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Huang H, Zhang M, Zhao Y, Li Y, Jin W, Guo R, Liu W, Cai B, Li J, Yuan S, Huang X, Lin X, Liang ZP, Li B, Luo J. Simultaneous high-resolution whole-brain MR spectroscopy and [ 18F]FDG PET for temporal lobe epilepsy. Eur J Nucl Med Mol Imaging 2024; 51:721-733. [PMID: 37823910 DOI: 10.1007/s00259-023-06465-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Accepted: 09/28/2023] [Indexed: 10/13/2023]
Abstract
PURPOSE Precise lateralizing the epileptogenic zone in patients with drug-resistant mesial temporal lobe epilepsy (mTLE) remains challenging, particularly when routine MRI scans are inconclusive (MRI-negative). This study aimed to investigate the synergy of fast, high-resolution, whole-brain MRSI in conjunction with simultaneous [18F]FDG PET for the lateralization of mTLE. METHODS Forty-eight drug-resistant mTLE patients (M/F 31/17, age 12-58) underwent MRSI and [18F]FDG PET on a hybrid PET/MR scanner. Lateralization of mTLE was evaluated by visual inspection and statistical classifiers of metabolic mappings against routine MRI. Additionally, this study explored how disease status influences the associations between altered N-acetyl aspartate (NAA) and FDG uptake using hierarchical moderated multiple regression. RESULTS The high-resolution whole-brain MRSI data offers metabolite maps at comparable resolution to [18F]FDG PET. Visual examinations of combined MRSI and [18F]FDG PET showed an mTLE lateralization accuracy rate of 91.7% in a 48-patient cohort, surpassing routine MRI (52.1%). Notably, out of 23 MRI-negative mTLE, combined MRSI and [18F]FDG PET helped detect 19 cases. Logistical regression models combining hippocampal NAA level and FDG uptake improved lateralization performance (AUC=0.856), while further incorporating extrahippocampal regions such as amygdala, thalamus, and superior temporal gyrus increased the AUC to 0.939. Concurrent MRSI/PET revealed a moderating influence of disease duration and hippocampal atrophy on the association between hippocampal NAA and glucose uptake, providing significant new insights into the disease's trajectory. CONCLUSION This paper reports the first metabolic imaging study using simultaneous high-resolution MRSI and [18F]FDG PET, which help visualize MRI-unidentifiable lesions and may thus advance diagnostic tools and management strategies for drug-resistant mTLE.
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Affiliation(s)
- Hui Huang
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Miao Zhang
- Department of Nuclear Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Yibo Zhao
- Beckman Institute for Advanced Sciences and Technology, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA
| | - Yudu Li
- Beckman Institute for Advanced Sciences and Technology, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA
- National Center for Supercomputing Applications, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA
| | - Wen Jin
- Beckman Institute for Advanced Sciences and Technology, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA
| | - Rong Guo
- Beckman Institute for Advanced Sciences and Technology, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA
- Siemens Medical Solutions USA, Inc, Urbana, IL, 61801, USA
| | - Wei Liu
- Department of Neurosurgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Bingyang Cai
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jiwei Li
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Siyu Yuan
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xinyun Huang
- Department of Nuclear Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Xiaozhu Lin
- Department of Nuclear Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Zhi-Pei Liang
- Beckman Institute for Advanced Sciences and Technology, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA
| | - Biao Li
- Department of Nuclear Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China.
