SPECT/CT image fusion for evaluation of iodine-125 seeds distribution in target organ

Objective To explore the role of SPECT/CT image fusion, combined with whole body scan, in evaluation of implanted iodine- 125 seeds distribution in the target organ. Methods From May 2008 to June 2009, 47 patients underwent iodine- 125 seed implantation in the Department of Nuclear Medicine, Zhongshan Hospital, Fudan University. Among 47 patients, 6 patients with prostate cancer received iodine-125 seed chain implantation under ultrasound guidance, and the remaining 41 patients with confirmed tumor history and concurrent cancer emboli at the portal vein or superior vena cava received stenting and iodine-125 seeds implantation into lumen of blood vessel under DSA guidance. All the patients underwent whole body scan and SPECT/CT imaging of the target organ after iodine-125 seeds implantation 24 h later. Seed distribution in target organ was evaluated by whole body scan combined with SPECT/CT imaging. Results The whole body scans provided accurate positioning for SPECT/CT scan but not any information for precise anatomical distribution of the seeds. SPECT/CT image fusion showed satisfactory seeds distribution in 5 of the 6 prostate cancer patients except for 1 patients in whom the seeds were implanted into right seminal vesicle. Of 41 patients with confirmed tumor history and portal vein or superior vena cava tumor thrombus, SPECT/CT fused imaging showed intraluminal seed chain at desired location in 40 cases except for 1 case where the seed chain was implanted in the superior vena cava and migrated to the right ventricle.Conclusion SPECT/CT fusion images may be used for evaluating 125I seed distribution in target organs and may identify any aberration in positioning of seeds, when combined with whole body scan. Key words: Tomography, emission-computed, single-photon; Radioisotopes; Iodine-125 seed; Prostate; Blood vessels