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Kiersnowski OC, Winston GP, Caciagli L, Biondetti E, Elbadri M, Buck S, Duncan JS, Thornton JS, Shmueli K, Vos SB. Quantitative susceptibility mapping identifies hippocampal and other subcortical grey matter tissue composition changes in temporal lobe epilepsy. Hum Brain Mapp 2023; 44:5047-5064. [PMID: 37493334 PMCID: PMC10502681 DOI: 10.1002/hbm.26432] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 07/04/2023] [Accepted: 07/07/2023] [Indexed: 07/27/2023] Open
Abstract
Temporal lobe epilepsy (TLE) is associated with widespread brain alterations. Using quantitative susceptibility mapping (QSM) alongside transverse relaxation rate (R 2 * ), we investigated regional brain susceptibility changes in 36 patients with left-sided (LTLE) or right-sided TLE (RTLE) secondary to hippocampal sclerosis, and 27 healthy controls (HC). We compared three susceptibility calculation methods to ensure image quality. Correlations of susceptibility andR 2 * with age of epilepsy onset, frequency of focal-to-bilateral tonic-clonic seizures (FBTCS), and neuropsychological test scores were examined. Weak-harmonic QSM (WH-QSM) successfully reduced noise and removed residual background field artefacts. Significant susceptibility increases were identified in the left putamen in the RTLE group compared to the LTLE group, the right putamen and right thalamus in the RTLE group compared to HC, and a significant susceptibility decrease in the left hippocampus in LTLE versus HC. LTLE patients who underwent epilepsy surgery showed significantly lower left-versus-right hippocampal susceptibility. SignificantR 2 * changes were found between TLE and HC groups in the amygdala, putamen, thalamus, and in the hippocampus. Specifically, decreased R2 * was found in the left and right hippocampus in LTLE and RTLE, respectively, compared to HC. Susceptibility andR 2 * were significantly correlated with cognitive test scores in the hippocampus, globus pallidus, and thalamus. FBTCS frequency correlated positively with ipsilateral thalamic and contralateral putamen susceptibility and withR 2 * in bilateral globi pallidi. Age of onset was correlated with susceptibility in the hippocampus and putamen, and withR 2 * in the caudate. Susceptibility andR 2 * changes observed in TLE groups suggest selective loss of low-myelinated neurons alongside iron redistribution in the hippocampi, predominantly ipsilaterally, indicating QSM's sensitivity to local pathology. Increased susceptibility andR 2 * in the thalamus and putamen suggest increased iron content and reflect disease severity.
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Affiliation(s)
- Oliver C. Kiersnowski
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Gavin P. Winston
- Department of Clinical and Experimental EpilepsyUniversity College LondonLondonUK
- Department of Medicine, Division of NeurologyQueen's UniversityKingstonCanada
| | - Lorenzo Caciagli
- Department of Clinical and Experimental EpilepsyUniversity College LondonLondonUK
- Department of BioengineeringUniversity of PennsylvaniaPhiladelphiaPennsylvaniaUSA
| | - Emma Biondetti
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
- Department of Neuroscience, Imaging and Clinical SciencesInstitute for Advanced Biomedical Technologies, “D'Annunzio” University of Chieti‐PescaraChietiItaly
| | - Maha Elbadri
- Department of NeurologyQueen Elizabeth HospitalBirminghamUK
| | - Sarah Buck
- Department of Clinical and Experimental EpilepsyUniversity College LondonLondonUK
| | - John S. Duncan
- Department of Clinical and Experimental EpilepsyUniversity College LondonLondonUK
| | - John S. Thornton
- Neuroradiological Academic UnitUCL Queen Square Institute of Neurology, University College LondonLondonUK
| | - Karin Shmueli
- Department of Medical Physics and Biomedical EngineeringUniversity College LondonLondonUK
| | - Sjoerd B. Vos
- Neuroradiological Academic UnitUCL Queen Square Institute of Neurology, University College LondonLondonUK
- Centre for Microscopy, Characterisation, and AnalysisThe University of Western AustraliaNedlandsAustralia
- Centre for Medical Image Computing, Computer Science departmentUniversity College LondonLondonUK
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Uher D, Drenthen GS, Schijns OEMG, Colon AJ, Hofman PAM, van Lanen RHGJ, Hoeberigs CM, Jansen JFA, Backes WH. Advances in Image Processing for Epileptogenic Zone Detection with MRI. Radiology 2023; 307:e220927. [PMID: 37129491 DOI: 10.1148/radiol.220927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Focal epilepsy is a common and severe neurologic disorder. Neuroimaging aims to identify the epileptogenic zone (EZ), preferably as a macroscopic structural lesion. For approximately a third of patients with chronic drug-resistant focal epilepsy, the EZ cannot be precisely identified using standard 3.0-T MRI. This may be due to either the EZ being undetectable at imaging or the seizure activity being caused by a physiologic abnormality rather than a structural lesion. Computational image processing has recently been shown to aid radiologic assessments and increase the success rate of uncovering suspicious regions by enhancing their visual conspicuity. While structural image analysis is at the forefront of EZ detection, physiologic image analysis has also been shown to provide valuable information about EZ location. This narrative review summarizes and explains the current state-of-the-art computational approaches for image analysis and presents their potential for EZ detection. Current limitations of the methods and possible future directions to augment EZ detection are discussed.
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Affiliation(s)
- Daniel Uher
- From the Department of Radiology and Nuclear Medicine (D.U., G.S.D., P.A.M.H., C.M.H., J.F.A.J., W.H.B.) and Department of Neurosurgery (O.E.M.G.S., R.H.G.J.v.L.), Maastricht University Medical Centre, P. Debyelaan 25, NL-6229 HX Maastricht, the Netherlands; School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, the Netherlands (D.U., G.S.D., O.E.M.G.S., R.H.G.J.v.L., J.F.A.J., W.H.B.); Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands (O.E.M.G.S., A.J.C., P.A.M.H., C.M.H., J.F.A.J.); and Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands (J.F.A.J.)
| | - Gerhard S Drenthen
- From the Department of Radiology and Nuclear Medicine (D.U., G.S.D., P.A.M.H., C.M.H., J.F.A.J., W.H.B.) and Department of Neurosurgery (O.E.M.G.S., R.H.G.J.v.L.), Maastricht University Medical Centre, P. Debyelaan 25, NL-6229 HX Maastricht, the Netherlands; School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, the Netherlands (D.U., G.S.D., O.E.M.G.S., R.H.G.J.v.L., J.F.A.J., W.H.B.); Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands (O.E.M.G.S., A.J.C., P.A.M.H., C.M.H., J.F.A.J.); and Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands (J.F.A.J.)
| | - Olaf E M G Schijns
- From the Department of Radiology and Nuclear Medicine (D.U., G.S.D., P.A.M.H., C.M.H., J.F.A.J., W.H.B.) and Department of Neurosurgery (O.E.M.G.S., R.H.G.J.v.L.), Maastricht University Medical Centre, P. Debyelaan 25, NL-6229 HX Maastricht, the Netherlands; School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, the Netherlands (D.U., G.S.D., O.E.M.G.S., R.H.G.J.v.L., J.F.A.J., W.H.B.); Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands (O.E.M.G.S., A.J.C., P.A.M.H., C.M.H., J.F.A.J.); and Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands (J.F.A.J.)
| | - Albert J Colon
- From the Department of Radiology and Nuclear Medicine (D.U., G.S.D., P.A.M.H., C.M.H., J.F.A.J., W.H.B.) and Department of Neurosurgery (O.E.M.G.S., R.H.G.J.v.L.), Maastricht University Medical Centre, P. Debyelaan 25, NL-6229 HX Maastricht, the Netherlands; School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, the Netherlands (D.U., G.S.D., O.E.M.G.S., R.H.G.J.v.L., J.F.A.J., W.H.B.); Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands (O.E.M.G.S., A.J.C., P.A.M.H., C.M.H., J.F.A.J.); and Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands (J.F.A.J.)
| | - Paul A M Hofman
- From the Department of Radiology and Nuclear Medicine (D.U., G.S.D., P.A.M.H., C.M.H., J.F.A.J., W.H.B.) and Department of Neurosurgery (O.E.M.G.S., R.H.G.J.v.L.), Maastricht University Medical Centre, P. Debyelaan 25, NL-6229 HX Maastricht, the Netherlands; School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, the Netherlands (D.U., G.S.D., O.E.M.G.S., R.H.G.J.v.L., J.F.A.J., W.H.B.); Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands (O.E.M.G.S., A.J.C., P.A.M.H., C.M.H., J.F.A.J.); and Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands (J.F.A.J.)