| | - Jie Luo
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
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Colon A, Osch MV, Buijs M, Grond J, Hillebrand A, Schijns O, Wagner G, Ossenblok P, Hofman P, Buchem M, Boon P. MEG-guided analysis of 7T-MRI in patients with epilepsy. Seizure 2018; 60:29-38. [DOI: 10.1016/j.seizure.2018.05.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 05/22/2018] [Accepted: 05/24/2018] [Indexed: 11/26/2022] Open
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van Veenendaal TM, Backes WH, Tse DHY, Scheenen TWJ, Klomp DW, Hofman PAM, Rouhl RPW, Vlooswijk MCG, Aldenkamp AP, Jansen JFA. High field imaging of large-scale neurotransmitter networks: Proof of concept and initial application to epilepsy. Neuroimage Clin 2018; 19:47-55. [PMID: 30035001 PMCID: PMC6051471 DOI: 10.1016/j.nicl.2018.04.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 03/22/2018] [Accepted: 04/01/2018] [Indexed: 01/05/2023]
Abstract
The brain can be considered a network, existing of multiple interconnected areas with various functions. MRI provides opportunities to map the large-scale network organization of the brain. We tap into the neurobiochemical dimension of these networks, as neuronal functioning and signal trafficking across distributed brain regions relies on the release and presence of neurotransmitters. Using high-field MR spectroscopic imaging at 7.0 T, we obtained a non-invasive snapshot of the spatial distribution of the neurotransmitters GABA and glutamate, and investigated interregional associations of these neurotransmitters. We demonstrate that interregional correlations of glutamate and GABA concentrations can be conceptualized as networks. Furthermore, patients with epilepsy display an increased number of glutamate and GABA connections and increased average strength of the GABA network. The increased glutamate and GABA connectivity in epilepsy might indicate a disrupted neurotransmitter balance. In addition to epilepsy, the 'neurotransmitter networks' concept might also provide new insights for other neurological diseases.
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Affiliation(s)
- Tamar M van Veenendaal
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center (MUMC+), The Netherlands; School for Mental Health and Neuroscience, Maastricht University, The Netherlands
| | - Walter H Backes
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center (MUMC+), The Netherlands; School for Mental Health and Neuroscience, Maastricht University, The Netherlands
| | - Desmond H Y Tse
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center (MUMC+), The Netherlands; Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, The Netherlands
| | - Tom W J Scheenen
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Dennis W Klomp
- Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Paul A M Hofman
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center (MUMC+), The Netherlands; School for Mental Health and Neuroscience, Maastricht University, The Netherlands; Academic Center for Epileptology Kempenhaeghe/MUMC+, Heeze and Maastricht, The Netherlands
| | - Rob P W Rouhl
- School for Mental Health and Neuroscience, Maastricht University, The Netherlands; Academic Center for Epileptology Kempenhaeghe/MUMC+, Heeze and Maastricht, The Netherlands; Department of Neurology, Maastricht University Medical Center, The Netherlands
| | - Marielle C G Vlooswijk
- School for Mental Health and Neuroscience, Maastricht University, The Netherlands; Academic Center for Epileptology Kempenhaeghe/MUMC+, Heeze and Maastricht, The Netherlands; Department of Neurology, Maastricht University Medical Center, The Netherlands
| | - Albert P Aldenkamp
- School for Mental Health and Neuroscience, Maastricht University, The Netherlands; Academic Center for Epileptology Kempenhaeghe/MUMC+, Heeze and Maastricht, The Netherlands; Department of Neurology, Maastricht University Medical Center, The Netherlands
| | - Jacobus F A Jansen
- Department of Radiology and Nuclear Medicine, Maastricht University Medical Center (MUMC+), The Netherlands; School for Mental Health and Neuroscience, Maastricht University, The Netherlands.
