The edge artifact in the point-spread function-based PET reconstruction at different sphere-to-background ratios of radioactivity

Objective The aim of this study was to quantitatively evaluate the edge artifacts in PET images reconstructed using the point-spread function (PSF) algorithm at different sphere-to-background ratios of radioactivity (SBRs). Methods We used a NEMA IEC body phantom consisting of six spheres with 37, 2...

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Bibliographic Details
Published in:Annals of nuclear medicine Vol. 30; no. 2; pp. 97 - 103
Main Authors: Kidera, Daisuke, Kihara, Ken, Akamatsu, Go, Mikasa, Shohei, Taniguchi, Takafumi, Tsutsui, Yuji, Takeshita, Toshiki, Maebatake, Akira, Miwa, Kenta, Sasaki, Masayuki
Format: Journal Article
Language:English
Published: Tokyo Springer Japan 01.02.2016
Springer Nature B.V
Subjects:
Algorithms
Image Processing, Computer-Assisted - methods
Imaging
Medicine
Medicine & Public Health
Nuclear Medicine
Original Article
Phantoms, Imaging
Positron-Emission Tomography
Radioactivity
Radiology
Signal-To-Noise Ratio
Tomography, X-Ray Computed
PET
Edge artifact
Point-spread function
ISSN:0914-7187, 1864-6433
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Summary:Objective The aim of this study was to quantitatively evaluate the edge artifacts in PET images reconstructed using the point-spread function (PSF) algorithm at different sphere-to-background ratios of radioactivity (SBRs). Methods We used a NEMA IEC body phantom consisting of six spheres with 37, 28, 22, 17, 13 and 10 mm in inner diameter. The background was filled with 18 F solution with a radioactivity concentration of 2.65 kBq/mL. We prepared three sets of phantoms with SBRs of 16, 8, 4 and 2. The PET data were acquired for 20 min using a Biograph mCT scanner. The images were reconstructed with the baseline ordered subsets expectation maximization (OSEM) algorithm, and with the OSEM + PSF correction model (PSF). For the image reconstruction, the number of iterations ranged from one to 10. The phantom PET image analyses were performed by a visual assessment of the PET images and profiles, a contrast recovery coefficient (CRC), which is the ratio of SBR in the images to the true SBR, and the percent change in the maximum count between the OSEM and PSF images (Δ % counts). Results In the PSF images, the spheres with a diameter of 17 mm or larger were surrounded by a dense edge in comparison with the OSEM images. In the spheres with a diameter of 22 mm or smaller, an overshoot appeared in the center of the spheres as a sharp peak in the PSF images in low SBR. These edge artifacts were clearly observed in relation to the increase of the SBR. The overestimation of the CRC was observed in 13 mm spheres in the PSF images. In the spheres with a diameter of 17 mm or smaller, the Δ % counts increased with an increasing SBR. The Δ % counts increased to 91 % in the 10-mm sphere at the SBR of 16. Conclusions The edge artifacts in the PET images reconstructed using the PSF algorithm increased with an increasing SBR. In the small spheres, the edge artifact was observed as a sharp peak at the center of spheres and could result in overestimation.
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ISSN:0914-7187
1864-6433
DOI:10.1007/s12149-015-1036-9