Assessment of Single Photon Emission Computed Tomography 123I-IMP Brain Scan Parameters Using Low Energy High Resolution Collimator and 3D Iterative Image Reconstruction Algorithm (Flash 3D)

Abstract Objective Statistical parametric mapping of 123I-IMP brain SPECT images has been used for brain disorders such as Alzheimer’s disease (AD) and dementia with Lewy bodies (DLB) for several decade. The analysis results highly dependent on the way how to construct the normal database (NDB), due to validity of spatial resolutions recovery, scatter and attenuation correction methods for quantification of SPECT value. And also, there is no NDB available for 3D image reconstruction algorithm (Flash 3D) so far. Purpose of this study is to evaluate whether the Siemens Symbia T6 SPECT/CT (Siemens Healthineers, Germany) with LEHR collimator and Flash3D reconstruction combined with computed tomography-attenuation correction (CT-AC) and scatter correction (SC) can be applied for 123I-IMP brain perfusion SPECT for Statistical image analysis.Methods LSF phantom, Cerebral blood flow brain phantom with skull cover (male bone, female bone, acrylic), cold rods phantom with male bone cover, and six chambers phantom with male bone cover were used. The acquisition time was determined by the SPECT count, that would be the condition of using SMS LEHR with 6 mCi of 123I-IMP administration and counting equivalent to 30 minutes of collection. The phantom conditions and the rotation radius (14, 15, 16cm) were changed and collected. Finally, the evaluation was performed using visual judgement by two independent nuclear medicine physicians, validity of spatial resolutions recovery, linearity of the radioactivity and SPECT value, and the gray-to-white matter count ratio were evaluated.Results Visual inspection of image determined image reconstruction with Gaussian filter 10mm should be used. The spatial resolutions were constant while change the rotation radius. There is good linearity relation between SPECT values and activity concentration of phantom, and the gray-to-white matter count ratio were almost the same while using male bone cover, female bone cover, and acrylic cover.Conclusions Siemens Symbia T6 SPECT/CT with LEHR collimator and Flash3D reconstruction combined with computed tomography - attenuation correction(CT-AC) and scatter correction (SC) can be used for SPECT 123I-IMP brain perfusion scanning with a LEHR collimator.