High Dose MicroCT Does Not Contribute Toward Improved MicroPET/CT Image Quantitative Accuracy and Can Limit Longitudinal Scanning of Small Animals

McDougald, Wendy; Collins, Richard; Green, Mark; Tavares, Adriana

doi:10.3389/fphy.2017.00050

Cited by 8 publications

(5 citation statements)

References 36 publications

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“…The Radcal ion chamber software stops collecting/measuring at 300 s. We previously showed the measured CT dose with the RadCal probe is linearly dependent on scan length (21). Therefore, CT protocols with a scan time longer than 5 min were measured to 300 s then the dose was calculated based on remaining frames and measured dose (Eq.…”

Section: Measurement Of Ionizing Radiation Doses From Ct Acquisition mentioning

confidence: 99%

Standardization of Preclinical PET/CT Imaging to Improve Quantitative Accuracy, Precision, and Reproducibility: A Multicenter Study

et al. 2019

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Preclinical PET/CT is a well-established noninvasive imaging tool for studying disease development/progression and the development of novel radiotracers and pharmaceuticals for clinical applications. Despite this pivotal role, standardization of preclinical PET/CT protocols, including CT absorbed dose guidelines, is essentially nonexistent. This study (1) quantitatively assesses the variability of current preclinical PET/CT acquisition and reconstruction protocols routinely used across multiple centers and scanners; and (2) proposes acquisition and reconstruction PET/CT protocols for standardization of multicenter data, optimized for routine scanning in the preclinical PET/CT laboratory. Methods: Five different commercial preclinical PET/CT scanners in Europe and the United States were enrolled. Seven different PET/CT phantoms were used for evaluating biases on default/general scanner protocols, followed by developing standardized protocols. PET, CT, and absorbed dose biases were assessed. Results: Site default CT protocols were the following: greatest extracted Hounsfield units (HU) were 133 HU for water and −967 HU for air; significant differences in all tissue equivalent material (TEM) groups were measured. The average CT absorbed doses for mouse and rat were 72 mGy and 40 mGy, respectively. Standardized CT protocol were the following: greatest extracted HU were −77 HU for water and −990 HU for air; TEM precision improved with a reduction in variability for each tissue group. The average CT absorbed dose for mouse and rat decreased to 37 mGy and 24 mGy, respectively. Site default PET protocols were the following: uniformity was substandard in one scanner, recovery coefficients (RCs) were either over-or underestimated (maximum of 43%), standard uptake values (SUVs) were biased by a maximum of 44%. Standardized PET protocols were the following: scanner with substandard uniformity improved by 36%, RC variability decreased by 13% points, and SUV accuracy improved to 10%. Conclusion: Data revealed important quantitative biases in preclinical PET/CT and absorbed doses with default protocols. Standardized protocols showed improvements in measured PET/CT accuracy and precision with reduced CT absorbed dose across sites. Adhering to standardized protocols generates reproducible and consistent preclinical imaging datasets, thus augmenting translation of research findings to the clinic.

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Section: Measurement Of Ionizing Radiation Doses From Ct Acquisition mentioning

confidence: 99%

Standardization of Preclinical PET/CT Imaging to Improve Quantitative Accuracy, Precision, and Reproducibility: A Multicenter Study

et al. 2019

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“…CT doses for scans for live mice typically range between 50 and 800 mGy using current scanning technologies (4–7) CT doses for studies of rodent bone metrics and other higher resolution protocols used in for ex vivo imaging are commonly >1 Gy (6, 7). CT exposure and dose minimization have been a constant subject of research over the years (8–18).…”

