F-18 FLT PET: A Noninvasive Diagnostic Tool for Visualization of the Bone Marrow Compartment in Patients With Aplastic Anemia: A Pilot Study

Rationale: A discordant relationship between bone marrow cellularity and peripheral blood findings is regularly noticed in patients with aplastic anemia (AA). Therefore, the feasibility of 3-F-18 fluoro-3-deoxy-L-thymidine (F-18 FLT PET was tested as a noninvasive tool to visualize the total distribution of the hematopoietic bone marrow compartment in AA at presentation or after treatment. Methods: In vivo scanning was performed with F-18 FLT PET in AA patients (n = 17), including patients upfront (n = 11) and following treatment (n = 6), in addition to peripheral blood cell counts and a bone marrow biopsy. Results: A striking abnormal F-18 FLT scan was observed in all patients upfront treatment, in particular a reduced uptake of the pelvis was shown, the area that is biopsied for the bone marrow biopsy. Following treatment, the number of solitary lesions with increased proliferative activity outside the pelvis was noticed in patients with partial response, whereas patients with a complete remission showed a homogenous uptake throughout the skeleton. Conclusion: This pilot study demonstrates that F-18 FLT scan provides a highly distinctive overview of the bone marrow compartment in AA that might be helpful for making a proper diagnosis and monitoring treatment response of AA patients.