| | - Rick H G J van Lanen
- From the Department of Radiology and Nuclear Medicine (D.U., G.S.D., P.A.M.H., C.M.H., J.F.A.J., W.H.B.) and Department of Neurosurgery (O.E.M.G.S., R.H.G.J.v.L.), Maastricht University Medical Centre, P. Debyelaan 25, NL-6229 HX Maastricht, the Netherlands; School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, the Netherlands (D.U., G.S.D., O.E.M.G.S., R.H.G.J.v.L., J.F.A.J., W.H.B.); Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands (O.E.M.G.S., A.J.C., P.A.M.H., C.M.H., J.F.A.J.); and Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands (J.F.A.J.)
| | - Christianne M Hoeberigs
- From the Department of Radiology and Nuclear Medicine (D.U., G.S.D., P.A.M.H., C.M.H., J.F.A.J., W.H.B.) and Department of Neurosurgery (O.E.M.G.S., R.H.G.J.v.L.), Maastricht University Medical Centre, P. Debyelaan 25, NL-6229 HX Maastricht, the Netherlands; School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, the Netherlands (D.U., G.S.D., O.E.M.G.S., R.H.G.J.v.L., J.F.A.J., W.H.B.); Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands (O.E.M.G.S., A.J.C., P.A.M.H., C.M.H., J.F.A.J.); and Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands (J.F.A.J.)
| | - Jacobus F A Jansen
- From the Department of Radiology and Nuclear Medicine (D.U., G.S.D., P.A.M.H., C.M.H., J.F.A.J., W.H.B.) and Department of Neurosurgery (O.E.M.G.S., R.H.G.J.v.L.), Maastricht University Medical Centre, P. Debyelaan 25, NL-6229 HX Maastricht, the Netherlands; School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, the Netherlands (D.U., G.S.D., O.E.M.G.S., R.H.G.J.v.L., J.F.A.J., W.H.B.); Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands (O.E.M.G.S., A.J.C., P.A.M.H., C.M.H., J.F.A.J.); and Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands (J.F.A.J.)
| | - Walter H Backes
- From the Department of Radiology and Nuclear Medicine (D.U., G.S.D., P.A.M.H., C.M.H., J.F.A.J., W.H.B.) and Department of Neurosurgery (O.E.M.G.S., R.H.G.J.v.L.), Maastricht University Medical Centre, P. Debyelaan 25, NL-6229 HX Maastricht, the Netherlands; School for Mental Health and Neuroscience (MHeNs), Maastricht University, Maastricht, the Netherlands (D.U., G.S.D., O.E.M.G.S., R.H.G.J.v.L., J.F.A.J., W.H.B.); Academic Center for Epileptology, Kempenhaeghe and Maastricht University Medical Centre, Heeze/Maastricht, the Netherlands (O.E.M.G.S., A.J.C., P.A.M.H., C.M.H., J.F.A.J.); and Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands (J.F.A.J.)
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Kasa LW, Peters T, Mirsattari SM, Jurkiewicz MT, Khan AR, A M Haast R. The role of the temporal pole in temporal lobe epilepsy: A diffusion kurtosis imaging study. Neuroimage Clin 2022; 36:103201. [PMID: 36126518 PMCID: PMC9486670 DOI: 10.1016/j.nicl.2022.103201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 12/14/2022]
Abstract
This study aimed to evaluate the use of diffusion kurtosis imaging (DKI) to detect microstructural abnormalities within the temporal pole (TP) and its temporopolar cortex in temporal lobe epilepsy (TLE) patients. DKI quantitative maps were obtained from fourteen lesional TLE and ten non-lesional TLE patients, along with twenty-three healthy controls. Data collected included mean (MK); radial (RK) and axial kurtosis (AK); mean diffusivity (MD) and axonal water fraction (AWF). Automated fiber quantification (AFQ) was used to quantify DKI measurements along the inferior longitudinal (ILF) and uncinate fasciculus (Unc). ILF and Unc tract profiles were compared between groups and tested for correlation with disease duration. To characterize temporopolar cortex microstructure, DKI maps were sampled at varying depths from superficial white matter (WM) towards the pial surface. Patients were separated according to the temporal lobe ipsilateral to seizure onset and their AFQ results were used as input for statistical analyses. Significant differences were observed between lesional TLE and controls, towards the most temporopolar segment of ILF and Unc proximal to the TP within the ipsilateral temporal lobe in left TLE patients for MK, RK, AWF and MD. No significant changes were observed with DKI maps in the non-lesional TLE group. DKI measurements correlated with disease duration, mostly towards the temporopolar segments of the WM bundles. Stronger differences in MK, RK and AWF within the temporopolar cortex were observed in the lesional TLE and noticeable differences (except for MD) in non-lesional TLE groups compared to controls. This study demonstrates that DKI has potential to detect subtle microstructural alterations within the temporopolar segments of the ILF and Unc and the connected temporopolar cortex in TLE patients including non-lesional TLE subjects. This could aid our understanding of the extrahippocampal areas, more specifically the temporal pole role in seizure generation in TLE and might inform surgical planning, leading to better seizure outcomes.
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Affiliation(s)
- Loxlan W Kasa
- Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada; School of Biomedical Engineering, Western University, London, Ontario, Canada
| | - Terry Peters
- Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada; School of Biomedical Engineering, Western University, London, Ontario, Canada; Department of Medical Biophysics, Western University, London, Ontario, Canada; Department of Medical Imaging, Western University, London, Ontario, Canada
| | - Seyed M Mirsattari
- Department of Medical Biophysics, Western University, London, Ontario, Canada; Department of Medical Imaging, Western University, London, Ontario, Canada; Department of Clinical Neurological Sciences, Western University, London, Ontario, Canada; Department of Psychology, Western University, London, Ontario, Canada
| | - Michael T Jurkiewicz
- Department of Medical Biophysics, Western University, London, Ontario, Canada; Department of Medical Imaging, Western University, London, Ontario, Canada; Department of Clinical Neurological Sciences, Western University, London, Ontario, Canada
| | - Ali R Khan
- Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada; School of Biomedical Engineering, Western University, London, Ontario, Canada; Department of Medical Biophysics, Western University, London, Ontario, Canada; Centre for Functional and Metabolic Mapping, Robarts Research Institute, Western University, London, Ontario, Canada.
| | - Roy A M Haast
- Centre for Functional and Metabolic Mapping, Robarts Research Institute, Western University, London, Ontario, Canada
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Explanations of Machine Learning Models in Repeated Nested Cross-Validation: An Application in Age Prediction Using Brain Complexity Features. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12136681] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
SHAP (Shapley additive explanations) is a framework for explainable AI that makes explanations locally and globally. In this work, we propose a general method to obtain representative SHAP values within a repeated nested cross-validation procedure and separately for the training and test sets of the different cross-validation rounds to assess the real generalization abilities of the explanations. We applied this method to predict individual age using brain complexity features extracted from MRI scans of 159 healthy subjects. In particular, we used four implementations of the fractal dimension (FD) of the cerebral cortex—a measurement of brain complexity. Representative SHAP values highlighted that the most recent implementation of the FD had the highest impact over the others and was among the top-ranking features for predicting age. SHAP rankings were not the same in the training and test sets, but the top-ranking features were consistent. In conclusion, we propose a method—and share all the source code—that allows a rigorous assessment of the SHAP explanations of a trained model in a repeated nested cross-validation setting.
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Hwang Y, Lee HR, Jo H, Kim D, Joo EY, Seo DW, Hong SB, Shon YM. Regional Ictal Hyperperfusion in the Contralateral Occipital Area May Be a Poor Prognostic Marker of Anterior Temporal Lobectomy: A SISCOM Analysis of MTLE Cases. Neuropsychiatr Dis Treat 2021; 17:2421-2427. [PMID: 34326640 PMCID: PMC8314682 DOI: 10.2147/ndt.s317915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 07/07/2021] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND AND OBJECTIVE Subtraction of ictal SPECT coregistered to MRI (SISCOM) provides complementary information for detecting the ictal onset zone, especially in patients with MRI-negative focal epilepsy, and provides additional useful information for predicting long-term postresection outcomes. This study sought to investigate the relationship between surgical failure and increased cerebral blood flow (CBF) pattern using SPECT in patients with mesial temporal lobe epilepsy with unilateral hippocampal sclerosis (MTLE-HS). METHODS Among 42 subjects who underwent anterior temporal lobectomy with amygdalohippocampectomy (ATL-AH) for MTLE-HS, 29 (69.0%) were seizure-free (SF group). Hyperperfusion was compared in 14 ipsilateral and contralateral brain regions in SISCOM images between the two groups. RESULTS The pattern of ictal hyperperfusion in temporal regions did not vary significantly between the SF and non-seizure-free (NSF) groups. However, CBF increases in the contralateral occipital area was more frequent in the NSF group than in the SF group. Furthermore, ictal hyperperfusion of the ipsilateral occipital and contralateral parietal areas tended to be more frequent in the NSF group. CONCLUSION The results indicate that poor ATL-AH surgical outcome is associated with a tendency of ictal hyperperfusion of the contralateral occipital cortex based on SISCOM analysis. The pattern of early ictal CBF changes implicating the propagation from temporal to occipital cortices can be considered a marker of poor surgical outcomes of ATL-AH in MTLE-HS patients.
