Performance evaluation of HiPET, a high sensitivity and high resolution preclinical PET tomograph

Gu, Zhichen; Taschereau, Richard; Vu, Nam T.; Prout, David; Lee, Jason T.; Chatziioannou, Arion F.

doi:10.1088/1361-6560/ab6b44

Cited by 35 publications

(36 citation statements)

References 53 publications

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“…[1][2][3][4] In the past over two decades, many small animal PET scanners with spatial resolutions of 1-2 mm have been developed. [5][6][7][8][9][10][11][12][13][14] If one wants to obtain the relative spatial resolution for imaging a mouse at the same level of imaging of a human with a clinical wholebody PET (3-5 mm), a small animal PET scanners need to have a spatial resolution of 0.3-0.5 mm. Improving the spatial resolution has always been one of the main foci of small animal PET scanner development.…”

Section: Introductionmentioning

confidence: 99%

“…Small animal positron emission tomography (PET) scanners are widely used in biomedical research 1–4 . In the past over two decades, many small animal PET scanners with spatial resolutions of 1–2 mm have been developed 5–14 . If one wants to obtain the relative spatial resolution for imaging a mouse at the same level of imaging of a human with a clinical whole‐body PET (3–5 mm), a small animal PET scanners need to have a spatial resolution of 0.3–0.5 mm.…”

Section: Introductionmentioning

confidence: 99%

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Ultra‐high‐resolution depth‐encoding small animal PET detectors: Using GAGG and LYSO crystal arrays

et al. 2022

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Purpose Small animal positron emission tomography (PET) scanners are widely used in current biomedical research. The study aimed to develop high‐efficiency and ultra‐high‐resolution detectors that could be used to develop a small animal PET scanner with high sensitivity and spatial resolution approaching to its physical limit. Methods Four crystal arrays were fabricated and measured in this study. Crystal arrays 1 and 2 consisted of 38 × 38 gadolinium aluminum gallium garnet (GAGG) and lutetium–yttrium oxyorthosilicate (LYSO) crystals of 0.4 × 0.4 × 20 mm3 size. Crystal array 3 consisted of 16 × 16 GAGG crystals of 0.3 × 0.3 × 20 mm3 size, and crystal array 4 consisted of 24 × 24 LYSO crystals 0.3 × 0.3 × 20 mm3 in size. The crystal arrays were dual‐ended readouts using 8 × 8 silicon photomultiplier (SiPM) arrays of 2 × 2 mm2 pixel area. The SiPM array was readout using a signal multiplexing circuit to convert the 64 output signals into four position‐encoding signals. The performances of the four detectors in terms of flood histogram, energy resolution, depth of interaction (DOI) resolution, and timing resolution were measured. Results The GAGG detectors provided better flood histograms, ∼30% higher photopeak amplitude, ∼20% higher energy resolution, ∼12% worse DOI resolution, and ∼15% worse timing resolution compared with LYSO detectors of the same crystal size. These four detectors provided DOI resolutions of <2 mm, energy resolutions of <22%, and timing resolutions of <1.6 ns. All crystals of 0.4 × 0.4 × 20 mm3 and 0.3 × 0.3 × 20 mm3 could be clearly resolved if the crystal array was 1 mm smaller in the four sides than that in the SiPM array. Conclusions High DOI resolution PET detectors were developed using both GAGG and LYSO arrays with crystal sizes of 0.3 and 0.4 mm, respectively, and a length of 20 mm. The detectors can be used in the future to develop small animal PET scanners, especially dedicated mouse imaging PET scanners, which can simultaneously achieve high sensitivity and ultra‐high spatial resolution.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ultra‐high‐resolution depth‐encoding small animal PET detectors: Using GAGG and LYSO crystal arrays

et al. 2022

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“…The optimization experiments in this work were performed with ~ 14 MBq [0.38 mCi], where each reaction often yielded enough product for multiple mouse scans 62 , 63 . Nevertheless, we wanted to explore whether one of the optimized compounds ([ 18 F]PBR06) could be scaled to clinically-relevant levels without changing any reaction conditions other than the amount of starting radioactivity.…”

Section: Resultsmentioning

confidence: 99%

Microliter-scale reaction arrays for economical high-throughput experimentation in radiochemistry