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Muhlhofer W, Tan Y, Mueller SG, Knowlton R. MRI
‐negative temporal lobe epilepsy—What do we know? Epilepsia 2017; 58:727-742. [DOI: 10.1111/epi.13699] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/11/2017] [Indexed: 01/01/2023]
Affiliation(s)
- Wolfgang Muhlhofer
- University of California San Francisco (UCSF) San Francisco California U.S.A
- University of Alabama Birmingham (UAB) Birmingham Alabama U.S.A
| | - Yee‐Leng Tan
- University of California San Francisco (UCSF) San Francisco California U.S.A
- National Neuroscience Institute Singapore Singapore
| | - Susanne G. Mueller
- University of California San Francisco (UCSF) San Francisco California U.S.A
- Center for Imaging of Neurodegenerative Diseases (CIND) San Francisco California U.S.A
- Department of Radiology UCSF San Francisco CaliforniaU.S.A
| | - Robert Knowlton
- University of California San Francisco (UCSF) San Francisco California U.S.A
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Tang Y, Xia W, Yu X, Zhou B, Luo C, Huang X, Chen Q, Gong Q, Zhou D. Short-term cerebral activity alterations after surgery in patients with unilateral mesial temporal lobe epilepsy associated with hippocampal sclerosis: A longitudinal resting-state fMRI study. Seizure 2017; 46:43-49. [DOI: 10.1016/j.seizure.2016.12.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 12/20/2016] [Accepted: 12/30/2016] [Indexed: 11/16/2022] Open
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Bagić A. Look back to leap forward: The emerging new role of magnetoencephalography (MEG) in nonlesional epilepsy. Clin Neurophysiol 2015; 127:60-66. [PMID: 26055337 DOI: 10.1016/j.clinph.2015.05.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 05/02/2015] [Accepted: 05/08/2015] [Indexed: 11/25/2022]
Abstract
This review considers accumulating evidence for a new role of MEG/MSI in increasing the diagnostic yield of supposedly negative MRIs, and suggests changes in the use of MEG/MSI in presurgical epilepsy evaluations. Specific alterations in practice protocols for both the MEG practitioner (i.e. physician magnetoencephalographer) and MEG user (i.e. referring physician) are proposed that should further enhance the overall value of MEG/MSI. Although advances in MEG analysis methods will likely become increasingly assisted by computers, interpretive competency and prudent clinical judgment remain irreplaceable.
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Affiliation(s)
- Anto Bagić
- University of Pittsburgh Comprehensive Epilepsy Center (UPCEC), UPMC MEG Epilepsy Program, Department of Neurology, University of Pittsburgh Medical School, Suite 811, Kaufmann Medical Building, 3471 Fifth Ave, Pittsburgh, PA 15213, USA.
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Pan JW, Kuzniecky RI. Utility of magnetic resonance spectroscopic imaging for human epilepsy. Quant Imaging Med Surg 2015; 5:313-22. [PMID: 25853088 DOI: 10.3978/j.issn.2223-4292.2015.01.03] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 01/15/2015] [Indexed: 01/07/2023]
Abstract
This review discusses the potential utility of broad based use of magnetic resonance (MR) spectroscopic imaging for human epilepsy and seizure localization. The clinical challenges are well known to the epilepsy community, intrinsic in the variability of location, volumetric size and network extent of epileptogenic tissue in individual patients. The technical challenges are also evident, with high performance requirements in multiple steps, including magnet homogeneity, detector performance, sequence design, speed of acquisition in addition to large territory spectral processing. We consider how MR spectroscopy and spectroscopic imaging has been informative for epilepsy thus far, with specific attention to what is measured, the interpretation of such measurements and technical performance challenges. Examples are shown from medial temporal lobe and neocortical epilepsies are considered from 4T, 7T and most recently 3T.
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Affiliation(s)
- Jullie W Pan
- 1 Departments of Neurology and Radiology, University of Pittsburgh School of Medicine, Pittsburgh, USA ; 2 Department of Neurology, NYU School of Medicine, New York, USA
| | - Ruben I Kuzniecky
- 1 Departments of Neurology and Radiology, University of Pittsburgh School of Medicine, Pittsburgh, USA ; 2 Department of Neurology, NYU School of Medicine, New York, USA
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8
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Lv RJ, Sun ZR, Cui T, Guan HZ, Ren HT, Shao XQ. Temporal lobe epilepsy with amygdala enlargement: a subtype of temporal lobe epilepsy. BMC Neurol 2014; 14:194. [PMID: 25269594 PMCID: PMC4210593 DOI: 10.1186/s12883-014-0194-z] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 09/24/2014] [Indexed: 12/05/2022] Open
Abstract
Background Some recent studies suggest that some imaging-negative temporal lobe epilepsy (TLE) had significant amygdala enlargement (AE). Contradictory data were also reported in previous studies regarding the association between AE and TLE. The present study was to investigate the clinical characters of a group of TLE with AE and compare the amygdala volume of the same patient before and after antiepileptic drugs treatment by a larger sample size. Methods This study recruited 33 mesial TLE patients with AE and 35 healthy volunteers. The clinical history, seizure semiology, electroencephalogram (EEG), fluorodeoxyglucose-positron emission tomography (FDG-PET) and amygdala volume were investigated. The amygdala volume were compared between ipsilateral and contralateral sides, TLE patients and 35 healthy controls, and patients at first and follow-up visit by 3.0 T MRI. Results Average seizure onset age was 42.0 years (SD 14.3). All patients had complex partial seizures, fourteen had occasional generalized tonic-clonic seizures which often happened during sleep. Ninety percent patients suffered from anxiety or depression. Thirty percent patients had memory decline. Interictal epileptiform discharges appeared predominantly in the anterior or inferior temporal area ipsilateral to AE. Interictal FDG-PET showed regional glucose hypometabolism in the ipsilateral temporal lobe. No hippocampal sclerosis (HS) was suspected in all patients. 22 patients demonstrated good seizure control and significantly reduced volume of the enlarged amygdala after treatment (P < 0.01). The other 11 patients showed initial response to treatment, followed by a gradual increase in seizure frequency over time, and no volume change of the enlarged amygdala after treatment. Conclusions TLE with AE probably represents a distinct nosological and probably less homogeneous syndrome which is most likely a subtype of TLE without ipsilateral HS. The chronic and long lasting inflammatory processes or focal cortical dysplasia could lead to amygdala enlargement possibly.
