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Larsson, Anne
Publications (10 of 65) Show all publications
Jakobson Mo, S., Axelsson, J., Jonasson, L., Larsson, A., Ögren, M. J., Ögren, M., . . . Riklund, K. (2018). Dopamine transporter imaging with [18F]FE-PE2I PET and [123I]FP-CIT SPECT – a clinical comparison. EJNMMI Research, 8, Article ID 100.
Open this publication in new window or tab >>Dopamine transporter imaging with [18F]FE-PE2I PET and [123I]FP-CIT SPECT – a clinical comparison
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2018 (English)In: EJNMMI Research, ISSN 2191-219X, E-ISSN 2191-219X, Vol. 8, article id 100Article in journal (Refereed) Published
Abstract [en]

Background: Dopamine transporter (DAT) imaging may be of diagnostic value in patients with clinically suspected parkinsonian disease. The purpose of this study was to compare the diagnostic performance of DAT imaging with positron emission computed tomography (PET), using the recently developed, highly DAT-selective radiopharmaceutical [18F]FE-PE2I (FE-PE2I), to the commercially available and frequently used method with [123I]FP-CIT (FP-CIT) single-photon emission computed tomography (SPECT) in early-stage idiopathic parkinsonian syndrome (PS).

Methods: Twenty-two patients with a clinical de novo diagnosis of PS and 28 healthy controls (HC) participating in an on-going clinical trial of FE-PE2I were analyzed in this study. Within the trial protocol, participants are clinically reassessed 2 years after inclusion. A commercially available software was used for automatic calculation of FP-CIT-specific uptake ratio (SUR). MRI-based volumes of interest combined with threshold PET segmentation were used for FE-PE2I binding potential relative to non-displaceable binding (BPND) quantification and specific uptake value ratios (SUVR).

Results: PET with FE-PE2I revealed significant differences between patients with a clinical de novo diagnosis of PS and healthy controls in striatal DAT availability (p < 0.001), with excellent accuracy of predicting dopaminergic deficit in early-stage PS. The effect sizes were calculated for FE-PE2I BPND (Glass’s Δ = 2.95), FE-PE2I SUVR (Glass’s Δ = 2.57), and FP-CIT SUR (Glass’s Δ = 2.29). The intraclass correlation (ICC) between FE-PE2I BPND FP-CIT SUR was high in the caudate (ICC = 0.923), putamen (ICC = 0.922), and striatum (ICC = 0.946), p < 0.001. Five of the 22 patients displayed preserved striatal DAT availability in the striatum with both methods. At follow-up, a non-PS clinical diagnosis was confirmed in three of these, while one was clinically diagnosed with corticobasal syndrome. In these patients, FE-PE2I binding was also normal in the substantia nigra (SN), while significantly reduced in the remaining patients. FE-PE2I measurement of the mean DAT availability in the putamen was strongly correlated with BPND in the SN (R = 0.816, p < 0.001). Olfaction and mean putamen DAT availability was correlated using both FE-PE2I BPND and FP-CIT SUR (R ≥ 0.616, p < 0.001).

Conclusion: DAT imaging with FE-PE2I PET yields excellent basic diagnostic differentiation in early-stage PS, at least as good as FP-CIT SPECT.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Parkinson's disease, PET, SPECT, Dopamine transporter (DAT), [F-18]FE-PE2I
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-154944 (URN)10.1186/s13550-018-0450-0 (DOI)000450488800002 ()30443684 (PubMedID)
Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2019-01-07Bibliographically approved
Lizana, H., Johansson, L., Axelsson, J., Larsson, A., Ögren, M., Linder, J., . . . Jakobson Mo, S. (2018). Whole-Body Biodistribution and Dosimetry of the Dopamine Transporter Radioligand 18F-FE-PE2I in Human Subjects. Journal of Nuclear Medicine, 59(8), 1275-1280
Open this publication in new window or tab >>Whole-Body Biodistribution and Dosimetry of the Dopamine Transporter Radioligand 18F-FE-PE2I in Human Subjects
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2018 (English)In: Journal of Nuclear Medicine, ISSN 0161-5505, E-ISSN 1535-5667, Vol. 59, no 8, p. 1275-1280Article in journal (Refereed) Published
Abstract [en]

