SPECT reconstruction using DCT-induced tight framelet regularization

Jiahan Zhang; Si Li; Yuesheng Xu; C. Ross Schmidtlein; Edward D. Lipson; David H. Feiglin; Andrzej Krol

doi:10.1117/12.2082118

18 March 2015 SPECT reconstruction using DCT-induced tight framelet regularization

Jiahan Zhang, Si Li, Yuesheng Xu, C. Ross Schmidtlein, Edward D. Lipson, David H. Feiglin, Andrzej Krol

Proceedings Volume 9412, Medical Imaging 2015: Physics of Medical Imaging; 94123H (2015) https://doi.org/10.1117/12.2082118
Event: SPIE Medical Imaging, 2015, Orlando, Florida, United States

Abstract

Wavelet transforms have been successfully applied in many fields of image processing. Yet, to our knowledge, they have never been directly incorporated to the objective function in Emission Computed Tomography (ECT) image reconstruction. Our aim has been to investigate if the ℓ1-norm of non-decimated discrete cosine transform (DCT) coefficients of the estimated radiotracer distribution could be effectively used as the regularization term for the penalized-likelihood (PL) reconstruction, where a regularizer is used to enforce the image smoothness in the reconstruction. In this study, the ℓ1-norm of 2D DCT wavelet decomposition was used as a regularization term. The Preconditioned Alternating Projection Algorithm (PAPA), which we proposed in earlier work to solve penalized likelihood (PL) reconstruction with non-differentiable regularizers, was used to solve this optimization problem. The DCT wavelet decompositions were performed on the transaxial reconstructed images. We reconstructed Monte Carlo simulated SPECT data obtained for a numerical phantom with Gaussian blobs as hot lesions and with a warm random lumpy background. Reconstructed images using the proposed method exhibited better noise suppression and improved lesion conspicuity, compared with images reconstructed using expectation maximization (EM) algorithm with Gaussian post filter (GPF). Also, the mean square error (MSE) was smaller, compared with EM-GPF. A critical and challenging aspect of this method was selection of optimal parameters. In summary, our numerical experiments demonstrated that the ℓ1-norm of discrete cosine transform (DCT) wavelet frame transform DCT regularizer shows promise for SPECT image reconstruction using PAPA method.

Citation Download Citation

Jiahan Zhang, Si Li, Yuesheng Xu, C. Ross Schmidtlein, Edward D. Lipson, David H. Feiglin, and Andrzej Krol "SPECT reconstruction using DCT-induced tight framelet regularization", Proc. SPIE 9412, Medical Imaging 2015: Physics of Medical Imaging, 94123H (18 March 2015); https://doi.org/10.1117/12.2082118

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