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Affiliation(s)
| | | | | | | | | | - Xiao-Qiu Shao
- Department of Neurology, Beijing Tiantan Hospital affiliated to Capital Medical University, 6 Tiantan Xi Li, Dongcheng District, Beijing, 100050, PR, China.
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Lee CY, Tabesh A, Spampinato MV, Helpern JA, Jensen JH, Bonilha L. Diffusional kurtosis imaging reveals a distinctive pattern of microstructural alternations in idiopathic generalized epilepsy. Acta Neurol Scand 2014; 130:148-55. [PMID: 24796428 DOI: 10.1111/ane.12257] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/03/2014] [Indexed: 01/10/2023]
Abstract
OBJECTIVES Idiopathic generalized epilepsy (IGE) arises from paroxysmal dysfunctions of the thalamo-cortical network. One of the hallmarks of IGE is the absence of visible abnormalities on routine magnetic resonance imaging (MRI). However, recent quantitative MRI studies showed cortical-subcortical structural abnormalities in IGE, but the extent of abnormalities has been inconsistent in the literature. The inconsistencies may be associated with complex microstructural abnormalities in IGE that are not completely detectable using conventional diffusion tensor imaging methods. The goal of this study was to investigate white-matter (WM) microstructural abnormalities in patients with IGE using diffusional kurtosis imaging (DKI). MATERIALS AND METHODS We obtained DKI and volumetric T1-weighted images from 14 patients with IGE and 25 matched healthy controls. Using tract-based spatial statistics, we performed voxel-wise group comparisons in the parametric maps generated from DKI: mean diffusivity (MD), fractional anisotropy (FA), and mean kurtosis (MK), and in probabilistic maps of WM volume generated by voxel-based morphometry. RESULTS We observed that conventional microstructural measures (MD and FA) revealed WM abnormalities in thalamo-cortical projections, whereas MK disclosed a broader pattern of WM abnormalities involving thalamo-cortical and cortical-cortical projections. CONCLUSIONS Even though IGE is traditionally considered a 'non-lesional' form of epilepsy, our results demonstrated pervasive thalamo-cortical WM microstructural abnormalities. Particularly, WM abnormalities shown by MK further extended into cortical-cortical projections. This suggests that the extent of microstructural abnormalities in thalamo-cortical projections in IGE may be better assessed through the diffusion metrics provided by DKI.
