One of the central limitations of PET/MRI is the lack of accurate means of attenuation correction, which leads to inaccurate and inconsistent quantification of radiotracer uptake. The inconsistency of PET quantification prevents the widespread adoption of PET/MRI in clinical trials, where a precise and reproducible measurement of radiotracer uptake is required. We propose in this application to develop a standard methodology to evaluate MR based attenuation correction techniques and the related PET quantitation accuracy in order to qualify PET/MRI scanners for clinical trials and clinical work. This work will be done in three specific aims. First, we will evaluate materials and create a physical phantom for evaluation of MR based attenuation correction techniques. We will subsequently validate the phantom using a patient study to demonstrate that we can accurately estimate deviations of measured activity using the PET/MRI phantom. Finally, we will harmonize the reconstruction parameters on the two available PET/MRI scanners and evaluate the reproducibility of the quantitative accuracy across 12 PET/ MRI sites split between the two PET/MRI manufacturers. Finally we will incorporate the PET/MRI harmonization data into a global harmonization study that includes both PET/MRI and PET/CT. Through the work described, we aim to create a standardized approach to evaluate the accuracy of PET quantification in the setting of PET/MRI. A standardized methodology will incent vendors to develop attenuation correction methods that result in more consistent uptake estimates across systems, and the ability to qualify scanners will help the adoption of PET/MRI into clinical trials and clinical care.

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The inclusion of PET/MRI into clinical trials and clinical care is limited by inaccurate quantification of radiotracer uptake. In order to create consistency in quantification we aim to develop a PET/MRI phantom and processes for PET/MRI scanner qualification and validation. The development of a phantom and process that allows for site qualification, will allow for the inclusion of PET/MRI into multicenter trials.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Special Emphasis Panel (ZRG1)
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Zhang, Yantian
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University of California San Francisco
Schools of Medicine
San Francisco
United States
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Leynes, Andrew P; Yang, Jaewon; Wiesinger, Florian et al. (2018) Zero-Echo-Time and Dixon Deep Pseudo-CT (ZeDD CT): Direct Generation of Pseudo-CT Images for Pelvic PET/MRI Attenuation Correction Using Deep Convolutional Neural Networks with Multiparametric MRI. J Nucl Med 59:852-858
Yang, Jaewon; Liu, Jing; Wiesinger, Florian et al. (2018) Developing an efficient phase-matched attenuation correction method for quiescent period PET in abdominal PET/MRI. Phys Med Biol 63:185002
Yang, Jaewon; Wiesinger, Florian; Kaushik, Sandeep et al. (2017) Evaluation of Sinus/Edge-Corrected Zero-Echo-Time-Based Attenuation Correction in Brain PET/MRI. J Nucl Med 58:1873-1879
Ehman, Eric C; Johnson, Geoffrey B; Villanueva-Meyer, Javier E et al. (2017) PET/MRI: Where might it replace PET/CT? J Magn Reson Imaging 46:1247-1262
Leynes, Andrew P; Yang, Jaewon; Shanbhag, Dattesh D et al. (2017) Hybrid ZTE/Dixon MR-based attenuation correction for quantitative uptake estimation of pelvic lesions in PET/MRI. Med Phys 44:902-913