Standardising MRI phantoms for quantitative image comparison

The challenge

Increasingly, medical imaging techniques, such as magnetic resonance imaging (MRI), need to perform in a standardised way. This requires the development of specialised phantoms that enable tests to be performed on the imaging equipment. Phantoms are devices designed to simulate the response and interactions of human tissues and organs with the imaging device, thus ensuring appropriate imaging quality in living subjects.

The results that MRI scans retrieve are pictures of the area analysed, which trained radiologists must evaluate qualitatively. However, comparing images from different scanners is a critical challenge for professionals using various machines and interpretation criteria. A paradigm shift is needed to address this issue. By turning the imaging system into a scientific apparatus for measurement of physical parameters, it is possible to shift from a qualitative framework to a quantitative one.

Given the complexity of the variables that quantitative imaging techniques aim to measure, the phantoms used to test these machines must provide standards for the calibration of such measurements. Suitable, universal test objects allow for MR parameters to be measured in a repeatable, traceable way. Despite successful use in medical research, the application of quantitative imaging techniques to the clinical field has been impaired by the lack of standardised phantoms.

The solution

Through NPL's medical imaging accelerator for industry programme, funded through the Industrial Strategy Challenge Fund, NPL worked with Gold Standard Phantoms to develop a novel phantom that can provide a multi-parametric reference for quantitative MRI. The new test object allows comparison of pictures from different machines against the same physical parameters in a standardised way. Reproducible and calibrated scientific data produced with these tools guarantee quality assurance and allow transposition of research results into the clinical field.

The impact

The standard phantom developed by NPL and Gold Standard Phantoms will be used to conduct a nationwide survey across hospitals in the UK to investigate the capability of the MRI scanners currently in use. Clinical trials making use of standard phantoms will be able to ensure consistency of results by reducing measurement uncertainty. This has the potential to speed up and improve confidence in drug trial studies.

Recent developments in machine learning-based algorithms for the interpretation of MRI scans will also benefit from these new phantoms. By relying on quantitative measures with known levels of uncertainty and error margins, artificial intelligence systems in radiology will gain experience and, possibly, learn methods of diagnosis more quickly.

Gold Standard Phantoms is a University College London Institute of Neurology spinout company which is developing, marketing and selling calibration services for Quantitative Medical Imaging. They are working in collaboration with the main stake holders in the field to provide a one-stop-shop integrated solution to the problem of maintenance of standards in quantitative medical imaging. They are working therefore with clinicians, radiographers and radiological societies, imaging manufacturing companies, the pharmaceutical industry and regulatory bodies, both national and supranational.

Their mission is to enable medical imaging to move from a pattern recognition-based technique to a quantitative and reproducible scientific measurement methodology. Gold Standard Phantoms aims to be the premier provider of calibration services for clinical quantitative medical imaging worldwide.

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