Clinical History
This is a 45 year-old female with a right distal femur lesion with chondroid matrix. Correlation is made to the 201-Thallium scan obtained previously.
Technique
The patient was administered 10 millicuries of 18 FDG and imaging was obtained 45 minutes post-injection. Images of the distal thighs and knees were obtained.
Findings
1.There is increased uptake in the right distal femur posteriorly, very near the knee joint. This correlated with the 201-thallium scan but shows up much more prominantly than does the thallium uptake.
2.There is also an area of increased uptake in the soft tissues anterior to the knee. Within a threshold SUV range of 1.5 a circumscribed area measuring 3.18 cm was measured. The mean within this area is 1.74 SUV, with the max being 2.08 SUV. This soft tissue uptake is not appreciated on the 201-thallium scan.
Impressions
A LESION WITHIN THE DISTAL RIGHT FEMUR, WITH A MAX SUV MEASUREMENT OF 2.08. THIS IS NEARLY
TWO TIMES THE AVERAGE TISSUE METABOLISM AND IT IS CONSISTANT WITH A NEOPLASTIC PROCESS. CORRELATION WITH THE PATHOLOGY OF THE TUMOR WILL BE OBTAINED. IN COMPARISON WITH THE 201-THALLIUM SCAN, THE PET IMAGES ARE MORE SENSITIVE AND EASIER TO INTERPRET.
Thallium-201 Tumor Scan
Clinical History
This is a 45-year-old female with pain in the right knee. Outside films and MRI show typical chondroid matrix suggesting enchondroma versus chondrosarcoma.
Technique
4.5 mCi of Thallium-201 was injected with planar imaging in the anterior and posterior projections at 20 minutes and 2 hours post-injection. The region of interest was drawn over the area in question and compared with the contralateral normal side.
Findings
The area of the lesion in the distal right femur activity is compared with contralateral side. At 20 minutes, the ratio of activity is 1.60. At two hours the ratio is 1.35. Abnormal is greater than 1.30.
Impressions
THE FINDINGS ARE CONSISTENT WITH A HIGH GRADE CHONDROSARCOMA. THE RESULTS WILL BE CORRELATED WITH A PET SCAN AS WELL AS THE PATHOLOGY RESULTS.
