Neuroradiology back to the future: brain imaging

History of Neurointervention

In this review article, we aim to provide a summary of the discoveries and developments that were instrumental in the evolution of the Neurointerventional field. We begin with developments in the advent of Diagnostic Cerebral Angiography and progress to cerebral aneurysm treatment, embolization in AVMs and ischemic stroke treatment. In the process we discuss many persons who were key in the development and maturation of the field. A pivotal aspect to rapid growth in the field has been the multidisciplinary involvement of the different neuroscience specialties and therefore we close out our discussion with excitement about ongoing and future developments in the field with a focus on treatments in the non-cerebrovascular disease realm.

Future of Neurology & Technology: Neuroimaging Made Accessible Using Low-Field, Portable MRI

In the 20th century, the advent of neuroimaging dramatically altered the field of neurologic care. However, despite iterative advances since the invention of CT and MRI, little progress has been made to bring MR neuroimaging to the point of care. Recently, the emergence of a low-field (<1 T) portable MRI (pMRI) is setting the stage to revolutionize the landscape of accessible neuroimaging. Users can transport the pMRI into a variety of locations, using a standard 110-220 V wall outlet. In this article, we discuss current applications for pMRI, including in the acute and critical care settings, the barriers to broad implementation, and future opportunities.

Volumetric MRI Findings in Mild Traumatic Brain Injury (mTBI) and Neuropsychological Outcome

Region of interest (ROI) volumetric assessment has become a standard technique in quantitative neuroimaging. ROI volume is thought to represent a coarse proxy for making inferences about the structural integrity of a brain region when compared to normative values representative of a healthy sample, adjusted for age and various demographic factors. This review focuses on structural volumetric analyses that have been performed in the study of neuropathological effects from mild traumatic brain injury (mTBI) in relation to neuropsychological outcome. From a ROI perspective, the probable candidate structures that are most likely affected in mTBI represent the target regions covered in this review. These include the corpus callosum, cingulate, thalamus, pituitary-hypothalamic area, basal ganglia, amygdala, and hippocampus and associated structures including the fornix and mammillary bodies, as well as whole brain and cerebral cortex along with the cerebellum. Ventricular volumetrics are also reviewed as an indirect assessment of parenchymal change in response to injury. This review demonstrates the potential role and limitations of examining structural changes in the ROIs mentioned above in relation to neuropsychological outcome. There is also discussion and review of the role that post-traumatic stress disorder (PTSD) may play in structural outcome in mTBI. As emphasized in the conclusions, structural volumetric findings in mTBI are likely just a single facet of what should be a multimodality approach to image analysis in mTBI, with an emphasis on how the injury damages or disrupts neural network integrity. The review provides an historical context to quantitative neuroimaging in neuropsychology along with commentary about future directions for volumetric neuroimaging research in mTBI.

Arachnoid Membranes: Crawling Back into Radiologic Consciousness

The arachnoid membranes are projections of connective tissue in the subarachnoid space that connect the arachnoid mater to the pia mater. These are underappreciated and largely unrecognized by most neuroradiologists despite being found to be increasingly important in the pathogenesis, imaging, and treatment of communicating hydrocephalus. This review aims to provide neuroradiologists with an overview of the history, embryology, histology, anatomy, and normal imaging appearance of these membranes, as well as some examples of their clinical importance.

'Somewhere between science and superstition': Religious outrage, horrific science, and The Exorcist (1973)

Science and religion pervade the 1973 horror The Exorcist (1973), and the film exists, as the movie's tagline suggests, 'somewhere between science and superstition'. Archival materials show the depth of research conducted by writer/director William Friedkin in his commitment to presenting and exploring emerging scientific procedures and accurate Catholic ritual. Where clinical and barbaric science fails, faith and ritual save the possessed child Reagan MacNeil (Linda Blair) from her demons. The Exorcist created media frenzy in 1973, with increased reports in the popular press of demon possessions, audience members convulsing and vomiting at screenings, and apparent religious and specifically Catholic moral outrage. However, the official Catholic response to The Exorcist was not as reactionary as the press claimed. The United States Conference of Catholic Bishops' Office of Film and Broadcasting (USCCB-OFB) officially and publicly condemned the film as being unsuitable for a wide audience, but reviews produced for the office by priests and lay Catholics and correspondence between the Vatican and the USCCB-OFB show that the church at least notionally interpreted it as a positive response to the power of faith. Warner Bros. Studios, however, were keen to promote stories of religious outrage to boost sales and news coverage - a marketing strategy that actively contradicted Friedkin's respectful and collaborative approach to working with both religious communities and medical professionals. Reports of Catholic outrage were a means of promoting The Exorcist rather than an accurate reflection of the Catholic Church's nuanced response to the film and its scientific and religious content.

