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Lee EY, Kim J, Prado-Rico JM, Du G, Lewis MM, Kong L, Kim BG, Hong YS, Yanosky JD, Mailman RB, Huang X. Higher hippocampal diffusivity values in welders are associated with greater R2* in the red nucleus and lower psychomotor performance. Neurotoxicology 2023; 96:53-68. [PMID: 36966945 PMCID: PMC10445214 DOI: 10.1016/j.neuro.2023.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 02/17/2023] [Accepted: 03/22/2023] [Indexed: 04/05/2023]
Abstract
INTRODUCTION Chronic excessive welding exposure may be related to higher metal accumulation and structural differences in different subcortical structures. We examined how welding affected brain structures and their associations with metal exposure and neurobehavioral consequences. METHODS Study includes 42 welders and 31 controls without a welding history. Welding-related structural differences were assessed by volume and diffusion tensor imaging (DTI) metrics in basal ganglia, red nucleus (RN), and hippocampus. Metal exposure was estimated by both exposure questionnaires and whole blood metal levels. Brain metal accumulations were estimated by R1 (for Mn) and R2* (for Fe). Neurobehavioral status was assessed by standard neuropsychological tests. RESULTS Compared to controls, welders displayed higher hippocampal mean (MD), axial (AD), and radial diffusivity (RD) (p's < 0.036), but similar DTI or volume in other ROIs (p's > 0.117). Welders had higher blood metal levels (p's < 0.004), higher caudate and RN R2* (p's < 0.014), and lower performance on processing/psychomotor speed, executive function, and visuospatial processing tasks (p's < 0.046). Higher caudate and RN R2* were associated with higher blood Fe and Pb (p's < 0.043), respectively. RN R2* was a significant predictor of all hippocampal diffusivity metrics (p's < 0.006). Higher hippocampal MD and RD values were associated with lower Trail Making Test-A scores (p's < 0.025). A mediation analysis of both groups revealed blood Pb indirectly affected hippocampal diffusivity via RN R2* (p's < 0.041). DISCUSSION Welding-related higher hippocampal diffusivity metrics may be associated with higher RN R2* and lower psychomotor speed performance. Future studies are warranted to test the role of Pb exposure in these findings.
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Affiliation(s)
- Eun-Young Lee
- Department of Health Care and Science, Dong-A University, Busan, South Korea.
| | - Juhee Kim
- Department of Health Care and Science, Dong-A University, Busan, South Korea
| | - Janina Manzieri Prado-Rico
- Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, USA
| | - Guangwei Du
- Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, USA
| | - Mechelle M Lewis
- Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, USA; Department of Pharmacology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, USA
| | - Lan Kong
- Department of Public Health Sciences, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, USA
| | - Byoung-Gwon Kim
- Department of Preventive Medicine, College of Medicine, Dong-A University, Busan, South Korea
| | - Young-Seoub Hong
- Department of Preventive Medicine, College of Medicine, Dong-A University, Busan, South Korea
| | - Jeff D Yanosky
- Department of Public Health Sciences, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, USA
| | - Richard B Mailman
- Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, USA; Department of Pharmacology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, USA
| | - Xuemei Huang
- Department of Neurology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, USA; Department of Pharmacology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, USA; Department of Radiology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, USA; Department of Neurosurgery, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, USA; Department of Kinesiology, Pennsylvania State University-Milton S. Hershey Medical Center, Hershey, PA 17033, USA.