F-18-(E)-N-(3-iodoprop-2-enyl)-2 beta-carbofluoroethoxy-3 beta-(4'-methylphenyl) nortropane (F-18-FE-PE2I) was recently developed and has shown adequate affinity and high selectivity for the dopamine transporter (DAT). Previous studies have shown promising results for F-18-FE-PE2I as a suitable radioligand for DAT imaging. In this study, we investigated the whole-body biodistribution and dosimetry of F-18-FE-PE2I in healthy volunteers to support its utility as a suitable PET imaging agent for the DAT. Methods: Five healthy volunteers were given a mean activity of 2.5 MBq/kg, and 3 PET scans, head to thigh, were performed immediately after injection followed by 4 whole-body PET/CT scans between 0.5 and 6 h after injection. Blood samples were drawn in connection with the whole-body scans, and all urine was collected until 6 h after injection. Volumes of interest were delineated around 17 organs on all images, and the areas under the time-activity curves were calculated to obtain the total number of decays in the organs. The absorbed doses to organs and the effective dose were calculated using the software IDAC. Results: The highest activity concentration was observed in the liver (0.9%-1.2% injected activity/100 g) up to 30 min after injection. At later time points, the highest concentration was seen in the gallbladder (1.1%-0.1% injected activity/100 g). The activity excreted with urine ranged between 23% and 34%, with a mean of 28%. The urinary bladder received the highest absorbed dose (119 mu Gy/MBq), followed by the liver (46 mu Gy/MBq). The effective dose was 23 mu Sv/MBq (range, 19-28 mu Sv/MBq), resulting in an effective dose of 4.6 mSv for an administered activity of 200 MBq. Conclusion: The effective dose is within the same order of magnitude as other commonly used PET imaging agents as well as DAT agents. The reasonable effective dose, together with the previously reported favorable characteristics for DAT imaging and quantification, indicates that F-18-FE-PE2I is a suitable radioligand for DAT imaging.

Keywords
F-18-FE-PE2I, dosimetry, biodistribution, DAT, effective dose
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-150823 (URN)10.2967/jnumed.117.197186 (DOI)000440582000020 ()29348315 (PubMedID)
Available from: 2018-08-21 Created: 2018-08-21 Last updated: 2018-08-21Bibliographically approved
Wallstén, E., Axelsson, J., Karlsson, M., Riklund, K. & Larsson, A. (2017). A Study of Dynamic PET Frame-Binning on the Reference Logan Binding Potential. IEEE Transactions on Radiation and Plasma Medical Sciences, 1(2), 128-135
Open this publication in new window or tab >>A Study of Dynamic PET Frame-Binning on the Reference Logan Binding Potential
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2017 (English)In: IEEE Transactions on Radiation and Plasma Medical Sciences, ISSN 2469-7311, Vol. 1, no 2, p. 128-135Article in journal (Refereed) Published
Abstract [en]

Objective: The reference Logan plot is a tool for determining the non-displaceable binding potential for dynamic PET exams using tracers with reversible bindings. Dynamic frame protocols affect noise in PET images and short frames can lead to quantitative uncertainties and noise-induced reconstruction bias. The aim of this study was to analyze the effect of frame binning on 11C-Raclopride striatal binding potential from reference Logan analysis. Methods: 12 healthy volunteers were scanned in list mode using 11C-raclopride, and the image data were reconstructed into 9 different frame binning schemes whereof 3 clinical schemes. Reconstruction was performed with 3 different algorithms, one based on filtered back projection (FBP) and two based on ordered subset expectation maximization (OSEM); one including resolution recovery. Logan plots were used for calculating the non-displaceable binding potential. Variation in binding potential was evaluated using Students t-tests. Results: It was found that frame lengths of up to 60 s gave significantly different results compared to the reference clinical protocol for OSEM, both with and without resolution recovery (maximum deviation: 10.3 % for the 15 s protocol). For FBP, frame lengths of up to 30 s gave significantly different results with a maximum deviation of 2.8 %. The higher sampling dependence of OSEM compared to FBP is likely due to noise-dependent bias in the OSEM algorithm, most apparent at high noise levels. Conclusions: Bias related to OSEM reconstruction of high-noise data is an important factor for dynamic PET protocols. Time frames of 120 s or more generate the most stable values for the striatum binding potential with the reference Logan plot for 11C-Raclopride brain PET.

