H Marquis1,2, D Deidda3, A Gillman4, K P Willowson5, Y Gholami1,2,6, T Hioki2, E Eslick5, K Thielemans7, D L Bailey8,9,10. 1. Sydney Vital Translational Cancer Research Centre, Sydney, Australia. 2. Institute of Medical Physics, University of Sydney, Sydney, Australia. 3. National Physical Laboratory, Teddington, UK. 4. Australian e-Health Research Centre, CSIRO, Brisbane, Australia. 5. Department of Nuclear Medicine, Royal North Shore Hospital, Sydney, Australia. 6. Faculty of Medicine and Health, University of Sydney, Sydney, Australia. 7. Institute of Nuclear Medicine, University College London, London, UK. 8. Sydney Vital Translational Cancer Research Centre, Sydney, Australia. dale.bailey@sydney.edu.au. 9. Department of Nuclear Medicine, Royal North Shore Hospital, Sydney, Australia. dale.bailey@sydney.edu.au. 10. Faculty of Medicine and Health, University of Sydney, Sydney, Australia. dale.bailey@sydney.edu.au.
Abstract
BACKGROUND: SPECT-derived dose estimates in tissues of diameter less than 3× system resolution are subject to significant losses due to the limited spatial resolution of the gamma camera. Incorporating resolution modelling (RM) into the SPECT reconstruction has been proposed as a possible solution; however, the images produced are prone to noise amplification and Gibbs artefacts. We propose a novel approach to SPECT reconstruction in a theranostic setting, which we term SPECTRE (single photon emission computed theranostic reconstruction); using a diagnostic PET image, with its superior resolution, to guide the SPECT reconstruction of the therapeutic equivalent. This report demonstrates a proof in principle of this approach. METHODS: We have employed the hybrid kernelised expectation maximisation (HKEM) algorithm implemented in STIR, with the aim of producing SPECT images with PET-equivalent resolution. We demonstrate its application in both a dual 68Ga/177Lu IEC phantom study and a clinical example using 64Cu/67Cu. RESULTS: SPECTRE is shown to produce images comparable in accuracy and recovery to PET with minimal introduction of artefacts and amplification of noise. CONCLUSION: The SPECTRE approach to image reconstruction shows improved quantitative accuracy with a reduction in noise amplification. SPECTRE shows great promise as a method of improving SPECT radioactivity concentrations, directly leading to more accurate dosimetry estimates in small structures and target lesions. Further investigation and optimisation of the algorithm parameters is needed before this reconstruction method can be utilised in a clinical setting.
BACKGROUND: SPECT-derived dose estimates in tissues of diameter less than 3× system resolution are subject to significant losses due to the limited spatial resolution of the gamma camera. Incorporating resolution modelling (RM) into the SPECT reconstruction has been proposed as a possible solution; however, the images produced are prone to noise amplification and Gibbs artefacts. We propose a novel approach to SPECT reconstruction in a theranostic setting, which we term SPECTRE (single photon emission computed theranostic reconstruction); using a diagnostic PET image, with its superior resolution, to guide the SPECT reconstruction of the therapeutic equivalent. This report demonstrates a proof in principle of this approach. METHODS: We have employed the hybrid kernelised expectation maximisation (HKEM) algorithm implemented in STIR, with the aim of producing SPECT images with PET-equivalent resolution. We demonstrate its application in both a dual 68Ga/177Lu IEC phantom study and a clinical example using 64Cu/67Cu. RESULTS: SPECTRE is shown to produce images comparable in accuracy and recovery to PET with minimal introduction of artefacts and amplification of noise. CONCLUSION: The SPECTRE approach to image reconstruction shows improved quantitative accuracy with a reduction in noise amplification. SPECTRE shows great promise as a method of improving SPECT radioactivity concentrations, directly leading to more accurate dosimetry estimates in small structures and target lesions. Further investigation and optimisation of the algorithm parameters is needed before this reconstruction method can be utilised in a clinical setting.
Authors: Kristof Baete; Johan Nuyts; Wim Van Paesschen; Paul Suetens; Patrick Dupont Journal: IEEE Trans Med Imaging Date: 2004-04 Impact factor: 10.048
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Authors: Daniel Deidda; Ana M Denis-Bacelar; Andrew J Fenwick; Kelley M Ferreira; Warda Heetun; Brian F Hutton; Andrew P Robinson; James Scuffham; Kris Thielemans Journal: EJNMMI Phys Date: 2022-04-04