Radioresistance in Glioblastoma and the Development of Radiosensitizers

Ionizing radiation is a common and effective therapeutic option for the treatment of glioblastoma (GBM). Unfortunately, some GBMs are relatively radioresistant and patients have worse outcomes after radiation treatment. The mechanisms underlying intrinsic radioresistance in GBM has been rigorously investigated over the past several years, but the complex interaction of the cellular molecules and signaling pathways involved in radioresistance remains incompletely defined. A clinically effective radiosensitizer that overcomes radioresistance has yet to be identified. In this review, we discuss the current status of radiation treatment in GBM, including advances in imaging techniques that have facilitated more accurate diagnosis, and the identified mechanisms of GBM radioresistance. In addition, we provide a summary of the candidate GBM radiosensitizers being investigated, including an update of subjects enrolled in clinical trials. Overall, this review highlights the importance of understanding the mechanisms of GBM radioresistance to facilitate the development of effective radiosensitizers.

The Lateral Ventricles: A Detailed Review of Anatomy, Development, and Anatomic Variations

The cerebral ventricles have been studied since the fourth century BC and were originally thought to harbor the soul and higher executive functions. During the infancy of neuroradiology, alterations to the ventricular shape and position on pneumoencephalography and ventriculography were signs of mass effect or volume loss. However, in the current era of high-resolution cross-sectional imaging, variation in ventricular anatomy is more easily detectable and its clinical significance is still being investigated. Interpreting radiologists must be aware of anatomic variations of the ventricular system to prevent mistaking normal variants for pathology. We will review of the anatomy and development of the lateral ventricles and discuss several ventricular variations.

Pneumoencephalography in the workup of neuropsychiatric illnesses: a historical perspective

Throughout history, neurosurgical procedures have been fundamental in advancing neuroscience; however, this has not always been without deleterious side effects or harmful consequences. While critical to the progression of clinical neuroscience during the early 20th century, yet, at the same time, poorly tolerated by patients, pneumoencephalography is one such procedure that exemplifies this juxtaposition. Presented herein are historical perspectives and reflections on the role of the pneumoencephalography in the diagnosis and treatment of neuropsychiatric illnesses.

Historical Perspective of Imaging Contrast Agents

Contrast agents were introduced early in the history of medical imaging. Iodine-based intravascular agents became the radiographic compounds of choice and refinements of their chemical structures led to the highly tolerated low-osmolarity agents in use today. Gadolinium became the most popular compound for MR imaging; however, recognition of nephrogenic systemic fibrosis and in vivo dechelation intensified research on their safety profile. Ultrasonography contrast media evolved from manual injections of air through agitated saline solutions to microbubbles with different gases. Research has concentrated on bubble stabilization and development of small but sufficiently echogenic particles.

The 100 most-cited articles in neuroimaging: A bibliometric analysis

The purpose of our study was to identify and characterize the 100 most-cited articles in neuroimaging. Based on the database of Journal Citation Reports, we selected 669 journals that were considered as potential outlets for neuroimaging articles. The Web of Science search tools were used to identify the 100 most-cited articles relevant to neuroimaging within the selected journals. The following information was recorded for each article: publication year, journal, category and impact factor of journal, number of citations, number of annual citations, authorship, department, institution, country, article type, imaging technique used, and topic. The 100 most-cited articles in neuroimaging were published between 1980 and 2012, with 1995-2004 producing 69 articles. Citations ranged from 4384 to 673 and annual citations ranged from 313.1 to 24.9. The majority of articles were published in radiology/imaging journals (n=75), originated in the United States (n=58), were original articles (n=63), used MRI as imaging modality (n=85), and dealt with imaging technique (n=45). The Oxford Centre for Functional Magnetic Resonance Imaging of the Brain at John Radcliffe Hospital (n=10) was the leading institutions and Karl J. Friston (n=11) was the most prolific author. Our study presents a detailed list and an analysis of the 100 most-cited articles in the field of neuroimaging, which provides an insight into historical developments and allows for recognition of the important advances in this field.

The History of the Kernohan Notch Revisited

The history of false localizing signs is intimately linked to the birth of modern neurology and the unraveling of the mysteries of localization through neurological examination at the end of the 19th century. This phenomenon has attracted much attention but has not been properly explained, even in the authoritative handbooks such as that by Oppenheim. A scholarly article written by Kernohan and Woltman in 1929 is considered to be a landmark in the history of neurology and neurosurgery in that it provided the definitive answer and an exhaustive explanation of the problem, leading some neurologists to conclude that the localization of a lesion is not an exact science. However, despite the professional manner in which Kernohan and Woltman presented their case, they did not offer an explanation. In another article published 2 years earlier in 1927, Groeneveld and Schaltenbrand provided a pathophysiological and anatomical explanation of the phenomenon, described in detail. Although Kernohan and Woltman themselves refer to that previous article, it was this article that provided the first logical, clear, indubitable explanation of the phenomenon that we today refer to as the Kernohan notch.