Keywords
¹¹C-Raclopride, binding potential, dynamic frame protocol, frame binning, Logan analysis, positron emission tomography, time sampling
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-146397 (URN)10.1109/TNS.2016.2639560 (DOI)
Available from: 2018-04-09 Created: 2018-04-09 Last updated: 2018-06-09Bibliographically approved
Lundman, J. A., Johansson, A., Olofsson, J., Axelsson, J., Larsson, A. & Nyholm, T. (2017). Effect of gradient field nonlinearity distortions in MRI-based attenuation maps for PET reconstruction. Physica medica (Testo stampato), 35, 1-6
Open this publication in new window or tab >>Effect of gradient field nonlinearity distortions in MRI-based attenuation maps for PET reconstruction
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2017 (English)In: Physica medica (Testo stampato), ISSN 1120-1797, E-ISSN 1724-191X, Vol. 35, p. 1-6Article in journal (Refereed) Published
Abstract [en]

Purpose: Attenuation correction is a requirement for quantification of the activity distribution in PET. The need to base attenuation correction on MRI instead of CT has arisen with the introduction of integrated PET/MRI systems. The aim was to describe the effect of residual gradient field nonlinearity distortions on PET attenuation correction.

Methods: MRI distortions caused by gradient field nonlinearity were simulated in CT images used for attenuation correction in PET reconstructions. The simulations yielded radial distortion of up to  at 15 cm from the scanner isocentre for distortion corrected images. The mean radial distortion of uncorrected images were 6.3 mm at the same distance. Reconstructions of PET data were performed using the distortion corrected images as well as the images where no correction had been applied.

Results: The mean relative difference in reconstructed PET uptake intensity due to incomplete distortion correction was less than ±5%. The magnitude of this difference varied between patients and the size of the distortions remaining after distortion correction.

Conclusions: Radial distortions of 2 mm at 15 cm radius from the scanner isocentre lead to PET attenuation correction errors smaller than 5%. Keeping the gradient field nonlinearity distortions below this limit can be a reasonable goal for MRI systems used for attenuation correction in PET for quantification purposes. A higher geometrical accuracy may, however, be warranted for quantification of peripheral lesions. These distortions can, e.g., be controlled at acceptance testing and subsequent quality assurance intervals.

Keywords
MRI, PET, Quality assurance, Attenuation correction, MRI distortions
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-133798 (URN)10.1016/j.ejmp.2017.02.019 (DOI)000397945200001 ()28283354 (PubMedID)
Available from: 2017-04-21 Created: 2017-04-21 Last updated: 2018-06-09Bibliographically approved
Lenfeldt, N., Holmlund, H., Larsson, A., Birgander, R. & Forsgren, L. (2016). Frontal white matter injuries predestine gait difficulties in Parkinson's disease. Acta Neurologica Scandinavica, 134(3), 210-218
Open this publication in new window or tab >>Frontal white matter injuries predestine gait difficulties in Parkinson's disease
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2016 (English)In: Acta Neurologica Scandinavica, ISSN 0001-6314, E-ISSN 1600-0404, Vol. 134, no 3, p. 210-218Article in journal (Refereed) Published
Abstract [en]

