The American Society of Functional Neuroradiology (ASFNR) became a reality at the 42nd annual meeting of the ASNR at Seattle, in June 2004. The mission of the ASFNR is primarily to facilitate the translation of functional neuroradiology into clinical neuroradiologic practice. The precise definition of the subspecialty, however, remains in the eye of the beholder. Although some will consider functional neuroradiology to be the clinical application of blood oxygenation level dependent functional MR imaging (fMRI), we have seldom witnessed single new imaging techniques that have replaced or revolutionized existing imaging or clinical strategies. Typically, new techniques enhance clinical neuroimaging capabilities incrementally as they are integrated into existing practice. From that perspective, basing a subspecialty on a single technique would appear short sighted. One may take a broader view, suggesting that a functional neuroradiologist is one who studies and implements functional MR imaging techniques of any type, including fMRI, magnetoencephalography (MEG), diffusion-tensor imaging (DTI), and perhaps even perfusion, blood volume, and molecular MR imaging and MR spectroscopy. Others, however, may take a more expansive position and suggest that it is the study of both MR and non-MR physiologic brain imaging, including CT positron emission tomography and other non-MR imaging techniques of the future.
At the same time, it is neither the mission of the society nor is it practical to absorb all that exists in the clinical neurosciences or even in neuroimaging research. This can lead us down the same impractical pathways that have hindered the implementation of basic neuroimaging developments into clinical practice in the past. The clinical translation of even 10% of the published functional neuroimaging research would be an optimistic goal. A targeted translation of new techniques is the most judicious approach to define functional neuroradiology. This will require the devising of practical and cost-effective applications that impact treatment algorithms. Our proficiency in this arena has been based on three primary skills: 1) understanding of the technical and physical principals underlying our specialty, 2) a broad understanding of pathophysiologic mechanisms, and 3) an ability to integrate imaging data from multiple techniques and modalities and to communicate vital information to our clinical colleagues. All the while, we should remain capable of rapidly upgrading our integrative strategies as new developments arise.
It seems most reasonable then to define functional neuroradiology by its role in clinical imaging scenarios and the role of a functional neuroradiologist by the clinical impact he or she can bring to bear on a clinical problem. Such an approach is more intuitive and is preferable to technique or technique-specific definitions. Concomitantly, isolating image-based functional information from disease-induced alterations of brain physiology or neurotransmission fails to capitalize on our clinical understanding of disease processes. It is the integration of multiple functional techniques that will empower functional neuroradiology in the clinic. A functional neuroradiologist should be one who is accomplished in both anatomic and physiologic brain imaging, irrespective of technique or sequence design. Functional neuroradiology should incorporate a thorough understanding of the functional and physiologic basis of brain abnormalities with our existing diagnostic arsenals and will require an understanding of functional brain anatomy, the effects of lesions on cortical and white matter function, and the physiologic and biologic determinants of brain diseases. Only through this perspective can new imaging technologies be optimized and incorporated into the clinical setting. Having said this, it is fMRI that has led us into a new era of clinical neuroimaging that emphasizes the value of image-based physiologic information in addition to our standard anatomic and morphologic approach.
So, the question remains: how will the ASFNR achieve its goals? First, the society will seek to develop and support standards for the practice of functional neuroradiology. Physiologic imaging techniques often require the acquisition of low signal-to-noise data as well as mapping strategies to reveal anatomic relationships. Consequently, the acquisition parameters and postprocessing strategies are more complex, cumbersome, and vulnerable to critical errors. Standardization is the first step in gathering the information needed to optimize both acquisition and postprocessing strategies of a variety of new techniques. In addition, one of the key constraining factors in acquiring functional information by using fMRI is paradigm design. Fostering the standardization of practical and effective functional paradigms is essential to optimize the yield of useful functional information. We must also draw on our understanding of basic physical and physiologic principals to define the limitations of functional and physiologic imaging techniques. Issues such as lesion-induced neurovascular uncoupling in fMRI and the inability to fully trace functionally distinct intersecting tracts by using DTI must be thoroughly addressed and appreciated by those in the field. Perfect functional or physiologic parameters are probably unattainable; nevertheless, quantifying the limitations of a technique in a given clinical imaging scenario is vital to the integrative approach of functional neuroradiology.
A second significant role of the ASFNR will be to develop and support standards for the training of functional neuroradiologists. This will include standardized training in the physical and physiologic principals underlying new imaging techniques and may be achieved through courses at meetings, written material, and web-based training. Whereas existing clinical training in neuroradiology emphasizes neuropathology, we need to increase emphasis on functional neuroanatomy and the clinical neurosciences. An understanding functional neuroanatomy is not a great leap for most neuroradiologists, who are already proficient in the multiplanar analysis of gross anatomy, yet it is the basis for translating functional imaging into clinical practice. As one begins to delve into the nuances of functional anatomy, it quickly becomes apparent that functional anatomy cannot be viewed in isolation from neurotransmission or neurophysiology. An understanding of how the brain works in total enables neuroradiologists to expand their capabilities beyond physiologic imaging. Such an understanding can be drawn upon in daily practice, is within easy reach of neuroradiologists and should be emphasized by ASFNR educational endeavors. A basic knowledge of functional neuroradiology, neurotransmission, and neurophysiology provides the basis for understanding the clinical neurosciences and the treatment strategies devised to counter neurologic diseases. Understanding the effects of treatment strategies will likewise shape the role of functional and physiologic imaging in clinical practice. Thus, a positive translational feedback will result from such educational pursuits.
A third important goal of the ASFNR will be to foster research in functional neuroradiology and, in the process, promote a close fellowship and exchange of ideas between neuroradiologists and colleagues in related fields, including basic science researchers. To translate new techniques into clinical practice, two key areas of research should be emphasized: 1) technological validation and 2) clinical validation. Technological validation is something neuroradiologists are quite comfortable with, although the challenge is made more significant by unique acquisition and postprocessing vulnerabilities of functional and physiologic imaging. Clinical validation, on the other hand, is relatively foreign to our field. There currently exists little level I or II evidence supporting the use of most neuroimaging techniques used in today’s clinical practice, despite the obvious benefits of such techniques to patients. In this new era, third-party payers and imaging vendors will require a higher level of clinical evidence to embrace new neuroimaging techniques as viable clinical tools. To this end, the ASFNR should facilitate multicenter, prospective studies by using appropriate reference standards. A fourth major goal of the ASFNR will be to establish channels for publication of scientific reports in the field of functional neuroradiology. The society will also seek to enhance its academic visibility by providing meetings for the reading and discussion of papers and the dissemination of knowledge regarding functional neuroradiology as part of the annual meeting of the ASNR or independent of that meeting. Through these and other efforts, the ASFNR hopes to promote the understanding of functional neuroradiology among patients, other health professionals, and public agencies and to enhance communications with these groups.
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