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Affiliation(s)
- Yoonha Hwang
- Department of Neurology, The Catholic University of Korea Eunpyeong St. Mary's Hospital, Seoul, Republic of Korea
| | - Hwa Reung Lee
- Department of Neurology, Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Hyunjin Jo
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.,Neuroscience Center, Samsung Medical Center, Seoul, Republic of Korea
| | - Dongyeop Kim
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.,Neuroscience Center, Samsung Medical Center, Seoul, Republic of Korea
| | - Eun Yeon Joo
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.,Neuroscience Center, Samsung Medical Center, Seoul, Republic of Korea
| | - Dae-Won Seo
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.,Neuroscience Center, Samsung Medical Center, Seoul, Republic of Korea
| | - Seung Bong Hong
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.,Neuroscience Center, Samsung Medical Center, Seoul, Republic of Korea
| | - Young-Min Shon
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.,Neuroscience Center, Samsung Medical Center, Seoul, Republic of Korea.,Department of Medical Device Management and Research, Samsung Advanced Institute for Health Sciences & Technology (SAHIST), Sungkyunkwan University, Seoul, Korea
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Sanjari Moghaddam H, Rahmani F, Aarabi MH, Nazem-Zadeh MR, Davoodi-Bojd E, Soltanian-Zadeh H. White matter microstructural differences between right and left mesial temporal lobe epilepsy. Acta Neurol Belg 2020; 120:1323-1331. [PMID: 30635771 DOI: 10.1007/s13760-019-01074-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 01/05/2019] [Indexed: 01/20/2023]
Abstract
PURPOSE Mesial temporal lobe epilepsy (mTLE) is a chronic focal epileptic disorder characterized by recalcitrant seizures often necessitating surgical intervention. Identifying the laterality of seizure focus is crucial for pre-surgical planning. We implemented diffusion MRI (DMRI) connectometry to identify differences in white matter connectivity in patients with left and right mTLE relative to healthy control subjects. METHOD We enrolled 12 patients with right mTLE, 12 patients with left mTLE, and 12 age/sex matched healthy controls (HCs). We used DMRI connectometry to identify local connectivity patterns of white matter tracts, based on quantitative anisotropy (QA). We compared QA of white matter to reconstruct tracts with significant difference in connectivity between patients and HCs and then between patients with left and right mTLE. RESULTS Right mTLE patients show higher anisotropy in left inferior longitudinal fasciculus (ILF) and forceps minor and lower QA in genu of corpus callosum (CC), bilateral corticospinal tracts (CSTs), and bilateral middle cerebellar peduncles (MCPs) compared to HCs. Left mTLE patients show higher anisotropy in genu of CC, bilateral CSTs, and right MCP and decreased anisotropy in forceps minor compared to HCs. Compared to patients with right mTLE, left mTLE patients showed increased and decreased connectivity in some major tracts. CONCLUSIONS Our study showed the pattern of microstructural disintegrity in mTLE patients relative to HCs. We demonstrated that left and right mTLE patients have discrepant alternations in their white matter microstructure. These results may indicate that left and right mTLE have different underlying pathologic mechanisms.
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Affiliation(s)
| | - Farzaneh Rahmani
- NeuroImaging Network (NIN), Universal Scientific Education and Research Network (USERN), Tehran, Iran
- Student's Scientific Research Center (SSRC), Tehran University of Medical Sciences, Tehran, Iran
| | | | - Mohammad-Reza Nazem-Zadeh
- Research Center for Science and Technology in Medicine (RCSTIM), Tehran University of Medical Sciences, Tehran, Iran
| | - Esmaeil Davoodi-Bojd
- Image Analysis Laboratory, Departments of Radiology and Research Administration, Henry Ford Health System, One Ford Place, 2F, Detroit, MI, 48202, USA
| | - Hamid Soltanian-Zadeh
- Control and Intelligent Processing Center of Excellence (CIPCE), School of Electrical and Computer Engineering, College of Engineering, University of Tehran, North Kargar Ave., Tehran, Iran.
- Image Analysis Laboratory, Departments of Radiology and Research Administration, Henry Ford Health System, One Ford Place, 2F, Detroit, MI, 48202, USA.
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García-Pallero MA, Hodaie M, Zhong J, Manzanares-Soler R, Navas M, Pastor J, Vega-Zelaya L, Delgado-Fernández J, Sola RG, Torres CV. Prediction of Laterality in Temporal Lobe Epilepsy Using White Matter Diffusion Metrics. World Neurosurg 2019; 128:e700-e708. [DOI: 10.1016/j.wneu.2019.04.238] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 04/25/2019] [Accepted: 04/26/2019] [Indexed: 11/16/2022]
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White matter correlates of disease duration in patients with temporal lobe epilepsy: updated review of literature. Neurol Sci 2019; 40:1209-1216. [PMID: 30868482 DOI: 10.1007/s10072-019-03818-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 02/27/2019] [Indexed: 12/14/2022]
Abstract
BACKGROUND Medial temporal lobe epilepsy (mTLE) has been associated with widespread white mater (WM) alternations in addition to mesial temporal sclerosis (MTS). Herein, we aimed to investigate the correlation between disease duration and WM structural abnormalities in mTLE using diffusion MRI (DMRI) connectometry approach. METHOD DMRI connectometry was conducted on 24 patients with mTLE. A multiple regression model was used to investigate white matter tracts with microstructural correlates to disease duration, controlling for age and sex. DMRI data were processed in the MNI space using q-space diffeomorphic reconstruction to obtain the spin distribution function (SDF). The SDF values were converted to quantitative anisotropy (QA) and used in further analyses. RESULTS Connectometry analysis identified impaired white matter QA of the following fibers to be correlated with disease duration: bilateral retrosplenial cingulum, bilateral fornix, right inferior longitudinal fasciculus (ILF), and genu of corpus callosum (CC) (FDR = 0.009). CONCLUSION Our results were obtained from DMRI connectometry, which indicates the connectivity and the level of diffusion in nerve fibers rather just the direction of diffusion. Compared to previous studies investigating the correlation between duration of epilepsy and white matter integrity in mTLE patients, we detected broader and somewhat different associations in midline structures and component of limbic system. However, further studies with larger sample sizes are required to elucidate previous and current results.
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Tsougos I, Kousi E, Georgoulias P, Kapsalaki E, Fountas KN. Neuroimaging methods in Epilepsy of Temporal Origin. Curr Med Imaging 2018; 15:39-51. [DOI: 10.2174/1573405613666170622114920] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 05/04/2017] [Accepted: 05/11/2017] [Indexed: 11/22/2022]
Abstract
Background:
Temporal Lobe Epilepsy (TLE) comprises the most common form of
symptomatic refractory focal epilepsy in adults. Accurate lateralization and localization of the
epileptogenic focus are a significant prerequisite for determining surgical candidacy once the
patient has been deemed medically intractable. Structural MR imaging, clinical,
electrophysiological, and neurophysiological data have an established role in the localization of the
epileptogenic foci. Nevertheless, hippocampal sclerosis cannot be detected on MR images in more
than 30% of patients with TLE, and the presurgical assessment remains controversial.
</P><P>
Discussion: In the last years, advanced MR imaging techniques, such as 1H-MRS, DWI, DTI,
DSCI, and fMRI, may provide valuable additional information regarding the physiological and
metabolic characterization of brain tissue. MR imaging has shifted towards functional and
molecular imaging, thus, promising to improve the accuracy regarding the lateralization and the
localization of the epileptogenic focus. Additionally, nuclear medicine studies, such as SPECT and
PET imaging modalities, have become an asset for the decoding of brain function and activity, and
can be diagnostically helpful as well, since they provide valuable data regarding the altered
metabolic activity of the seizure foci.
Conclusion:
Overall, advanced MRI, SPECT, and PET imaging techniques are increasingly
becoming an essential part of TLE diagnostics, when the epileptogenic area is not identified on
structural MRI or when structural MRI, clinical, and electrophysiological findings are not in
concordance.
