Document Type : Original Article
Program in Health and Welfare, Graduate School of Comprehensive Scientific Research, Prefectural University of Hiroshima
Department of Radiology, Kurashiki Central Hospital
Program in Biological System Sciences, Graduate on School of Comprehensive Scientific Research, Prefectural University of Hiroshima
Department of Nursing，Hyogo University of Health Sciences
Objective(s): A novel IQ-SPECTTM method has become widely used in clinical studies. The present study compares the quality of myocardial perfusion images (MPI) acquired using the IQ-SPECTTM (IQ-mode),conventional (180° apart: C-mode) and L-mode (90° apart: L-mode) systems. We assessed spatial resolution, image reproducibility and quantifiability using various physical phantoms.
Methods: SPECT images were acquired using a dual-headed gamma camera with C-mode, L-mode, and IQ-mode acquisition systems from line source, pai and cardiac phantoms containing solutions of 99mTc. The line source phantom was placed in the center of the orbit and at ± 4.0, ± 8.0, ± 12.0, ± 16.0 and ± 20.0 cm off center. We examined quantifiability using the pai phantom comprising six chambers containing 0.0, 0.016, 0.03, 0.045, 0.062, and 0.074 MBq/mLof 99m-Tc and cross-calibrating the SPECT counts. Image resolution and reproducibility were quantified as myocardial wall thickness (MWT) and %uptake using polar maps.
Results: The full width at half maximum (FWHM) of the IQ-mode in the center was increased by 11% as compared with C-mode, and FWHM in the periphery was increased 41% compared with FWHM at the center. Calibrated SPECT counts were essentially the same when quantified using IQ-and C-modes. IQ-SPECT images of MWT were significantly improved (P<0.001) over L-mode, and C-mode SPECT imaging with IQ-mode became increasingly inhomogeneous, both visually and quantitatively (C-mode vs. L-mode, ns; C-mode vs. IQ-mode, P<0.05).
Conclusion: Myocardial perfusion images acquired by IQ-SPECT were comparable to those acquired by conventional and L-mode SPECT, but with significantly improved resolution and quality. Our results suggest that IQ-SPECT is the optimal technology for myocardial perfusion SPECT imaging.