Differential impact of multi-focus fan beam collimation with L-mode and conventional systems on the accuracy of myocardial perfusion imaging: Quantitative evaluation using phantoms

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. materials and 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