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Affiliation(s)
- C.-Y. Lee
- Department of Radiology and Radiological Science; Medical University of South Carolina; Charleston SC USA
- Center for Biomedical Imaging; Medical University of South Carolina; Charleston SC USA
| | - A. Tabesh
- Department of Radiology and Radiological Science; Medical University of South Carolina; Charleston SC USA
- Center for Biomedical Imaging; Medical University of South Carolina; Charleston SC USA
| | - M. V. Spampinato
- Department of Radiology and Radiological Science; Medical University of South Carolina; Charleston SC USA
- Center for Biomedical Imaging; Medical University of South Carolina; Charleston SC USA
| | - J. A. Helpern
- Department of Radiology and Radiological Science; Medical University of South Carolina; Charleston SC USA
- Center for Biomedical Imaging; Medical University of South Carolina; Charleston SC USA
| | - J. H. Jensen
- Department of Radiology and Radiological Science; Medical University of South Carolina; Charleston SC USA
- Center for Biomedical Imaging; Medical University of South Carolina; Charleston SC USA
| | - L. Bonilha
- Center for Biomedical Imaging; Medical University of South Carolina; Charleston SC USA
- Division of Neurology; Department of Neurosciences; Comprehensive Epilepsy Center; Medical University of South Carolina; Charleston SC USA
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Xu Q, Zhang Z, Liao W, Xiang L, Yang F, Wang Z, Chen G, Tan Q, Jiao Q, Lu G. Time-shift homotopic connectivity in mesial temporal lobe epilepsy. AJNR Am J Neuroradiol 2014; 35:1746-52. [PMID: 24742802 DOI: 10.3174/ajnr.a3934] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND AND PURPOSE Voxel-mirrored intrinsic functional connectivity allows the depiction of interhemispheric homotopic connections in the human brain, whereas time-shift intrinsic functional connectivity allows the detection of the extent of brain injury by measuring hemodynamic properties. We combined time-shift voxel-mirrored homotopic connectivity analyses to investigate the alterations in homotopic connectivity in mesial temporal lobe epilepsy and assessed the value of applying this approach to epilepsy lateralization and the prediction of surgical outcomes in mesial temporal lobe epilepsy. MATERIALS AND METHODS Resting-state functional MR imaging data were acquired from patients with unilateral mesial temporal lobe epilepsy (n=62) (31 left- and 31 right-side) and healthy controls (n=33). Dynamic interhemispheric homotopic architecture seeding from each hemisphere was individually calculated by 0, 1, 2, and 3 repetition time time-shift voxel-mirrored homotopic connectivity. Voxel-mirrored homotopic connectivity maps were compared between the patient and control groups by using 1-way ANOVA for each time-shift condition, separately. Group comparisons were further performed on the laterality of voxel-mirrored homotopic connectivity in each time-shift condition. Finally, we correlated the interhemispheric homotopic connection to the surgical outcomes in a portion of the patients (n=20). RESULTS The patients with mesial temporal lobe epilepsy showed decreased homotopic connectivity in the mesial temporal structures, temporal pole, and striatum. Alterations of the bihemispheric homotopic connectivity were lateralized along with delays in the time-shift in mesial temporal lobe epilepsy. The patients with unsuccessful surgical outcomes presented larger interhemispheric voxel-mirrored homotopic connectivity differences. CONCLUSIONS This study showed whole patterns of dynamic alterations of interhemispheric homotopic connectivity in mesial temporal lobe epilepsy, extending the knowledge of abnormalities in interhemispheric connectivity in this condition. Time-shift voxel-mirrored homotopic connectivity has the potential for lateralization of unilateral mesial temporal lobe epilepsy and may have the capability of predicting surgical outcomes in this condition.
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Affiliation(s)
- Q Xu
- From the Departments of Medical Imaging (Q.X., Z.Z., W.L., L.X., Q.J., G.L.)
| | - Z Zhang
- From the Departments of Medical Imaging (Q.X., Z.Z., W.L., L.X., Q.J., G.L.)
| | - W Liao
- From the Departments of Medical Imaging (Q.X., Z.Z., W.L., L.X., Q.J., G.L.) Center for Cognition and Brain Disorders and the Affiliated Hospital (W.L.), Hangzhou Normal University, Hangzhou, China Zhejiang Key Laboratory for Research in Assessment of Cognitive Impairments (W.L.), Hangzhou, China
| | - L Xiang
- From the Departments of Medical Imaging (Q.X., Z.Z., W.L., L.X., Q.J., G.L.)
| | | | - Z Wang
- Department of Medical Imaging (Z.W.), Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, China
| | | | - Q Tan
- Neurosurgery (Q.T.), Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
| | - Q Jiao
- From the Departments of Medical Imaging (Q.X., Z.Z., W.L., L.X., Q.J., G.L.) Department of Medical Imaging (Q.J.), Taishan Medical College, TaiAn, China
| | - G Lu
- From the Departments of Medical Imaging (Q.X., Z.Z., W.L., L.X., Q.J., G.L.)