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Affiliation(s)
- Ioannis Tsougos
- Department of Medical Physics, School of Medicine, University of Thessaly, Larisa, Greece
| | - Evanthia Kousi
- The Royal Marsden NHS Foundation Trust, London, United Kingdom
| | - Panagiotis Georgoulias
- Department of Medical Physics, School of Medicine, University of Thessaly, Larisa, Greece
| | - Eftychia Kapsalaki
- Department of Medical Physics, School of Medicine, University of Thessaly, Larisa, Greece
| | - Kostas N. Fountas
- Department of Medical Physics, School of Medicine, University of Thessaly, Larisa, Greece
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10
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Deleo F, Thom M, Concha L, Bernasconi A, Bernhardt BC, Bernasconi N. Histological and MRI markers of white matter damage in focal epilepsy. Epilepsy Res 2017; 140:29-38. [PMID: 29227798 DOI: 10.1016/j.eplepsyres.2017.11.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/10/2017] [Accepted: 11/20/2017] [Indexed: 12/21/2022]
Abstract
Growing evidence highlights the importance of white matter in the pathogenesis of focal epilepsy. Ex vivo and post-mortem studies show pathological changes in epileptic patients in white matter myelination, axonal integrity, and cellular composition. Diffusion-weighted MRI and its analytical extensions, particularly diffusion tensor imaging (DTI), have been the most widely used technique to image the white matter in vivo for the last two decades, and have shown microstructural alterations in multiple tracts both in the vicinity and at distance from the epileptogenic focus. These techniques have also shown promising ability to predict cognitive status and response to pharmacological or surgical treatments. More recently, the hypothesis that focal epilepsy may be more adequately described as a system-level disorder has motivated a shift towards the study of macroscale brain connectivity. This review will cover emerging findings contributing to our understanding of white matter alterations in focal epilepsy, studied by means of histological and ultrastructural analyses, diffusion MRI, and large-scale network analysis. Focus is put on temporal lobe epilepsy and focal cortical dysplasia. This topic was addressed in a special interest group on neuroimaging at the 70th annual meeting of the American Epilepsy Society, held in Houston December 2-6, 2016.
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Affiliation(s)
- Francesco Deleo
- NeuroImaging of Epilepsy Laboratory, Montreal Neurological Institute, McGill University, Canada
| | - Maria Thom
- Division of Neuropathology and Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
| | - Luis Concha
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, Mexico
| | - Andrea Bernasconi
- NeuroImaging of Epilepsy Laboratory, Montreal Neurological Institute, McGill University, Canada
| | - Boris C Bernhardt
- NeuroImaging of Epilepsy Laboratory, Montreal Neurological Institute, McGill University, Canada; Multimodal Imaging and Connectome Analysis Laboratory, Montreal Neurological Institute, McGill University, Canada
| | - Neda Bernasconi
- NeuroImaging of Epilepsy Laboratory, Montreal Neurological Institute, McGill University, Canada.
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11
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Tract-specific atrophy in focal epilepsy: Disease, genetics, or seizures? Ann Neurol 2017; 81:240-250. [DOI: 10.1002/ana.24848] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 11/29/2016] [Accepted: 12/11/2016] [Indexed: 12/13/2022]
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12
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Kreilkamp BA, Weber B, Richardson MP, Keller SS. Automated tractography in patients with temporal lobe epilepsy using TRActs Constrained by UnderLying Anatomy (TRACULA). Neuroimage Clin 2017; 14:67-76. [PMID: 28138428 PMCID: PMC5257189 DOI: 10.1016/j.nicl.2017.01.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 12/06/2016] [Accepted: 01/04/2017] [Indexed: 12/19/2022]
Abstract
PURPOSE A detailed understanding of white matter tract alterations in patients with temporal lobe epilepsy (TLE) is important as it may provide useful information for likely side of seizure onset, cognitive impairment and postoperative prognosis. However, most diffusion-tensor imaging (DTI) studies have relied on manual reconstruction of tract bundles, despite the recent development of automated techniques. In the present study, we used an automated white matter tractography analysis approach to quantify temporal lobe white matter tract alterations in TLE and determine the relationships between tract alterations, the extent of hippocampal atrophy and the chronicity and severity of the disorder. METHODS We acquired preoperative T1-weighted and DTI data in 64 patients with well-characterized TLE, with imaging and histopathological evidence of hippocampal sclerosis. Identical acquisitions were collected for 44 age- and sex-matched healthy controls. We employed automatic probabilistic tractography DTI analysis using TRActs Constrained by UnderLying Anatomy (TRACULA) available in context of Freesurfer software for the reconstruction of major temporal lobe tract bundles. We determined the factors influencing probabilistic tract reconstruction and investigated alterations of DTI scalar metrics along white matter tracts with respect to hippocampal volume, which was automatically estimated using Freesurfer's morphometric pipelines. We also explored the relationships between white matter tract alterations and duration of epilepsy, age of onset of epilepsy and seizure burden (defined as a function of seizure frequency and duration of epilepsy). RESULTS Whole-tract diffusion characteristics of patients with TLE differed according to side of epilepsy and were significantly different between patients and controls. Waypoint comparisons along each tract revealed that patients had significantly altered tissue characteristics of the ipsilateral inferior-longitudinal, uncinate fasciculus, superior longitudinal fasciculus and cingulum relative to controls. Changes were more widespread (ipsilaterally and contralaterally) in patients with left TLE while patients with right TLE showed changes that remained spatially confined in ipsilateral tract regions. We found no relationship between DTI alterations and volume of the epileptogenic hippocampus. DTI alterations of anterior ipsilateral uncinate and inferior-longitudinal fasciculus correlated with duration of epilepsy (over and above effects of age) and age at onset of epilepsy. Seizure burden correlated with tissue characteristics of the uncinate fasciculus. CONCLUSION This study shows that TRACULA permits the detection of alterations of DTI tract scalar metrics in patients with TLE. It also provides the opportunity to explore relationships with structural volume measurements and clinical variables along white matter tracts. Our data suggests that the anterior temporal lobe portions of the uncinate and inferior-longitudinal fasciculus may be particularly vulnerable to pathological alterations in patients with TLE. These alterations are unrelated to the extent of hippocampal atrophy (and therefore potentially mediated by independent mechanisms) but influenced by chronicity and severity of the disorder.
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Affiliation(s)
- Barbara A.K. Kreilkamp
- Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, UK
- Department of Neuroradiology, The Walton Centre NHS Foundation Trust, Liverpool, UK
| | - Bernd Weber
- Department of Epileptology, University of Bonn, Germany
- Department of NeuroCognition/Imaging, Life&Brain Research Center, Bonn, Germany
| | - Mark P. Richardson
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
| | - Simon S. Keller
- Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, UK
- Department of Neuroradiology, The Walton Centre NHS Foundation Trust, Liverpool, UK
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK
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13
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Slinger G, Sinke MRT, Braun KPJ, Otte WM. White matter abnormalities at a regional and voxel level in focal and generalized epilepsy: A systematic review and meta-analysis. NEUROIMAGE-CLINICAL 2016; 12:902-909. [PMID: 27882296 PMCID: PMC5114611 DOI: 10.1016/j.nicl.2016.10.025] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 10/25/2016] [Accepted: 10/31/2016] [Indexed: 12/24/2022]
Abstract
Objective Since the introduction of diffusion tensor imaging, white matter abnormalities in epilepsy have been studied extensively. However, the affected areas reported, the extent of abnormalities and the association with relevant clinical parameters are highly variable. We aimed to obtain a more consistent estimate of white matter abnormalities and their association with clinical parameters in different epilepsy types. Methods We systematically searched for differences in white matter fractional anisotropy and mean diffusivity, at regional and voxel level, between people with epilepsy and healthy controls. Meta-analyses were used to quantify the directionality and extent of these differences. Correlations between white matter differences and age of epilepsy onset, duration of epilepsy and sex were assessed with meta-regressions. Results Forty-two studies, with 1027 people with epilepsy and 1122 controls, were included with regional data. Sixteen voxel-based studies were also included. People with temporal or frontal lobe epilepsy had significantly decreased fractional anisotropy (Δ –0.021, 95% confidence interval –0.026 to –0.016) and increased mean diffusivity (Δ0.026 × 10–3 mm2/s, 0.012 to 0.039) in the commissural, association and projection white matter fibers. White matter was much less affected in generalized epilepsy. White matter changes in people with focal epilepsy correlated with age at onset, epilepsy duration and sex. Significance This study provides a better estimation of white matter changes in different epilepsies. Effects are particularly found in people with focal epilepsy. Correlations with the duration of focal epilepsy support the hypothesis that these changes are, at least partly, a consequence of seizures and may warrant early surgery. Future studies need to guarantee adequate group sizes, as white matter differences in epilepsy are small. White matter FA and MD are more affected in focal than in generalized epilepsy. Epilepsy subtypes show distinct patterns of affected white matter regions. White matter integrity is altered both ipsi- and contralaterally in focal epilepsy. White matter changes in focal epilepsy seem to be a consequence of seizures.