Ríos

Holloway

Chao

et al. 2022

Sci Rep

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The increasing number of positron-emission tomography (PET) tracers being developed to aid drug development and create new diagnostics has led to an increased need for radiosynthesis development and optimization. Current radiosynthesis instruments are designed to produce large-scale clinical batches and are often limited to performing a single synthesis before they must be decontaminated by waiting for radionuclide decay, followed by thorough cleaning or disposal of synthesizer components. Though with some radiosynthesizers it is possible to perform a few sequential radiosyntheses in a day, none allow for parallel radiosyntheses. Throughput of one or a few experiments per day is not well suited for rapid optimization experiments. To combat these limitations, we leverage the advantages of droplet-radiochemistry to create a new platform for high-throughput experimentation in radiochemistry. This system contains an array of 4 heaters, each used to heat a set of 16 reactions on a small chip, enabling 64 parallel reactions for the rapid optimization of conditions in any stage of a multi-step radiosynthesis process. As examples, we study the syntheses of several 18F-labeled radiopharmaceuticals ([18F]Flumazenil, [18F]PBR06, [18F]Fallypride, and [18F]FEPPA), performing > 800 experiments to explore the influence of parameters including base type, base amount, precursor amount, solvent, reaction temperature, and reaction time. The experiments were carried out within only 15 experiment days, and the small volume (~ 10 μL compared to the ~ 1 mL scale of conventional instruments) consumed ~ 100 × less precursor per datapoint. This new method paves the way for more comprehensive optimization studies in radiochemistry and substantially shortening PET tracer development timelines.

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“…In the previous publications that described the performance evaluation results of different small animal PET scanners, the sensitivity, SF, and NECR of several EWs were usually provided, but the spatial resolution and image quality were only provided for one EW. Almost all performance parameters are only provided for one TW 8–32 . It is well known that the sensitivity of a PET scanner increases as the EW and TW become wider.…”

Section: Introductionmentioning

confidence: 99%

Physical and imaging performance of SIAT aPET under different energy windows and timing windows

et al. 2022

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Purpose The performance of small animal PET scanners depends on the energy window (EW) and timing window (TW). In National Electrical Manufacturers Association (NEMA) Standards Publication NU 4–2008, detailed procedures of the performance measurements are defined, but the EW and TW are not specified. In this work, the effects of EW and TW on the physical and imaging performance of Shenzhen Institute of Advanced Technology small animal PET (SIAT aPET) will be evaluated. Methods First, the flood histogram, energy resolution, and timing resolution were measured for a detector of SIAT aPET. Second, the spatial resolutions were measured with different EWs. Third, the sensitivities, the scatter fractions (SFs), and noise equivalent count rates (NECRs) of a mouse‐sized phantom and a rat‐sized phantom, the recovery coefficients (RCs) of rods of different sizes, and the percentage standard deviation (%STD) of the NEMA image quality phantom were measured for different EWs and TWs. Last, images of a hot rod phantom, a mouse heart, and a rat brain were acquired from the scanner with different EWs. Results The SIAT aPET detectors provided good flood histograms such that all but the corner crystals can be resolved even with lower energies of 250–350 keV, an average energy resolution of 21.1 ± 1.9%, and an average timing resolution of 2.63 ± 0.69 ns. The average spatial resolutions obtained with EWs of 250–350 keV and 450–550 keV are 0.68 mm and 0.75 mm. For EWs of 250–750 keV, 350–750 keV, and 450–750 keV with a fixed TW of 12 ns, the sensitivities at the center of field of view (FOV) are 16.0%, 11.9%, and 8.2%, the peak NECRs of a mouse‐sized phantom are 355.6 kcps, 324.4 kcps, and 249.4 kcps, and the peak NECRs of a rat‐sized phantom are 148.5 kcps, 144.3 kcps, and 117.7 kcps, respectively. For the TWs of 4 ns, 8 ns,12 ns, and 20 ns with a fixed EW of 350–750 keV, the sensitivities at the center of FOV are 9.6%, 11.4%, 11.9%, and 12.2%, the peak NECRs of a mouse‐sized phantom are 260.1 kcps, 311.5 kcps, 324.4 kcps and 324.9 kcps, and the peak NECRs of a rat‐sized phantom are 110.5 kcps, 137.3 kcps, 144.3 kcps, and 142.6 kcps, respectively. Narrowing the EW and TW improves the RCs of rods of all sizes, and the %STD of images obtained with different EWs and TWs are similar. Rods with diameter down to 0.8 mm can be visually resolved from images of the hot rod phantom obtained with different EWs. Images of mouse heart with high spatial resolution and rat brain with detail brain structure were obtained with different EWs. Images of both phantom and in vivo animals obtained with different EWs only showed subtle difference. Conclusion The performance of SIAT aPET under different EWs and TWs was compared. The EW and TW affect the sensitivity, SF, and NECR but not the spatial resolution and animal images of SIAT aPET, which imply that careful optimization of the EW and TW is not required.

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Performance evaluation of HiPET, a high sensitivity and high resolution preclinical PET tomograph

Cited by 35 publications

References 53 publications

Ultra‐high‐resolution depth‐encoding small animal PET detectors: Using GAGG and LYSO crystal arrays

Ultra‐high‐resolution depth‐encoding small animal PET detectors: Using GAGG and LYSO crystal arrays

Microliter-scale reaction arrays for economical high-throughput experimentation in radiochemistry

Physical and imaging performance of SIAT aPET under different energy windows and timing windows

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