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PET Oncology: Non-Small Cell Lung Cancer
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Jake Sartain
Senior Nuclear Medicine Student Technologist
Medical College of Georgia


Bill Butts, MA, CNMT
PET Technologist
University Hospital


Mary Anne Owen, MHE, RT(N)
Asistant Professor,
Nuclear Medicine Technology
Medical College of Georgia



Patient History


The patient is a 57 year old white female with a previous history of lung cancer. She previously had a CT scan on 10/1/03 which was used in fusing with her PET scan which was performed on 2/3/04.

Instructor's Comments:
Q: Is there any significant impact to such a lapse of time between the CT and P.E.T. procedure?



Radiopharmacy


11.78 mCi of F-18 FDG was injected via catheter in right antecubital vein.



Procedure


After the injection the patient was reclined back and asked to sit still and relax.

Instructor's Comments:

Q: What happens if the patient is uncomfortable and wants to get up and walk around or use the rest room?

After 30 minutes a technologist went into the room to remove the catheter. After another 20 minutes the patient was sat up and asked to empty her bladder before the scan to reduce her exposure and improve the images to come.

Instructor's Comments:
Q: How does the bladder relate to the normal biodistribution of FDG-18 in the human body?



Positioning


The patient positioned supine on the table with a Velcro strap around her torso and her hands above her head. The table was then elevated and moved forward into the gantry. Using lasers, the patient was marked from her eyebrows and again at her upper thigh (“Eyes to thighs”). The result was 6 bed lengths.

Instructor's Comments:

Q: What is a bed length?
Q: Is this a universal standard?



Findings


The images were reviewed by a radiologist in parasagittal, transaxial, and transcoronal planes. As noted on the patient’s previous CT exam there is a very large mass identified within the left upper lung. There is associated central photopenia which is consistent with necrosis. The standard uptake value (SUV) associated with the mass is markedly elevated at 9.225 grams/ml.

 

Instructor's Comments:

Q: How are these units significant?

The also is a nodule identified in the left lower lobe with another nodule being identified in the right middle lobe. These both have elevated SUV levels and are consistent with metastatic lesions.

Instructor's Comments:
Q: What factors make this consistent with metastatic lesions?
Q: Does this mean for sure that the patient is positive for lung cancer doesn’t have to have a biopsy?

There is also increased activity identified within multiple mediastinal lymph nodes.

 

Instructor's Comments:
What does associated central photopenia mean?

Discussion (click to view)

General

The radiologist also noted very intense increased activity associated with the uterus. On the patients CT exam performed at the imaging center on 1/13/04 the uterus was noted to be markedly enlarged with a heterogeneous pattern of attenuation. The presence of the associated significant increase in activity is unusual and the possibility of neoplasm involving the uterus would have to be considered.

Instructor's Comments:
Q: What is the sensitivity of FDG-18 for ovarian or uteren cancer as primary neoplasms?
Q: Is the uterus a common location for metastatic lesions associated with lung cancer?

There is also an adjacent focus of abnormally increased activity seen posteriorly within the pelvis on the left side which is thought likely due to abnormal activity within an iliac lymph node.



Instrumentation


The scanner used is a GE PET Advance Nxi. This scanner does not have a CT scanner built in with it, but it is compatible if one was to be added.

Instructor's Comments:
Q: If the CT scanner is not built in to the computer, how is the P.E.T. image fused with the CT image?

The scanner first starts with a five-minute emission scan, which means that the patient is emitting photons, picked up by the block detectors. Next, there is a two-minute transmission scan. Germanium rods are extended and transmit radiation through the patient. This is used to determine the attenuation coefficient for each bed so that the computer can apply attenuation correction during processing.

Instructor's Comments:
Q: What is the value or significance of attenuation correction in positron annihilation detection in P.E.T. imaging technology?

The next bed position begins with the transmission scan since the rods are already in place, and then continues with the emission scan. The third bed position begins with emission then goes to transmission and so on.

Instructor's Comments:

Q: What’s a bed?



Processing


The processing is done internally by the computer on each image obtained. No necessary operator interaction is needed with processing, meaning that no limits or angles need to be determined.


Instructor's Comments:
Q: What does the COMPUTER do (inside the black box) to make a picture that is diagnostically accurate?
Q: How are the CT images fused with the P.E.T. image?
Q: Is this done automatically?

Q: What kind of technologist image manipulation, or knowledge of anatomy and/or physiology is required to make sure the images match up?


Technologist's Concerns