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Affiliation(s)
- Geertruida Slinger
- Biomedical MR Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht, The Netherlands
| | - Michel R T Sinke
- Biomedical MR Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht, The Netherlands
| | - Kees P J Braun
- Department of Pediatric Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands
| | - Willem M Otte
- Biomedical MR Imaging and Spectroscopy Group, Center for Image Sciences, University Medical Center Utrecht, The Netherlands; Department of Pediatric Neurology, Brain Center Rudolf Magnus, University Medical Center Utrecht, The Netherlands
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14
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Chen NC, Chuang YC, Huang CW, Lui CC, Lee CC, Hsu SW, Lin PH, Lu YT, Chang YT, Hsu CW, Chang CC. Interictal serum brain-derived neurotrophic factor level reflects white matter integrity, epilepsy severity, and cognitive dysfunction in chronic temporal lobe epilepsy. Epilepsy Behav 2016; 59:147-54. [PMID: 27152461 DOI: 10.1016/j.yebeh.2016.02.029] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 02/07/2016] [Accepted: 02/21/2016] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Most patients with temporal lobe epilepsy (TLE) have epileptic foci originating from the medial temporal lobe, particularly the hippocampus. Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin growth factor mainly expressed in the hippocampus, though it is not known whether the circulating level of BDNF reflects cognitive performance or white matter structural changes in chronic TLE. METHODS Thirty-four patients with TLE and 22 healthy controls were enrolled for standardized cognitive tests, diffusion tensor imaging, and serum BDNF measurement. The patients were further divided into a subgroup with unilateral TLE (n=23) and a subgroup with bilateral TLE (n=11) for clinical and neuroimaging comparisons. RESULTS There were significantly lower BDNF levels in the patients with TLE compared with the controls, with significance contributed mainly from the subgroup with bilateral TLE, which also had more frequent seizures. The BDNF levels correlated with epilepsy duration (σ=-0.355; p=0.040) and fractional anisotropy (FA) in the left temporal lobe, left thalamus, and right hippocampus. Using a regression model, BDNF level predicted verbal memory score. Further, design fluency scores were predicted by serum BDNF level via the interactions with left temporal FA. CONCLUSIONS Serum BDNF levels reflected longer epilepsy duration, impaired white matter integrity, and poor cognitive function in patients with chronic TLE.
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Affiliation(s)
- Nai-Ching Chen
- Cognition and Aging Center, Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan; Department of Health and Beauty, Shu-Zen College of Medicine and Management, Taiwan
| | - Yao-Chung Chuang
- Cognition and Aging Center, Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan; Department of Neurology, Faculty of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chi-Wei Huang
- Cognition and Aging Center, Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan; Department of Health and Beauty, Shu-Zen College of Medicine and Management, Taiwan
| | - Chun-Chung Lui
- Department of Radiology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Chen-Chang Lee
- Department of Radiology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Shih-Wei Hsu
- Department of Radiology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Pin-Hsuan Lin
- Department of Health and Beauty, Shu-Zen College of Medicine and Management, Taiwan
| | - Yan-Ting Lu
- Cognition and Aging Center, Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Ya-Ting Chang
- Cognition and Aging Center, Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan; Department of Health and Beauty, Shu-Zen College of Medicine and Management, Taiwan
| | - Che-Wei Hsu
- Cognition and Aging Center, Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan
| | - Chiung-Chih Chang
- Cognition and Aging Center, Department of Neurology, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan.
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15
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Wirsich J, Perry A, Ridley B, Proix T, Golos M, Bénar C, Ranjeva JP, Bartolomei F, Breakspear M, Jirsa V, Guye M. Whole-brain analytic measures of network communication reveal increased structure-function correlation in right temporal lobe epilepsy. NEUROIMAGE-CLINICAL 2016; 11:707-718. [PMID: 27330970 PMCID: PMC4909094 DOI: 10.1016/j.nicl.2016.05.010] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 03/15/2016] [Accepted: 05/18/2016] [Indexed: 12/13/2022]
Abstract
The in vivo structure-function relationship is key to understanding brain network reorganization due to pathologies. This relationship is likely to be particularly complex in brain network diseases such as temporal lobe epilepsy, in which disturbed large-scale systems are involved in both transient electrical events and long-lasting functional and structural impairments. Herein, we estimated this relationship by analyzing the correlation between structural connectivity and functional connectivity in terms of analytical network communication parameters. As such, we targeted the gradual topological structure-function reorganization caused by the pathology not only at the whole brain scale but also both in core and peripheral regions of the brain. We acquired diffusion (dMRI) and resting-state fMRI (rsfMRI) data in seven right-lateralized TLE (rTLE) patients and fourteen healthy controls and analyzed the structure-function relationship by using analytical network communication metrics derived from the structural connectome. In rTLE patients, we found a widespread hypercorrelated functional network. Network communication analysis revealed greater unspecific branching of the shortest path (search information) in the structural connectome and a higher global correlation between the structural and functional connectivity for the patient group. We also found evidence for a preserved structural rich-club in the patient group. In sum, global augmentation of structure-function correlation might be linked to a smaller functional repertoire in rTLE patients, while sparing the central core of the brain which may represent a pathway that facilitates the spread of seizures.
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Key Words
- CSD, constrained spherical deconvolution
- CSF, cerebrospinal fluid
- FA, fractional anisotropy
- FCA, analytic functional connectivity
- FCD, functional connectivity dynamics
- FOD, fiber orientation distribution
- Functional connectivity
- NBS, network based statistics
- Network based statistics
- Network communication
- Rich club
- Structural connectivity
- Temporal lobe epilepsy
- dMRI, diffusion magnetic resonance imaging
- rTLE, right temporal lobe epilepsy
- rsfMRI, resting state functional magnetic resonance imaging
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Affiliation(s)
- Jonathan Wirsich
- Aix-Marseille Université, CNRS, CRMBM UMR 7339, 13385 Marseille, France; APHM, Hôpitaux de la Timone, Pôle d'imagerie Médicale, CEMEREM, 13005 Marseille, France; Aix-Marseille Université, Institut de Neurosciences des Systèmes, 13385 Marseille, France; INSERM, UMR_S 1106, 13385 Marseille, France.
| | - Alistair Perry
- Centre for Healthy Brain Ageing (CHeBA), School of Psychiatry, University of New South Wales, Sydney, NSW, Australia; School of Psychiatry, University of New South Wales, Sydney, NSW 2052, Australia; Systems Neuroscience Group, QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, QLD 4006, Australia.
| | - Ben Ridley
- Aix-Marseille Université, CNRS, CRMBM UMR 7339, 13385 Marseille, France; APHM, Hôpitaux de la Timone, Pôle d'imagerie Médicale, CEMEREM, 13005 Marseille, France.
| | - Timothée Proix
- Aix-Marseille Université, Institut de Neurosciences des Systèmes, 13385 Marseille, France; INSERM, UMR_S 1106, 13385 Marseille, France.
| | - Mathieu Golos
- Aix-Marseille Université, Institut de Neurosciences des Systèmes, 13385 Marseille, France; INSERM, UMR_S 1106, 13385 Marseille, France.
| | - Christian Bénar
- Aix-Marseille Université, Institut de Neurosciences des Systèmes, 13385 Marseille, France; INSERM, UMR_S 1106, 13385 Marseille, France.
| | - Jean-Philippe Ranjeva
- Aix-Marseille Université, CNRS, CRMBM UMR 7339, 13385 Marseille, France; APHM, Hôpitaux de la Timone, Pôle d'imagerie Médicale, CEMEREM, 13005 Marseille, France.
| | - Fabrice Bartolomei
- Aix-Marseille Université, Institut de Neurosciences des Systèmes, 13385 Marseille, France; INSERM, UMR_S 1106, 13385 Marseille, France; APHM, Hôpitaux de la Timone, Pôle de Neurosciences Cliniques, Service de Neurophysiologie Clinique, 13005 Marseille, France.
| | - Michael Breakspear
- School of Psychiatry, University of New South Wales, Sydney, NSW 2052, Australia; Systems Neuroscience Group, QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, QLD 4006, Australia; Metro North Mental Health Services, Brisbane, QLD 4006, Australia.
| | - Viktor Jirsa
- Aix-Marseille Université, Institut de Neurosciences des Systèmes, 13385 Marseille, France; INSERM, UMR_S 1106, 13385 Marseille, France.
| | - Maxime Guye
- Aix-Marseille Université, CNRS, CRMBM UMR 7339, 13385 Marseille, France; APHM, Hôpitaux de la Timone, Pôle d'imagerie Médicale, CEMEREM, 13005 Marseille, France.
