A Novel Magnetic Resonance Quality Assurance Phantom (KMRP-4): Multi-Site Comparison With the American College of Radiology Phantom

Purpose: To propose a novel standard magnetic resonance imaging (MRI) phantom, here-after called the Korea Magnetic Resonance Phantom-4th edition (KMRP-4). Its related quality control (QC) assessment protocols and its comparison with the American College of Radiology (ACR) phantom and its QC assessment protocols. Materials and Methods: Internally, the KMRP-4 phantom is composed of cubic and tri-angular vessels, brain tissue structures, and a uniform region designed to facilitate a vari-ety of QC protocols. Using magnetic resonance (MR) images of these structures, we quan-titatively evaluated a total of 10 parameters, seven from those of existing ACR protocols (i.e., geometric accuracy, high-contrast spatial resolution, slice thickness accuracy, slice po-sition accuracy, image intensity uniformity, percent signal ghosting, and low-contrast object detectability) and three additional parameters for evaluating vessel conspicuity, brain tissue contrast, and signal-to-noise ratio (SNR) introduced in the KMRP-4 protocols. Twenty-two MRI systems of 0.32–3.0 T static magnetic field strength were tested using both ACR and KMRP-4 phantoms. Mann–Whitney U-tests were performed on the seven evaluation items of the ACR method to compare KMRP-4 and ACR methods. Results: The results of Mann–Whitney U-test demonstrated that p-values were more than 0.05 for all seven items that could be assessed with both ACR and KMRP-4, indicating similar results between the two methods. Additionally, assessments of vessel conspicuity, brain tissue contrast, and SNR using the KMRP-4 method demonstrated utility of the KMRP-4 phantom. Conclusion: A novel standard phantom and related QC methods were developed to perform objective, observer-independent, and semi-automatic QC tests. Quantitative comparisons of MR images with KMPR-4 and ACR phantoms were performed. Results demonstrated the utility of the newly proposed KMRP-4 phantom and its related QC methods.