A standard SI traceable phantom suitable for qMRI: design, manufacture and characterisation

Abstract

Quantitative MRI uses conventional clinical MRI hardware to make measurements of physical quantities. It also offers the opportunity to benchmark scanners in specific applications by characterising their measurement performance. This allows independent assessment of different scanners, products and services. Quantitation requires evaluation of the uncertainty and bias in the measurement process and as such requires a metrological framework. This process can be supported by the use of a reference object (phantom) that contains clinically relevant MRI quantities that are traceable to primary standards. Currently, there are very few traceable MRI standards available, and none cover all the forms of quantitative MRI that are being deployed clinically. The objective of this paper is to provide a metrological framework to build on and support the standardisation of qMRI through the provision of improved reference standards that are compatible with quantitative approaches. Here, we describe the design, construction, characterisation and measurement uncertainty of a traceable and metrologically quantified phantom. The phantom design is modular and comprises 30 distinct vials containing well-characterised, traceable solutions with reported uncertainty for the following MRI measurands: T1, T2, iron content and fat fraction.