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16
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Individual feature maps: a patient-specific analysis tool with applications in temporal lobe epilepsy. Int J Comput Assist Radiol Surg 2015; 11:53-71. [PMID: 26567092 DOI: 10.1007/s11548-015-1258-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 07/01/2015] [Indexed: 10/22/2022]
Abstract
PURPOSE MRI-based diagnosis of temporal lobe epilepsy (TLE) can be challenging when pathology is not visually evident due to low image contrast or small lesion size. Computer-assisted analyses are able to detect lesions common in a specific patient population, but most techniques do not address clinically relevant individual pathologies resulting from the heterogeneous etiology of the disease. We propose a novel method to supplement the radiological inspection of TLE patients (n = 15) providing patient-specific quantitative assessment. METHOD Regions of interest are defined across the brain and volume, relaxometry, and diffusion features are extracted from them. Statistical comparisons between individual patients and a healthy control group (n = 17) are performed on these features, identifying and visualizing significant differences through individual feature maps. Four maps are created per patient showing differences in intensity, asymmetry, and volume. RESULTS Detailed reports were generated per patient. Abnormal hippocampal intensity and volume differences were detected in all patients diagnosed with mesial temporal sclerosis (MTS). Abnormal intensities in the temporal cortex were identified in patients with no MTS. A laterality score correctly distinguished left from right TLE in 12 out of 15 patients. CONCLUSION The proposed focus on subject-specific quantitative changes has the potential of improving the assessment of TLE patients using MRI techniques, possibly even redefining current imaging protocols for TLE.
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17
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Whelan CD, Alhusaini S, O'Hanlon E, Cheung M, Iyer PM, Meaney JF, Fagan AJ, Boyle G, Delanty N, Doherty CP, Cavalleri GL. White matter alterations in patients with MRI-negative temporal lobe epilepsy and their asymptomatic siblings. Epilepsia 2015; 56:1551-61. [DOI: 10.1111/epi.13103] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2015] [Indexed: 12/27/2022]
Affiliation(s)
- Christopher D. Whelan
- Molecular and Cellular Therapeutics Department; Royal College of Surgeons in Ireland; Dublin Ireland
- Imaging Genetics Center; Mark and Mary Stevens Neuroimaging and Informatics Institute; University of Southern California; Los Angeles California U.S.A
| | - Saud Alhusaini
- Molecular and Cellular Therapeutics Department; Royal College of Surgeons in Ireland; Dublin Ireland
| | - Erik O'Hanlon
- Department of Psychiatry; Royal College of Surgeons in Ireland; Dublin 2 Ireland
| | - Maria Cheung
- Molecular and Cellular Therapeutics Department; Royal College of Surgeons in Ireland; Dublin Ireland
| | | | - James F. Meaney
- Centre for Advanced Medical Imaging (CAMI); St. James's Hospital; Dublin Ireland
| | - Andrew J. Fagan
- Centre for Advanced Medical Imaging (CAMI); St. James's Hospital; Dublin Ireland
| | - Gerard Boyle
- Centre for Advanced Medical Imaging (CAMI); St. James's Hospital; Dublin Ireland
| | - Norman Delanty
- Molecular and Cellular Therapeutics Department; Royal College of Surgeons in Ireland; Dublin Ireland
- Division of Neurology; Beaumont Hospital; Dublin Ireland
| | | | - Gianpiero L. Cavalleri
- Molecular and Cellular Therapeutics Department; Royal College of Surgeons in Ireland; Dublin Ireland
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18
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Bonilha L, Keller SS. Quantitative MRI in refractory temporal lobe epilepsy: relationship with surgical outcomes. Quant Imaging Med Surg 2015; 5:204-24. [PMID: 25853080 DOI: 10.3978/j.issn.2223-4292.2015.01.01] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 01/07/2015] [Indexed: 11/14/2022]
Abstract
Medically intractable temporal lobe epilepsy (TLE) remains a serious health problem. Across treatment centers, up to 40% of patients with TLE will continue to experience persistent postoperative seizures at 2-year follow-up. It is unknown why such a large number of patients continue to experience seizures despite being suitable candidates for resective surgery. Preoperative quantitative MRI techniques may provide useful information on why some patients continue to experience disabling seizures, and may have the potential to develop prognostic markers of surgical outcome. In this article, we provide an overview of how quantitative MRI morphometric and diffusion tensor imaging (DTI) data have improved the understanding of brain structural alterations in patients with refractory TLE. We subsequently review the studies that have applied quantitative structural imaging techniques to identify the neuroanatomical factors that are most strongly related to a poor postoperative prognosis. In summary, quantitative imaging studies strongly suggest that TLE is a disorder affecting a network of neurobiological systems, characterized by multiple and inter-related limbic and extra-limbic network abnormalities. The relationship between brain alterations and postoperative outcome are less consistent, but there is emerging evidence suggesting that seizures are less likely to remit with surgery when presurgical abnormalities are observed in the connectivity supporting brain regions serving as network nodes located outside the resected temporal lobe. Future work, possibly harnessing the potential from multimodal imaging approaches, may further elucidate the etiology of persistent postoperative seizures in patients with refractory TLE. Furthermore, quantitative imaging techniques may be explored to provide individualized measures of postoperative seizure freedom outcome.
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Affiliation(s)
- Leonardo Bonilha
- 1 Department of Neurology and Neurosurgery, Medical University of South Carolina, Charleston, SC 29425, USA ; 2 Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK ; 3 Department of Radiology, The Walton Centre NHS Foundation Trust, Liverpool, UK ; 4 Department of Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Simon S Keller
- 1 Department of Neurology and Neurosurgery, Medical University of South Carolina, Charleston, SC 29425, USA ; 2 Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, Liverpool, UK ; 3 Department of Radiology, The Walton Centre NHS Foundation Trust, Liverpool, UK ; 4 Department of Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
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19
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Rodríguez-Cruces R, Concha L. White matter in temporal lobe epilepsy: clinico-pathological correlates of water diffusion abnormalities. Quant Imaging Med Surg 2015; 5:264-78. [PMID: 25853084 DOI: 10.3978/j.issn.2223-4292.2015.02.06] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/14/2015] [Indexed: 02/05/2023]
Abstract
Using magnetic resonance imaging, it is possible to measure the behavior of diffusing water molecules, and the metrics derived can be used as indirect markers of tissue micro-architectural properties. Numerous reports have demonstrated that patients with temporal lobe epilepsy (TLE) have water diffusion abnormalities in several white matter structures located within and beyond the epileptogenic temporal lobe, showing that TLE is not a focal disorder, but rather a brain network disease. Differences in severity and spatial extent between patients with or without mesial temporal sclerosis (MTS), as well as differences related to hemispheric seizure onset, are suggestive of different pathophysiological mechanisms behind different forms of TLE, which in turn result in specific cognitive disabilities. The biological interpretation of diffusion abnormalities is based on a wealth of information from animal models of white matter damage, and is supported by recent reports that directly correlate diffusion metrics with histological characteristics of surgical specimens of TLE patients. Thus, there is now more evidence showing that the increased mean diffusivity (MD) and concomitant reductions of diffusion anisotropy that are frequently observed in several white matter bundles in TLE patients reflect reduced axonal density (increased extra-axonal space) due to smaller-caliber axons, and abnormalities in the myelin sheaths of the remaining axons. Whether these histological and diffusion features are a predisposing factor for epilepsy or secondary to seizures is still uncertain; some reports suggest the latter. This article summarizes recent findings in this field and provides a synopsis of the histological features seen most frequently in post-surgical specimens of TLE patients in an effort to aid the interpretation of white matter diffusion abnormalities.
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Affiliation(s)
- Raúl Rodríguez-Cruces
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, México
| | - Luis Concha
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, México
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20
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Wagner G, De la Cruz F, Schachtzabel C, Güllmar D, Schultz CC, Schlösser RG, Bär KJ, Koch K. Structural and functional dysconnectivity of the fronto-thalamic system in schizophrenia: a DCM-DTI study. Cortex 2015; 66:35-45. [PMID: 25797657 DOI: 10.1016/j.cortex.2015.02.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/20/2015] [Accepted: 02/11/2015] [Indexed: 01/20/2023]
Abstract
Evidence suggests that cognitive deficits are a core feature of schizophrenia. The concept of "cognitive dysmetria" has been introduced to characterize disintegration of fronto-thalamic-cerebellar circuitry which constitutes a key network for a variety of neuropsychological symptoms in schizophrenia. The present multimodal study aimed at investigating effective and structural connectivity of the fronto-thalamic circuitry in schizophrenia. fMRI effective connectivity analysis using dynamic causal modeling (DCM) and diffusion tensor imaging (DTI) were combined to examine cognitive control processes in 38 patients with schizophrenia and 40 matched healthy controls. Significantly lower fractional anisotropy (FA) was detected in patients in the right anterior limb of the internal capsule (ALIC), the right thalamus and the right corpus callosum. During Stroop task performance patients demonstrated significantly lower activation relative to healthy controls in a predominantly right lateralized fronto-thalamo-cerebellar network. An abnormal effective connectivity was observed in the right connections between thalamus, anterior cingulate and dorsolateral prefrontal cortex. FA in the ALIC was significantly correlated with the thalamic BOLD signal, cognitive performance and fronto-thalamic effective connectivity in patients. Present data provide evidence for the notion of a structural and functional defect in the fronto-thalamo-cerebellar circuitry, which may be the basis of specific cognitive impairments in schizophrenia.
