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The Role of CT-Based Attenuation Correction and Collimator Blurring Correction in Striatal Spect Quantification.

Warwick JM, Rubow S, du Toit M, Beetge E, Carey P, Dupont P - Int J Mol Imaging (2011)

Bottom Line: Recovery values (phantom data) or average-specific uptake ratios (patient data) for the different reconstructions were compared at similar noise levels.Results.Conclusions.

View Article: PubMed Central - PubMed

Affiliation: Nuclear Medicine, Faculty of Health Sciences, Stellenbosch University and Tygerberg Hospital, Tygerberg, 7505, Cape Town, South Africa.

ABSTRACT
Purpose. Striatal single photon emission computed tomography (SPECT) imaging of the dopaminergic system is becoming increasingly used for clinical and research studies. The question about the value of nonuniform attenuation correction has become more relevant with the increasing availability of hybrid SPECT-CT scanners. In this study, the value of nonuniform attenuation correction and correction for collimator blurring were determined using both phantom data and patient data. Methods. SPECT imaging was performed using 7 anthropomorphic phantom measurements, and 14 patient studies using [I-123]-FP-CIT (DATSCAN). SPECT reconstruction was performed using uniform and nonuniform attenuation correction and collimator blurring corrections. Recovery values (phantom data) or average-specific uptake ratios (patient data) for the different reconstructions were compared at similar noise levels. Results. For the phantom data, improved recovery was found with nonuniform attenuation correction and collimator blurring corrections, with further improvement when performed together. However, for patient data the highest average specific uptake ratio was obtained using collimator blurring correction without nonuniform attenuation correction, probably due to subtle SPECT-CT misregistration. Conclusions. This study suggests that an optimal brain SPECT reconstruction (in terms of the lowest bias) in patients would include a correction for collimator blurring and uniform attenuation correction.

No MeSH data available.


Related in: MedlinePlus

Striatal (red, green) and occipital (purple) volumes of interest used for the phantom study defined using the CT image of the phantom acquired with water in the background chamber and air in the striatal chambers (a). For the patient study using the Hermes Brass software striatal (light green, orange, red, yellow) and occipital (dark blue) volumes were used (b). Frontal (light blue) and cerebellar (green) volumes were not used for this study.
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Related In: Results  -  Collection


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fig1: Striatal (red, green) and occipital (purple) volumes of interest used for the phantom study defined using the CT image of the phantom acquired with water in the background chamber and air in the striatal chambers (a). For the patient study using the Hermes Brass software striatal (light green, orange, red, yellow) and occipital (dark blue) volumes were used (b). Frontal (light blue) and cerebellar (green) volumes were not used for this study.

Mentions: A phantom CT study was performed with the main brain volume filled with water, while the striatal volumes contained air, which will be referred to as the phantom-air study. The CT image derived from the phantom-air study, and all reconstructed SPECT images and CT-based attenuation maps from the 8 phantom SPECT-CT studies were converted from interfile to ANALYZE format using MRIcro software [26]. The reconstructed SPECT images and CT based attenuation maps were all coregistered to the same space as the phantom-air study using a mutual information algorithm with Statistical Parametric Mapping software (SPM version 2, http://www.fil.ion.ucl.ac.uk/spm/, Wellcome Department of Cognitive Neurology, UK). Using MRIcro and the phantom-air CT image, 3-dimensional VOIs were drawn for the left striatum, right striatum, and a background volume located posteriorly in the main brain volume (Figure 1(a)). In each voxel of the two striatal VOIs, the specific uptake ratio (SUR) was calculated using formula (1) with the background activity being equal to the mean activity within the background VOI and the “striatal activity” being the activity in the voxel. For each VOI, a mean SURmean and standard deviation SURSD was determined. These values were determined for each VOI (v), for each phantom measurement (p), for each type of reconstruction (r), and for each smoothing kernel (s).


The Role of CT-Based Attenuation Correction and Collimator Blurring Correction in Striatal Spect Quantification.

Warwick JM, Rubow S, du Toit M, Beetge E, Carey P, Dupont P - Int J Mol Imaging (2011)

Striatal (red, green) and occipital (purple) volumes of interest used for the phantom study defined using the CT image of the phantom acquired with water in the background chamber and air in the striatal chambers (a). For the patient study using the Hermes Brass software striatal (light green, orange, red, yellow) and occipital (dark blue) volumes were used (b). Frontal (light blue) and cerebellar (green) volumes were not used for this study.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3094814&req=5

fig1: Striatal (red, green) and occipital (purple) volumes of interest used for the phantom study defined using the CT image of the phantom acquired with water in the background chamber and air in the striatal chambers (a). For the patient study using the Hermes Brass software striatal (light green, orange, red, yellow) and occipital (dark blue) volumes were used (b). Frontal (light blue) and cerebellar (green) volumes were not used for this study.
Mentions: A phantom CT study was performed with the main brain volume filled with water, while the striatal volumes contained air, which will be referred to as the phantom-air study. The CT image derived from the phantom-air study, and all reconstructed SPECT images and CT-based attenuation maps from the 8 phantom SPECT-CT studies were converted from interfile to ANALYZE format using MRIcro software [26]. The reconstructed SPECT images and CT based attenuation maps were all coregistered to the same space as the phantom-air study using a mutual information algorithm with Statistical Parametric Mapping software (SPM version 2, http://www.fil.ion.ucl.ac.uk/spm/, Wellcome Department of Cognitive Neurology, UK). Using MRIcro and the phantom-air CT image, 3-dimensional VOIs were drawn for the left striatum, right striatum, and a background volume located posteriorly in the main brain volume (Figure 1(a)). In each voxel of the two striatal VOIs, the specific uptake ratio (SUR) was calculated using formula (1) with the background activity being equal to the mean activity within the background VOI and the “striatal activity” being the activity in the voxel. For each VOI, a mean SURmean and standard deviation SURSD was determined. These values were determined for each VOI (v), for each phantom measurement (p), for each type of reconstruction (r), and for each smoothing kernel (s).

Bottom Line: Recovery values (phantom data) or average-specific uptake ratios (patient data) for the different reconstructions were compared at similar noise levels.Results.Conclusions.

View Article: PubMed Central - PubMed

Affiliation: Nuclear Medicine, Faculty of Health Sciences, Stellenbosch University and Tygerberg Hospital, Tygerberg, 7505, Cape Town, South Africa.

ABSTRACT
Purpose. Striatal single photon emission computed tomography (SPECT) imaging of the dopaminergic system is becoming increasingly used for clinical and research studies. The question about the value of nonuniform attenuation correction has become more relevant with the increasing availability of hybrid SPECT-CT scanners. In this study, the value of nonuniform attenuation correction and correction for collimator blurring were determined using both phantom data and patient data. Methods. SPECT imaging was performed using 7 anthropomorphic phantom measurements, and 14 patient studies using [I-123]-FP-CIT (DATSCAN). SPECT reconstruction was performed using uniform and nonuniform attenuation correction and collimator blurring corrections. Recovery values (phantom data) or average-specific uptake ratios (patient data) for the different reconstructions were compared at similar noise levels. Results. For the phantom data, improved recovery was found with nonuniform attenuation correction and collimator blurring corrections, with further improvement when performed together. However, for patient data the highest average specific uptake ratio was obtained using collimator blurring correction without nonuniform attenuation correction, probably due to subtle SPECT-CT misregistration. Conclusions. This study suggests that an optimal brain SPECT reconstruction (in terms of the lowest bias) in patients would include a correction for collimator blurring and uniform attenuation correction.

No MeSH data available.


Related in: MedlinePlus