Quantifying Morphology and Physiology of the Human Body Using MRI PDF

Preface

Magnetic resonance imaging (MRI) remains a truly unique medical imaging system because of the breadth of information that one can acquire from it. The macromolecular makeup of tissues can be studied indirectly by way of relaxation mechanisms (T₁, T_1ρ, T₂, T₂^*) or magnetization-transfer phenomenon. Diffusion imaging detects microstructural changes. Flow and perfusion imaging, which are powerful modalities, aid in the evaluation of cardiovascular diseases. However, for the most part, the information is analyzed qualitatively, using a particular mechanism to modulate the image voxel intensities. For instance, the relaxation mechanisms serve as weighting factors to generate contrast in images; they are rarely quantified. Similarly, the amount of molecular diffusion is utilized as a contrast mechanism in diffusion-weighted imaging, and the quantitative measurements were not used in most cases. While visual assessments by physicians have been effective, quantitative measurements from tissues could complement the existing practices in achieving more accurate diagnoses or determining disease stages. It is interesting that a metric similar to the Hounsfield unit has not been established for clinical MRI technology. It could prove highly useful sometimes in making a challenging decision.

Researchers in the field recognize the growing need for quantitative MRI applications. Consequently, recent international meetings have placed greater emphasis on this topic. For instance, several International Society of Magnetic Resonance in Medicine (ISMRM) sessions and symposia focused on this. Also, the 2012 Radiological Society of North America (RSNA) meeting features about 17 sessions with "Quantitative Imaging" in their titles. MRI system manufacturers also have noticed the growing importance of quantitative MRI. They have started to include new data acquisition techniques with easy-to-use software interfaces for processing and analysis. This considerable growing interest in the field has driven the need for a comprehensive body of knowledge for the scientific community. In addition, clinicians and researchers who would like to use these novel techniques in their practices need a good reference manual. Therefore, the idea for this book began to flourish shortly after I gave a talk on Quantitative Brain Imaging at the 51st annual meeting of the American Association of Physicists in Medicine (AAPM) in 2009.

In order to deliver the latest science on a broad range of topics, internationally renowned experts in respective fields participated in this book. Each chapter provides comprehensive information about data acquisition, processing, and analysis techniques. Then, various clinical applications are presented. Some of the techniques described in the book are uniquely tailored for the brain or other organs; therefore, the book is divided into two main parts: (1) brain and (2) body. This classification makes it easier for the readers to focus on techniques that are more relevant to their interests. However, some of the techniques, such as diffusion-weighted imaging and diffusion tensor imaging, have widespread applications. Thus, the readers can see their applications in brain imaging, cancer imaging, or musculoskeletal imaging. The last three chapters of this book are dedicated to newly emerging quantitative techniques that explore tissue properties other than the presence of protons (or other MRI-observable nuclei) and their interactions with the environment. These new techniques provide unique information about electromagnetic and mechanical properties of tissues. They introduce new frontiers of study into various disease mechanisms.

Because of the growing importance of quantitative MRI, we believe that this book is an indispensable reference for basic scientists and clinicians who would like to explore in vivo MRI techniques to quantify changes in the morphology and physiology of tissues caused by various disease mechanisms.

First of all, I express my deep gratitude to all the authors for their outstanding contributions. After I drafted the outline of each chapter, I contacted the world experts in their respective fields. They kindly accepted my invitation and put in an enormous amount of work to explain the details of their cutting-edge work for the readers. Finally, I thank John Navas, PhD, for giving me the encouragement and guidance to initiate this book project; Amber Donley and Rachel Holt for their help and guidance in editing the manuscript. I am also very grateful to Kim Pechman, PhD, for her help in proofreading the chapters. Her dedicated work on the manuscripts ensured that the text is free of major errors.

Color Figures Available for Download

Many figures were produced in color, but there are too many to fit into the book. There are 32 color figures that appear as grayscale in the text, but are clearly indicated as available for download. The reader may obtain these images from the CRC Press Web site at http://www.crcpress.com/product/isbn/9781439852651. Readers are urged to check this Web site periodically, as these figures will be updated as science develops.