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

We studied the impact of simultaneous dual-isotope acquisition on I-123/Tc-99m mismatch assessment using two CZT cameras (DNM 530c, GE Healthcare and DSPECT, Biosensors International). We used an anthropomorphic torso phantom (respectively filled with a solution of I-123 alone, Tc-99m alone, and a mixture of I-123 and Tc-99m) and its cardiac insert with two defects mimicking two matched and mismatched defects. Mismatch extent and reconstructed image contrast were evaluated. The acquisition mode (single vs dual) significantly impacted (i) Tc-99m (but not I-123) reconstructed segmental activities using both camera (P < .001), and (ii) image contrast (using I-123 and DNM 530c, P < .0001; and using both I-123 and Tc-99m 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 (I-123 and Tc-99m). This study found no impact of the acquisition mode (single vs dual) or the type of camera (DSPECT vs DNM 530c) on I-123 and Tc-99m defect size and mismatch, providing a new step toward simultaneous dual-isotope acquisition for combined innervation and perfusion assessment.