Katy Keenan with Phreddie (image) National Institute of Standards and Technology (NIST) Share Print E-Mail Caption NIST engineer Katy Keenan opens Phreddie, a phantom for calibrating MRI machines that is traceable to standardized values. The phantom is filled with small plastic containers of various salt solutions that mimic tissues of the human body. Credit Jacobson/NIST Usage Restrictions Please use correct credit Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.