Objectives: This study applies diffusion tensor imaging (DTI) to determine differences in neuronal integrity between motor phenotypes in Parkinson's disease. Material and Methods: One hundred and twenty-two patients (47 females, mean age = 70.3 years) were included at baseline. Forty patients were tremor dominant (TD), 64 had postural imbalance and gait difficulty (PIGD), and 18 patients were indeterminate. The DTI was repeated after one, three and 5 years, including reassessment of phenotype. DTI was quantified using fractional anisotropy (FA), and mean, radial and axial diffusion. Targeted white matter involved six regions of interests (ROIs) in prefrontal cortex (PFC), the entrance to the external capsule (EEC) and lateral to the horn of the anterior ventricle (LVAH). Grey matter involved the basal ganglia. Data were analysed using mixed linear models with P < 0.05 (Bonferroni corrected) as significance threshold. Results: PIGD and Indeterminate had reduced FA and axial diffusion in PFC, EEC and LVAH compared to Tremor dominant (P < 0.05). Basal ganglia showed no differences. Post hoc analysis showed that FA correlated negatively, and mean and radial diffusion positively, to PIGD symptoms in EEC, LVAH and four ROIs in PFC (P < 0.05). Tremor symptoms showed no correlations. Patients converting to PIGD and Indeterminate had lower FA, and higher mean and radial diffusion, at baseline in EEC, LVAH and four areas in PFC compared to non-converting patients (P < 0.05). Conclusion: Degeneration in frontal white matter is connected to PIGD symptoms in Parkinson's disease and if present at an early stage, the risk for conversion to the PIGD phenotype increases.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2016
Keywords
parkinsonism, diffusion tensor imaging, gait, tremor, anisotropy
National Category
Neurology Neurosciences
Identifiers
urn:nbn:se:umu:diva-125534 (URN)10.1111/ane.12532 (DOI)000381033500006 ()27465659 (PubMedID)
Available from: 2016-09-19 Created: 2016-09-13 Last updated: 2018-06-07Bibliographically approved
Häggström, I., Axelsson, J., Schmidtlein, R., Karlsson, M., Garpebring, A., Johansson, L., . . . Larsson, A. (2015). A Monte Carlo study of the dependence of early frame sampling on uncertainty and bias in pharmacokinetic parameters from dynamic PET. Journal of Nuclear Medicine Technology, 43(1), 53-60
Open this publication in new window or tab >>A Monte Carlo study of the dependence of early frame sampling on uncertainty and bias in pharmacokinetic parameters from dynamic PET
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2015 (English)In: Journal of Nuclear Medicine Technology, ISSN 0091-4916, E-ISSN 1535-5675, Vol. 43, no 1, p. 53-60Article in journal (Refereed) Published
Abstract [en]

Compartmental modeling of dynamic PET data enables quantifi- cation of tracer kinetics in vivo, through the calculated model parameters. In this study, we aimed to investigate the effect of early frame sampling and reconstruction method on pharmacokinetic parameters obtained from a 2-tissue model, in terms of bias and uncertainty (SD). Methods: The GATE Monte Carlo software was used to simulate 2 · 15 dynamic 3′-deoxy-3′-18F-fluorothymidine (18F-FLT) brain PET studies, typical in terms of noise level and kinetic parameters. The data were reconstructed by both 3- dimensional (3D) filtered backprojection with reprojection (3DRP) and 3D ordered-subset expectation maximization (OSEM) into 6 dynamic image sets with different early frame durations of 1, 2, 4, 6, 10, and 15 s. Bias and SD were evaluated for fitted parameter estimates, calculated from regions of interest. Results: The 2-tissue-model parameter estimates K1, k2, and fraction of arterial blood in tissue depended on early frame sampling, and a sampling of 6–15 s generally minimized bias and SD. The shortest sampling of 1 s yielded a 25% and 42% larger bias than the other schemes, for 3DRP and OSEM, respectively, and a parameter uncertainty that was 10%–70% higher. The schemes from 4 to 15 s were generally not significantly different in regards to bias and SD. Typically, the reconstruction method 3DRP yielded less framesampling dependence and less uncertain results, compared with OSEM, but was on average more biased. Conclusion: Of the 6 sampling schemes investigated in this study, an early frame duration of 6–15 s generally kept both bias and uncertainty to a minimum, for both 3DRP and OSEM reconstructions. Veryshort frames of 1 s should be avoided because they typically resulted in the largest parameter bias and uncertainty. Furthermore, 3DRP may be p

Keywords
dynamic PET, Monte Carlo; GATE, compartment modeling, frame sampling
National Category
Other Physics Topics Medical Image Processing
Research subject
radiofysik
Identifiers
urn:nbn:se:umu:diva-95128 (URN)10.2967/jnmt.114.141754 (DOI)
Funder
Swedish National Infrastructure for Computing (SNIC), HPC2N-2009-001
Available from: 2014-10-22 Created: 2014-10-22 Last updated: 2018-06-07Bibliographically approved
Lenfeldt, N., Larsson, A., Nyberg, L., Birgander, R. & Forsgren, L. (2015). Fractional anisotropy in the substantia nigra in Parkinson's disease: a complex picture. European Journal of Neurology, 22(10), 1410-1416
Open this publication in new window or tab >>Fractional anisotropy in the substantia nigra in Parkinson's disease: a complex picture
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2015 (English)In: European Journal of Neurology, ISSN 1351-5101, E-ISSN 1468-1331, Vol. 22, no 10, p. 1410-1416Article in journal (Refereed) Published
Abstract [en]

