Advanced Approaches to Pediatric Neuroimaging

I am pleased to present you with this special issue for the Journal of Pediatric Neurology: Advanced Approaches to Pediatric Neuroimaging. In preparation for this issue, we reached out to pediatric imaging specialists from academic centers throughout North America, and asked them to offer personal insight into their respective areas of expertise. The following pages contain the dedication and creativity of a talented group of doctors, and for me, it has been a true privilege to have collaborated with them.

The primary challenge we encountered when compiling this issue was how to define “advanced imaging.” Pediatric neuroradiology is a rapidly expanding field that evolves with each new iteration of technology or ideological breakthrough. A common misconception regarding advanced neuroradiology techniques is that the newest and most complicated imaging option always provides the best information. In actuality, the “best study” choice is a determinate of appropriateness, ultimately influenced by multiple factors, such as patient age, developmental/behavioral status, disease acuity, medical comorbidities, resource availability, and personal socioeconomic factors. In many circumstances, different scanning techniques will provide complementary information, and so a multimodality imaging approach is often required to obtain a truly comprehensive answer. This principle is highlighted in the article on the imaging evaluation of abusive head injury in children, by Guerin et al, for example.

For many others, “advanced imaging” is synonymous with basic science investigations, which are often performed in controlled testing environments or developed with proprietary research workflows that may prove difficult for most readers to implement in their own clinics. Although few things are more vital to the future of medical advancement than basic science research, we opted to focus this issue on presenting practical overviews that would help imaging providers develop and optimize their own clinical setting. With this in mind, we have enclosed several articles that help to demystify and translate the worlds of magnetic resonance (MR) spectroscopy, functional MRI, and other sophisticated imaging techniques into the everyday clinical practice of pediatric neuroradiologists.

So, if there was a subtitle for this issue, I would venture that it might be “Try This at Home!” although with a disclaimer of “results may vary” being issued immediately thereafter. At its core, neuroradiology—like most medical practices—contains equal parts of art and science or, rather, it is an art form arising from the extreme distillation of scientific principles (in this case being the noninvasive generation of medical images). Therefore, the outcomes of advanced techniques are susceptible to variability, according to the system specifications or personnel at a particular institution, and what works for one practice might work differently for another. In other words, the skillful application of a low-cost technique can outshine the brutish execution of a high-cost technique. As such, we were fortunate to be able to include expert reviews on the principles and techniques of cranial ultrasound and dual-energy computed tomography (CT) in pediatric imaging.

For advanced imaging to occur, three things must be present: (1) a priori knowledge of the mechanisms underlying the process that is being targeted for evaluation, (2) infrastructure for obtaining and interpreting the information in a manner that is safe and practical, (3) and a supportive clinical network to receive and apply the information. For example, violation of the first requirement leads to “blind scanning” practices, in which examinations are either performed without reasonable pretest probability, as a stalling tactic, or with suboptimal protocol designs, which contributes to poor informational yield that is often outweighed by the risk or “dose” of the procedure itself. This is a problem that can be exacerbated by emerging trends in industrialized medicine, such as the overemphasis of patient turnaround times and electronic ordering practices that subvert the lines of direct clinician–radiologist communication. More than ever, it is important for radiologists to understand the strengths and limits of each modality for a given indication, as well as appreciate the pathophysiologic and clinical concepts underlying a suspected disease entity. For example, knowledge regarding the histopathologic basis and subsequent imaging features of focal cortical dysplasias (as detailed in this issue by Gadde and Schwartz) helps us to understand and create other emerging concepts in epilepsy imaging, such as hybrid PET-MRI.

Before embarking into advanced images practices, it is also prudent to familiarize ourselves with the potential adverse effects that may accompany each planned intervention. Most clinical providers who routinely order imaging procedures are already generally aware of the concept of radiation dose, particularly when it is presented in the form of a child's exposure to radiographs, CT imaging, and nuclear medicine. Concerns from providers and parents surrounding the long-term effects of ionizing radiation in children have led to a palpable behavioral response throughout the medical community, which has manifested as a growing resistance to the utilization of photon-based modalities in favor of nonionizing techniques, such as ultrasound and MRI. On the radiology side, coordinated efforts to reduce unnecessary radiation exposure in children have also flourished, including the “Image Gently” and ALARA (as low as reasonably allowable) campaigns.

However, we must also be mindful of the “hidden dose” that accompanies even nonirradiating modalities and learn to extend the ALARA principle to all radiologic interventions. Aside from theoretical concerns surrounding SAR and gadolinium exposure, even basic MRI examinations in children typically require lengthy room setup and scanning times, which can introduce new and unexpected risks to the pediatric patient. In critically ill patients, for example, preparation for an MRI might necessitate the changing out of lines, monitoring equipment, and ventilation hardware—all potential sources for introducing medical error—not to mention the time spent off the unit away from the primary care team, the potential delays in making critical diagnoses, and limiting scanner access to other ill patients through increased traffic. Furthermore, many young or developmentally challenged patients will often require some measure sedation or general anesthesia for the examination to be diagnostic, and this added intervention carries its own independent risks. Since sedation plays such an integral role for many advanced imaging practices, it is necessary for pediatric imagers and ordering providers to have a conceptual grasp of the types, benefits, and risks of different anesthesia agents that may be utilized when a prolonged exam is planned—this information is detailed in the review by Fawole and Webber.

Another major challenge is that advanced imaging practices can be time consuming and labor intensive, sometimes requiring extensive postprocessing work “offline” or the purchase of separate software packages—this can translate into increased cost to the system and the patient. In some cases, the added burden on the clinical workflow created by advanced imaging may not be financially supported—perhaps due to a combination of reduced reimbursement rates and limited research funds—thereby pushing some imaging centers to limit or abandon such work altogether out of deference to daily logistics. On the other hand, insouciant advanced imaging practices can be a driving factor for out-of-control medical costs, potentially compounding a family's initial health concerns with a form of financial terror despite comparatively little return on their investment. Ultimately, the development and maintenance of advanced imaging protocols only make sense when they are coupled with a supportive clinical environment that can optimally apply the information that is sought after in the first place. In the modern world, there can be a tendency to try to “outrun” fundamental healthcare problems solely through the pursuit of more advanced technology, whether it is the next wonder drug, the latest surgical tool, or a new type of scanner. However, the ultimate goal of actual good health is only achieved when children first have their basic medical rights provided for, including primary healthcare, nutrition, shelter, safety, and education. Although the solutions to many of these problems are well beyond the scope of everyday radiology, we should still keep in mind that before meaningful advanced medical practices can occur, we must first ensure that a child's access to basic healthcare is preserved and protected—it is the bedrock upon which everything else is built.

While keeping all of this in mind, it is my hope that you will find these articles stimulating, and that you will be inspired to try new things as well.