Optimization of PROPELLER Methods for Quantitative MRI of Liver CancerPublic Deposited
Hepatocellular carcinoma (HCC) is the most common primary malignant liver tumor, with the highest incidence in Asia. Developed countries, including the United States, have had an 80% increase in HCC incidence over the last 15-20 years. Magnetic Resonance Imaging (MRI) is a promising imaging modality with superior soft tissue contrast for liver lesion detection and type differentiation. Conventional MRI encountered challenges due to the lack of functional information for quantitative evaluation of tissue microstructural properties. Diffusion-weighted MRI (DWI) water mobility measurements can be useful for non-invasive interrogation of tissue microstructures. DWI can differentiate viable and necrotic tumor tissues. Furthermore, DWI may detect early changes of water mobility properties secondary to therapyinduced tumor tissue destruction and thus serve as a biomarker for prediction of therapy response. The most commonly used single-shot DWI techniques are superior in avoiding motion artifacts; however, they are limited by image distortion, chemical shift artifacts and reduced spatial resolution. The multi-shot PROPELLER (Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction) techniques employ a novel data acquisition strategy less sensitive to motion artifacts and susceptibility artifacts, offering the potential of high quality abdominal imaging applications. The purpose of this work is to develop and optimize PROPELLER techniques to provide quantitative DW-PROPELLER MRI and PROPELLER T2 mapping in abdominal imaging for characterization of liver tumor tissues, functional guidance of percutaneous liver interventions and evaluation of hepatocarcinogenesis progression. First, conventional single-shot DWI techniques were evaluated for liver tumor tissue characterization and therapy response assessment. Second, DW-PROPELLER and DW-SPLICE-PROPELLER techniques were developed to provide abdominal DWI with superior image quality compared to single shot DWI. Third, DW-PROPELLER techniques were applied in animal liver tumor models for quantitative assessment of tumor viability and for functional guidance during percutaneous intervention procedures. Fourth, a modified PROPELLER approach for T2 mapping was developed to provide accurate and robust abdominal T2 mapping. Fifth, quantitative multidimensional PROPELLER MRI was performed to evaluate Diethylnitrosamine-Induced Hepatocarcinogenesis in Wistar Rat. Finally, the targeted-PROPELLER technique was developed to image a limited field-of-view with reduced imaging time, improved spatial resolution and robust regional motion corrections.