Compared Performance of High-Sensitivity Cameras Dedicated to Myocardial Perfusion SPECT: A Comprehensive Analysis of Phantom and Human Images

Abstract

Differences in the performance of cadmium-zinc-telluride (CZT) cameras or collimation systems that have recently been commercialized for myocardial SPECT remain unclear. In the present study, the performance of 3 of these systems was compared by a comprehensive analysis of phantom and human SPECT images. Methods: We evaluated the Discovery NM 530c and DSPECT CZT cameras, as well as the Symbia Anger camera equipped with an astigmatic (IQÁSPECT) or parallel-hole (conventional SPECT) collimator. Physical performance was compared on reconstructed SPECT images from a phantom and from comparable groups of healthy subjects. Results: Classifications were as follows, in order of performance. For count sensitivity on cardiac phantom images (countsÁs 21 ÁMBq 21 ), DSPECT had a sensitivity of 850; Discovery NM 530c, 460; IQÁSPECT, 390; and conventional SPECT, 130. This classification was similar to that of myocardial counts normalized to injected activities from human images (respective mean values, in countsÁs 21 ÁMBq 21 : 11.4 6 2.6, 5.6 6 1.4, 2.7 6 0.7, and 0.6 6 0.1). For central spatial resolution: Discovery NM 530c was 6.7 mm; DSPECT, 8.6 mm; IQÁSPECT, 15.0 mm; and conventional SPECT, 15.3 mm, also in accordance with the analysis of the sharpness of myocardial contours on human images (in cm 21 : 1.02 6 0.17, 0.92 6 0.11, 0.64 6 0.12, and 0.65 6 0.06, respectively). For contrast-to-noise ratio on the phantom: Discovery NM 530c had a ratio of 4.6; DSPECT, 4.1; IQÁSPECT, 3.9; and conventional SPECT, 3.5, similar to ratios documented on human images (5.2 6 1.0, 4.5 6 0.5, 3.9 6 0.6, and 3.4 6 0.3, respectively). Conclusion: The performance of CZT cameras is dramatically higher than that of Anger cameras, even for human SPECT images. However, CZT cameras differ in that spatial resolution and contrast-to-noise ratio are better with the Discovery NM 530c, whereas count sensitivity is markedly higher with the DSPECT.Key Words: CZT-cameras; high-speed SPECT; myocardial perfusion imaging; count sensitivity St ress myocardial SPECT has been markedly enhanced by the recent commercialization of cameras with semiconductor (cadmium-zinc-telluride [CZT]) detectors or new collimation systems. These improved systems enhance the sensitivity of count detection and thereby enable recording times or tracer doses to be reduced, a property that has highly favorable consequences on patient comfort and radiation exposure (1-4). This enhancement is based mainly on acquisitions that are heart-centric but obtained with very different technologies: first, for the IQÁSPECT system (Siemens Medical Solutions (5-8)), an Anger camera equipped with collimators convergent on the image center (astigmatic collimators); second, for the DSPECT system (Spectrum Dynamics (9-13)), mobile columns of CZT detectors with wide parallel-hole collimators; and third, for the Discovery NM 530c system (GE Healthcare (14-21)), fixed CZT detectors with multipinhole collimators.The respective performance of these new cameras and collimation systems has been analyzed, but ...

Moving ahead with CZT technology

“…In view of the above, it may at first glance appear that the latest generation of gamma cameras with cadmium-zinc-telluride (CZT)-based semiconductor detector technology may offer some advantage with this regard as they allow a significant reduction of acquisition times (i.e., a reduction to 2-3 min) due to the combination of increased overall system sensitivity and the miniaturized detectors that enable a stationary camera design without the need of rotation of the detectors around the patient. [4][5][6] However, a number of new aspects concerning motion artifacts and detection arise from these novel CZT scanners that should be taken into consideration: Firstly, any patient motion will simultaneously affect all the detectors and, within the drastically shortened image acquisition time, will have a relatively higher negative impact on image quality than during the longer acquisition with conventional SPECT cameras simply because counts acquired during such patient movements will affect a greater proportion of the overall count statistics. The latter may be particularly true for motion patterns such as ''bounce'' movement (i.e., the single occurrence of returning motion).…”

Nuclear myocardial perfusion imaging using thallium-201 with a novel multifocal collimator SPECT/CT: IQ-SPECT versus conventional protocols in normal subjects

“…The results of this study would help to standardize the image database. In IQ-SPECT, reducing acquisition time may reduce the likelihood of patient of motion artifacts, may increase camera efficiency, and may lead to improved patient throughput, although it may increase the image noise [25,26].…”

Dynamic SPECT: evolution of a widely available tool for the assessment of coronary flow reserve

“…These improvements, in addition to allowing focused imaging of the heart and the use of new reconstruction algorithms, enable dynamic SPECT with kinetic analysis of 99m Tc-MIBI myocardial concentrations to be performed in animals and humans [17][18][19][20], providing incremental diagnostic information over perfusion data alone [17]. Further studies are needed to assess whether availability of transmission to correct for attenuation may enable better modelling of 99m Tc-labelled tracer kinetics.…”