For seasoned neurologic veterans like me who trained in an era when neuroimaging meant the seemingly barbaric practice of pneumoencephalography, direct carotid puncture, and the vague hot spots of radionuclide imaging, today’s modern neuroimaging seems nothing short of miraculous. True, in the early 1970s we marveled at the first computerized tomographic images, grainy representations that we can only laugh at today. Even the prototype magnetic resonance (MR) images of the early 1980s seem strangely primitive to the modern neurologist. Along with the introduction of a host of pharmacologic agents, the dramatic advance of neuroimaging in the past 3 decades has truly revolutionized the practice of neurology. Thus, although no issue of CONTINUUM neglects an appropriate discussion of neuroimaging, it is timely and fitting that we devote this issue to the subject of neuroimaging.
Many, as Dr Jack Greenberg writes in his foreword, lament our relinquishing “ownership” of this field to radiologists. Nonetheless, the modern neurologist must have a keen grasp of the panoply of imaging modalities now available to investigate a clinical problem as well as the capability of interpreting those images in the specific clinical context.
No longer are we restricted to the representation of anatomic structures, exquisite though those images may be. Now, added to our repertoire is the ability to acquire information about blood flow, tissue metabolism, and brain function through a variety of recently developed and sometimes rapidly improving techniques. The creativity of physicists, engineers, and clinical scientists, combined with the seemingly endless opportunities afforded by an increasingly digital world, has resulted in a steady stream of new and better imaging methods that complement and augment our clinical skills.
We must never forget, however, that an image is not a diagnosis. And, in fact, today it is often nothing more than a graphic translation of digital bytes. It is the neurologist who must combine that valuable information with his or her knowledge of a particular patient in order to arrive at a proper diagnosis.
Dr Laszlo Mechtler has assembled an outstanding faculty to approach the subject of neuroimaging and has systematically organized the issue by nosologic categories. The first three chapters are devoted to the critical area of vascular diseases, for which imaging plays not only an important diagnostic role, but often is intimately involved in the therapeutic approach. Dr David Liebeskind begins with a discussion of ischemic stroke, including extensive discussion of the appropriate imaging plan in the emergency department setting. Next, Dr Camilo Gomez reviews the choices available for the patient with intracranial hemorrhage, emphasizing the evolving and expanding role of MRI. Completing this trilogy, Dr Ronald Alberico reviews the subject of intracranial vascular malformations and aneurysms, emphasizing the pros and cons of various options for imaging the cranial (and spinal) circulation.
Moving away from vascular disease, Drs Komal Shah and Victor Levin address neuro-oncology, analyzing the use of modern imaging techniques in helping to distinguish between neoplastic and non-neoplastic diagnoses, as well as helping to understand the sometimes befuddling clinical picture in a patient who has already undergone treatment. Next, Dr Mechtler himself addresses the subject of headache. In addition to providing an extensive discussion of the role of neuroimaging in the differential diagnosis of headache, Dr Mechtler also thoughtfully reviews the common situation of incidental findings on MRI done because a patient has reported headache. The field of demyelinating disease has experienced a tremendous impact from MRI. Indeed, diagnosis of multiple sclerosis (MS) has been revolutionized by incorporation of MRI information into the original and subsequently revised McDonald criteria. Dr Istvan Pirko examines the important information we’ve learned about MS through MRI, including recent knowledge of the extensive gray matter involvement as well as the recent advances in our understanding of neuromyelitis optica.
In his discussion of the neuroimaging of dementia, Dr Joseph Masdeu highlights a number of advances that facilitate discrimination among the variety of degenerative dementias, including a discussion of the new amyloid-identifying agent Pittsburgh Compound B. He also emphasizes the role neuroimaging can play in the evaluation of new therapies for dementia. Perhaps no area of neuroimaging has utilized metabolic imaging more than movement disorders. Dr Michael Hutchinson reviews the use of PET imaging, as well as more conventional modalities, for a variety of both hypokinetic and hyperkinetic movement disorders. Dr Rubin Kuzniecky’s chapter on the neuroimaging of epilepsy includes descriptions of the findings in malformations of cortical development that lead to seizures and discussion of the role of neuroimaging in selection of patients for epileptic surgery, among other topics. Finally, in the last formal chapter, Drs Eric Potts and Patrick Capone deviate from the pattern of chapters devoted to single disease categories to look at neuroimaging on an organ basis—namely its application to a variety of diseases of the spine. Spinal imaging has, perhaps, lagged behind brain imaging in quality of resolution, but advances are continuing at a rapid pace.
As usual, we provide a discussion of an ethical issue related to the subject at hand. Dr Eran Klein analyzes a case that invokes a number of frequently encountered ethical principles, but specifically relates it to decisions about neuroimaging. Dr Bret Lindsay offers a fascinating patient management problem that will help you test your understanding of many of the points discussed throughout this issue. Finally, I urge you to both test and bolster your comprehension of neuroimaging by tackling the multiple-choice questions devised for this issue by Drs Julie Hammack and Steven Lewis. You will find that the clinical vignettes contained therein have great applicability to your neurologic practice.
This issue of CONTINUUM provides yet another special bonus. Dr Mechtler and colleagues have provided a CD-ROM that contains a wealth of case material featuring numerous neuroimages that may reinforce the old adage that one picture is worth a thousand words. This material may also be viewed online by subscribers, along with the rest of the issue, on CONTINUUM’s website at www.aan.com/go/elibrary/continuum. But, remember, not even a thousand images will replace one well-informed, conscientious, compassionate neurologist!
—Aaron E. Miller, MD