Optimization of Image Reconstruction Method of Cerebral Blood Flow Perfusion Imaging with Digital CZT SPECT

Abstract

\n Purpose: To evaluate the effects of filtered back projection (FBP), ordered subset expectation maximisation (OSEM), and different filters on cadmium zinc telluride single photon emission computed tomography (CZT SPECT) cerebral blood perfusion image quality to optimise the image reconstruction method.Methods: Jaszczak phantom and patients with clinical cerebral ischemia were selected as study subjects. Under routine clinical conditions, tomographic imaging was performed on the phantom and patients with clinical cerebral ischemia. Image processing included image reconstruction using filtered back projection with Chang’s attenuation correction (FBPChangAC) and OSEM algorithm with CT-based attenuation correction (CTAC), scatter correction (SC), resolution recovery (RR) (OSEMCTAC-SC-RR), and the filtering method used Butterworth (Bw) and Gauss (Gs) filters. Visual and semi-quantitative parameters (integral uniformity, root mean square noise (RMS noise), and contrast and contrast-to-noise ratio (CNR)) were used to evaluate image quality to optimise image reconstruction parameters. One-way and two-way ANOVA were used to process phantom and clinical data.Results: In the tomographic images of phantom and brain imaging of patients, FBP+Bw had the best uniformity and the lowest noise level, while OSEM+Bw had the best contrast. Semi-quantitative analysis showed that the integral uniformity of FBP+Bw was significantly higher than that of OSEM+Bw and OSEM+Gs (p <0.05), and that the RMS noise of FBP+Bw was significantly lower than that of OSEM+Bw and OSEM+Gs (p <0.001). The contrast of FBP+Bw and OSEM+Bw in the cold sphere diameter ≥ 2 cm group was significantly higher than that of OSEM+Gs (p <0.001), while the CNR of FBP+Bw was significantly higher than that of OSEM+Bw and OSEM+Gs (p <0.001) ; the contrast of OSEM+Bw cold sphere diameter < 2 cm was significantly higher than that of FBP+Bw (p <0.01). The semi-quantitative analysis results of the patient s cerebral perfusion tomography were consistent with the model.Conclusion: In CZT SPECT cerebral blood flow perfusion imaging, images with lesion sizes greater than 2 cm were suitable for FBP+Bw (fc=0.40, n=10), and the image with lesion size less than 2 cm was suitable for OSEM+Bw (EM=60, fc=0.45, n=10). The reconstruction method of OSEM+Gs (EM=80, full width at half maximum [FWHM]=3.25) was not suitable for cerebral blood perfusion imaging.