A performance comparison of novel cadmium-zinc-telluride camera and conventional SPECT/CT using anthropomorphic torso phantom and water bags to simulate soft tissue and breast attenuation.

PURPOSES

This study was aimed to compare the physical performances of cadmium-zinc-telluride (CZT) camera and conventional Anger camera. An anthropomorphic torso phantom and water bags to simulate breasts were used to evaluate artifacts arising from soft tissue attenuation.

MATERIALS AND METHODS

Linear source studies were performed to evaluate extrinsic resolution of CZT camera (Discovery NM 530c, GE) and conventional single-photon emission computed tomography (SPECT) Anger camera (Symbia T2, Siemens). Three sets of phantom experiments: cardiac phantom only (phantom H), anthropomorphic torso phantom added (phantom T), and torso phantom with water bags attached (phantom B), with Tc-99m were performed on both scanners. Imaging performances were evaluated through count sensitivity, contrast-to-noise ratio, quantitative sharpness profile, wall thickness, perfusion uniformity (measured by standard deviation of perfusion percentage of 20 segments using quantitative perfusion SPECT (QPS) software, Cedars-Sinai), and visual imaging quality (using 20-segment sum defect scores (SDS) of QPS) for CZT camera, conventional SPECT without and with computed tomography transmission attenuation correction (AC).

RESULTS

CZT cameras had higher extrinsic resolution than conventional SPECT. Myocardium count sensitivity of CZT camera is about threefold of conventional SPECT. Contrast-to-noise ratios and sharpness profiles are higher on CZT camera but degraded while extracardiac soft tissue presented. Myocardial walls measured on CZT images were thicker. Images of CZT had lower SDS, while AC reduced the differences of SDS between CZT and CC. Perfusion images from CZT had the better uniformity than SPECT without or with AC. Breast attenuation was less prominent on CZT camera than conventional SPECT, while inferior and inferolateral segments still suffer marked soft tissue attenuation on CZT camera.

CONCLUSIONS

CZT camera has better physical performance and image quality with less artificial perfusion defects than conventional SPECT. CZT camera also has less breast attenuation than conventional SPECT. However, extracardiac soft tissue may degrade the superior performance of CZT camera, and attenuation correction methods are still needed to solve the attenuation issues in inferior and inferolateral myocardium.