A Headrest Made of Extruded Polystyrene Reduces the Influence of Attenuation Correction on Human Brain SPECT Images

Previous reports suggest that a headrest made of carbon signifi-cantly influences cerebral blood flow in the anterior and posterior regions by image reconstruction and attenuation correction (AC). The present study aimed to develop a headrest that reduces the influence of the AC process on human brain SPECT. Methods: To validate the performance of a headrest made of extruded polysty-rene (XPS), 10 healthy controls and 43 patients with cerebrovascu-lar disease underwent 99mTc-ethyl cysteinate dimer SPECT using a carbon headrest and an XPS headrest. We evaluated the anterior -to-posterior and middle-to-posterior ratio of the brain regions in filtered backprojection (FBP) Chang AC, ordered-subset expecta-tion maximization (OSEM) Chang AC, and OSEM CT-based AC. Results: The anterior-to-posterior ratio was significantly higher with the carbon headrest than with the XPS headrest in FBP Chang AC and OSEM Chang AC (P , 0.001). There was no significant differ-ence between the materials in OSEM CT-based AC. The middle -to-posterior ratio did not differ to a statistically significant extent in any correction process. Conclusion: Acquisition of brain SPECT images with an XPS headrest and processing by the FBP or OSEM Chang AC method enables the influence of the headrest to be reduced, especially in anterior and posterior brain regions.