18F-FLT PET in hematologic disorders: A novel technique to analyze the bone marrow compartment

Few diagnostic procedures are available to determine the degree of bone marrow cellularity and the numbers of cycling cells in patients with bone marrow disorders. Noninvasive imaging of the bone marrow compartment may be helpful. The PET tracer 3'-fluoro-3'-deoxy-L-thymidine (F-18-FLT) has been developed recently. F-18-FLT uptake is related to the rate of DNA synthesis and increases with higher proliferation rates in many types of cancer. Background uptake of F-18-FLT in bone marrow is common. F-18-FLT PET might, therefore, visualize the high cycling activity of hematopoietic cells in the bone marrow compartment. Therefore, we investigated the feasibility of visualization and quantification of the activity of the bone marrow compartment with F-18-FLT PET to distinguish different hematologic disorders. Methods: Clinical and laboratory data of 18 patients with myelodysplasia (MDS), chronic myeloproliferative disorders, myelofibrosis, aplastic anemia, or multiple myeloma were correlated with the results of F-18-FLT PET using visual analysis and the standardized uptake value (SUV). Findings were compared with those of healthy control subjects (n = 14). Results: With SUV and visual analysis, a distinction could be made between MDS (n = 9), chronic myeloproliferative disorders In = 3), and myelofibrosis (n = 3) compared with healthy control subjects. A significant increase in F-18-FLT uptake was observed in all of the studied patients with MDS and myeloproliferative disorders. In contrast, patients with myelofibrosis and aplastic anemia (n = 1) demonstrated a decline in bone marrow F-18-FLT uptake compared with healthy control subjects. Comparable results were observed in osteolytic lesions of patients with multiple myeloma (n = 2). Conclusion: F-18-FLT PET can be used to visualize the proliferative activity of the bone marrow compartment and may be helpful to distinguish separate hematologic disorders.