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Advanced Imaging Techniques in the Diagnosis of Nonlesional Epilepsy: MRI, MRS, PET, and SPECT. Epilepsy Curr 2014; 14:121-4. [PMID: 24940151 DOI: 10.5698/1535-7597-14.3.121] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Once patients have a diagnosis of localization related epilepsy (LRE), it is critical to further classify those patients into lesional or nonlesional for treatment and prognostic reasons. An individual with LRE may be classified as nonlesional for two reasons: 1) a lesion may not exist; that is, the structural abnormality that gives rise to seizures may be at the channel level or be spatially distributed in such a way that it would not be accurately termed a lesion, or 2) a lesion exists but is so subtle that standard clinical imaging is not sensitive enough to discriminate between the lesion and surrounding healthy brain tissue. As with any technology and disease process, this definition is dynamic, as we know that future imaging techniques will be developed and new disease mechanisms will be discovered, making detection of the epileptogenic underlying abnormality an ever-changing target.
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Abstract
Epilepsy is one of the most common chronic neurological conditions worldwide. Anti-epileptic drugs (AEDs) can suppress seizures, but do not affect the underlying epileptic state, and many epilepsy patients are unable to attain seizure control with AEDs. To cure or prevent epilepsy, disease-modifying interventions that inhibit or reverse the disease process of epileptogenesis must be developed. A major limitation in the development and implementation of such an intervention is the current poor understanding, and the lack of reliable biomarkers, of the epileptogenic process. Neuroimaging represents a non-invasive medical and research tool with the ability to identify early pathophysiological changes involved in epileptogenesis, monitor disease progression, and assess the effectiveness of possible therapies. Here we will provide an overview of studies conducted in animal models and in patients with epilepsy that have utilized various neuroimaging modalities to investigate epileptogenesis.
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Affiliation(s)
- Sandy R Shultz
- Department of Medicine, The Melbourne Brain Centre, The Royal Melbourne Hospital, The University of Melbourne, Building 144, Royal Parade, Parkville, VIC, 3010, Australia,
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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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Helbok R, Claassen J. Multimodal invasive monitoring in status epilepticus: what is the evidence it has a place? Epilepsia 2013; 54 Suppl 6:57-60. [PMID: 24001075 DOI: 10.1111/epi.12279] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The underlying pathophysiology of status epilepticus (SE) remains mostly invisible to the clinician in the intensive care unit (ICU) setting. In animal studies associated hemodynamic and brain neurochemical changes have been well described. In the last decade, bedside invasive neuromonitoring techniques allow the assessments of changes in focal and global cerebral physiology associated with ictal activity on the tissue level in humans. Recent studies demonstrate that laboratory research insufficiently replicates the complexity of the human condition. Herein we summarize the current knowledge gained from human studies integrating cortical electrographic and brain tissue metabolic and hemodynamic information into the current pathophysiologic concept of SE in humans. With increasing experience gained by the use of extended neuromonitoring, we are more and more able to understand associated hemodynamic and brain neurochemical changes in patients with SE. In the future, this information can potentially provide integrated pathophysiologic end points into SE treatment concepts.
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Affiliation(s)
- Raimund Helbok
- Department of Neurology, Division of Neurocritical Care, Innsbruck Medical University, Anichstrasse 35, Innsbruck, Austria.
