Physics in medicine and biology · 2026
Dimensionality reduction for partial-volume correction in quantitative SPECT.
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Gustafsson Johan, Larsson Erik, Sjogreen-Gleisner Katarina
Аннотация
OBJECTIVE: The aim of this paper is to develop a method for region-based post-reconstruction partial-volume correction (PVC) of SPECT images, which explicitly estimates the mean activity concentration in regions without assuming strict intra-regional uniformity.
APPROACH: Partial-volume correction was applied to177Lu-SPECT images obtained from the simulation of eight anthropomorphic phantoms as well as two example patients. Both sets of data were reconstructed using OS-EM with ten subsets and up to 40 iterations, including compensation for attenuation, scatter, and spatial resolution. Reconstructed images were deconvolved using the van Cittert algorithm and Lucy-Richardson algorithm, both implemented on images represented as standard cuboid voxels or as regional voxels, consisting of regions defined from whole-image segmentation. Methods embedding regional voxels were applied both assuming region-wise uniform activity concentration and incorporating perturbations in the form of cosine series to relax the uniformity assumption. For comparison, images were also processed with the iterative Yang method and MIRD recovery coefficients. Evaluation was performed with respect to the estimated activity concentration for kidneys, spleen, and tumours, as well as the total activity in the images.
MAIN RESULTS: Mean activity-concentration errors prior to PVC were (-22.6±11.5) %, (-13.8±2.1) %, and (-7.4±2.8) % for tumours, kidneys, and spleen, respectively. Region-perturbed van Cittert deconvolution with order 4 reduced these errors to (2.3±7.7) %, (0.3±2.2) %, and (4.0±1.6) % while the errors for region-perturbed Lucy-Richardson deconvolution of order 4 were (0.3±8.0) %, (0.0±1.6) %, (2.6±0.5) %. Corresponding results for the iterative Yang method were (2.8±21) %, (-0.3±2.1) %, and (3.8±2.4) % and using MIRD recovery coefficients (-5.0±14.2) %, (-7.1±1.9) %, and (-0.6±3.1) %.
SIGNIFICANCE: Region-based PVC improves the accuracy of quantitative SPECT, and the inclusion of cosine perturbations allows for a gradual relaxation of the uniformity assumption.
APPROACH: Partial-volume correction was applied to177Lu-SPECT images obtained from the simulation of eight anthropomorphic phantoms as well as two example patients. Both sets of data were reconstructed using OS-EM with ten subsets and up to 40 iterations, including compensation for attenuation, scatter, and spatial resolution. Reconstructed images were deconvolved using the van Cittert algorithm and Lucy-Richardson algorithm, both implemented on images represented as standard cuboid voxels or as regional voxels, consisting of regions defined from whole-image segmentation. Methods embedding regional voxels were applied both assuming region-wise uniform activity concentration and incorporating perturbations in the form of cosine series to relax the uniformity assumption. For comparison, images were also processed with the iterative Yang method and MIRD recovery coefficients. Evaluation was performed with respect to the estimated activity concentration for kidneys, spleen, and tumours, as well as the total activity in the images.
MAIN RESULTS: Mean activity-concentration errors prior to PVC were (-22.6±11.5) %, (-13.8±2.1) %, and (-7.4±2.8) % for tumours, kidneys, and spleen, respectively. Region-perturbed van Cittert deconvolution with order 4 reduced these errors to (2.3±7.7) %, (0.3±2.2) %, and (4.0±1.6) % while the errors for region-perturbed Lucy-Richardson deconvolution of order 4 were (0.3±8.0) %, (0.0±1.6) %, (2.6±0.5) %. Corresponding results for the iterative Yang method were (2.8±21) %, (-0.3±2.1) %, and (3.8±2.4) % and using MIRD recovery coefficients (-5.0±14.2) %, (-7.1±1.9) %, and (-0.6±3.1) %.
SIGNIFICANCE: Region-based PVC improves the accuracy of quantitative SPECT, and the inclusion of cosine perturbations allows for a gradual relaxation of the uniformity assumption.