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Wallstén, Elin
Publications (3 of 3) Show all publications
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
Wallstén, E., Axelsson, J., Sundström, T., Riklund, K. & Larsson, A. (2013). Subcentimeter Tumor Lesion Delineation for High-Resolution 18F-FDG PET Images: Optimizing Correction for Partial-Volume Effects.. Journal of Nuclear Medicine Technology, 41(2), 85-91
Open this publication in new window or tab >>Subcentimeter Tumor Lesion Delineation for High-Resolution 18F-FDG PET Images: Optimizing Correction for Partial-Volume Effects.
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2013 (English)In: Journal of Nuclear Medicine Technology, ISSN 0091-4916, E-ISSN 1535-5675, Vol. 41, no 2, p. 85-91Article in journal (Refereed) Published
Abstract [en]

In PET, partial-volume effects cause errors in estimation of size and activity for small objects with radiopharmaceutical uptake. Recent methods for image reconstruction, compared with traditional reconstruction techniques, include algorithms for resolution recovery that result in images with higher resolution and enable quantification of size and activity of smaller objects. The purpose of this study was to evaluate a combination of 2 algorithms for volume delineation and partial-volume correction on uptake volumes smaller than 0.7 mL using image reconstruction algorithms with and without resolution recovery.

METHODS: Volumes of interests (VOIs) were delineated using a threshold intensity calculated as a weighted sum of tumor and background intensities. These VOIs were used for calculating correction factors by convolving a tumor mask with the system point-spread function. The methods algorithms were evaluated using a phantom constructed from 5 small different-sized balloons filled with (18)F-FDG in background activity. Six different backgrounds were used. Data were acquired using a PET/CT scanner, and the images were reconstructed using 2 iterative algorithms, one of which used a resolution recovery algorithm.

RESULTS: For the images reconstructed using the resolution recovery algorithm, the method for volume delineation resulted in VOI sizes that were correct within 1 SD for all balloons of a volume of 0.35 mL (equivalent diameter, 8.8 mm) and larger, in all backgrounds. For the images reconstructed without resolution recovery, the VOI sizes were background-dependent and generally less accurate. Correct volume delineations generally led to accurate activity estimates.

CONCLUSION: The algorithms tested on the phantom developed for this study could, for this PET camera and these reconstruction algorithms, be used for accurate volume delineation and activity quantification of lesions 0.35 mL and larger.

Place, publisher, year, edition, pages
Society of Nuclear Medicine and Molecular Imaging, 2013
Keywords
PET, partial-volume effects, partial volume correction, volume delineation, resolution recovery
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:umu:diva-76744 (URN)10.2967/jnmt.112.117234 (DOI)23658206 (PubMedID)
Available from: 2013-07-12 Created: 2013-07-12 Last updated: 2018-06-08Bibliographically approved
Wallstén, E., Axelsson, J., Karlsson, M., Riklund, K., Nyberg, L., Häggström, I. & Larsson, A. (2013). The Influence of Time Sampling on Parameters in the Logan Plot. In: 2013 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC): . Paper presented at 60th IEEE Nuclear Science Symposium (NSS) / Medical Imaging Conference (MIC) / 20th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors, OCT 27-NOV 02, 2013, Seoul, SOUTH KOREA.
Open this publication in new window or tab >>The Influence of Time Sampling on Parameters in the Logan Plot
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2013 (English)In: 2013 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC), 2013Conference paper, Published paper (Refereed)
Abstract [en]

The Logan plot is a graphical method for reversible tracer bindings. The bias and uncertainties of this method have previously been analyzed with respect to noise, but little is known about the direct effects from varying the time sampling scheme. This study aims to investigate the effect of time sampling on the binding potential from the reference Logan plot. Image data from seven healthy subjects imaged with [11C]raclopride was reconstructed into six dynamic series of equal length time frames with frame times between 15 s and 480 s. Images were reconstructed using both filtered back projection (FBP) and a resolution enhanced ordered subset expectation maximization (OSEM) algorithm, SharpIR. For each sampling scheme, the nondisplaceable binding potential (BPND) parameter was calculated from the reference Logan plot with cerebellum as a reference region. The variation in BPND was analyzed as percentage deviations from the BPND for the 480 s scheme. R-2 of the linear fit was also analyzed. Comparison between all sampling schemes showed that the largest deviation in BPND was 7.4% between the 15 s sampling scheme and the 480 s sampling scheme reconstructed with SharpIR. The corresponding deviation for FBP images was 1.6%. R-2 was highest for long time frames, but all R-2 values were above 0.997 in this study.

National Category
Medical Image Processing Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-129852 (URN)10.1109/NSSMIC.2013.6829389 (DOI)000347163501203 ()978-1-4799-0534-8 (ISBN)
Conference
60th IEEE Nuclear Science Symposium (NSS) / Medical Imaging Conference (MIC) / 20th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors, OCT 27-NOV 02, 2013, Seoul, SOUTH KOREA
Available from: 2017-01-11 Created: 2017-01-09 Last updated: 2018-06-09Bibliographically approved
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