Image registration in quantitative inversion recovery MRI and applications in heart and lungs

The aims of this thesis are to develop fast, accurate and clinically applicable motion-correction solutions in T1 mapping acquisitions in cardiac and lung imaging. In order to maximise clinical applicability, this thesis focuses on using automated post processing solutions which minimise the time-cost to patients, clinical staff and MRI scanner scheduling. This has been achieved in 4 separate but related original pieces of work: • Chapter 3: A novel method for correcting accidental respiratory motion in Modified Look Locker Inversion Recovery (MOLLI) sequences for cardiac T1 mapping is presented and compared to an established, alternative method. The method presented produces synthetic images via an inversion recovery model. It is shown that both methods successfully improve image registration, but that the method presented here uses less post-processing time. • Chapter 4: The method discussed in Chapter 3 is implemented and evaluated in a large cohort of patients with pulmonary hypertension to assess the diagnostic and prognostic value of T1 mapping in this patient cohort. Although myocardial T1 was found to be significantly elevated in patients with pulmonary hypertension, the diagnostic and prognostic value of myocardial T1 was found to be limited. • Chapter 5: The method discussed in Chapter 3 was extended to free breathing lung T1 mapping, and implemented in patients with idiopathic pulmonary fibrosis (IPF) and healthy volunteers. The method is shown to register free breathing Look-Locker lung images successfully. The results show that free breathing lung T1 can discriminate between patients with IPF and healthy volunteers. Free breathing lung T1 is significantly lower and more heterogeneous in patients with IPF compared to healthy volunteers. • Chapter 6: The method discussed in Chapter 5 is extended to free breathing cardiac MOLLI sequences, and is implemented in healthy volunteers. It is shown that the images are successfully motion corrected in the short axis plane, though the results are likely to be less precise due to out of plane motion. The myocardial T1 is shown to be significantly affected by oxygen enhanced imaging, and is significantly higher during free breathing, compared to breath hold