Nico J. J. Arezza^1,2, Jorge G. Burneo³, Ali R. Khan^1,2,4, and Corey A. Baron^1,2,4
1Medical Biophysics, Western University, London, ON, Canada, ²Centre for Functional and Metabolic Mapping, Robarts Research Institute, London, ON, Canada, ³Epilepsy Program, Clinical Neurological Sciences, Western University, London, ON, Canada, ⁴School of Biomedical Engineering, Western University, London, ON, Canada

Drug-resistant temporal lobe epilepsy (TLE) can often be treated surgically, but successful intervention depends on the use of imaging to localize the epileptic focus. Here, microscopic fractional anisotropy (μFA), fractional anisotropy (FA), and mean diffusivity (MD) were investigated to assess their sensitivities to abnormalities in TLE. μFA was significantly reduced in the ipsilateral hippocampal subfield containing the cornu ammonis 3/4 and dentate gyrus (p=0.0044), suggesting that it may be sensitive to pathological hippocampal abnormalities. Furthermore, differences between ipsilateral and contralateral μFA and MD, but not FA, correlated with ipsilateral atrophy in that same region.

Ting-Yu Su¹, Yingying Tang², Joon Yul Choi¹, Siyuan Hu³, Ken Sakaie⁴, Hiroatsu Murakami¹, Stephen Jones⁴, Imad Najm¹, Dan Ma³, and Zhong Irene Wang^1
1Epilepsy Center, Cleveland Clinic, Cleveland, OH, United States, ²Department of Neurology, West China Hospital of Sichuan University, Chengdu, China, ³Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States, ⁴Imaging Institute, Cleveland Clinic, Cleveland, OH, United States

MR fingerprinting (MRF) is an advanced quantitative MR technique that allows for efficient acquisition of multiparametric tissue maps. We applied high-resolution 3D MRF to examine T1 and T2 changes in 30 pharmacoresistant focal epilepsy patients with negative MRI, using a voxel-wise group-analysis approach. Forty age-and-gender-matched healthy controls were also included for comparison. Significant T1 increase was detected in the temporal pole, mesial temporal, and superior temporal regions, as well as the orbitofrontal cortex, ipsilateral to the side of the epilepsy. These MRF-detected subtle tissue property changes suggest potential structural damage in the ipsilateral limbic network in MRI-negative pharmacoresistant focal epilepsy.

Anish Vinay Sathe¹, Michael Kogan², KiChang Kang¹, Jingya Miao¹, Mashaal Syed¹, Isaiah Ailes¹, Caio Matias¹, Feroze Mohamed¹, Ashwini Sharan¹, and Mahdi Alizadeh^1
1Thomas Jefferson University, Philadelphia, PA, United States, ²The University of New Mexico, Albuquerque, NM, United States

Mesial temporal sclerosis (MTS) is a severe form of temporal lobe epilepsy. Resection is the treatment of choice for refractory MTS but can still show seizure recurrence. We used seed-to-voxel analysis via amplitude synchronization to determine alterations in functional connectivity in MTS based on seizure-free status one year post-resection. Positive and negative correlations between temporal lobe structures and other brain regions were calculated and compared. We found changes in connectivity in MTS between ascending reticular activating system structures such as the thalamus and brainstem and temporal lobe structures. We also found differences in connectivity alterations between seizure-free and non-seizure-free patients.

Gustavo Chau Loo Kung¹, Andrew Chiu², Zachary Davey³, Nicole Mouchawar⁴, Mackenzie Carlson¹, Douglas Martin⁵, Kevin Graber³, Babak Razavi³, Jennifer McNab⁴, and Michael Zeineh^4
1Bioengineering, Stanford University, Stanford, CA, United States, ²Radiology, Stanford Medicine, Stanford, CA, United States, ³Neurology & Neurological Sciences, Stanford Medicine, Stanford, CA, United States, ⁴Radiology Department, Stanford University, Stanford, CA, United States, ⁵University Hospitals, 11100 Euclid Ave, OH, United States

We performed subfield characterization of Mesial Temporal Sclerosis (MTS) using diffusion metrics. Analysis of MRI from 57 temporal lobe epilepsy patients was based on categorization from medical records, initial clinical radiological reads, and diagnostic changes after subfield DTI analyses. We observed differences in mean diffusivity, axial diffusivity and orientation dispersion in the dentate gyrus of patients with MTS. Differences between MTS and control patients were more pronounced in left MTS.  We demonstrate how these methods may aid in the MRI identification of MTS.

