Development and Validation of Novel Quantitative MRI Techniques in Liver


Book Description

MRI methods to evaluate diffuse hepatic diseases have advanced substantially in recent years, with a particular focus on chemical shift encoded (CSE)-MRI. However, the systematic evaluation of these methods requires the development of highly controlled quantitative imaging test objects ("phantoms"). In addition, CSE-MRI methods face major limitations, particularly their high sensitivity to physiological motion, and challenges in measuring parameters such as magnetic susceptibility (an emerging biomarker for tissue iron deposition). In this thesis, technical developments are introduced to address these challenges in both quantitative imaging phantoms and quantitative liver MRI methods. Novel quantitative MRI phantoms were designed and developed to mimic the simultaneous presence of fat, iron, and fibrosis in the liver by controlling different MR biomarkers while mimicking in vivo liver signals. An MRI and CT compatible fat phantom was developed and evaluated in a round-robin multi-center multi-vendor study. Motion-robust free breathing 2D sequential CSE-MRI method with flip angle modulation (FAM) and centric encoding approach was developed to achieve high SNR performance and minimal T1 bias simultaneously for liver fat and iron quantification. To further boost SNR performance, motion-corrected averaging method was combined with FAM CSE-MRI. Finally, a recently proposed liver quantitative susceptibility mapping (QSM) method was evaluated across iron levels and acquisition protocols at 1.5T and 3.0T, using superconducting quantum interference device (SQUID) liver susceptometry as the reference. Overall, these developments in this thesis have advanced MRI of the liver towards becoming a truly quantitative imaging modality.







Improving Diagnosis in Health Care


Book Description

Getting the right diagnosis is a key aspect of health care - it provides an explanation of a patient's health problem and informs subsequent health care decisions. The diagnostic process is a complex, collaborative activity that involves clinical reasoning and information gathering to determine a patient's health problem. According to Improving Diagnosis in Health Care, diagnostic errors-inaccurate or delayed diagnoses-persist throughout all settings of care and continue to harm an unacceptable number of patients. It is likely that most people will experience at least one diagnostic error in their lifetime, sometimes with devastating consequences. Diagnostic errors may cause harm to patients by preventing or delaying appropriate treatment, providing unnecessary or harmful treatment, or resulting in psychological or financial repercussions. The committee concluded that improving the diagnostic process is not only possible, but also represents a moral, professional, and public health imperative. Improving Diagnosis in Health Care, a continuation of the landmark Institute of Medicine reports To Err Is Human (2000) and Crossing the Quality Chasm (2001), finds that diagnosis-and, in particular, the occurrence of diagnostic errorsâ€"has been largely unappreciated in efforts to improve the quality and safety of health care. Without a dedicated focus on improving diagnosis, diagnostic errors will likely worsen as the delivery of health care and the diagnostic process continue to increase in complexity. Just as the diagnostic process is a collaborative activity, improving diagnosis will require collaboration and a widespread commitment to change among health care professionals, health care organizations, patients and their families, researchers, and policy makers. The recommendations of Improving Diagnosis in Health Care contribute to the growing momentum for change in this crucial area of health care quality and safety.




Quantitative Magnetic Resonance Imaging


Book Description

Quantitative Magnetic Resonance Imaging is a 'go-to' reference for methods and applications of quantitative magnetic resonance imaging, with specific sections on Relaxometry, Perfusion, and Diffusion. Each section will start with an explanation of the basic techniques for mapping the tissue property in question, including a description of the challenges that arise when using these basic approaches. For properties which can be measured in multiple ways, each of these basic methods will be described in separate chapters. Following the basics, a chapter in each section presents more advanced and recently proposed techniques for quantitative tissue property mapping, with a concluding chapter on clinical applications. The reader will learn: - The basic physics behind tissue property mapping - How to implement basic pulse sequences for the quantitative measurement of tissue properties - The strengths and limitations to the basic and more rapid methods for mapping the magnetic relaxation properties T1, T2, and T2* - The pros and cons for different approaches to mapping perfusion - The methods of Diffusion-weighted imaging and how this approach can be used to generate diffusion tensor - maps and more complex representations of diffusion - How flow, magneto-electric tissue property, fat fraction, exchange, elastography, and temperature mapping are performed - How fast imaging approaches including parallel imaging, compressed sensing, and Magnetic Resonance - Fingerprinting can be used to accelerate or improve tissue property mapping schemes - How tissue property mapping is used clinically in different organs - Structured to cater for MRI researchers and graduate students with a wide variety of backgrounds - Explains basic methods for quantitatively measuring tissue properties with MRI - including T1, T2, perfusion, diffusion, fat and iron fraction, elastography, flow, susceptibility - enabling the implementation of pulse sequences to perform measurements - Shows the limitations of the techniques and explains the challenges to the clinical adoption of these traditional methods, presenting the latest research in rapid quantitative imaging which has the possibility to tackle these challenges - Each section contains a chapter explaining the basics of novel ideas for quantitative mapping, such as compressed sensing and Magnetic Resonance Fingerprinting-based approaches




Evaluation of Biomarkers and Surrogate Endpoints in Chronic Disease


Book Description

Many people naturally assume that the claims made for foods and nutritional supplements have the same degree of scientific grounding as those for medication, but that is not always the case. The IOM recommends that the FDA adopt a consistent scientific framework for biomarker evaluation in order to achieve a rigorous and transparent process.




Mammography and Beyond


Book Description

Each year more than 180,000 new cases of breast cancer are diagnosed in women in the U.S. If cancer is detected when small and local, treatment options are less dangerous, intrusive, and costly-and more likely to lead to a cure. Yet those simple facts belie the complexity of developing and disseminating acceptable techniques for breast cancer diagnosis. Even the most exciting new technologies remain clouded with uncertainty. Mammography and Beyond provides a comprehensive and up-to-date perspective on the state of breast cancer screening and diagnosis and recommends steps for developing the most reliable breast cancer detection methods possible. This book reviews the dramatic expansion of breast cancer awareness and screening, examining the capabilities and limitations of current and emerging technologies for breast cancer detection and their effectiveness at actually reducing deaths. The committee discusses issues including national policy toward breast cancer detection, roles of public and private agencies, problems in determining the success of a technique, availability of detection methods to specific populations of women, women's experience during the detection process, cost-benefit analyses, and more. Examining current practices and specifying research and other needs, Mammography and Beyond will be an indispensable resource to policy makers, public health officials, medical practitioners, researchers, women's health advocates, and concerned women and their families.




PET/MRI


Book Description

In compiling this textbook on the exciting novel imaging modality of PET/MRI, the editors have brought together a truly international group of experts in the field. The book is divided into two parts. The first part covers methodology and equipment and includes chapters on basic molecular medicine, contrast agents, MR attenuation and validation, and quantitative MRI and PET motion correction. The second part of the book focuses on clinical applications in oncology, cardiology, and neurology. Imaging of major neoplasms is covered in a series of individual chapters. Further chapters address functional and metabolic cardiovascular examinations and major central nervous system applications such as brain tumors and dementias. This book will be of interest to all radiologists and nuclear medicine physicians who wish to learn more about the latest developments in this important emerging imaging modality and its applications.