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Affiliation(s)
- Gerd Wagner
- Department of Psychiatry and Psychotherapy, Jena University Hospital, Germany.
| | | | | | - Daniel Güllmar
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology I, Jena University Hospital, Germany
| | - C Christoph Schultz
- Department of Psychiatry and Psychotherapy, Jena University Hospital, Germany
| | - Ralf G Schlösser
- Department of Psychiatry and Psychotherapy, Jena University Hospital, Germany
| | - Karl-Jürgen Bär
- Department of Psychiatry and Psychotherapy, Jena University Hospital, Germany
| | - Kathrin Koch
- Department of Neuroradiology, Klinikum rechts der Isar, Technische Universität München TUM, Munich, Germany; TUM-Neuroimaging Center of Klinikum rechts der Isar, Technische Universität München TUM, Munich, Germany
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21
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Bonilha L, Lee CY, Jensen JH, Tabesh A, Spampinato MV, Edwards JC, Breedlove J, Helpern JA. Altered microstructure in temporal lobe epilepsy: a diffusional kurtosis imaging study. AJNR Am J Neuroradiol 2014; 36:719-24. [PMID: 25500311 DOI: 10.3174/ajnr.a4185] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Accepted: 10/19/2014] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Temporal lobe epilepsy is associated with regional abnormalities in tissue microstructure, as demonstrated by DTI. However, the full extent of these abnormalities has not yet been defined because DTI conveys only a fraction of the information potentially accessible with diffusion MR imaging. In this study, we assessed the added value of diffusional kurtosis imaging, an extension of DTI, to evaluate microstructural abnormalities in patients with temporal lobe epilepsy. MATERIALS AND METHODS Thirty-two patients with left temporal lobe epilepsy and 36 matched healthy subjects underwent diffusion MR imaging. To evaluate abnormalities in patients, we performed voxelwise analyses, assessing DTI-derived mean diffusivity, fractional anisotropy, and diffusional kurtosis imaging-derived mean diffusional kurtosis, as well as diffusional kurtosis imaging and DTI-derived axial and radial components, comparing patients with controls. RESULTS We replicated findings from previous studies demonstrating a reduction in fractional anisotropy and an increase in mean diffusivity preferentially affecting, but not restricted to, the temporal lobe ipsilateral to seizure onset. We also noted a pronounced pattern of diffusional kurtosis imaging abnormalities in gray and white matter tissues, often extending into regions that were not detected as abnormal by DTI measures. CONCLUSIONS Diffusional kurtosis is a sensitive and complementary measure of microstructural compromise in patients with temporal lobe epilepsy. It provides additional information regarding the anatomic distribution and degree of damage in this condition. Diffusional kurtosis imaging may be used as a biomarker for disease severity, clinical phenotypes, and treatment monitoring in epilepsy.
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Affiliation(s)
- L Bonilha
- From the Departments of Neurology and Neurosurgery (L.B., J.C.E.) Comprehensive Epilepsy Center (L.B., J.C.E., J.B.) Center for Biomedical Imaging (L.B., C.-Y.L., J.H.J., A.T., M.V.S.), Medical University of South Carolina, Charleston, South Carolina.
| | - C-Y Lee
- Radiology and Radiological Science (C.-Y.L., J.H.J., A.T., M.V.S., J.A.H.) Center for Biomedical Imaging (L.B., C.-Y.L., J.H.J., A.T., M.V.S.), Medical University of South Carolina, Charleston, South Carolina
| | - J H Jensen
- Radiology and Radiological Science (C.-Y.L., J.H.J., A.T., M.V.S., J.A.H.) Center for Biomedical Imaging (L.B., C.-Y.L., J.H.J., A.T., M.V.S.), Medical University of South Carolina, Charleston, South Carolina
| | - A Tabesh
- Radiology and Radiological Science (C.-Y.L., J.H.J., A.T., M.V.S., J.A.H.) Center for Biomedical Imaging (L.B., C.-Y.L., J.H.J., A.T., M.V.S.), Medical University of South Carolina, Charleston, South Carolina
| | - M V Spampinato
- Radiology and Radiological Science (C.-Y.L., J.H.J., A.T., M.V.S., J.A.H.) Center for Biomedical Imaging (L.B., C.-Y.L., J.H.J., A.T., M.V.S.), Medical University of South Carolina, Charleston, South Carolina
| | - J C Edwards
- From the Departments of Neurology and Neurosurgery (L.B., J.C.E.) Comprehensive Epilepsy Center (L.B., J.C.E., J.B.)
| | - J Breedlove
- Comprehensive Epilepsy Center (L.B., J.C.E., J.B.)
| | - J A Helpern
- Radiology and Radiological Science (C.-Y.L., J.H.J., A.T., M.V.S., J.A.H.)
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Chaudhary UJ, Duncan JS. Applications of blood-oxygen-level-dependent functional magnetic resonance imaging and diffusion tensor imaging in epilepsy. Neuroimaging Clin N Am 2014; 24:671-94. [PMID: 25441507 DOI: 10.1016/j.nic.2014.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The lifetime prevalence of epilepsy ranges from 2.7 to 12.4 per 1000 in Western countries. Around 30% of patients with epilepsy remain refractory to antiepileptic drugs and continue to have seizures. Noninvasive imaging techniques such as functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) have helped to better understand mechanisms of seizure generation and propagation, and to localize epileptic, eloquent, and cognitive networks. In this review, the clinical applications of fMRI and DTI are discussed, for mapping cognitive and epileptic networks and organization of white matter tracts in individuals with epilepsy.
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Affiliation(s)
- Umair J Chaudhary
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK; MRI Unit, Epilepsy Society, Chesham Lane, Chalfont St Peter, Buckinghamshire SL9 0RJ, UK.
| | - John S Duncan
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK; MRI Unit, Epilepsy Society, Chesham Lane, Chalfont St Peter, Buckinghamshire SL9 0RJ, UK; Queen Square Division, UCLH NHS Foundation Trust, Queen Square, London WC1N 3BG, UK
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23
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Deppe M, Marinell J, Krämer J, Duning T, Ruck T, Simon OJ, Zipp F, Wiendl H, Meuth SG. Increased cortical curvature reflects white matter atrophy in individual patients with early multiple sclerosis. NEUROIMAGE-CLINICAL 2014; 6:475-87. [PMID: 25610761 PMCID: PMC4299934 DOI: 10.1016/j.nicl.2014.02.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Revised: 02/14/2014] [Accepted: 02/19/2014] [Indexed: 11/21/2022]
Abstract
Objective White matter atrophy occurs independently of lesions in multiple sclerosis. In contrast to lesion detection, the quantitative assessment of white matter atrophy in individual patients has been regarded as a major challenge. We therefore tested the hypothesis that white matter atrophy (WMA) is present at the very beginning of multiple sclerosis (MS) and in virtually each individual patient. To find a new sensitive and robust marker for WMA we investigated the relationship between cortical surface area, white matter volume (WMV), and whole-brain-surface-averaged rectified cortical extrinsic curvature. Based on geometrical considerations we hypothesized that cortical curvature increases if WMV decreases and the cortical surface area remains constant. Methods In total, 95 participants were enrolled: 30 patients with early and advanced relapsing–remitting MS; 30 age-matched control subjects; 30 patients with Alzheimer's disease (AD) and 5 patients with clinically isolated syndrome (CIS). Results 29/30 MS and 5/5 CIS patients showed lower WMV than expected from their intracranial volume (average reduction 13.0%, P < 10− 10), while the cortical surface area showed no significant differences compared with controls. The estimated WMV reductions were correlated with an increase in cortical curvature (R = 0.62, P = 0.000001). Discriminant analysis revealed that the curvature increase was highly specific for the MS and CIS groups (96.7% correct assignments between MS and control groups) and was significantly correlated with reduction of white matter fractional anisotropy, as determined by diffusion tensor imaging and the Expanded Disability Status Scale. As expected by the predominant gray and WM degeneration in AD, no systematic curvature increase was observed in AD. Conclusion Whole-brain-averaged cortical extrinsic curvature appears to be a specific and quantitative marker for a WMV–cortex disproportionality and allows us to assess “pure” WMA without being confounded by intracranial volume. WMA seems to be a characteristic symptom in early MS and can already occur in patients with CIS and should thus be considered in future MS research and clinical studies. We suggest cortical curvature as marker for selective white matter atrophy (WMA). This geometric marker is more specific and sensitive than volumetric measures. It is not confounded by intra-cranial volume, age, and gender. WMA seems to be a characteristic symptom in early multiple sclerosis. WMA can be also detected in patients with a clinical isolated symptom.