Background and purpose: This study employs magnetic resonance imaging (MRI) diffusion tensor imaging to compare diffusion measures in the brains of patients with Parkinson's disease (PD) with healthy controls using longitudinal data. Methods: One-hundred and twenty-two patients and 34 controls were included at baseline. The MRI investigations were repeated after 1, 3 and 5 years. The diffusion measures were quantified using fractional anisotropy and mean, radial and axial diffusion (FA, MD, RD, AD). Regions of interest included the anterior, middle and posterior substantia nigra (SN), but also other areas. Linear models were used to test for the effect of disease and hemispheric lateralization. The P value was set at 0.05 (Bonferroni corrected). Results: Fractional anisotropy and AD were increased in the three nigral subareas in PD (P < 0.01), but MD and RD were unaltered. The right SN had higher FA than the left in all subareas (P < 0.01). MD and AD were increased in the right anterior part (P < 0.04), whereas MD and RD were decreased in the right middle and posterior parts (P < 0.001). The left middle cerebellar peduncle had increased FA and AD (P < 0.001) and decreased MD and RD (P < 0.01) compared to the right. Diffusion measures did not progress over time and side differences were not related to disease or lateralization of symptoms. Conclusions: Increased FA in the SN in PD indicates gliosis and inflammation in the nuclei, but possibly also intrusion of surrounding fibres into the shrinking structure. The hemispheric side differences of diffusion might reflect natural lateralization of connectivity, but their relation to PD must be studied further.

Keywords
diffusion imaging, fractional anisotropy, lateralization, Parkinson, substantia nigra
National Category
Neurology
Identifiers
urn:nbn:se:umu:diva-111012 (URN)10.1111/ene.12760 (DOI)000362672700012 ()26118635 (PubMedID)
Available from: 2015-11-04 Created: 2015-11-02 Last updated: 2018-06-07Bibliographically approved
Berthon, B., Häggström, I., Apte, A., Beattie, B. J., Kirov, A. S., Humm, J. L., . . . Schmidtlein, C. R. (2015). PETSTEP: generation of synthetic PET lesions for fast evaluation of segmentation methods. Physica medica (Testo stampato), 31(8), 969-980
Open this publication in new window or tab >>PETSTEP: generation of synthetic PET lesions for fast evaluation of segmentation methods
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2015 (English)In: Physica medica (Testo stampato), ISSN 1120-1797, E-ISSN 1724-191X, Vol. 31, no 8, p. 969-980Article in journal (Refereed) Published
Abstract [en]

Purpose: This work describes PETSTEP (PET Simulator of Tracers via Emission Projection): a faster and more accessible alternative to Monte Carlo (MC) simulation generating realistic PET images, for studies assessing image features and segmentation techniques.

Methods: PETSTEP was implemented within Matlab as open source software. It allows generating threedimensional PET images from PET/CT data or synthetic CT and PET maps, with user-drawn lesions and user-set acquisition and reconstruction parameters. PETSTEP was used to reproduce images of the NEMA body phantom acquired on a GE Discovery 690 PET/CT scanner, and simulated with MC for the GE Discovery LS scanner, and to generate realistic Head and Neck scans. Finally the sensitivity (S) and Positive Predictive Value (PPV) of three automatic segmentation methods were compared when applied to the scanner-acquired and PETSTEP-simulated NEMA images.

Results: PETSTEP produced 3D phantom and clinical images within 4 and 6 min respectively on a single core 2.7 GHz computer. PETSTEP images of the NEMA phantom had mean intensities within 2% of the scanner-acquired image for both background and largest insert, and 16% larger background Full Width at Half Maximum. Similar results were obtained when comparing PETSTEP images to MC simulated data. The S and PPV obtained with simulated phantom images were statistically significantly lower than for the original images, but led to the same conclusions with respect to the evaluated segmentation methods.