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Wang YH, Wang ZM, Wei PH, Lu C, Fan XT, Ren LK, Shan YZ, Lu J, Zhao GG. Lateralizing the affected side of hippocampal sclerosis with quantitative high angular resolution diffusion scalars: a preliminary approach validated by diffusion spectrum imaging. ANNALS OF TRANSLATIONAL MEDICINE 2021; 9:297. [PMID: 33708924 PMCID: PMC7944293 DOI: 10.21037/atm-20-5719] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Background Conflicts in regarding the lateralization of the seizure onset for mesial temporal lobe epilepsy (MTLE) are frequently encountered during presurgical evaluation. As a more elaborate, quantified protocol, indices of diffusion spectrum imaging (DSI) might be sensitive to evaluate the seizure involvement. However, the accuracy was less revealed. Herein, we determined the lateralizing value of the DSI indices among MTLE patients. Methods Eleven MTLE patients were enrolled together with 11 matched health contrasts. All the participants underwent a DSI scan and with reconstruction of the diffusion scalar, including quantitative anisotropy (QA), isotropic (ISO), and track density imaging (TDI) values. Statistics of these indices were applied to identify the differences between the healthy and ipsilateral sides, and those between the patients and the controls, with special attention to areas of the crura of fornix (FORX), the parahippocampal radiation of the cingulum (PHCR), the hippocampus (HP), parahippocampus (PHC), amygdala (AM) and entorhinal cortex (EC). Results Regarding lateralization, TDI of the FORX and the PHCR reached an AUC value of 0.95 and 0.93, respectively (P<0.05), and QA, ISO, TDI of the PHCR, as well as TDI of the FORX were statistically significant amongst the laterals of the patients (P<0.05). Also, the QA of the PHCR were statistically different in the patients' ipsilateral side relative to the contrasts (P<0.017). The diffusion level on different grey matter structures were significantly decreased including HP, AM and EC in GQI space (P<0.017). Conclusions The quantitative diffusion scalars of the DSI, especially TDI of the FORX and the PHCR, are sensitive indices to define the ipsilateral side for MTLE patients. For preliminary exploration, the use of quantitative DSI scalars may help to improve the seizure outcome by increasing the accuracy of localization and lateralization for MTLE.
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Affiliation(s)
- Yi-He Wang
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Zhen-Ming Wang
- Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Peng-Hu Wei
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Chao Lu
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Xiao-Tong Fan
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Lian-Kun Ren
- Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yong-Zhi Shan
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Jie Lu
- Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing, China.,Department of Nuclear Medicine, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Guo-Guang Zhao
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China.,Center of Epilepsy, Beijing Institute for Brain Disorder, Beijing, China
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Lee EY, Flynn MR, Du G, Lewis MM, Kong L, Yanosky JD, Mailman RB, Huang X. Higher Hippocampal Mean Diffusivity Values in Asymptomatic Welders. Toxicol Sci 2020; 168:486-496. [PMID: 30629252 DOI: 10.1093/toxsci/kfz011] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Chronic high-level manganese (Mn)-induced neurotoxicity has been associated with Mn accumulation in the basal ganglia and higher risk for developing parkinsonism. Recent studies in Mn-exposed animals revealed Mn accumulation in the hippocampus, the presence of Aβ diffuse plaques, and deficits in associative learning, the latter being hallmarks of Alzheimer's disease (AD) or related disorders. This and recent evidence of hippocampal Mn accumulation in welders prompted us to test the hypothesis that welders with chronic Mn exposure would display changes in the hippocampus. Subjects with (welders; n = 42) or without (controls; n = 31) welding history were studied. Mn exposure was estimated by occupational questionnaires, whole blood Mn, and R1 imaging (estimate of short-term brain Mn accumulation). Hippocampal diffusion tensor imaging (DTI; estimate of microstructural brain changes) and volume were determined. Compared with controls, welders displayed no significant difference in hippocampal volume (p = .165). Welders, however, exhibited higher DTI hippocampal mean diffusivity (MD) values compared with controls (p = .035) that was evident particularly in older welders (>50 years, p = .002). Hippocampal MD was associated significantly with age in welders (R = 0.59; p < .001) but not in controls (p = .16). Moreover, higher hippocampal MD values (age adjusted) were associated with long-term cumulative Mn exposure (R = 0.36, p = .021). Welders with chronic exposure have higher MD values in the hippocampus that become greater with increasing age, a brain change that is similar to that observed in those at risk for AD. The current results suggest that Mn exposure, coupled with aging, may make welders more vulnerable to AD or AD-like changes.
