Usefulness of ACR MRI Phantom for Quality Assurance of MRI Instruments

ABSTRACT

PURPOSE: To examine whether the ACR phantom could be used in quality standards for magnetic resonance imaging (MRI) instruments in Korea. MATERIALS AND METHODS: We conducted the phantom test using the ACR MRI phantom in 20 MRI instruments currently used in Korea. According to ACR criteria, we acquired the phantom images which were then assessed by the following seven tests: geometric accuracy, high spatial resolution, slice thickness accuracy, slice position accuracy, image intensity uniformity, percent signal ghosting, and low contrast object detectability. The phantom images were interpreted by three experienced radiologists according to ACR criteria. Then, we examined the failure rate of each test and evaluated the inter-observer variation in the measurements and test failure. RESULTS: The failure rate of each test could be broken into the following components: geometric accuracy (11-21%), high contrast spatial resolution (10-15%), slice thickness accuracy (6-22%), slice position accuracy (5-17%), image intensity uniformity (6%), percent signal ghosting (16%), and low contrast object detectability (8-10%). In this series, all the failure rates were less than 30%. In addition, no inter-observer variation was seen in the measurements and test failure. CONCLUSION: ACR MRI phantom promises to be established as the standard phantom for MRI instruments in Korea because of its objectivity in assessing the phantom images.