Commentary Quantitative MR For Epilepsy: A Clinical and Research Tool?

An explosion in the use of quantitative magnetic resonance (MR) for the investigation of epilepsy has taken place during the last 5 years. Assessment of structural brain changes with MRbased volumetrics ( 1-7) or T2 relaxometry (8-1 0) is an ideal model for integrating research with clinical decision making. These techniques have furthered our understanding not only of brain dysfunction (in this case hippocampal sclerosis) but also of brain function (in this case the hippocampus). Quantitative techniques have found a place in the preoperative assessment of hippocampal sclerosis because of their increased sensitivity over visual inspection (11). Most quantitative MR investigations for epilepsy have concentrated on measuring brain volumes rather than relaxation times. Using this method, the degree of hippocampal atrophy can be quantified and compared with other variables for both research and clinical purposes. Hippocampal atrophy already has been shown to correlate with hippocampal sclerosis, lateralization of the electroencephalographic abnormalities, degree of hippocampal neuronal loss, verbal memory performance, and postoperative seizure control The manuscript by Grunewald et al (8) in this issue of AJNR, as well as a related paper by Jackson et al (9), describes a different quantitative technique for studying epilepsy. They found T2 relaxometry to be a reliable and sensitive method for detecting hippocampal sclerosis (for T2 values greater than 116 milliseconds). An older study by Matsuda et al also used T2 values to uncover hippocampal sclerosis (10). Although these findings are intriguing, one might ask why we should be interested in this quantitative technique for determining hippocampal sclerosis, when a reliable, sensitive, and specific method already exists? The answer lies with the biological factors that are the basis for the MR findings . The underlying mechanism for T2 prolongation may be independent of the mechanism producing the atrophic changes. This could have important implications for the following clinical and research questions: 1. Can T2 values help identify the additional 5% to 15% of patients with hippocampal Address reprint requests to Richard A . Bronen, MD

The changing landscape in epilepsy imaging: Unmasking subtle and unique entities

Dramatic changes have occurred recently in the field of epilepsy, including a fundamental shift in the etiology of epileptogenic substrates found at surgery. Hippocampal sclerosis is no longer the most common etiology found at epilepsy surgery and this decrease has been associated with an increase in the incidence of focal cortical dysplasia and encephaloceles. Significant advances have been made in molecular biology and genetics underlying the basis of malformations of cortical development, and our ability to detect epileptogenic abnormalities with MR imaging has markedly improved. This article begins with a discussion of these trends and reviews imaging techniques essential for detecting of subtle epilepsy findings. Representative examples of subtle imaging findings are presented, which are often overlooked but should not be missed. These include temporal lobe encephaloceles, malformations of cortical development (and especially focal cortical dysplasia), hippocampal sclerosis, hippocampal malformation (also known as HIMAL), ulegyria, autoimmune encephalitis, and Rasmussen’s encephalitis. Recent findings on the pathophysiology and genetic underpinnings of several causes of localization-related epilepsy are incorporated. For instance, it has been recently found that focal cortical dysplasia IIb, tuberous sclerosis, hemimegalencephaly, and gangliogliomas are all the result of mutations of the mTOR pathway for cell growth

Presurgical language fMRI: Clinical practices and patient outcomes in epilepsy surgical planning

The goal of this study was to document current clinical practice and report patient outcomes in presurgical language functional MRI (fMRI) for epilepsy surgery. Epilepsy surgical programs worldwide were surveyed as to the utility, implementation, and efficacy of language fMRI in the clinic; 82 programs responded. Respondents were predominantly US (61%) academic programs (85%), and evaluated adults (44%), adults and children (40%), or children only (16%). Nearly all (96%) reported using language fMRI. Surprisingly, fMRI is used to guide surgical margins (44% of programs) as well as lateralize language (100%). Sites using fMRI for localization most often use a distance margin around activation of 10mm. While considered useful, 56% of programs reported at least one instance of disagreement with other measures. Direct brain stimulation typically confirmed fMRI findings (74%) when guiding margins, but instances of unpredicted decline were reported by 17% of programs and 54% reported unexpected preservation of function. Programs reporting unexpected decline did not clearly differ from those which did not. Clinicians using fMRI to guide surgical margins do not typically map known language-critical areas beyond Broca's and Wernicke's. This initial data shows many clinical teams are confident using fMRI not only for language lateralization but also to guide surgical margins. Reported cases of unexpected language preservation when fMRI activation is resected, and cases of language decline when it is not, emphasize a critical need for further validation. Comprehensive studies comparing commonly-used fMRI paradigms to predict stimulation mapping and post-surgical language decline remain of high importance