Benoit Testud^1,2, Roy A.M. Haast^1,2, Julia Scholly^1,2,3,4, Hugo Dary^1,2, Arnaud Le Troter^1,2, Jean-Philippe Ranjeva^1,2, Fabrice Bartolomei^3,4, and Maxime Guye^1,2
1Aix-Marseille Université, CNRS, CRMBM, Marseille, France, ²APHM La Timone, CEMEREM, Marseille, France, ³Aix-Marseille Université, INSERM, INS, Marseille, France, ⁴Department of Epileptology, APHM La Timone, Marseille, France

This work evaluated differences in thalamic morphometry and T₁ across drug-resistant temporal (TLE) and non-temporal lobe epilepsy (nTLE) patients using 7T MRI. Results show bilateral thalamic atrophy across all patients, with strongest effects observed in TLE patients and ipsilateral pulvinar and mediodorsal nuclei. Moreover, T₁ appeared lower, especially in medial, lateral, and posterior nuclei. While T₁ was lowest across nTLE patients, an ipsi- vs contralateral effect was uniquely present in TLE patients. Future, joint analyses with other available myelin- and iron sensitive metrics (e.g., tissue susceptibility and diffusivity), connectivity features and clinical features will increase sensitivity to differentiate among patients.

Huan Ma¹, Jianzhong Yang², Dewei Sun¹, Dafu Zhang¹, Yan Zhang², Jing Yuan², and Xiaoyong Zhang^3
1Department of Radiology, The Third Affiliated Hospital of Kunming Medical University, Kunming, Yunnan Province, China, ²Department of Psychiatry, The Second Affiliated Hospital of Kunming Medical University, Kunming, Yunnan Province, China, ³Clinical Science, Philips Healthcare, Chengdu, China, Chengdu, China

We obtained sMRI data from unmedicated adolescents and young adults with MDD, StD and well-matched healthy control subjects, and identified radiomics features from gray and white matter, and establish classification models. The accuracies and AUC were 86.75%, 0.93 for distinguishing MDD from HC, 70.51%, 0.69 for discriminating StD from HC, and 59.15%, 0.66 for differentiating MDD from StD, respectively. These findings provide preliminary evidence that radiomics features of brain structure are valid for discriminating MDD and StD from HCs. The MRI-based radiomics approach, with further improvement and validation, is a potential facilitating method to clinical diagnosis of mental illness.

Faye McKenna¹, Veronica Yu Sui¹, and Mariana Lazar^1
1Radiology, New York University School of Medicine, New York, NY, United States

We investigated the intravoxel incoherent imaging (IVIM) effect on neurite orientation dispersion and density imaging (NODDI) metric calculations in both healthy controls (N=36) and a clinical population of individuals with a psychotic spectrum disorder (PSD) (N=55) by extending the original model to include a microvascular blood compartment. We found that without controlling for the IVIM effect, several NODDI metrics were possibly misestimated, which subsequently affected group comparisons and results.

Mackenzie Langan^1,2, Ameen Al Qadi^1,2, Gaurav Verma¹, Bradley Delman³, James Murrough⁴, Priti Balchandani*¹, and Laurel Morris*^4
1Biomedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, United States, ²Icahn School of Medicine, Graduate School of Biomedical Sciences, New York, NY, United States, ³Diagnostic, Molecular and Interventional Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States, ⁴Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY, United States

We performed a novel 7T analysis of volumetric, microstructural and tractographic measures in the hypothalamus in MDD and matched controls. We uncovered significant differences in FA from left anterior superior and left tubular inferior, and discovered correlations between these regions and clinical measures of depression and anxiety. These findings warrant further investigations of microstructural integrity within the hypothalamus in patients with MDD and provide a basis for exploration of microstructural integrity within other neuropsychiatric disorders characterized by dysregulated mood and anxiety.

