Oxford Nottingham EPSRC and MRC Centre for Doctoral Training in Biomedical Imaging

Lead Research Organisation: University of Oxford
Department Name: Biomedical Imaging CDT


Quantitative magnetic resonance imaging enables characterization of T1 and T2* relaxation times, important biomarkers of liver fibrosis, inflammation and hepatic iron overload. These constitute important tools in non-alcoholic fatty liver disease (NAFLD) patient stratification [1]-[4]. 2D T1 maps of a single slice are usually acquired through an inversion or saturation recovery-based sequence (MOLLI, ShMOLLI, SASHA) [5]-[8]. Acquiring a 3D T1 map would allow better characterization and spatial localization of inflammation and fibrosis as well as opening up possible applications connected with tumour imaging in liver cancer patients.
Value to the scientific community from the three-year DPhil project will be documented by the publication of three articles in peer-reviewed journals. The first paper will focus on developing two alternative 3D T1 mapping methods, using the variable flip angle (VFA) Dixon sequence at 3T commercially available on Siemens scanners. The first method is the Reference Region Variable Flip Angle (RRVFA) [9] applied to the liver of patients with a high percentage of fat; the second is an application of the VFA without a constraint on the percentage of fat in the liver [10]. Field inhomogeneities of the transmitted (B1+) radiofrequency (RF) pulses affect the accuracy of T1 values. Therefore, a novel B1+ map will be developed together with the 3D T1 maps and compared with existing B1+ mapping methods. The accuracy of the proposed methods in determining T1 values will be validated in phantoms against the current gold standard inversion-recovery T1 mapping method [11] as well as in vivo using a multi-repetition time (TR) multi-echo time (TE) 1H spectroscopy stimulated echo acquisition mode sequence [12]. The RRVFA and VFA 3D T1 mapping optimized protocols will be validated in patients taking part in two different studies: Liver Investigation Testing Marker Utility in Steatohepatitis (LITMUS) and Effects of Dietary Intervention and Surgery on NAFLD (EDISON).
The planned second article will focus on evaluating inter-vendor reproducibility of the above described RRVFA and the VFA 3D T1 mapping methods that will be developed using Siemens product-based sequences, when employed on GE Healthcare and Philips scanners. For this purpose, collaborations will be established with the University of Cambridge and/or the University of Nottingham.
The projected third paper will compare the accuracy and precision of the RRVFA and the VFA 3D T1 mapping methods to existing 2D single-slice T1 mapping methods, such as the MOLLI, ShMOLLI and SASHA sequences.
The project falls within the EPSRC medical imaging areas, especially the application of magnetic resonance imaging to derive valuable clinical diagnostic tools for the liver. It will be performed in collaboration with both the University of Oxford, at the Oxford Centre for Clinical Magnetic Resonance Research, and Perspectum Diagnostics.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/R512333/1 01/10/2017 30/09/2021
1943814 Studentship EP/R512333/1 01/10/2017 30/09/2021 Gabriela De Matos Gomes Belsley
Description The main outcome of the project is to obtain liver longitudinal relaxation times, T1, using widely available MRI product sequences such that it can be widespread across healthcare providers. The variable flip angle spoiled gradient recalled satisfies this criterium and I have thoroughly been studying its signal output during my first year of the DPhil. We found that the estimation of T1 with this sequence is highly dependent on the accurate and precise knowledge of the excitation flip angle. To this end, I have developed a method to map the flip angle in the liver (B1+ mapping) and a pipeline to estimate the T1.
Exploitation Route The repeatability and reproducibility of the method developed to measure the B1+ and T1 will be tested on healthy livers using Siemens MRI scanners. The main outcome will be a paper that will contribute to the base knowledge of researchers working in the quantitative MRI field, namely T1 and B1+ mapping.
Its potential to measure liver T1 in patients with liver disease (hepatocellular carcinoma, cirrhosis, non-alcoholic fatty liver disease) will also be investigated and may help to further diagnose and stratify these diseases.
Sectors Healthcare