Abstract
BackgroundBone SPECT/CT has been shown to offer superior sensitivity and specificity compared to conventional whole-body planar scanning. Furthermore, bone SPECT/CT allows quantitative imaging, which is challenging with planar methods. In order to gain better quantitative accuracy, Bayesian reconstruction algorithms, including both image derived and anatomically guided priors, have been utilized in reconstruction in PET/CT scanning, but they have not been widely used in SPECT/CT studies. Therefore, the aim of this work was to evaluate the performance of CT-guided reconstruction in quantitative bone SPECT.MethodsThree Bayesian reconstruction methods were evaluated against the conventional ordered subsets expectation maximization (OSEM) reconstruction method. One of the studied Bayesian methods was the relative difference prior (RDP), which has recently gained popularity in PET reconstruction. The other two methods, anatomically guided smoothing prior (AMAP-S) and anatomically guided relative difference prior (AMAP-R), utilized anatomical information from the CT scan. The reconstruction methods were evaluated in terms of quantitative accuracy with artificial lesions inserted in clinical patient studies and with 20 real clinical patients. Maximum and mean standardized uptake values (SUVs) of the lesions were defined.ResultsThe analyses showed that all studied Bayesian methods performed better than OSEM and the anatomical priors also outperformed RDP. The average relative error in mean SUV for the artificial lesion study for OSEM, RDP, AMAP-S, and AMAP-R was − 53%, − 35%, − 15%, and − 10%, when the CT study had matching lesions. In the patient study, the RDP method gave 16 ± 9% higher maximum SUV values than OSEM, while AMAP-S and AMAP-R offered increases of 36 ± 8% and 36 ± 9%, respectively. Mean SUV increased for RDP, AMAP-S, and AMAP-R by 18 ± 9%, 26 ± 5%, and 33 ± 5% when compared to OSEM.ConclusionsThe Bayesian methods with anatomical prior, especially the relative difference prior-based method (AMAP-R), outperformed OSEM and reconstruction without anatomical prior in terms of quantitative accuracy.
Highlights
Bone Single-photon emission computed tomography (SPECT)/Computed tomography (CT) has been shown to offer superior sensitivity and specificity compared to conventional whole-body planar scanning
In addition to improved lesion detection, bone SPECT/CT allows quantitative and semiquantitative imaging: for example, the images can be reported in standardized uptake values (SUVs) analogous to routine Positron emission tomography (PET) imaging [2]
Quantitative bone SPECT/CT, holds promise in aiding patient follow-up and interpatient comparisons. It might help in the interpretation of bone SPECT studies, e.g., by allowing global scaling based on SUV, removing scaling difficulties due to hot bladder, or it might provide easier detection of the super-scan phenomenon [4], because there is no need to relate bone uptake to kidney uptake
Summary
Bone SPECT/CT has been shown to offer superior sensitivity and specificity compared to conventional whole-body planar scanning. Bone SPECT/CT allows quantitative imaging, which is challenging with planar methods. In order to gain better quantitative accuracy, Bayesian reconstruction algorithms, including both image derived and anatomically guided priors, have been utilized in reconstruction in PET/CT scanning, but they have not been widely used in SPECT/CT studies. Quantitative bone SPECT/CT, holds promise in aiding patient follow-up and interpatient comparisons. It might help in the interpretation of bone SPECT studies, e.g., by allowing global scaling based on SUV, removing scaling difficulties due to hot bladder, or it might provide easier detection of the super-scan phenomenon [4], because there is no need to relate bone uptake to kidney uptake
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