Impact of Time-of-Flight PET/CT with a Large Axial Field of View for Reducing Whole-Body Acquisition Time

Akamatsu, Go; Uba, Koji; Taniguchi, Takafumi; Mitsumoto, Katsuhiko; Narisue, Akihiro; Tsutsui, Yuji; Sasaki, Masayuki

doi:10.2967/jnmt.114.140665

Cited by 16 publications

(6 citation statements)

References 9 publications

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“…Scanner sensitivity was close to the value measured on the same system in [27]. It is better than for other systems with comparable FOV: 5.6 cps/kBq for the Biograph mCT Flow with 16.2-cm axial FOV [13] and 5.7 cps/kBq for the Vereos Digital with an axial FOV of 16.4 cm [17] (Table 3). These values are all below those for systems with larger FOV [3, 27], as would be predicted from solid angle considerations, although of course other factors such as detector efficiency play a role as well in determining systems sensitivity.…”

Section: Discussionsupporting

confidence: 75%

Performance characteristics of silicon photomultiplier based 15-cm AFOV TOF PET/CT

Vandendriessche

Uribe²,

Bertin³

et al. 2019

EJNMMI Phys

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Background This paper describes the National Electrical Manufacturers Association (NEMA) system performance of the Discovery MI 3-ring PET/CT (GE Healthcare) installed in Bruges, Belgium. This time-of-flight (TOF) PET camera is based on silicon photomultipliers instead of photomultiplier tubes. Methods The NEMA NU2-2012 standard was used to evaluate spatial resolution, sensitivity, image quality (IQ) and count rate curves of the system. Timing and energy resolution were determined. Results Full width at half maximum (FWHM) of spatial resolution in radial, tangential and axial direction was 4.69, 4.08 and 4.68 mm at 1 cm; 5.58, 4.64 and 5.83 mm at 10 cm; and 7.53, 5.08 and 5.47 mm at 20 cm from the centre of the field of view (FOV) for the filtered backprojection reconstruction. For non-TOF ordered subset expectation maximization (OSEM) reconstruction without point spread function (PSF) correction, FWHM was 3.87, 3.69 and 4.15 mm at 1 cm; 4.80, 3.81 and 4.87 mm at 10 cm; and 7.38, 4.16 and 3.98 mm at 20 cm. Sensitivity was 7.258 cps/kBq at the centre of the FOV and 7.117 cps/kBq at 10-cm radial offset. Contrast recovery (CR) using the IQ phantom for the TOF OSEM reconstruction without PSF correction was 47.4, 59.3, 67.0 and 77.0% for the 10-, 13-, 17- and 22-mm radioactive spheres and 82.5 and 85.1% for the 28- and 37-mm non-radioactive spheres. Background variability (BV) was 16.4, 12.1, 9.1, 6.6, 5.1 and 3.8% for the 10-, 13-, 17-, 22-, 28- and 37-mm spheres. Lung error was 8.5%. Peak noise equivalent count rate (NECR) was 102.3 kcps at 23.0 kBq/ml with a scatter fraction of 41.2%. Maximum accuracy error was 3.88%. Coincidence timing resolution was 375.6 ps FWHM. Energy resolution was 9.3% FWHM. Q.Clear reconstruction significantly improved CR and reduced BV compared with OSEM. Conclusion System sensitivity and NECR are lower and IQ phantom’s BV is higher compared with larger axial FOV (AFOV) scanners like the 4-ring discovery MI, as expected from the smaller solid angle of the 3-ring system. The other NEMA performance parameters are all comparable with those of the larger AFOV scanners.

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Section: Discussionsupporting

confidence: 75%

Performance characteristics of silicon photomultiplier based 15-cm AFOV TOF PET/CT

Vandendriessche

Uribe²,

Bertin³

et al. 2019

EJNMMI Phys

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“…The number of blocks per detector ring was 48 and the total number of blocks was 144. The system sensitivity was 5.4 cps/kBq [ 18 ]. Scanning parameters for CT were as follows: 120 kV, 100 mA, 5-mm slice thickness, 0.5 s rotation.…”

