|
FDG Uptake in Brown Fat
RADIOLOGY REPORT:
PET/CT BREAST IMAGING INITIAL
09/13/05
HISTORY: 55-year-old female with history of bilateral mastectomies
in 2002 for breast cancer. She completed chemotherapy in October of
2002. Study is requested for restaging.
TECHNIQUE: Imaging was performed from top of head to hips. Emission
and transmission imaging was used for attenuation correction.
Coronal, axial, and sagittal reconstructions were performed as well
as 3D volume rendering with iterative reconstruction. Correction was
performed for random events. A noncontrasted, nondiagnostic computed
tomography was performed for attenuation correction and anatomical
localization purposes only.
ADMINISTERED RADIOPHARMACEUTICAL: 23.7-mCi of F-18
fluorodeoxyglucose in the left antecubital fossa with a residual of
0.14-mCi. Patient's height is 5 feet and weight was 123 pounds.
Blood sugar was 80-mg% at the time of injection.
COMPARISON: No prior PET scan for comparison.
FINDINGS: There is extensive focal intense activity identified in
the supraclavicular and infraclavicular region as well as the
cervical and paraspinous region bilaterally consistent with activity
in brown fat. This makes these areas impossible to fully evaluate
for metastatic disease. There are no other focal areas of abnormal
activity identified on the remainder of the study.
There is mild diffuse activity in the thoracic and lumbar spine with
an SUV of 1.4 by lean body mass at L3. This is homogeneous in
appearance. Review of the computed tomography demonstrates no
obvious abnormalities.
IMPRESSION:
1. DIFFUSE, EXTENSIVE UPTAKE IN THE SUPRACLAVICULAR, INFRACLAVICULAR,
POSTERIOR CERVICAL, AND PARASPINOUS REGIONS MOST LIKELY REPRESENTING
UPTAKE IN BROWN FAT. HOWEVER, IT IS IMPOSSIBLE TO FULLY EVALUATE
THESE AREAS FOR METASTATIC DISEASE. RECOMMEND CONTRASTED COMPUTED
TOMOGRAPHY FOR EVALUATION.
2. NO OTHER FOCAL ABNORMAL ACTIVITY IDENTIFIED ON THE STUDY TO
SUGGEST METASTATIC DISEASE.
Teaching Note:
FDG uptake may be seen
in supraclavicular area fat (USA-fat),
known colloquially as brown fat. Compared with typical
fat, brown fat is metabolically active, residing in several areas of
the body. It is the same type of fat that bears have that is
influenced by their state of hibernation. It can be found in
different areas of the body, including around the coronary arteries,
and it may be there to keep those arteries warm. The
brown fat artifact is more commonly seen in women; it becomes more
active when patients are in a cold or shivering state. Brown fat
artifact can be tempered by keeping patients warm. Brown fat
uses glucose intensely and it can interfere with reading the scan in
the neck, so head and neck cancers can be exceedingly challenging to
read. The artifact is especially troubling when evaluating
young women for breast cancer. A key aspect of that assessment is
detection of supraclavicular nodes, and brown fat can get in the way
of a clear view.
Articles about "USA-Fat" or Brown
Fat:
Uptake in Supraclavicular Area Fat ("USA-Fat"): Description on
18F-FDG PET/CT, J Nucl Med 2003; 44-170-176
Intense 18F-FDG Uptake in Brown Fat Can Be Reduced Pharmacologically,
J Nucl Med July 2004; 45:1189-1193.
"USA-Fat": Prevalence is Related to Ambient Outdoor Temperature -
Evaluation with 18F-FDG PET/CT, J Nucl Med August 2003; 44:
1267-1270.
BACK
© 2005 Nuclear Education Online
- Images courtesy of University
of Arkansas for Medical Sciences Dept of Nuclear Medicine.
|
