Radiolabeling of cidofovir with technetium-99m and biodistribution studies

Radiolabeling cidofovir with technetium-99m (99mTc-CDV) is an innovative procedure that enables real-time monitoring of the drug. Essays were performed in vitro, showing high radiolabel stability within 24 h. Blood clearance, biodistribution studies, and scintigraphic images were performed in healthy mice in order to evaluate the profile of the drug in vivo. 99mTc-CDV showed biphasic blood circulation time and significant kidney uptake, indicating that 99mTc-CDV is preferentially eliminated by the renal route. Bones also showed important uptake throughout the experiment. In summary, cidofovir was successfully labeled with technetium-99m and might be used in further studies to track the drug.

99mTc-HDP Pinhole SPECT Findings of Foot Reflex Sympathetic Dystrophy: Radiographic and MRI Correlation and a Speculation about Subperiosteal Bone Resorption

Reflex sympathetic dystrophy (RSD) is a common rheumatic disorder manifesting painful swelling, discoloration, stiffening and atrophy of the skin. Radiographic alterations include small, spotty subperiosteal bone resorption (SBR) and diffuse porosis, and MR imaging shows bone and soft-tissue edema. The purposes of current investigation were to assess 99mTc HDP pinhole SPECT (pSPECT) findings of RSD, to correlate them with those of radiography and MRI and to speculate about causative mechanism of SBR which characterizes RSD. pSPECT was performed in five patients with RSD of the foot. pSPECT showed small, discrete, spotty hot areas in the subperiosteal zones of ankle bones in all five patients. Diffusely increased tracer uptake was seen in the retrocalcaneal surface where the calcaneal tendon inserts in two patients with atrophic RSD. pSPECT and radiographic correlation showed spotty hot areas, that reflect focally activated bone turnover, to closely match with SBR. Further correlation with MRI showed both spotty hot areas and SBR to coincide in location with the insertions of ligaments and tendons, onto which pulling strain is constantly exerted. In contrast, the disuse osteoporosis in unstrained bones did not show any more significantly increased tracer uptake than normal cancellous bones.