Karl F Stupic1, Maureen Ainslie2, Michael A Boss3, Cecil Charles2, Andrew M Dienstfrey1, Jeffrey L Evelhoch4, Paul Finn5, Zydrunas Gimbutas1, Jeffrey L Gunter6, Derek L G Hill7, Clifford R Jack6, Edward F Jackson8, Todor Karaulanov9, Kathryn E Keenan1, Guoying Liu10, Michele N Martin1, Pottumarthi V Prasad11, Nikki S Rentz1, Chun Yuan12, Stephen E Russek1. 1. Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado, USA. 2. Department of Radiology, Duke University, Durham, North Carolina, USA. 3. American College of Radiology, Philadelphia, Pennsylvania, USA. 4. Merck Research Laboratories, West Point, Pennsylvania, USA. 5. University of California, Los Angeles, California, USA. 6. Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA. 7. Centre for Medical Image Computing, University College London, London, United Kingdom. 8. Medical Physics, University of Wisconsin, Madison, Wisconsin, USA. 9. CaliberMRI, Inc., Boulder, Colorado, USA. 10. National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland, USA. 11. Radiology/CAI, NorthShore University HealthSystem, Evanston, Illinois, USA. 12. Radiology, University of Washington, Seattle, Washington, USA.
Abstract
PURPOSE: A standard MRI system phantom has been designed and fabricated to assess scanner performance, stability, comparability and assess the accuracy of quantitative relaxation time imaging. The phantom is unique in having traceability to the International System of Units, a high level of precision, and monitoring by a national metrology institute. Here, we describe the phantom design, construction, imaging protocols, and measurement of geometric distortion, resolution, slice profile, signal-to-noise ratio (SNR), proton-spin relaxation times, image uniformity and proton density. METHODS: The system phantom, designed by the International Society of Magnetic Resonance in Medicine ad hoc committee on Standards for Quantitative MR, is a 200 mm spherical structure that contains a 57-element fiducial array; two relaxation time arrays; a proton density/SNR array; resolution and slice-profile insets. Standard imaging protocols are presented, which provide rapid assessment of geometric distortion, image uniformity, T1 and T2 mapping, image resolution, slice profile, and SNR. RESULTS: Fiducial array analysis gives assessment of intrinsic geometric distortions, which can vary considerably between scanners and correction techniques. This analysis also measures scanner/coil image uniformity, spatial calibration accuracy, and local volume distortion. An advanced resolution analysis gives both scanner and protocol contributions. SNR analysis gives both temporal and spatial contributions. CONCLUSIONS: A standard system phantom is useful for characterization of scanner performance, monitoring a scanner over time, and to compare different scanners. This type of calibration structure is useful for quality assurance, benchmarking quantitative MRI protocols, and to transition MRI from a qualitative imaging technique to a precise metrology with documented accuracy and uncertainty.
PURPOSE: A standard MRI system phantom has been designed and fabricated to assess scanner performance, stability, comparability and assess the accuracy of quantitative relaxation time imaging. The phantom is unique in having traceability to the International System of Units, a high level of precision, and monitoring by a national metrology institute. Here, we describe the phantom design, construction, imaging protocols, and measurement of geometric distortion, resolution, slice profile, signal-to-noise ratio (SNR), proton-spin relaxation times, image uniformity and proton density. METHODS: The system phantom, designed by the International Society of Magnetic Resonance in Medicine ad hoc committee on Standards for Quantitative MR, is a 200 mm spherical structure that contains a 57-element fiducial array; two relaxation time arrays; a proton density/SNR array; resolution and slice-profile insets. Standard imaging protocols are presented, which provide rapid assessment of geometric distortion, image uniformity, T1 and T2 mapping, image resolution, slice profile, and SNR. RESULTS: Fiducial array analysis gives assessment of intrinsic geometric distortions, which can vary considerably between scanners and correction techniques. This analysis also measures scanner/coil image uniformity, spatial calibration accuracy, and local volume distortion. An advanced resolution analysis gives both scanner and protocol contributions. SNR analysis gives both temporal and spatial contributions. CONCLUSIONS: A standard system phantom is useful for characterization of scanner performance, monitoring a scanner over time, and to compare different scanners. This type of calibration structure is useful for quality assurance, benchmarking quantitative MRI protocols, and to transition MRI from a qualitative imaging technique to a precise metrology with documented accuracy and uncertainty.
Authors: Nikolai J Mickevicius; Joshua P Kim; Jiwei Zhao; Zachary S Morris; Newton J Hurst; Carri K Glide-Hurst Journal: Med Phys Date: 2021-09-18 Impact factor: 4.071
Authors: Kathryn E Keenan; Zydrunas Gimbutas; Andrew Dienstfrey; Karl F Stupic; Michael A Boss; Stephen E Russek; Thomas L Chenevert; P V Prasad; Junyu Guo; Wilburn E Reddick; Kim M Cecil; Amita Shukla-Dave; David Aramburu Nunez; Amaresh Shridhar Konar; Michael Z Liu; Sachin R Jambawalikar; Lawrence H Schwartz; Jie Zheng; Peng Hu; Edward F Jackson Journal: PLoS One Date: 2021-06-30 Impact factor: 3.240