Impacts of different reconstruction methods on the image quality of cadmium-zinc-telluride-based single photon...

The objective was to evaluate the impacts of different reconstruction methods [filtered back projection (FBP) and ordered subset expectation maximization (OSEM)] and different filters (Butterworth filter and Gaussian filter) on the image quality in cadmium-zinc-telluride (CZT)-based single photon emission computed tomography (SPECT)/computed tomography (CT) pulmonary perfusion imaging.

A combinations including FBP with Butterworth filter, OSEM with Butterworth filter (OSEM + Butterworth filter ), and OSEM with Gaussian filter (OSEM + Gaussian filter) were used during SPECT image reconstruction. Visual and quantitative parameters [root mean square (RMS) noise, contrast and contrast-to-noise ratio (CNR)] were used to evaluate image quality.

The OSEM + Gaussian filter had better RMS noise and CNR than those of the FBP + Butterworth filter or OSEM + Butterworth filter, while the OSEM + Butterworth filter had the best contrast. The highest visual scores were obtained by OSEM + Gaussian filter ( P  < 0.0001). In the lesion size <2 cm group, the contrast ( P < 0.01) and visual scores ( P < 0.001) of OSEM + Butterworth filter were better than those of the other two groups. In the lesion size ≥2 cm group, the RMS noise and visual scores of OSEM + Gaussian filter were better than those of the other two groups.

In CZT SPECT/CT pulmonary perfusion imaging, this study recommended the clinical use of the OSEM + Gaussian filter combination for reconstruction in both conventional and larger lesions, the OSEM + Butterworth filter image postprocessing method might be advantageous in small lesions.