Conclusions: PETSTEP allows fast simulation of synthetic images reproducing scanner-acquired PET data and shows great promise for the evaluation of PET segmentation methods.

Keywords
Positron emission tomography, Digital phantoms, Simulation, Image segmentation, Synthetic lesions
National Category
Other Physics Topics Cancer and Oncology Radiology, Nuclear Medicine and Medical Imaging
Research subject
radiofysik
Identifiers
urn:nbn:se:umu:diva-95493 (URN)10.1016/j.ejmp.2015.07.139 (DOI)000366660400017 ()26321409 (PubMedID)
Funder
Swedish National Infrastructure for Computing (SNIC), 2014/1-260
Available from: 2014-10-30 Created: 2014-10-30 Last updated: 2018-06-07Bibliographically approved
Berthon, B., Häggström, I., Apte, A., Beattie, B., Kirov, A., Humm, J., . . . Schmidtlein, C. (2014). A Fast Positron Emission Tomography Simulator for Synthetic Lesion Simulation. European Journal of Nuclear Medicine and Molecular Imaging, 41(2), S367-S367
Open this publication in new window or tab >>A Fast Positron Emission Tomography Simulator for Synthetic Lesion Simulation
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2014 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 41, no 2, p. S367-S367Article in journal, Meeting abstract (Other academic) Published
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:umu:diva-100989 (URN)000348841901029 ()
External cooperation:
Funder
Swedish National Infrastructure for Computing (SNIC)
Available from: 2015-03-16 Created: 2015-03-16 Last updated: 2018-06-07Bibliographically approved
Häggström, I., Schmidtlein, C. R., Karlsson, M. & Larsson, A. (2014). Compartment Modeling of Dynamic Brain PET: The Effect of Scatter Corrections on Parameter Errors. In: : . Paper presented at AAPM. AAPM
Open this publication in new window or tab >>Compartment Modeling of Dynamic Brain PET: The Effect of Scatter Corrections on Parameter Errors
2014 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

Purpose: To investigate the effects of corrections for random and scattered coincidences on kinetic parameters in brain tumors, by using ten Monte Carlo (MC) simulated dynamic FLT-PET brain scans.

 

Methods: The GATE MC software was used to simulate ten repetitions of a 1 hour dynamic FLT-PET scan of a voxelized head phantom. The phantom comprised six normal head tissues, plus inserted regions for blood and tumor tissue. Different time-activity-curves (TACs) for all eight tissue types were used in the simulation and were generated in Matlab using a 2-tissue model with preset parameter values (K1,k2,k3,k4,Va,Ki). The PET data was reconstructed into 28 frames by both ordered-subset expectation maximization (OSEM) and 3D filtered back-projection (3DFBP). Five image sets were reconstructed, all with normalization and different additional corrections C (A=attenuation, R=random, S=scatter): Trues (AC), trues+randoms (ARC), trues+scatters (ASC), total counts (ARSC) and total counts (AC). Corrections for randoms and scatters were based on real random and scatter sinograms that were back-projected, blurred and then forward projected and scaled to match the real counts. Weighted non-linear-least-squares fitting of TACs from the blood and tumor regions was used to obtain parameter estimates.

 

Results: The bias was not significantly different for trues (AC), trues+randoms (ARC), trues+scatters (ASC) and total counts (ARSC) for either 3DFBP or OSEM (p<0.05). Total counts with only AC stood out however, with an up to 160% larger bias. In general, there was no difference in bias found between 3DFBP and OSEM, except in parameter Va and Ki.

 

Conclusion: According to our results, the methodology of correcting the PET data for randoms and scatters performed well for the dynamic images where frames have much lower counts compared to static images. Generally, no bias was introduced by the corrections and their importance was emphasized since omitting them increased bias extensively.

Place, publisher, year, edition, pages
AAPM, 2014
National Category
Medical Image Processing
Research subject
radiofysik
Identifiers
urn:nbn:se:umu:diva-98532 (URN)
Conference
AAPM
Funder
Swedish National Infrastructure for Computing (SNIC), 2014/1-260
Available from: 2015-01-23 Created: 2015-01-23 Last updated: 2018-06-07
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