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Affiliation(s)
- Eun-Young Lee
- Department of Neurology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, Pennsylvania 17033.,Department of Health Care and Science, Dong-A University, Busan, South Korea 49315
| | - Michael R Flynn
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Guangwei Du
- Department of Neurology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, Pennsylvania 17033
| | - Mechelle M Lewis
- Department of Neurology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, Pennsylvania 17033.,Department of Pharmacology
| | - Lan Kong
- Department of Public Health Sciences
| | | | - Richard B Mailman
- Department of Neurology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, Pennsylvania 17033.,Department of Pharmacology
| | - Xuemei Huang
- Department of Neurology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, Pennsylvania 17033.,Department of Pharmacology.,Department of Radiology.,Department of Neurosurgery.,Department of Kinesiology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey, Pennsylvania 17033
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A comparative evaluation of bilateral hippocampus and amygdala volumes with ADC values in pediatric primary idiopathic partial epilepsy patients. JOURNAL OF SURGERY AND MEDICINE 2019. [DOI: 10.28982/josam.630645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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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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Evaluation of apparent diffusion coefficient measurements of brain injury in type 2 diabetics with retinopathy by diffusion-weighted MRI at 3.0 T. Neuroreport 2018; 28:69-74. [PMID: 27846040 DOI: 10.1097/wnr.0000000000000703] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Diabetes is often associated with impairments in brain functioning. However, the injury of specific functioning areas of the brain is not clear. To address this problem, the present study was designed to investigate possible brain functioning change in specific brain areas, particularly in areas associated with vision function, in patients with proliferative and nonproliferative diabetic retinopathy (PDR and NPDR) using the diffusion-weighted imaging technology. Conventional MRI was performed in 45 diabetic patients, 30 of whom had diabetic retinopathy (DR) involvement (half PDR, and half NPDR) and 15 of whom were diabetic patients without retinopathy and with normal ophthalmologic examination. The apparent diffusion coefficient (ADC) values were calculated in the orbitofrontal cortex (OFC), cingulated gyrus, thalamus, dorsomedial and dorsolateral frontal cortex, and corona radiate. The ADC values of the OFC, cingulated gyrus, and visual cortex were significantly increased in patients with PDR and NPDR compared with both patients without retinopathy and the control group (P<0.01). The ADC values of the OFC, cingulated gyrus, and visual cortex were significantly increased in patients with PDR compared with NPDR. The duration of disease and values of hemoglobin A1c were significantly correlated with ADC values of the OFC, cingulated gyrus, and visual cortex, respectively (P<0.01 or <0.05). We observed significantly increased ADC values of the visual center (OFC, cingulated gyrus, and visual cortex), supporting the association between DR and impairment in brain functioning. Diffusion-weighted imaging may serve to assess subclinical neurological involvement in DR, even when brain structural changes are absent.
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Abnormal spontaneous brain activity in type 2 diabetic retinopathy revealed by amplitude of low-frequency fluctuations: a resting-state fMRI study. Clin Radiol 2017; 72:340.e1-340.e7. [DOI: 10.1016/j.crad.2016.11.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 10/11/2016] [Accepted: 11/21/2016] [Indexed: 12/17/2022]
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8
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Changes of normal appearing optic nerve head on diffusion-weighted imaging in patients with diabetic retinopathy. Clin Imaging 2017; 42:60-63. [DOI: 10.1016/j.clinimag.2016.11.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 10/31/2016] [Accepted: 11/15/2016] [Indexed: 01/20/2023]
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Stylianou P, Hoffmann C, Blat I, Harnof S. Neuroimaging for patient selection for medial temporal lobe epilepsy surgery: Part 1 Structural neuroimaging. J Clin Neurosci 2015; 23:14-22. [PMID: 26362835 DOI: 10.1016/j.jocn.2015.04.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 03/27/2015] [Accepted: 04/05/2015] [Indexed: 11/19/2022]
Abstract
The objective of part one of this review is to present the structural neuroimaging techniques that are currently used to evaluate patients with temporal lobe epilepsy (TLE), and to discuss their potential to define patient eligibility for medial temporal lobe surgery. A PubMed query, using Medline and Embase, and subsequent review, was performed for all English language studies published after 1990, reporting neuroimaging methods for the evaluation of patients with TLE. The extracted data included demographic variables, population and study design, imaging methods, gold standard methods, imaging findings, surgical outcomes and conclusions. Overall, 56 papers were reviewed, including a total of 1517 patients. This review highlights the following structural neuroimaging techniques: MRI, diffusion-weighted imaging, tractography, electroencephalography and magnetoencephalography. The developments in neuroimaging during the last decades have led to remarkable improvements in surgical precision, postsurgical outcome, prognosis, and the rate of seizure control in patients with TLE. The use of multiple imaging methods provides improved outcomes, and further improvements will be possible with future studies of larger patient cohorts.
