Characterization of Human Prostate Cancer Using Sodium Magnetic Resonance Imaging

Overtreatment of prostate cancer is a significant problem in the health care of men. Development of non-invasive imaging tools for improved characterization of prostate lesions has the potential to reduce overtreatment. In this thesis work, we will evaluate the ability of tissue sodium concentration obtained from sodium magnetic resonance imaging (sodium-MRI) to characterize in vivo prostate lesions. Imaging data, including multi-parametric magnetic resonance imaging (mpMRI) and sodium-MRI, were obtained from a cohort of men with biopsy-proven prostate cancer and compared to digitized whole-mount histopathology after prostatectomy. Histopathology was independently graded for Gleason score to be used as the ground truth of tumour aggression. These imaging data were all accurately co-registered, allowing for direct comparison of imaging contrast to Gleason score. The results of this thesis work suggest that tissue sodium concentration assessed by sodium-MRI has utility as a part of a “non-invasive imaging-assay” to accurately characterize prostate cancer lesions. Sodium-MRI can provide clinically useful, complementary information to mpMRI; ultimately leading to better characterization of prostate lesions throughout the whole prostate. This has potential to improve patient outcomes of men with low-risk disease who do opt for active surveillance instead of treatment

Load-Independent And Regional Measures Of Cardiac Function Via Real-Time Mri

LOAD-INDEPENDENT AND REGIONAL MEASURES OF CARDIAC FUNCTION VIA REAL-TIME MRI Francisco Jose Contijoch Robert C Gorman, MD Expansion of infarcted tissue during left ventricular (LV) remodeling after a myocardial infarction is associated with poor long-term prognosis. Several interventions have been developed to limit infarct expansion by modifying the material properties of the infarcted or surrounding borderzone tissue. Measures of myocardial function and material properties can be obtained non-invasively via imaging. However, these measures are sensitive to variations in loading conditions and acquisition of load-independent measures have been limited by surgically invasive procedures and limited spatial resolution. In this dissertation, a real-time magnetic resonance imaging (MRI) technique was validated in clinical patients and instrumented animals, several technical improvements in MRI acquisition and reconstruction were presented for improved imaging resolution, load-independent measures were obtained in animal studies via non-invasive imaging, and regional variations in function were measured in both na�ve and post-infarction animals. Specifically, a golden-angle radial MRI acquisition with non-Cartesian SENSE-based reconstruction with an exposure time less than 95 ms and a frame rate above 89 fps allows for accurate estimation of LV slice volume in clinical patients and instrumented animals. Two technical developments were pursued to improve image quality and spatial resolution. First, the slice volume obtained can be used as a self-navigator signal to generate retrospectively-gated, high-resolution datasets of multiple beat morphologies. Second, cross-correlation of the ECG with previously observed values resulted in accurate interpretation of cardiac phase in patients with arrhythmias and allowed for multi-shot imaging of dynamic scenarios. Synchronizing the measured LV slice volume with an LV pressure signal allowed for pressure-volume loops and corresponding load-independent measures of function to be obtained in instrumented animals. Acquiring LV slice volume at multiple slice locations revealed regional differences in contractile function. Motion-tracking of the myocardium during real-time imaging allowed for differences in contractile function between normal, borderzone, and infarcted myocardium to be measured. Lastly, application of real-time imaging to patients with arrhythmias revealed the variable impact of ectopic beats on global hemodynamic function, depending on frequency and ectopic pattern. This work established the feasibility of obtaining load-independent measures of function via real-time MRI and illustrated regional variations in cardiac function

Investigation of Endogenous In-Vivo Sodium Concentration in Human Prostate Cancer Measured With 23Na Magnetic Resonance Imaging

Prostate cancer (PCa) is the most common malignancy in men. Aggressive prostate tumours must be identified, differentiated from indolent tumours, and treated to ensure survival of the patient. Currently, clinicians use a combination of multi-parametric magnetic resonance imaging (mpMRI) contrasts to improve PCa detection. While these techniques provide very good spatial resolution, the specificity is often insufficient to unequivocally identify malignant lesions. Utilizing specialized MRI hardware developed for sensitive in-vivo detection of sodium, this work has investigated differences in sodium concentration between healthy and malignant prostate tissue. Patients with biopsy-proven PCa underwent conventional mpMRI and sodium MRI followed by radical prostatectomy. Subsequent whole-mount histopathology of the excised prostate was then contoured according to Gleason Grade, a radiological assessment of tumour stage and aggressiveness for PCa. Tissue sodium concentration (TSC) measured by sodium MRI was successfully co-registered with standard image contrasts from multi-parametric MRI and also with pathologist confirmed histopathology as the gold standard. This proposed method provides quantitative, in-vivo sodium information from cancerous human prostates. The results of this study establish the relationship between TSC and malignant PCa, which could prove useful in initial characterization of the disease and for active surveillance of indolent lesions

Modified mass-spring system for physically based deformation modeling

Mass-spring systems are considered the simplest and most intuitive of all deformable models. They are computationally efficient, and can handle large deformations with ease. But they suffer several intrinsic limitations. In this book a modified mass-spring system for physically based deformation modeling that addresses the limitations and solves them elegantly is presented. Several implementations in modeling breast mechanics, heart mechanics and for elastic images registration are presented

Modified mass-spring system for physically based deformation modeling

Mass-spring systems are considered the simplest and most intuitive of all deformable models. They are computationally efficient, and can handle large deformations with ease. But they suffer several intrinsic limitations. In this book a modified mass-spring system for physically based deformation modeling that addresses the limitations and solves them elegantly is presented. Several implementations in modeling breast mechanics, heart mechanics and for elastic images registration are presented

A multimodal neuroimaging study of somatosensory system

The thesis is the result of a training by the Magnetoencephalography (MEG)-lab by the Center mind/brain science of the university of Trento. Final goal of the analysis was answering the question if MEG is capable to capture activities from the subcortical brain areas and to follow the neural information flow up along the fibers to the cortex. First aim of the thesis is describing the project and developing of an experiment on the somatosensory system that I executed by the CIMeC. The somatosensory system was activated by applying electrical stimulation to the median nerve and MEG signal during this stimulation was recorded. Also MRI and diffusion MRI data of the subject were collected. Further aim of the thesis is to describe the analysis I executed on the collected data. For this purpose the MEG source localization was executed and also Monte-Carlo simulation. The data obtained were integrated with the information obtained from diffusion MRI. Satisfactory results were obtained although we could not prove definitely the result

Functional brain imaging with fMRI and MEG

The work described in this thesis was performed by the author, except where indicated. All the studies were accomplished on the 3 Tesla system within the Magnetic Resonance Centre at the University of Nottingham, and the Wellcome Trust MEG Laboratory at the Aston University during the period between October 1999 and June 2005. Functional Magnetic Resonance Imaging (fMRI) and Magnetoencephalography (MEG) are two promising brain function research modalities, sensitive to the hemodynamic and electrophysiological responses respectively during brain activites. The feasibility of joint employment of both modalities was examined in both spatial and temporal domains. A somatosensory tactile stimulus was adopted to induce simple functional reaction. It was shown that a reasonable spatial correspondence between fMRI and MEG can be established. Attempts were made on MEG recordings to extract suitable aspects for temporal features matching fMRI with a method reflecting the physical principles. It was shown that the this method is capable of exposing the nature of neural electric activities, although further development is required to perfect the strategy