Scatter and cross-talk corrections in simultaneous Tc-99m/I-123 brain SPECT using constrained factor analysis and artificial neural networks

Fakhri, Georges El; Maksud, Philippe; Kijewski, Marie Foley; Haberi, M.O.; Todd-Pokropek, A; Aurengo, André; Moore, Stephen

doi:10.1109/23.873018

Cited by 28 publications

(15 citation statements)

References 14 publications

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“…Template C was created using images obtained in 5 healthy volunteers (mean age 5 58.8 6 16 y) acquired with a triple-head camera. In this center, projections were acquired in 8 energy windows ranging from 79 to 179 keV, corrected for scatter using a validated artificial neural network (27) and reconstructed with an iterative algorithm that modeled attenuation and variable collimator response in the projector/backprojector of an OSEM algorithm (Fig. 1).…”

Section: Creation Of 3 Additional Normalization Templatesmentioning

confidence: 99%

Validation of a Standardized Normalization Template for Statistical Parametric Mapping Analysis of 123I-FP-CIT Images

Kas¹,

Payoux²,

Habert³

et al. 2007

Journal of Nuclear Medicine

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(PD). Quantification of 123 I-FP-CIT images is performed at equilibrium using a ratio (BR) of specific (striatal) to nonspecific (occipital) uptake with values obtained from regions of interest drawn manually over these structures. Statistical parametric mapping (SPM) is a fully automated voxel-based statistical approach that has great potential in the context of DAT imaging. However, the accuracy of the spatial normalization provided by SPM has not been validated for 123 I-FP-CIT images. Our first aim was to create an 123 I-FP-CIT template that does not require the acquisition of patient-specific MRI and to validate the spatial normalization procedure. Next, we hypothesized that this customized template could be used by different SPECT centers without affecting the outcomes of imaging analyses. Methods: The spatial normalization to the customized template created with SPM (template A1) was validated using 123 I-FP-CIT images obtained from 6 subjects with essential tremor (ET) with normal DAT status and 6 PD patients. Variability in BR values due to the normalization was evaluated using striatal volume of interest (VOI). To determine whether different SPECT centers could use a unique 123 I-FP-CIT template, we generated 3 other 123 I-FP-CIT templates using different subjects and image-processing schemes. The interchangeability of these templates was assessed using (a) putamen BR values analyzed with the intraclass correlation coefficient (ICC) and the Bland-Altman graphical analysis, and (b) SPM analysis comparing the results of group comparisons-that is, ET versus PD, obtained after normalization to each of the 4 templates. Results: There was no significant difference between pre-and postnormalization striatal BR values in our study. The mean variability calculated with putamen VOI values after normalization to each template was ,10%, with the lowest ICC of 98%. Intergroup analyses performed with VOI and SPM approaches provided similar results independently of the template used. Conclusion: SPM normalization was accurate even in subjects with low striatal 123 I-FP-CIT uptake, making it a promising approach for automatic analysis of 123 I-FP-CIT images using a single customized template at different centers. Parki nson's disease (PD) is characterized by the progressive degeneration of nigrostriatal dopaminergic neurons. This neurodegenerative process is associated with a loss of striatal dopamine transporters (DATs) as shown by postmortem studies (1,2). Therefore, in vivo measurement of DAT density with PET or SPECT is an early marker of the dopaminergic cell loss in subjects with parkinsonian symptoms or in asymptomatic carriers of genetic mutations causing PD (3-7). In clinical routine, DAT SPECT images are often analyzed visually. However, quantitative analysis is useful to differentiate subjects with subtle localized or diffuse loss of DATs that can be difficult to sort out by visual inspection alone. Moreover, quantification is mandatory to measure disease progression (7-11) and to assess the efficacy of ne...

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Section: Creation Of 3 Additional Normalization Templatesmentioning

confidence: 99%

Validation of a Standardized Normalization Template for Statistical Parametric Mapping Analysis of 123I-FP-CIT Images

Kas¹,

Payoux²,

Habert³

et al. 2007

Journal of Nuclear Medicine

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“…Downscatter effects have been studied extensively in simultaneous Tl-201=Tc-99m cardiac SPECT. 30 [32][33][34] These methods provide an arsenal of methods for modeling object downscatter and collimator interactions and iterative reconstruction based compensation methods.…”

Section: Introductionmentioning

confidence: 99%

Development and evaluation of a model-based downscatter compensation method for quantitative I-131 SPECT

Song

et al. 2011

Med. Phys.

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Purpose: The radionuclide 131 I has found widespread use in targeted radionuclide therapy (TRT), partly due to the fact that it emits photons that can be imaged to perform treatment planning or posttherapy dose verification as well as beta rays that are suitable for therapy. In both the treatment planning and dose verification applications, it is necessary to estimate the activity distribution in organs or tumors at several time points. In vivo estimates of the 131 I activity distribution at each time point can be obtained from quantitative single-photon emission computed tomography (QSPECT) images and organ activity estimates can be obtained either from QSPECT images or quantification of planar projection data. However, in addition to the photon used for imaging, 131 I decay results in emission of a number of other higher-energy photons with significant abundances. These higher-energy photons can scatter in the body, collimator, or detector and be counted in the 364 keV photopeak energy window, resulting in reduced image contrast and degraded quantitative accuracy; these photons are referred to as downscatter. The goal of this study was to develop and evaluate a model-based downscatter compensation method specifically designed for the compensation of high-energy photons emitted by 131 I and detected in the imaging energy window. Methods: In the evaluation study, we used a Monte Carlo simulation (MCS) code that had previously been validated for other radionuclides. Thus, in preparation for the evaluation study, we first validated the code for 131 I imaging simulation by comparison with experimental data. Next, we assessed the accuracy of the downscatter model by comparing downscatter estimates with MCS results. Finally, we combined the downscatter model with iterative reconstruction-based compensation for attenuation (A) and scatter (S) and the full (D) collimator-detector response of the 364 keV photons to form a comprehensive compensation method. We evaluated this combined method in terms of quantitative accuracy using the realistic 3D NCAT phantom and an activity distribution obtained from patient studies. We compared the accuracy of organ activity estimates in images reconstructed with and without addition of downscatter compensation from projections with and without downscatter contamination. Results: We observed that the proposed method provided substantial improvements in accuracy compared to no downscatter compensation and had accuracies comparable to reconstructions from projections without downscatter contamination.Conclusions: The results demonstrate that the proposed model-based downscatter compensation method is effective and may have a role in quantitative 131 I imaging.

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“…Some applied compensation methods with three or four windows to estimate the scattered photons [8][9]. Furthermore, spectral factor analysis (SFA) [10] and artificial neural network (ANN) have been used to reduce scatter and cross-talk [11][12][13][14][15].…”

Section: Independent Component Analysis (Ica)mentioning

confidence: 99%

Separation of Two Radionuclides in Simultaneous Dual-Isotope Imaging With Independent Component Analysis

Chang

Huang

et al. 2006

Biomed. Eng. Appl. Basis Commun.

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Scatter and cross-talk corrections in simultaneous Tc-99m/I-123 brain SPECT using constrained factor analysis and artificial neural networks

Cited by 28 publications

References 14 publications

Validation of a Standardized Normalization Template for Statistical Parametric Mapping Analysis of 123I-FP-CIT Images

Validation of a Standardized Normalization Template for Statistical Parametric Mapping Analysis of 123I-FP-CIT Images

Development and evaluation of a model-based downscatter compensation method for quantitative I-131 SPECT

Separation of Two Radionuclides in Simultaneous Dual-Isotope Imaging With Independent Component Analysis

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