Description
The advent of clinical MR imaging (MRI) in the 1980s heralded a new era in the ability to image the brain in vivo. MRI allows the detailed depiction of brain anatomy and pathology with unprecedented spatial resolution and soft-tissue contrast. It is also relatively safe and completely non-invasive. Nevertheless, the sensitivity and specificity with which structural MRI alone can define the wide range of neurological disease is limited.
The last decade has also seen the development of physiological MR techniques, whereby information concerning tissue function as well as structure is obtained. These techniques include diffusion, perfusion, and MR spectroscopy, which provide information on tissue ultra-structure, blood flow, and biochemistry, respectively. Information of this type supplements and complements that from clinical or structural imaging investigations, often providing important surrogate markers of disease pathophysiology or therapeutic response.
These techniques, previously only available in a research environment, are now accessible on most MR systems and can readily be incorporated into clinical imaging examinations. To date, however, there has been a paucity of literature in a single volume to support those wishing to apply physiological imaging studies in a clinical context. The aim of this book is to address the appropriate clinical application and interpretation of diffusion, perfusion, and spectroscopy.
The first section of the book describes the physical principles underlying each technique, as well as the potential associated artifacts and pitfalls.The second section addresses applications in the different branches of clinical neuroscience. Chapters are grouped according to pathology, and are preceded by overviews that aim to place these methodologies in a broader clinical perspective. Illustrative case reports are included throughout the book.
We recognize that the term”functional MRI” (fMRI) has become synonymous with studies of localized brain activation, mostly using “blood oxygen leveldependent” (BOLD) contrast. This approach, which continues to contribute to the understanding of the relationship between brain structure and function, is well covered in other texts and is not addressed in this volume. Likewise, magnetization transfer imaging, and methods for post-processing structural data, for example volumetric analysis, or MRI relaxometry, are not included.While these techniques are the subject of much research effort, they are not widely available at the time of writing, and have yet to find a definitive clinical role.
The aim of this book is to create a reference work for those techniques that can be widely applied, not just at academic medical centers. Currently, diffusion, perfusion, and spectroscopy are the physiological techniques most likely to be used routinely. Our hope is that this book will provide a balanced reference work for physiological MRI in real clinical practice. The overall aim is to optimize the use of these techniques to increase the sensitivity and specificity of theMRimaging examination, and thereby improve the management of individual patients.