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Affiliation(s)
- Petros Stylianou
- Department of Neurosurgery, The Chaim Sheba Medical Center, Nissim Aloni 16, Tel Aviv-Yafo 62919, Israel.
| | - Chen Hoffmann
- Department of Radiology, The Chaim Sheba Medical Center, Tel Hashomer, Israel
| | - Ilan Blat
- Department of Neurology, The Chaim Sheba Medical Center, Tel Hashomer, Israel
| | - Sagi Harnof
- Department of Neurosurgery, The Chaim Sheba Medical Center, Nissim Aloni 16, Tel Aviv-Yafo 62919, Israel
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Abstract
Epilepsy is the most common serious neurological disease. Seizures are refractory to medication in approximately 30% of patients with focal epilepsy, and surgical treatment is potentially curative should the epileptic focus be accurately localized. MRI has revolutionized the investigation of such patients; however, up to 20% of patients with refractory focal epilepsy have an undetermined etiological basis for their epilepsy despite extensive investigation. Diffusion imaging is an advanced MRI technique that is sensitive to the molecular displacement of water molecules and provides additional information on the microstructural arrangement of tissue. Both qualitative and quantitative analyses of the interictal and peri-ictal states are possible and provide valuable insights into the epileptic brain in vivo. Furthermore, advanced postacquisition processing can reveal additional information on, for example, anatomical connectivity. The description, application and limitations of diffusion imaging in epilepsy are the focus of this review. Future directions of research required in this area are also discussed in the context of existing literature.
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Affiliation(s)
- Fergus J Rugg-Gunn
- Institute of Neurology, Department of Clinical & Experimental Epilepsy, University College London, Queen Square, London, UK.
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Yu A, Wang X, Xu G, Li Y, Qin W, Li K, Wang Y. A functional MRI study of language networks in left medial temporal lobe epilepsy. Eur J Radiol 2011; 80:441-4. [DOI: 10.1016/j.ejrad.2010.06.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Accepted: 06/10/2010] [Indexed: 11/15/2022]
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Abstract
The incidence of epilepsy in the elderly has increased steadily over the last few decades. In some industrialized countries, one-third of the population is expected to be over the age of 65 in 2030. Therefore, we will face a dramatic increase in the number of elderly patients with epilepsy, many of whom will likely present comorbidities. This increase will put a heavy burden on health care and pension systems. This article focuses on epidemiology, diagnosis and treatment in epilepsies in the elderlies and outlines current research as well as future requirements for research. The diagnosis of epilepsy in the elderly can be difficult and may require long-term video-EEG monitoring. Stroke is the most frequent etiology in epilepsies in the elderlies. Status epilepticus in acute symptomatic epilepsies often results in fatality and may become an increasing health problem. The article also describes the current strategies in antiepileptic drug treatment and epilepsy surgery in the elderly. Novel antiepileptic drugs are necessary as current antiepileptics have strong interaction potentials and harmful side effects, making them ill-suboptimal for treating epilepsy in the elderly.
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Affiliation(s)
- H Stefan
- University Hospital Erlangen, Epilepsy Center, Germany.