Section: Introductionmentioning

confidence: 99%

Low-Dose Imaging in a New Preclinical Total-Body PET/CT Scanner

et al. 2019

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Ionizing radiation constitutes a health risk to imaging scientists and study animals. Both PET and CT produce ionizing radiation. CT doses in pre-clinical in vivo imaging typically range from 50 to 1,000 mGy and biological effects in mice at this dose range have been previously described. [ 18 F]FDG body doses in mice have been estimated to be in the range of 100 mGy for [ 18 F]FDG. Yearly, the average whole body doses due to handling of activity by PET technologists are reported to be 3–8 mSv. A preclinical PET/CT system is presented with design features which make it suitable for small animal low-dose imaging. The CT subsystem uses a X-source power that is optimized for small animal imaging. The system design incorporates a spatial beam shaper coupled with a highly sensitive flat-panel detector and very fast acquisition (<10 s) which allows for whole body scans with doses as low as 3 mGy. The mouse total-body PET subsystem uses a detector architecture based on continuous crystals, coupled to SiPM arrays and a readout based in rows and columns. The PET field of view is 150 mm axial and 80 mm transaxial. The high solid-angle coverage of the sample and the use of continuous crystals achieve a sensitivity of 9% (NEMA) that can be leveraged for use of low tracer doses and/or performing rapid scans. The low-dose imaging capabilities of the total-body PET subsystem were tested with NEMA phantoms, in tumor models, a mouse bone metabolism scan and a rat heart dynamic scan. The CT imaging capabilities were tested in mice and in a low contrast phantom. The PET low-dose phantom and animal experiments provide evidence that image quality suitable for preclinical PET studies is achieved. Furthermore, CT image contrast using low dose scan settings was suitable as a reference for PET scans. Total-body mouse PET/CT studies could be completed with total doses of <10 mGy.

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“…In some cases, the micro-PET study is combined with a micro-CT scan to provide an anatomical reference image or for attenuation correction. Typical micro-CT doses range from 50 − 1,000 mGy [7] while 18 F-FDG doses in mice are within 100 mGy [8]. Dose reduction strategies with DL denoising are also applicable in micro-CT imaging.…”

Section: Discussionmentioning

confidence: 99%

“…considering available blood volume in small animal) but also by the equipment saturation. Micro-PET is often combined with micro-computed tomography (CT) and such dual-modality protocols deliver additional radiation dose to the rodents [7,8].…”

Section: Introductionmentioning

confidence: 99%

Image Denoising of Low-Dose PET Mouse Scans with Deep Learning: Validation Study for Preclinical Imaging Applicability

Muller,

Vervenne,

Maebe

et al. 2023

Mol Imaging Biol

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Positron Emission Tomography (PET) image quality can be improved by higher injected activity and/or longer acquisition time, but both may often not be practical in preclinical imaging. Common preclinical radioactive doses (10 MBq) have been shown to cause deterministic changes in biological pathways.Reducing the injected tracer activity and/or shortening the scan time inevitably results in low-count acquisitions which poses a challenge because of the inherent noise introduction. We present an imagebased deep learning (DL) framework for denoising lower count micro-PET images. Procedures:For 36 mice, a 15-min 18 F-FDG (8.15 ± 1.34 MBq) PET scan was acquired at 40 min post-injection on the Molecubes b-CUBE (in list mode). The 15-min acquisition (high-count) was parsed into smaller time fractions of 7.50, 3.75, 1.50 and 0.75 mins to emulate images reconstructed at 50, 25, 10 and 5% of the full counts, respectively. A 2D U-Net was trained with mean-squared-error loss on 28 high-low count image pairs. Results:The DL algorithms were visually and quantitatively compared to spatial and edge-preserving denoising lters; the DL-based methods effectively removed image noise and recovered image details much better while keeping quantitative (SUV) accuracy. The largest improvement in image quality was seen in the images reconstructed with 10 and 5% of the counts (equivalent to sub-1-MBq or sub-1-min mouse imaging). The DL-based denoising framework was also successfully applied on the NEMA-NU4 phantom and different tracer studies ( 18 F-PSMA, 18 F-FAPI and 68 Ga-FAPI). Conclusion:Visual and quantitative results support the superior performance and robustness in image denoising of the implemented DL models for low statistics micro-PET. This offers tremendous exibility in optimizing scan protocols with reduced tracer doses or shorter durations.

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High Dose MicroCT Does Not Contribute Toward Improved MicroPET/CT Image Quantitative Accuracy and Can Limit Longitudinal Scanning of Small Animals

Cited by 8 publications

References 36 publications

Standardization of Preclinical PET/CT Imaging to Improve Quantitative Accuracy, Precision, and Reproducibility: A Multicenter Study

Standardization of Preclinical PET/CT Imaging to Improve Quantitative Accuracy, Precision, and Reproducibility: A Multicenter Study

Low-Dose Imaging in a New Preclinical Total-Body PET/CT Scanner

Image Denoising of Low-Dose PET Mouse Scans with Deep Learning: Validation Study for Preclinical Imaging Applicability

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