Repeatability and Reproducibility of Quantitative MRCP

Biliary-related conditions, such as autoimmune conditions Primary Biliary Cholangitis (PBC), and Primary Sclerosing Cholangitis (PSC), and also cancers such as cholangiocarcinoma, affect tens of thousands of individuals in the UK each year. All biliary conditions require careful tracking of the structure and integrity of the biliary tree so that intervention can be carefully planned and with that, outcomes improved.

The current non-invasive gold-standard for assessment of the biliary tree is MRI-based Magnetic Resonance Cholangiopancreatography (MRCP). This method uses no contrast and takes up to 10 minutes to obtain within a normal scan event. However, there are several limitations to its use which include, images having great variability in quality and are used mainly for qualitative analysis. Using conventional MRCP a consultant can, depending on image quality; identify key structures, inform diagnosis, and give a general assessment on the health of the biliary tree structure. However, current MRCP imaging only allows limited quantitative assessment of the ducts. More extensive, objective quantification has the potential to dramatically improve the usability of MRCP imaging.With this in mind, imaging scientists at Perspectum Diagnostics have developed a hessian-based mathematical model to enhance conventional MRCP to a 3D geometric model of the biliary tree, 'Quantitative MRCP'. This enables quantitative measurement of bile duct width, orientation, branching point and curvative metrics.

The technology has been validated against 3D printed phantoms for accuracy, and early clinical research has demonstrated the technology has potential for clinical impact, with improvement in radiologist performance versus conventional non-enhanced MRCP imaging (Vikal et al 2017). Thus, further research into the technology and its viability as an enhancement to current procedure is necessary if it is to replace conventional MRCP as the primary method of non-invasive biliary assessment.

Integral to the development of any new technology, is demonstration of the repeatability and reproducibility of the method. This is the inter-examination variability in results. Quantitative MRCP aims to act as a tool to not only improve assessment of the current status of the biliary tree, but also act as a mechanism to track change within the ducts. Thus, it must be established that any change between scans is due to change in the physiology of the individual and not due to a quirk or fault of the technology.

The above will be tested by a series of scans performed on an individual over a short period of time, for which the condition of the biliary tree within that individual can be assumed to be constant. Between each scan, subject and coil repositioning will occur. The study will recruit a group of adult volunteers, from both diseased groups and healthy groups in order to achieve a range of physiological biliary metrics.

Quantitative MRCP is an MRI based method, requiring no contrast, however consuming a drink containing manganese improves the quality of MRCP images significantly (Frisch et al., 2017), and therefore patients are routinely asked to drink pineapple juice (naturally high in manganese) before having a clinical MRCP scan. At present, multiparametric MRI to assess the health of liver tissue is performed in a fasted state (Banerjee et al., 2014), however, in order to offer a comprehensive liver scan including both MRCP and multiparametric MRI in the same scan, it is important to understand whether consuming pineapple juice will affect the multiparametric MRI measurements of cT1, PDFF and T2*.

MRI is safe and non-invasive, with no known risks to patients as long as they are appropriately screened to ensure they have no contraindications to MRI (e.g.pacemaker, metal implant that is not certified as MR-safe).