[Impact of Differences in Radiopharmaceuticals on Brain Perfusion SPECT Phantom Examination Using the Hoffman 3D Brain Phantom].

Purpose: This study aimed to clarify the effects of radiopharmaceuticals and buffer solutions on the accuracy of the Hoffman phantom examination.

Methods: The Hoffman phantom was prepared using the water immersion method and was injected with 3 different solutions: ¹²³I-MIBG, ¹²³I-IMP only, and ¹²³I-IMP plus buffer solution. Single photon emission computed tomography (SPECT) / computed tomography (CT) imaging was performed at 3-time points: immediately after encapsulation, after 10 min of stirring, and after 20 min of stirring. The relative SPECT counts and left-right ratios of the images obtained under each condition were evaluated.

Results: The results revealed that the buffer solution facilitated the mixing of ¹²³I-IMP, affecting the initial distribution of the radiopharmaceutical. However, after 20 min of stirring, no significant differences were observed in the relative SPECT counts and the left-right ratio of SPECT images among the different solutions, regardless of the radiopharmaceutical type or the presence of the buffer, in most regions.

Conclusion: Buffer solution promotes the mixing process; however, it was confirmed that sufficient agitation alone can produce comparable SPECT images, indicating that the use of a buffer may not be necessary if proper agitation is ensured during phantom preparation.