Dual-Energy CT: What the Neuroradiologist Should Know

Because of the different attenuations of tissues at different energy levels, dual-energy CT offers tissue differentiation and characterization, reduction of artifacts, and remodeling of contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR), hereby creating new opportunities and insights in CT imaging. The applications for dual-energy imaging in neuroradiology are various and still expanding. Automated bone removal is used in CT angiography and CT venography of the intracranial vessels. Monoenergetic reconstructions can be used in patients with or without metal implants in the brain and spine to reduce artifacts, improve CNR and SNR, or to improve iodine conspicuity. Differentiation of iodine and hemorrhage is used in high-density lesions, after intra-arterial recanalization in stroke patients or after administration of contrast media. Detection of underlying (vascular and non-vascular) pathology and spot sign can be used in patients presenting with (acute) intracranial hemorrhage.

The role of imaging in the development of neurosurgery

The development of modern neurosurgery was, and remains, intimately associated with developments in radiology. Neuroimaging advances have been instrumental in improving patient care and reducing both morbidity and mortality for neurosurgical patients. The purpose of this narrative review is to provide the contemporary neurosurgeon with an overview of the history of the development of radiology as applied to neurosurgery. The focus is on cranial imaging but the spine is also discussed. This article demonstrates the remarkable advancements that have shaped our modern surgical specialty. Today, almost 120 years after the discovery of the X-ray, the neurosurgeon has a wide array of neuroimaging tools at their disposal, that have led to better knowledge to inform diagnosis and management, selection of appropriate patients and surgical targets, as well as optimal surgical approaches. Modern neurosurgery is based on the appropriate use of these investigations. The pace of neuroimaging and neurosurgical advances continues and the future promises to be as, if not more, exciting as the past and present described in this paper.

Advanced imaging modalities in the detection of cerebral vasospasm

The pathophysiology of cerebral vasospasm following aneurysmal subarachnoid hemorrhage (SAH) is complex and is not entirely understood. Mechanistic insights have been gained through advances in the capabilities of diagnostic imaging. Core techniques have focused on the assessment of vessel caliber, tissue metabolism, and/or regional perfusion parameters. Advances in imaging have provided clinicians with a multifaceted approach to assist in the detection of cerebral vasospasm and the diagnosis of delayed ischemic neurologic deficits (DIND). However, a single test or algorithm with broad efficacy remains elusive. This paper examines both anatomical and physiological imaging modalities applicable to post-SAH vasospasm and offers a historical background. We consider cerebral blood flow velocities measured by Transcranial Doppler Ultrasonography (TCD). Structural imaging techniques, including catheter-based Digital Subtraction Angiography (DSA), CT Angiography (CTA), and MR Angiography (MRA), are reviewed. We examine physiologic assessment by PET, HMPAO SPECT, ¹³³Xe Clearance, Xenon-Enhanced CT (Xe/CT), Perfusion CT (PCT), and Diffusion-Weighted/MR Perfusion Imaging. Comparative advantages and limitations are discussed.

Neuroradiology back to the future: head and neck imaging

SUMMARY

Imaging of the head and neck was initially described within the first year after Roentgen's discovery of the x-ray and was used to localize foreign bodies in the head and neck area, including the orbital, laryngeal, and esophageal regions. Subsequently, x-rays were used to evaluate the air-filled paranasal sinuses, the pneumatized temporal bone, and the upper aerodigestive tract. Special views for evaluating these structures were developed by early investigators. As contrast agents were developed, a variety of invasive procedures were developed to assess the structures of the head and neck. CT and MR imaging were applied to the extracranial head and neck slightly later than the brain and spine; these modalities revolutionized head and neck radiology, finally allowing assessment of the deeper structures of this complex anatomic region.

Neuroradiology back to the future: spine imaging

Although radiography of the spine began shortly after Roentgen's discovery in 1895, there was little written in the medical literature about spine imaging until nearly 25 years later with the development of myelography, first by using air and then a variety of positive contrast agents. The history of spine imaging before CT and MR imaging is, in large part, a history of the development of contrast agents for intrathecal use. The advent of CT and, more important, MR imaging revolutionized spine imaging. The spinal cord and its surrounding structures could now be noninvasively visualized in great detail. In situations in which myelography is still necessary, advances in contrast agents have made the procedure less painful with fewer side effects. In this historical review, we will trace the evolution of spine imaging that has led to less invasive techniques for the evaluation of the spine and its contents and has resulted in more rapid, more specific diagnosis, therapy, and improved outcomes.