Section: Methodsmentioning

confidence: 99%

Improvement in PET/CT image quality in overweight patients with PSF and TOF

et al. 2014

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ObjectiveThe aim of this study was to evaluate the effect of the point spread function (PSF) and time of flight (TOF) on PET/CT images of overweight patients in relation to the iteration number and the acquisition time.MethodsThis study consisted of a phantom study and a clinical study. The NEMA IEC body phantom and a 40 cm diameter large phantom (LG phantom) simulating an overweight patient were used in this study. Both phantoms were filled with 18F solution with a sphere to background ratio of 4:1. The PET data were reconstructed with the baseline ordered-subsets expectation maximization (OSEM) algorithm, with the OSEM + PSF model, with the OSEM + TOF model and with the OSEM + PSF + TOF model. The clinical study was a retrospective analysis of 66 patients who underwent 18F-FDG PET/CT. The image quality was evaluated using the background variability (coefficient of variance, CVphantom and CVliver) and the contrast (CONTHOT and SNR).ResultsIn phantom study, the CVphantom of the LG phantom was higher than that of the NEMA phantom. The PSF decreased the CVphantom of the LG phantom to the NEMA phantom level. The TOF information accelerated the CVphantom plateau earlier. The best relationship between the CVphantom and the CONTHOT was observed for the OSEM + PSF + TOF. In clinical study, the combination of PSF and TOF decreased the CVliver for overweight patients to that for normal weight patients while it increased the SNR similarly between two patient groups.ConclusionThe combination of the PSF and TOF correction improved the image quality of the LG phantom and overweight patients.

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“…Improvements in system performance such as in photon sensitivity, time resolution, and spatial resolution are expected to enhance lesion detection, low-dose patient imaging, and individualized treatment planning and evaluation (2). Many recent commercial PET-based systems have been evaluated using the National Electrical Manufacturers Association (NEMA) NU-2 standards, as previously reported (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15).…”

mentioning

confidence: 99%

“…NEMA NU-2 Measurements for Other Commercial PET Scanners With 16.2-cm axial FOV(11). Value is unclear in reference.…”

mentioning

confidence: 99%

Studies of a Next-Generation Silicon-Photomultiplier–Based Time-of-Flight PET/CT System

Hsu

Ilan

Peterson³

et al. 2017

J Nucl Med

207

249

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This article presents system performance studies for the Discovery MI PET/CT system, a new time-of-flight system based on silicon photomultipliers. System performance and clinical imaging were compared between this next-generation system and other commercially available PET/CT and PET/MR systems, as well as between different reconstruction algorithms. Spatial resolution, sensitivity, noise-equivalent counting rate, scatter fraction, counting rate accuracy, and image quality were characterized with the National Electrical Manufacturers Association NU-2 2012 standards. Energy resolution and coincidence time resolution were measured. Tests were conducted independently on two Discovery MI scanners installed at Stanford University and Uppsala University, and the results were averaged. Back-to-back patient scans were also performed between the Discovery MI, Discovery 690 PET/CT, and SIGNA PET/MR systems. Clinical images were reconstructed using both ordered-subset expectation maximization and Q.Clear (block-sequential regularized expectation maximization with point-spread function modeling) and were examined qualitatively. The averaged full widths at half maximum (FWHMs) of the radial/tangential/axial spatial resolution reconstructed with filtered backprojection at 1, 10, and 20 cm from the system center were, respectively, 4.10/4.19/4.48 mm, 5.47/4.49/6.01 mm, and 7.53/4.90/6.10 mm. The averaged sensitivity was 13.7 cps/kBq at the center of the field of view. The averaged peak noise-equivalent counting rate was 193.4 kcps at 21.9 kBq/mL, with a scatter fraction of 40.6%. The averaged contrast recovery coefficients for the image-quality phantom were 53.7, 64.0, 73.1, 82.7, 86.8, and 90.7 for the 10-, 13-, 17-, 22-, 28-, and 37-mm-diameter spheres, respectively. The average photopeak energy resolution was 9.40% FWHM, and the average coincidence time resolution was 375.4 ps FWHM. Clinical image comparisons between the PET/CT systems demonstrated the high quality of the Discovery MI. Comparisons between the Discovery MI and SIGNA showed a similar spatial resolution and overall imaging performance. Lastly, the results indicated significantly enhanced image quality and contrast-to-noise performance for Q.Clear, compared with ordered-subset expectation maximization. Excellent performance was achieved with the Discovery MI, including 375 ps FWHM coincidence time resolution and sensitivity of 14 cps/kBq. Comparisons between reconstruction algorithms and other multimodal silicon photomultiplier and non-silicon photomultiplier PET detector system designs indicated that performance can be substantially enhanced with this next-generation system.

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Impact of Time-of-Flight PET/CT with a Large Axial Field of View for Reducing Whole-Body Acquisition Time

Cited by 16 publications

References 9 publications

Performance characteristics of silicon photomultiplier based 15-cm AFOV TOF PET/CT

Performance characteristics of silicon photomultiplier based 15-cm AFOV TOF PET/CT

Improvement in PET/CT image quality in overweight patients with PSF and TOF

Studies of a Next-Generation Silicon-Photomultiplier–Based Time-of-Flight PET/CT System

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