Precise fusion of MRI and dual energy In-111 WBC/Tc-99m HDP SPECT/CT in diabetic foot using companion CT

Objectives The purpose of our study was to correctly fuse MRI and SPECT In-111 WBC and Tc-99m HDP images. The fused images could be used to assess proper surgical approach in treatment of diabetic foot.

Methods Nine patients who had dual energy In-111 WBC/Tc-99m HDP SPECT/CT and MRI studies within a week, were investigated in an ongoing project. A GE Infinia 4 SPECT/CT camera and Siemens MAGNETOM 1.5T MRI system were used in this study. First, the MRI and corresponding CT images were coregistrated using a transformation based on normalized mutual information (1). The transformation was saved and used for MRI and In-111 SPECT fusion. A phantom study was also performed.

Results The phantom study with In-111 and Tc-99m hot spheres showed that MRI/SPECT alignment using the approach described above produced registration with 0.7 +/- 0.4 mm accuracy in all three dimensions (3D). The nine clinical cases were visually evaluated by 3 observers and showed high fusion accuracy. The results indicate that accurate fusion of In-111 WBC and Tc-99m HDP SPECT/CT and MRI of feet can be regularly attained.

Conclusions The In-111/Tc-HMPO SPECT/CT and MRI studies of diabetic foot can be accurately fused and compared. This is expected to beneficially impact patient care and management.