BME.10 A phantom for quality assurance of a 9.4T MRI

• Christian Lee
• Tuyen Mai
• David Miller
• Jesus Ramos
• Alexandra Vorobyeva

Magnetic resonance imaging (MRI) is one of the most widely used modalities for diagnostics and imaging of humans or research on animals. Ensuring that equipment is properly calibrated is crucial to providing good quality images. Phantoms are quality assurance devices that assist in the calibration of MRI machines, thanks to their precisely manufactured components which can help assess image quality, image alignment, etc. While a variety of commercial phantoms exist in the market, researchers at the Preclinical Imaging Core Lab do not have an effective phantom that can assess the quality of their 9.4T small animal MRI. Current standardized methods for quality assurance are well-established for human MRI, but it is not the case for animal-scale systems. This project aims to design a quality assurance phantom for the 9.4T MRI machine that can test five equipment functions: geometric accuracy, high-contrast spatial resolution, slice thickness accuracy, slice position accuracy and image intensity uniformity within coil dimensions of 72 mm. Inner components of our phantom are assembled from laser-cut acrylic pieces, with the outer body made from a polycarbonate pipe, allowing it to be much less expensive compared to other commercial phantoms. During verification testing, we placed the inner component of the phantom on a granite flat-surface plate and used a caliper to conduct 20 trials of measurements to verify the dimensional accuracy of our slice position accuracy structures. Using ANOVA and individual pair-wise t-test, we identified no significant difference between the distance from the crossing of the slice position accuracy wedges to the bottom of the phantom. This verifies that our device can test whether MRI slices are correctly located and are perpendicular to the MRI coil. By introducing this small quality assurance phantom, we hope to create an affordable and easily accessible alternative for labs using small animal-scale MRI systems.