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Pan JW, Duckrow RB, Gerrard J, Ong C, Hirsch LJ, Resor SR, Zhang Y, Petroff O, Spencer S, Hetherington HP, Spencer DD. 7T MR spectroscopic imaging in the localization of surgical epilepsy. Epilepsia 2013; 54:1668-78. [PMID: 23895497 DOI: 10.1111/epi.12322] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2013] [Indexed: 11/28/2022]
Abstract
PURPOSE With the success that surgical approaches can provide for localization-related epilepsy, accurate seizure localization remains important. Although magnetic resonance (MR) spectroscopy has had success in earlier studies in medial temporal lobe epilepsy, there have been fewer studies evaluating its use in a broader range of localization-related epilepsy. With improvements in signal-to-noise with ultra-high field MR, we report on the use of high resolution 7T MR spectroscopic imaging (MRSI) in 25 surgically treated patients studied over a 3.5-year period. METHODS Patients were included in this analysis if the region of MRSI study included the surgical resection region. Concordance between region of MRSI abnormalities and of surgical resection was classified into three groups (complete, partial, or no agreement) and outcome was dichotomized by International League Against Epilepsy (ILAE) I-III and IV-VI groups. MRSI was performed with repetition time/echo time 1.5 s/40 msec in two-dimensional (2D) or three-dimensional (3D) encoding for robust detection of singlets N-acetyl aspartate (NAA), creatine (Cr), and choline with abnormalities in NAA/Cr determined with correction for tissue content of gray matter. KEY FINDINGS The concordance between MRSI-determined abnormality and surgical resection region was significantly related to outcome: Outcome was better if the resected tissue was metabolically abnormal. All 14 patients with complete resection of the region with the most severe metabolic abnormality had good outcome, including five requiring intracranial electroencephalography (EEG) analysis, whereas only 3/11 without complete resection of the most severe metabolic abnormality had good outcome (p < 0.001). SIGNIFICANCE This is consistent with the seizure-onset zone being characterized by metabolic dysfunction and suggests that high resolution MRSI can help define these regions for the purposes of outcome prediction.
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Affiliation(s)
- Jullie W Pan
- Department of Neurology and Radiology, University of Pittsburg, Pittsburg, Pennsylvania 15213, USA.
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Weaver KE, Chaovalitwongse WA, Novotny EJ, Poliakov A, Grabowski TG, Ojemann JG. Local functional connectivity as a pre-surgical tool for seizure focus identification in non-lesion, focal epilepsy. Front Neurol 2013; 4:43. [PMID: 23641233 PMCID: PMC3640210 DOI: 10.3389/fneur.2013.00043] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 04/17/2013] [Indexed: 11/30/2022] Open
Abstract
Successful resection of cortical tissue engendering seizure activity is efficacious for the treatment of refractory, focal epilepsy. The pre-operative localization of the seizure focus is therefore critical to yielding positive, post-operative outcomes. In a small proportion of focal epilepsy patients presenting with normal MRI, identification of the seizure focus is significantly more challenging. We examined the capacity of resting state functional MRI (rsfMRI) to identify the seizure focus in a group of four non-lesion, focal (NLF) epilepsy individuals. We predicted that computing patterns of local functional connectivity in and around the epileptogenic zone combined with a specific reference to the corresponding region within the contralateral hemisphere would reliably predict the location of the seizure focus. We first averaged voxel-wise regional homogeneity (ReHo) across regions of interest (ROIs) from a standardized, probabilistic atlas for each NLF subject as well as 16 age- and gender-matched controls. To examine contralateral effects, we computed a ratio of the mean pair-wise correlations of all voxels within a ROI with the corresponding contralateral region (IntraRegional Connectivity – IRC). For each subject, ROIs were ranked (from lowest to highest) on ReHo, IRC, and the mean of the two values. At the group level, we observed a significant decrease in the rank for ROI harboring the seizure focus for the ReHo rankings as well as for the mean rank. At the individual level, the seizure focus ReHo rank was within bottom 10% lowest ranked ROIs for all four NLF epilepsy patients and three out of the four for the IRC rankings. However, when the two ranks were combined (averaging across ReHo and IRC ranks and scalars), the seizure focus ROI was either the lowest or second lowest ranked ROI for three out of the four epilepsy subjects. This suggests that rsfMRI may serve as an adjunct pre-surgical tool, facilitating the identification of the seizure focus in focal epilepsy.
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Affiliation(s)
- K E Weaver
- Department of Radiology, University of Washington Seattle, WA, USA ; Integrated Brain Imaging Center, University of Washington Seattle, WA, USA
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Neuroimaging in Epilepsy: Towards Structural Cellular Imaging. Can J Neurol Sci 2012. [DOI: 10.1017/s0317167100018102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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