Background. A novel three-dimensional (3D) iterative image reconstruction method (3D-OSEM) has been developed that in phantom studies yielded comparable image quality at one half the imaging time. In this study, we compared standard (STD) and rapid (nSPEED) protocols for diagnostic quality of images and quantitation of end-diastolic volume (EDV), endsystolic volume (ESV), left ventricular ejection fraction (LVEF), and perfusion defect severity.Methods. At 11 US community centers, 448 patients prospectively underwent rest-stressgated SPECT imaging using Tc-99m-labeled agent. The difference in quality and diagnostic equivalence of STD and nSPEED images were blindly evaluated by three experts. Defect intensity was quantitated as %normal in the three coronary artery territories.Results. Studies were abnormal in 40% of patients. In 98.7% of stress and 98% of rest images, the nSPEED image quality was identical to or better than the STD images. nSPEED images were diagnostically equivalent to the STD in 444/448 (99%) patients. A high correlation was observed between nSPEED and STD studies for measurement of EDV (Y = 0.957X, R 2 5 0.99), ESV (Y = 0.962X, R 2 5 0.99), and LVEF (Y = 1.005X, R 2 5 0.96). STD and nSPEED studies were not significantly different (P = ns) for quantitative perfusion defect severity.Conclusion. Rapid, gated rest-stress myocardial perfusion upright SPECT imaging may be achieved without compromising perfusion and function information. (J Nucl Cardiol 2009;16:351-7.)

BackgroundWe developed a cardiac SPECT system (X-ACT) with low dose volume CT transmission-based attenuation correction (AC). Three solid-state detectors are configured to form a triple-head system for emission scans and reconfigured to form a 69-cm field-of-view detector arc for transmission scans. A near mono-energetic transmission line source is produced from the collimated fluorescence x-ray emitted from a lead target when the target is illuminated by a narrow polychromatic x-ray beam from an x-ray tube. Transmission scans can be completed in 1 min with insignificant patient dose (deep dose equivalent <5 μSv).MethodsWe used phantom studies to evaluate (1) the accuracy of the reconstructed attenuation maps, (2) the effect of AC on image uniformity, and (3) the effect of AC on defect contrast (DC). The phantoms we used included an ACR phantom, an anthropomorphic phantom with a uniform cardiac insert, and an anthropomorphic phantom with two defects in the cardiac insert.ResultsThe reconstructed attenuation coefficient of water at 140 keV was .150 ± .003/cm in the uniform region of the ACR phantom, .151 ± .003/cm and .151 ± .002/cm in the liver and cardiac regions of the anthropomorphic phantom. The ACR phantom images with AC showed correction of the bowing effect due to attenuation in the images without AC (NC). The 17-segment scores of the images of the uniform cardiac insert were 78.3 ± 6.5 before and 87.9 ± 3.3 after AC (average ± standard deviation). The inferior-to-anterior wall ratio and the septal-to-lateral wall ratio were .99 and 1.16 before and 1.02 and 1.00 after AC. The DC of the two defects was .528 and .156 before and .628 and .173 after AC.ConclusionThe X-ACT system generated accurate attenuation maps with 1-minute transmission scans. AC improved image quality and uniformity over NC.

We report the development of a CdZnTe gamma ray imager whose advantages over the conventional Anger camera include 1) improved contrast resulting from superior energy resolution and unambiguous position determination and 2) the small size and weight and high reliability inherent in an all-solid-state construction. It provides high energy resolution and peak efficiency by incorporating Digirad's new SpectrumPlusTM detector technology. The new imager employs a modular design, in which each 1" x 1" module incorporates a monolithic 64-element CdZnTe detector array and ASIC-based circuity that provides signal conditioning for every channel, identification of valid events and addressing fimctions. Imagers with a wide range of sizes and shapes can be assembled by tiling modules together on a specially designed signal routing board.

BackgroundIn cardiac SPECT perfusion imaging, motion correction of the data is critical to the minimization of motion introduced artifacts in the reconstructed images. Software-based (data-driven) motion correction techniques are the most convenient and economical approaches to fulfill this purpose. However, the accuracy is significantly affected by how the data complexities, such as activity overlap, non-uniform tissue attenuation, and noise are handled.MethodsWe developed STASYS, a new, fully automatic technique, for motion detection and correction in cardiac SPECT. We evaluated the performance of STASYS by comparing its effectiveness of motion correcting patient studies with the current industry standard software (Cedars-Sinai MoCo) through blind readings by two readers independently.ResultsFor 204 patient studies from multiple clinical sites, the first reader identified (1) 69 studies with medium to large axial motion, of which STASYS perfectly or significantly corrected 86.9% and MoCo 72.5%; and (2) 20 studies with medium to large lateral motion, of which STASYS perfectly or significantly corrected 80.0% and MoCo 60.0%. The second reader identified (1) 84 studies with medium to large axial motion, of which STASYS perfectly or significantly corrected 82.2% and MoCo 76.2%; and (2) 34 studies with medium to large lateral motion, of which STASYS perfectly or significantly corrected 58.9% and MoCo 50.0%.ConclusionsWe developed a fully automatic software-based motion correction technique, STASYS, for cardiac SPECT. Clinical studies showed that STASYS was effective and corrected a larger percent of cardiac SPECT studies than the current industrial standard software.

No abstract