First assessment of simultaneous dual isotope ( 123 I/ 99m Tc) cardiac SPECT on two different CZT cameras: A phantom study.

BACKGROUND: We studied the impact of simultaneous dual-isotope acquisition on 123 I/99m Tc mismatch assessment using two CZT cameras (DNM 530c, GE Healthcare and DSPECT, Biosensors International).

METHODS: We used an anthropomorphic torso phantom (respectively filled with a solution of 123 I alone, 99m Tc alone, and a mixture of 123 I and 99m Tc) and its cardiac insert with two defects mimicking two matched and mismatched defects. Mismatch extent and reconstructed image contrast were evaluated.

RESULTS: The acquisition mode (single vs dual) significantly impacted (i) 99m Tc (but not 123 I) reconstructed segmental activities using both camera (P < .001), and (ii) image contrast (using 123 I and DNM 530c, P < .0001; and using both 123 I and 99m Tc with DSPECT, P < .0001). However, the defect and mismatch size were not impacted by the type of acquisition. With both DNM 530c and DSPECT, Lin's concordance correlation coefficient and Bland-Altman analysis demonstrated an almost perfect concordance and agreement between single- and simultaneous dual-isotope segmental activity (123 I and 99m Tc).

CONCLUSIONS: This study found no impact of the acquisition mode (single vs dual) or the type of camera (DSPECT vs DNM 530c) on 123 I and 99m Tc defect size and mismatch, providing a new step toward simultaneous dual-isotope acquisition for combined innervation and perfusion assessment.