Positron emission tomography with FDG may provide useful preoperative clinical information in patients who have adipose tissue tumors.
The conclusion emerged from an evaluation of 16 patients with adipose tissue tumors confirmed by biopsy or surgery. The tumors comprised 3 lipomas, 7 low-grade liposarcomas, and 6 high-grade liposarcomas, said Dr. Sarah Reimer, a radiologist at University Hospitals in Cleveland.
Analysis by PET with FDG showed good quantitative correlation with biopsy and surgical findings, but the technique did not demonstrate good qualitative correlations. In 9 of the 16 patients, the tumors also were evaluated by PET with O-15 labeled water in an effort to approximate tumor perfusion.
The study arose from the known associations between tumor metabolism and grade and between tumor perfusion and grade. Investigators speculated that PET with FDG or O-15 labeled water might provide useful preoperative information about the extent and grade of adipose-tissue tumors.
"Adipose tissue tumors have a high potential for sampling error because they tend to be heterogenous and large," Reimer said. "The tumors are not easily stratified by either CT or MR, and that's an important issue because tumor grade usually determines the surgical approach."
For PET with FDG, quantitative analysis by peak standard uptake values (SUV) showed a good correlation between the histologic grade of the tumors (r=.903, p=.0007). The correlation was less impressive for the O-15 labeled water studies (r=.764, p=.0219). No significant qualitative correlations emerged between intensity FDG uptake or water distribution and tumor cellularity, pleomorphism, or necrosis.
"On the basis of these results, we believe that PET with FDG may be useful in the preoperative evaluation of adipose tissue tumors," Reimer said. "The quantitative analysis is more useful than the qualitative analysis, and the FDG data are more useful than those obtained with O-15 labeled water."