Climigration? Population and climate change in Arctic Alaska

Residents of towns and villages in Arctic Alaska live on “the front line of climate change.” Some communities face immediate threats from erosion and flooding associated with thawing permafrost, increasing river flows, and reduced sea ice protection of shorelines. The term climigration, referring to migration caused by climate change, originally was coined for these places. Although initial applications emphasized the need for government relocation policies, it has elsewhere been applied more broadly to encompass unplanned migration as well. Some historical movements have been attributed to climate change, but closer study tends to find multiple causes, making it difficult to quantify the climate contribution. Clearer attribution might come from comparisons of migration rates among places that are similar in most respects, apart from known climatic impacts. We apply this approach using annual 1990–2014 time series on 43 Arctic Alaska towns and villages. Within-community time plots show no indication of enhanced out-migration from the most at-risk communities. More formally, there is no significant difference between net migration rates of at-risk and other places, testing several alternative classifications. Although climigration is not detectable to date, growing risks make either planned or unplanned movements unavoidable in the near future

Presurgical language fMRI: Technical practices in epilepsy surgical planning

Little is known about how language functional MRI (fMRI) is executed in clinical practice in spite of its widespread use. Here we comprehensively documented its execution in surgical planning in epilepsy. A questionnaire focusing on cognitive design, image acquisition, analysis and interpretation, and practical considerations was developed. Individuals responsible for collecting, analyzing, and interpreting clinical language fMRI data at 63 epilepsy surgical programs responded. The central finding was of marked heterogeneity in all aspects of fMRI. Most programs use multiple tasks, with a fifth routinely using 2, 3, 4, or 5 tasks with a modal run duration of 5 min. Variants of over 15 protocols are in routine use with forms of noun-verb generation, verbal fluency, and semantic decision-making used most often. Nearly all aspects of data acquisition and analysis vary markedly. Neither of the two best-validated protocols was used by more than 10% of respondents. Preprocessing steps are broadly consistent across sites, language-related blood flow is most often identified using general linear modeling (76% of respondents), and statistical thresholding typically varies by patient (79%). The software SPM is most often used. fMRI programs inconsistently include input from experts with all required skills (imaging, cognitive assessment, MR physics, statistical analysis, and brain-behavior relationships). These data highlight marked gaps between the evidence supporting fMRI and its clinical application. Teams performing language fMRI may benefit from evaluating practice with reference to the best-validated protocols to date and ensuring individuals trained in all aspects of fMRI are involved to optimize patient care

Transitioning From Radiology Training to Academic Faculty: The Importance of Mentorship

Transitioning from radiology residency to academic faculty presents many challenges. In this review, we discuss the importance of introspection and mentorship to successfully navigate this process. Key points include alignment of goals with those of the institution, formation of a mentorship program, and periodic reassessment of career goals. These tips and tools can help make the transition from residency to academic faculty more seamless

Transitioning from Radiology Training to Academic Faculty: Defining Your Role and Interests

Transitioning from radiology training to academic faculty presents many challenges. In this review, we discuss strategies to navigate this process and to facilitate success through appropriate selection of career tracks. Various modern avenues include roles as a Clinician-Educator, Clinician-Investigator, and Clinician-Administrator. Selection of the appropriate career track based on personal interests and institutional culture is critical for early and long-term career satisfaction