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

Kidera, Daisuke; Kihara, Ken; Akamatsu, Go; Mikasa, Shohei; Taniguchi, Takafumi; Tsutsui, Yuji; Maebatake, Akira; Miwa, Koichi; Sasaki, Masayuki

doi:10.1007/s12149-015-1036-9

Cited by 27 publications

(16 citation statements)

References 20 publications

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“…Kidera et al reported that the PSF model resulted in the greatest increase in contrast RC for 13-mm hot spheres. Spheres between 10 and 17 mm showed improvement in contrast RC, whereas no such improvement was noted for larger spheres (22). Our results also showed that PSF correction increased the DI in spheres 8 mm or larger but not in spheres smaller than 8 mm.…”

Section: Discussionsupporting

confidence: 62%

Time-of-Flight Information Improved the Detectability of Subcentimeter Spheres Using a Clinical PET/CT Scanner

Hashimoto

Morita

Tsutsui

et al. 2018

J. Nucl. Med. Technol.

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Recent advancements in clinical PET/CT scanners have improved the detectability of small lesions. However, the ideal reconstruction parameters for detecting small lesions have not yet been sufficiently clarified. The purpose of this study was to investigate the detectability of subcentimeter spheres using a clinical PET/CT scanner. We used a clinical PET/CT scanner to obtain the data of a National Electrical Manufacturers Association body phantom consisting of 6 small spheres (inner diameters, 4.0, 5.0, 6.2, 7.9, 10, and 37 mm) containingF solution. The background activity was 2.65 kBq/mL, and the sphere-to-background ratio was 8. The PET data obtained for 2 and 120 min were reconstructed using ordered-subsets expectation maximization (OSEM), OSEM + point-spread function (PSF), and OSEM + time-of-flight (TOF) with voxel sizes of 2.04 × 2.04 × 2.00 mm (2-mm voxels) and 4.07 × 4.07 × 3.99 mm (4-mm voxels). A gaussian filter was not used. The image quality was evaluated by visual assessment, as well as by physical assessment of the detectability index and recovery coefficients. According to the visual assessment, the detectability of the spheres improved using TOF and a longer acquisition. Using the OSEM+TOF model, the smallest visually detected spheres were 5 mm in diameter with a 120-min acquisition and 6 mm in diameter with a 2-min acquisition. According to physical assessment, the detectability of spheres 10 mm or smaller using the OSEM+TOF image was superior to that using the OSEM image. In addition, the detectability of each hot sphere and recovery coefficient with 2-mm voxels was superior to that with 4-mm voxels. Although OSEM+PSF images showed less background noise, detectability and the recovery coefficient were not improved for spheres 8 mm or smaller. The TOF model with 2-mm voxels improved the detectability of subcentimeter hot spheres on a clinical PET/CT scanner.

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Section: Discussionsupporting

confidence: 62%

Time-of-Flight Information Improved the Detectability of Subcentimeter Spheres Using a Clinical PET/CT Scanner

Hashimoto

Morita

Tsutsui

et al. 2018

J. Nucl. Med. Technol.

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“…PSF correction has been reported to result in overestimation due to edge artifacts in small regions and is therefore a problem for quantification (25). We previously reported that edge artifacts were observed as a sharp peak at the center of small hot spheres (26). Zhang et al found that edge artifacts were unclear in areas of low radioactivity (27).…”

Section: Discussionmentioning

confidence: 97%

The Influence of Minimal Misalignment on the Repeatability of PET Images Examined by the Repositioning of Point Sources

Maebatake

Morita

Akamatsu

et al. 2018

J. Nucl. Med. Technol.

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We aimed to evaluate the influence of minimal misalignment of a hot spot on the repeatability of PET images using repositioning of point sources. Methods: Point sources with an inner diameter of 1 mm were made with 1 μL of 18 F solution. Seven point sources were placed on the x-axis in the field of view. For fixed-position imaging, PET data were acquired for 10 min 5 times serially. For variable-position imaging, PET data were acquired for 10 min each with the point sources placed at 0, ±0.5, and ±1.0 mm in the x-axis direction. The data were reconstructed using ordered-subsets expectation maximization (OSEM) and OSEM plus point-spread function (PSF). The image matrix was 128 • 128, 200 • 200, 256 • 256, 400 • 400, and 512 • 512 pixels. The normalized maximum count (rMax), the coefficient of variance (CV max), and the full width at half maximum were analyzed. Results: The hot spots on OSEM images far from the center became faint and broad, whereas those on OSEM1PSF images became small and dense. Although rMax was overestimated at the 5-cm position on OSEM images, rMax at other positions was overestimated on OSEM1PSF images with a matrix of at least 256 • 256. rMax showed a similar pattern in fixed-and variable-position images. CV max in fixedposition OSEM images was less than 2%, irrespective of matrix size. In contrast, CV max in variable-position images was higher than in fixed-position images. CV max was higher for OSEM1PSF images than for OSEM images. The full width at half maximum increased at positions far from the center on OSEM images but was stable at all positions on OSEM1PSF images. Conclusion: The repeatability of the small hot spot was affected by the minimal misalignment, especially on OSEM1PSF images. Precise positioning is necessary if PET is to be used as a biomarker. Professionals should recognize that PSF correction worsens the repeatability of the small hot spot although improving the spatial resolution of PET images.

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“…1) [24]. Allerdings wurde für diese PSF-Rekonstruktionen auch gezeigt, dass typische Randwert-Überschätzungen (Gibson-Artefakte) auftreten können, was bei quantitativen Betrachtungen zu Problemen führen kann [25,26].…”

Section: Algorithmenunclassified

Von PET und PET/CT zur PET/MRT: Ein technologisches Update

Büther

2018

Nuklearmediziner

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ZusammenfassungDer vorliegende Beitrag beleuchtet die wichtigsten technologischen Neuerungen auf dem Gebiet der Positronen-Emissions-Tomografie (PET) der letzten Jahre. Sowohl auf Seiten der Hardware als auch im Bereich der eingesetzten Algorithmen sorgt der Fortschritt dafür, dass die PET-Bildgebung einer der grundlegenden Pfeiler der nuklearmedizinischen Diagnostik bleiben wird. Insbesondere neue Detektoren (Szintillatormaterialien, Lichtdetektoren, Elektronik) – nicht nur für die neue PET/MRT-Bildgebung, sondern auch für die konventionelle PET/CT-Bildgebung – als auch neue Rekonstruktions- und Korrekturmethoden (iterative sowie Flugzeit- und Punktspreizantwort-basierte Rekonstruktionen, Schwächungs- und Bewegungskorrektur) sind für diese Entwicklung verantwortlich. Besonders im Hinblick auf gesteigerte Sensitivitäten und räumliche Auflösung ergeben sich hiermit interessante Perspektiven sowohl für die Grundlagenforschung als auch für klinische Anwendungen.

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

Abstract: 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.

Cited by 27 publications

References 20 publications

Time-of-Flight Information Improved the Detectability of Subcentimeter Spheres Using a Clinical PET/CT Scanner

Time-of-Flight Information Improved the Detectability of Subcentimeter Spheres Using a Clinical PET/CT Scanner

The Influence of Minimal Misalignment on the Repeatability of PET Images Examined by the Repositioning of Point Sources

Von PET und PET/CT zur PET/MRT: Ein technologisches Update

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