Differences in attenuation pattern in myocardial SPECT between CZT and conventional gamma cameras

Background

: In myocardial perfusion imaging (MPI), single-photon emission tomography (SPECT) soft-tissue attenuation by the abdomen, breasts, and lateral chest wall may create artifacts that mimic true perfusion defects. This may cause misdiagnosis of myocardial perfusion. The aim of the present study was to compare the localization, extent, and depth of attenuation artifacts in MPI SPECT for a multi-pinhole cadmium zinc telluride (CZT) camera vs a conventional gamma camera.

Methods

: Phantom and patient measurements were performed using a CZT camera (GE NM 530c) and a conventional gamma camera (GE Ventri). All images were attenuation corrected with externally acquired low-dose computed tomography. The localization, extent, and depth of the attenuation artifact were quantified by comparing attenuation-corrected and non-attenuation-corrected images.

Results

: Attenuation artifacts were shifted from the inferolateral wall to the lateral wall using the CZT camera compared to a conventional camera in both the patient and the phantom. The extent of the attenuation artifact was significantly larger for the CZT camera compared to the conventional camera (23 ± 5% vs 15 ± 5%, P < .001) for patients and the result was similar for the phantom (28% vs 19%). Furthermore, the depth of the attenuation artifact (percent of maximum counts) was less pronounced for the CZT camera than for the conventional camera, both for phantom measurements (73% vs 67%) and patients (72 ± 3% vs 68 ± 4%, P < .001).

Conclusions

: Attenuation artifacts are found in different locations to different extents and depths when using a CZT camera vs a conventional gamma camera for MPI SPECT. This should be taken into consideration when evaluating MPI SPECT studies to avoid misinterpretation of myocardial perfusion distribution.