Zarah van der Pal¹, Kristine Walhovd^2,3, Inge Amlien², Antonia Kaiser¹, Hilde Geurts⁴, Liesbeth Reneman¹, and Anouk Schrantee^1
1Department of Radiology & Nuclear Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands, ²Department of Psychology, Center for Lifespan Changes in Brain and Cognition, University of Oslo, Oslo, Norway, ³Departments of Radiology and Nuclear Medicine, Oslo University, Oslo, Norway, ⁴Dutch Autism and ADHD Research Center, Amsterdam Brain and Cognition, University of Amsterdam, Amsterdam, Netherlands

Stimulant medication is commonly used in treatment for attention-deficit/hyperactivity disorder, yet its effects on brain development remain unclear. This study investigated the long-term age-dependent effects of stimulants on cortical development after a 4-year naturalistic follow-up of adolescents and adults with ADHD using T1-weighted scans. Medication use was higher in adolescents than adults, and ADHD symptoms improved in both age groups. In line with literature on cortical development, analyses revealed reductions in apparent cortical thickness in adolescents only. However, we observed no effect of medication use on change in cortical thickness, suggesting previously identified psychostimulant effects may be transient.

Marissa DiPiero^1,2, Hassan Cordash^2,3, Molly B. Prigge⁴, Jace B. King⁴, Carolyn K. King⁴, Nicholas Lange⁵, Erin D. Bigler^6,7,8,9, Brandon A. Zielinski^4,6,10, Jeffrey Anderson⁴, Janet E. Lainhart^2,11, Andrew Alexander^2,11,12, and Douglas C. Dean III^2,12,13
1Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, United States, ²Waisman Center, Madison, WI, United States, ³School of Computer, Data & Information Sciences, University of Wisconsin-Madison, Madison, WI, United States, ⁴Radiology, University of Utah, Salt Lake City, UT, United States, ⁵Psychiatry, Harvard School of Medicine, Boston, MA, United States, ⁶Neurology, University of Utah, Salt Lake City, UT, United States, ⁷Psychiatry, University of Utah, Salt Lake City, UT, United States, ⁸Psychology and Neuroscience Center, Brigham Young University, Provo, UT, United States, ⁹Neurology, University of California-Davis, Davis, CA, United States, ¹⁰Pediatrics, University of Utah, Salt Lake City, UT, United States, ¹¹Psychiatry, University of Wisconsin-Madison, Madison, WI, United States, ¹²Medical Physics, University of Wisconsin-Madison, Madison, WI, United States, ¹³Pediatrics, University of Wisconsin-Madison, Madison, WI, United States

Advanced diffusion MRI techniques, such as Neurite Orientation Dispersion and Density Imaging (NODDI), may be used to improve characterization of gray matter (GM) and white matter (WM) microstructure of the brain. In this work, we used Gray Matter Based Spatial Statistics and Tract Based Spatial Statistics to investigate cortical GM and WM microstructural differences in individuals with autism spectrum disorder (ASD). Group differences and age by group interaction models were assessed. We demonstrate wide-spread alterations in GM and WM microstructure in ASD. Findings provide unique evidence of altered neurodevelopmental processes affecting microstructural development in ASD that persist into adulthood.    

Daphne Boucherie¹, Sean van Mil¹, Liesbeth Reneman¹, Markus Hollmann², and Anouk Schrantee^1
1Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centres, University of Amsterdam, Amsterdam, Netherlands, ²Department of Anaesthesiology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands

The therapeutic antidepressant effect of S-ketamine has been linked to changes in glutamatergic neurotransmission. Here, we investigated the value of dynamic functional MRS compared to static MRS in detecting dose-dependent effects of subanesthetic S-ketamine on glutamate in the anterior cingulate cortex. Although significant dose-dependent subjective dissociative effects of S-ketamine were observed, we did not find significantly different glutamate changes between placebo, low-dose S-ketamine and high-dose S-ketamine, using either a “static” or “dynamic” analysis approach. Nevertheless, exploratory analyses suggest that glutamate might be modulated at specific time-points after S-ketamine administration, illustrating the potential additional information obtained from a dynamic approach.