The aim of this study was to investigate the efficacy of compressed sensing (CS)-based iterative reconstruction (CS-IR) from undersampled projection data in 123I-N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane single-photon emission computed tomography (SPECT).
We used the cylinder/sphere and the striatal digital phantom models. The number of projections was set at 120, 90, 60, 40, and 30 projections. SPECT images were reconstructed using filtered back-projection (FBP), maximum likelihood-expectation maximization (ML-EM), and CS-IR. The total-variation transform with local image gradient in L1-norm was adopted in our CS algorithm. The efficacy of CS-IR was examined in terms of the spatial resolution, recovery coefficient, aspect ratio (ASR), activity concentration linearity, percent coefficient of variation (%CV), and specific binding ratio.
As the number of projections decreased, the following results were observed. No differences of the spatial resolution and activity concentration linearity were observed between reconstruction methods. However, ASR for FBP slightly increased in contrast to ML-EM and CS-IR for which ASR remained constant. There were not any clear differences between recovery coefficients obtained from each reconstruction. The %CV obtained by CS-IR was significantly superior to that obtained by other reconstructions at all number of projections: for example, the %CV obtained by 60 projection CS-IR was equivalent to that obtained by 120 projection FBP and ML-EM. The specific binding ratio did not change with the number of projections, and there were no significant differences between FBP, ML-EM, and CS-IR.
We have demonstrated that CS-IR with decreased number of projections can provide a good image quality compared with commonly used SPECT reconstruction methods. This CS could help to reduce overall acquisition time in 123I-N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane SPECT, particularly.
Departments of aMedical Radiological Technology, Faculty of Health Sciences
bRadiology, Kyorin University Hospital, Tokyo, Japan
Correspondence to Norikazu Matsutomo, PhD, Department of Medical Radiological Technology, Faculty of Health Sciences, Kyorin University, A-420, 5-4-1 Shimorenjaku Mitaka-shi, 181-8612 Tokyo, Japan Tel: +81 422 478 000; e-mail: email@example.com
Received July 14, 2018
Received in revised form October 2, 2018
Accepted October 8, 2018