies

A 90-year-old male with a recent diagnosis of diffuse large B cell lymphoma underwent FDG PET/CT for initial staging.

Figure 1. A large hypermetabolic mass (SUV max 32.8) is seen in the right neck level 2 region, measures 6.4 x 5.4 cm, likely representing conglomerate lymphadenopathy. There is additional FDG avid left cervical lymph node level 2A, measures 2.1 x 1.9 cm (SUV max = 26.6).

Figure 2. There is hypermetabolic density (SUV max = 19.9) in the porta hepatis region and pretracheal (SUV max = 14.8), representing lymphadenopathy.  These findings are consistent with the diagnosis of diffuse large B-cell lymphoma.

WHAT TO EXPECT DURING AND AFTER PET/CT IMAGING

  • Avoid any significant exercise for at least 24-hour prior to your exam.
  • Fast for at least 6 hours prior to your appointment.
  • If you are diabetic, you will receive special instructions the night before the scan to prepare for the test.
  • Our nuclear technologist will inject painless radiotracer IV (intravenous). Usually, the majority of radiotracers take 30-45 minutes to travel through your body. During this waiting period, you will be asked to rest and avoid eating or vigorous exercise.
  • You will be moved to the PET/CT scanner. The average scanning time is about 20 minutes.
  • When the test is complete, you may resume your normal activities.
  • The radiotracer will pass through your body through urine, stool, and natural radioactive decay.
  • We encourage you to drink plenty of water after the test.

For more information and to schedule an appointment, please contact our Clarksville location.