Tests > Imaging and Special Tests

Last Update: 02/15/2008

About Imaging | Compare Imaging | Bone scans | CT scans 
Gallium scans | Lymphangiogram | MRI | PET scans | Ultrasound  
Ultrasound Endoscopy

Monitoring Disease and Response to Treatment

Related Topic:

Remissions & Response - background

Assessment of Lymphoma with imaging - 

an overview by Barry L Shulkin, MD, MBA, published on Medscape

"Although the technique is unable to detect disease in normal-sized nodes, CT is an excellent method for staging of lymphoma. It cannot distinguish residual scar tissue from persistent tumor after therapy, and it is not a viable method for detecting bone involvement.

MRI is very good for finding central nervous system and bone marrow involvement associated with lymphoma; however, at present, MRI is impractical as a whole-body scan. 

Gallium-67 scintigraphy is a good method for the primary staging of Hodgkin's disease and high-grade non-Hodgkin's lymphoma (NHL). Dr. Federle noted during the session that gallium scanning is a poor method for staging low-grade NHL and for staging abdominal lymphoma.^[1] This factor relates to technique; the use of modern gamma cameras, high-dose gallium, SPECT scanning, and delayed images can improve the staging of low-grade NHL and abdominal lymphoma.

PET alone is useful for staging lymphoma. It can detect disease in normal-sized nodes and overlooked sites, such as bone and mesentery. It is also accurate for detecting central nervous system involvement. PET may change the stage in 41% of cases and finds 25% more hepatic and splenic involvement than CT. There are, however, both false-positive and false-negative results for bone marrow involvement. During therapy, PET can detect response as soon as following one cycle of chemotherapy. It is more accurate than CT for distinguishing fibrosis from active tumor following therapy (96% vs 63%) and again can find disease in hidden sites.

There are pitfalls using PET alone for the evaluation of patients with lymphomas. Areas of normal uptake (heart, gut, muscle, kidneys, bladder, brain) may hide disease. False-positive findings can be caused by infections, sarcoidosis, thymic hyperplasia, and other conditions that cause FDG uptake. Low-grade tumors may not accumulate FDG, and studies may be technically inadequate in patients with diabetes not optimally controlled and obese patients. Likewise, small lesions can be missed.

PET has been shown to be useful in the management of patients with lymphoma at the time of diagnosis for staging, early during therapy for prognosis, and for the distinction of residual tumor from scar following therapy.

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Imaging procedures and special tests are described here; also links to abstracts that discuss emerging practices. 

Both CT and MR imaging can be used to identify and show changes in nodal lesions.

MR imaging can also show abnormal cells in the bone marrow.

Newer high field MRI's [which do not use radiation] are getting better at resolving smaller lesions and if done properly can also assist in monitoring. (Contraindications of MRI  include to name a few--the "metal" objects you referred to, cardiac pacemakers/defibrillators, aneurysm clips, ear implants, pregnancy, breast feeding, claustrophobia and being able to lie on your back for approximately 45 or so minutes.)" - Marc (LymphomaVaccine list)

FAQ: Regarding exposure to ionizing radiation:
There is radiation exposure for PET and CT scans. The maximum amount of whole body exposure someone can receive from radiation-based imaging is as follows:

PET F-18 FDG is around 1,000 mrems.

CAT Scans of the Chest, Abdomen and Pelvis will yield an exposure of over 3X 
that amount. Radiology info on the web quotes the exposure for a
CT Chest = 760 mrems
CT Abdomen = 1,200 mrems
CT Abdomen/Pelvis = 2,760 mrems

Both CT and PET yield many advantages to diagnosing/monitoring disease and should be used when necessary.

Fast fact - to keep things in perspective: The average person in the United 
States receives approximately 350 mrems of exposure/yr from natural sources." - Marc (lymphomaVaccine list)

About Imaging

Comparing Types and Monitoring for Minimal Disease

Comparing MR and CT imaging for NHL

Comparing PET and Gallium imaging

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This painless test detects abnormalities in the bones.

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A specialized X-ray of the lymph nodes. 

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Magnetic resonance imaging (MRI) is less commonly used to measure tumor burden and response to treatment. However, improvements in this technology may make it the preferred tool in the near future, if not today.

Contrast agents speed up the rate at which tissue responds to stimulation from magnetic and radio waves. As a result, the signals produce stronger and clearer images.

Search for ACR accredited Diagnostic Imaging Centers 

ACR accreditation means: "Your hospital, clinic or health center has voluntarily gone through a rigorous review process to be sure it meets nationally accepted standards.  The personnel are well qualified, through education and certification, to perform and interpret your medical images and administer your radiation therapy treatments. The equipment is appropriate for the test or treatment you will receive, and the facility meets or exceeds quality assurance and safety guidelines."

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We moved this topic here.
 

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Ultrasound use sound waves to make up a picture called a sonogram. The image produced lets your doctor determine if organs are enlarged or if tumors are present. 

A special jelly is spread over your abdomen. A small device is passed over the area that produces and receives sound waves. The echoes are converted into a picture using a computer. It is a painless and safe procedure. It may take just 15-20 minutes.

Ultrasound is especially good at imaging diseases of soft tissues that do not show up as well on x-rays. It is also good at distinguishing fluid-filled cysts from tumors.

This test may also be used to determine where to place a needle to obtain a core biopsy or a needle aspiration biopsy.

Ultrasound is an imaging technique that uses sound waves to produce pictures. However, as sound waves do not travel well through air, occasionally certain abdominal organs are not well seen due to air in the digestive tract.

Endoscopic ultrasound (EUS) combines an ultrasound processor on the tip of an endoscope, allowing for improved ultrasound imaging of the GI tract and the abdominal organs adjacent to it. This is a result of the closer proximity of the probe to the organs of interest as well as the ability to remove the air from within the digestive tract via the endoscope.

Adapted from: ucsf.edu

MALT and EUS