F-18-fluorothymidine-PET evaluation of bone marrow transplant in a rat model

The success of bone marrow transplantation in hematologic and oncologic diseases depends upon the ability to provide adequate hematologic and immunologic support in a timely manner. There is no current imaging tool for the evaluation of the bone marrow compartment in the peri-transplant period. In this study, we tested our hypothesis that whole-body positron emission tomography using fluorine-18 (F-18)-fluorothymidine has the ability to provide information about the functioning normal bone marrow and its physiologic distribution.

Wistar Furth rats were irradiated with 950 cGy followed 2 days later by syngeneic bone marrow transplantation. The animals were subjected to positron emission tomography using F-18-fluorothymidine imaging before and after ablation as well as after 4, 7, and 14 days after bone marrow transplantation. In a different set of syngeneic bone marrow transplant model, positron emission tomography using F-18-fluorodeoxyglucose was carried out for comparison. Imaging results were correlated with marrow histology upon necropsy.

F-18-fluorothymidine images showed definitive recovery of marrow within 4 days after transplant. In contrast, F-18-fluorodeoxyglucose was unable to present a corresponding picture. Sternum and humerus marrow in the images were analyzed by drawing three-dimensional regions of interest to obtain quantitative uptake value of tracers, which corroborated the image data.

We conclude that positron emission tomography using F-18-fluorothymidine offers a clinically useful noninvasive technique to evaluate bone marrow injury and recovery.