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Key Words
- 3D, three-dimensional
- CI, confidence interval
- CIS, clinically isolated syndrome
- Cortex
- Cortical curvature
- DTI, diffusion tensor imaging
- EDSS, Expanded Disability Status Scale
- EVAL, Münster Neuroimaging Evaluation System
- FA, fractional anisotropy
- FOV, field of view
- GM, gray matter
- GMV, gray matter volume
- GRAPPA, generalized autocalibrating partially parallel acquisition
- ICV, intracranial volume
- Imaging
- MRI
- Multiple sclerosis
- ROI, region of interest
- SD, standard deviation
- TE, echo time
- TR, repetition time
- TSE, turbo spin-echo
- WM, white matter
- WMV, white matter volume
- eWMV, estimated white matter volume
- ΔWMV, WMV − eWMV
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Affiliation(s)
- Michael Deppe
- Department of Neurology, Westfälische Wilhelms University, Münster, Germany
| | - Jasmin Marinell
- Department of Neurology, Westfälische Wilhelms University, Münster, Germany
| | - Julia Krämer
- Department of Neurology, Westfälische Wilhelms University, Münster, Germany
| | - Thomas Duning
- Department of Neurology, Westfälische Wilhelms University, Münster, Germany
| | - Tobias Ruck
- Department of Neurology, Westfälische Wilhelms University, Münster, Germany
| | - Ole J Simon
- Department of Neurology, Westfälische Wilhelms University, Münster, Germany
| | - Frauke Zipp
- Department of Neurology, Rhine Main Neuroscience Network, Johannes Gutenberg University Medical Centre Mainz, Germany
| | - Heinz Wiendl
- Department of Neurology, Westfälische Wilhelms University, Münster, Germany
| | - Sven G Meuth
- Department of Neurology, Westfälische Wilhelms University, Münster, Germany
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Abstract
Limbic epilepsy refers to a condition that consists of epileptic seizures that originate in or preferentially involve the limbic system. The majority of cases are medically refractory, necessitating surgical resection when possible. However, even resection of structures thought to be responsible for seizure generation may not leave a patient seizure free. While mesial temporal lobe limbic structures are centrally involved, there is growing evidence that the epileptogenic network consists of a broader area, involving structures outside of the temporal lobe and the limbic system. Information on structural, functional, and metabolic connectivity in patients with limbic epilepsy is available from a large body of studies employing methods such as MRI, EEG, MEG, fMRI, PET, and SPECT scanning, implicating the involvement of various brain regions in the epileptogenic network. To date, there are no consistent and conclusive findings to define the exact boundaries of this network, but it is possible that in the future studies of network connectivity in the individual patient may allow more tailored treatment and prognosis in terms of surgical resection.
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Concomitant fractional anisotropy and volumetric abnormalities in temporal lobe epilepsy: cross-sectional evidence for progressive neurologic injury. PLoS One 2012; 7:e46791. [PMID: 23071638 PMCID: PMC3469561 DOI: 10.1371/journal.pone.0046791] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 09/06/2012] [Indexed: 11/19/2022] Open
Abstract
Background In patients with temporal lobe epilepsy and associated hippocampal sclerosis (TLEhs) there are brain abnormalities extending beyond the presumed epileptogenic zone as revealed separately in conventional magnetic resonance imaging (MRI) and MR diffusion tensor imaging (DTI) studies. However, little is known about the relation between macroscopic atrophy (revealed by volumetric MRI) and microstructural degeneration (inferred by DTI). Methodology/Principal Findings For 62 patients with unilateral TLEhs and 68 healthy controls, we determined volumes and mean fractional anisotropy (FA) of ipsilateral and contralateral brain structures from T1-weighted and DTI data, respectively. We report significant volume atrophy and FA alterations of temporal lobe, subcortical and callosal regions, which were more diffuse and bilateral in patients with left TLEhs relative to right TLEhs. We observed significant relationships between volume loss and mean FA, particularly of the thalamus and putamen bilaterally. When corrected for age, duration of epilepsy was significantly correlated with FA loss of an anatomically plausible route - including ipsilateral parahippocampal gyrus and temporal lobe white matter, the thalamus bilaterally, and posterior regions of the corpus callosum that contain temporal lobe fibres - that may be suggestive of progressive brain degeneration in response to recurrent seizures. Conclusions/Significance Chronic TLEhs is associated with interrelated DTI-derived and volume-derived brain degenerative abnormalities that are influenced by the duration of the disorder and the side of seizure onset. This work confirms previously contradictory findings by employing multi-modal imaging techniques in parallel in a large sample of patients.
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Liu M, Concha L, Lebel C, Beaulieu C, Gross DW. Mesial temporal sclerosis is linked with more widespread white matter changes in temporal lobe epilepsy. NEUROIMAGE-CLINICAL 2012; 1:99-105. [PMID: 24179742 PMCID: PMC3757721 DOI: 10.1016/j.nicl.2012.09.010] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 09/19/2012] [Accepted: 09/22/2012] [Indexed: 12/04/2022]
Abstract
Temporal lobe epilepsy patients with unilateral mesial temporal sclerosis (TLE + uMTS) have been demonstrated to have extensive white matter abnormalities both ipsilateral and contralateral to the seizure onset zone. However, comparatively less is known about the white matter integrity of TLE patients without MTS (non-lesional TLE, nl-TLE). The purpose of the study was to investigate the diffusion properties of thirteen major white matter tracts in patients with TLE + uMTS and nl-TLE. Diffusion tensor imaging (DTI) was performed on 23 TLE + uMTS (15 left MTS and 8 right MTS), 15 nl-TLE and 21 controls. Thirteen tracts were delineated by tractography and their diffusion parameters compared for the two TLE groups relative to controls, with left and right hemispheres combined per tract. A subgroup analysis investigated left and right MTS separately. Compared to controls, reduced anisotropy was detected in ten tracts for TLE + uMTS, but only the parahippocampal cingulum and tapetum for nl-TLE. Right MTS subgroup showed reduced anisotropy in 7 tracts bilaterally (3 limbic, 3 association, 1 projection) and 2 tracts ipsilaterally (1 association, 1 projection) and the body of the corpus callosum whereas the left MTS subgroup showed reduced anisotropy in 4 tracts bilaterally (2 limbic, 1 association, 1 projection) and 2 tracts ipsilaterally (1 limbic, 1 association). Diffusion abnormalities in tracts were observed within and beyond the temporal lobe in TLE + uMTS and were more widespread than in nl-TLE. Patients with right MTS had more extensive, bilateral abnormalities in comparison to left MTS. These findings suggest different dysfunctional networks in TLE patients with and without MTS.
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Affiliation(s)
- Min Liu
- Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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Progression of microstructural putamen alterations in a case of symptomatic recurrent seizures using diffusion tensor imaging. Seizure 2012; 21:478-81. [PMID: 22546528 PMCID: PMC3778939 DOI: 10.1016/j.seizure.2012.03.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 02/13/2012] [Accepted: 03/29/2012] [Indexed: 11/24/2022] Open
Abstract
Microstructural alterations of the putamen were recently reported in patients with partial and generalized epilepsy disorders. However, it is unknown whether these alterations pre-exist or are secondary to recurrent seizures. Here we investigated the progression of putamen fractional anisotropy (FA) alterations in a case of recurrent psychomotor seizures using longitudinal diffusion tensor imaging (DTI) shortly before (DTI-1) and after a psychomotor seizure (DTI-2). We obtained FA values of a hypothesis-guided putamen region-of-interest (ROI) and seven exploratory ROIs. FA values from both DTIs were compared with reference values from 19 controls. Relative to controls, the patient's putamen FA was increased at DTI-1 (13% left putamen, 7% right putamen), an effect that was exacerbated at DTI-2 (24% left putamen (p < 0.05), 20% right putamen). In the exploratory ROIs we found FA reductions in the corticospinal tract, temporal lobe, and occipital lobe (p < 0.05) relative to controls at DTI-1 and DTI-2. In contrast to the putamen, all exploratory ROIs showed no relevant FA change between DTI-1 and DTI-2. These results suggest that recurrent seizures may lead to progressive microstructural putamen alterations.
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