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Wang XQ, Lang SY, Hong LU, Lin MA, Yan-Ling MAO, Yang F. Changes in extrafrontal integrity and cognition in frontal lobe epilepsy: a diffusion tensor imaging study. Epilepsy Behav 2011; 20:471-7. [PMID: 21296621 DOI: 10.1016/j.yebeh.2010.12.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2010] [Revised: 12/22/2010] [Accepted: 12/22/2010] [Indexed: 10/18/2022]
Abstract
We used diffusion tensor imaging to characterize microstructural changes and their associations with cognition in Chinese patients with frontal lobe epilepsy (FLE). We examined 18 adult patients with FLE and 20 healthy controls. Compared with normal controls, patients with FLE had increased mean diffusivity (MD) in the right frontal lobe and decreased fractional anisotropy (FA) in both thalami. Patients with FLE also had decreased FA in the right frontal lobe that correlated with patient age at seizure onset and increased MD in the left thalamus that correlated with duration of epilepsy. Patients with FLE performed significantly worse on nearly all cognitive tasks, and there was a positive correlation between Mini-Mental Status Examination scores and FA in the left frontal lobe and the left thalamus. Our results suggest that the thalamus might be an important extrafrontal structure involved in FLE and that a longer duration of epilepsy might result in more abnormalities in the thalamus. Our results also support the hypothesis that the left frontal lobe white matter and the thalamus contribute to cognitive impairment in patients with FLE.
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Affiliation(s)
- Xiang-Qing Wang
- Department of Neurology, Chinese PLA General Hospital, Beijing, China.
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Ahmadi ME, Hagler DJ, McDonald CR, Tecoma ES, Iragui VJ, Dale AM, Halgren E. Side matters: diffusion tensor imaging tractography in left and right temporal lobe epilepsy. AJNR Am J Neuroradiol 2009; 30:1740-7. [PMID: 19509072 DOI: 10.3174/ajnr.a1650] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Noninvasive imaging plays a pivotal role in lateralization of the seizure focus in presurgical patients with temporal lobe epilepsy (TLE). Our goal was to evaluate the utility of diffusion tensor imaging (DTI) tractography in TLE. MATERIALS AND METHODS Twenty-one patients with TLE (11 right, 10 left TLE) and 21 controls were enrolled. A 1.5T MR imaging scanner was used to obtain 51 diffusion-gradient-direction images per subject. Eight pairs of white matter fiber tracts were traced, and fiber tract fractional anisotropy (FA) was calculated and compared with controls. Fiber tract FA asymmetry and discriminant function analysis were evaluated in all subjects and fiber tracts respectively. RESULTS Compared with controls, patients with TLE demonstrated decreased FA in 5 ipsilateral fiber tracts. Patients with left TLE had 6 ipsilateral and 4 contralateral fiber tracts with decreased FA. Patients with right TLE had 4 ipsilateral but no contralateral tracts with decreased FA compared with controls. Right-sided FA asymmetry was demonstrated in patients with right TLE for 5 fiber tracts, and left-sided asymmetry, for patients with left TLE for 1 fiber tract. Discriminant function analysis correctly categorized patients into left-versus-right TLE in 90% of all cases (100% correct in all patients without hippocampal sclerosis) by using uncinate fasciculus and parahippocampal fiber tracts. CONCLUSIONS We found widespread reductions in fiber tract FA in patients with TLE, which were most pronounced ipsilateral to the seizure focus. Patients with left TLE had greater, more diffuse changes, whereas patients with right TLE showed changes that were primarily ipsilateral. Disease was lateralized to a high degree independent of identifiable hippocampal pathology noted on conventional MR imaging.
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Affiliation(s)
- M E Ahmadi
- Multimodal Imaging Laboratory, University of California, San Diego, CA 92103-8756, USA.
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Yu JT, Tan L. Diffusion-weighted magnetic resonance imaging demonstrates parenchymal pathophysiological changes in epilepsy. ACTA ACUST UNITED AC 2008; 59:34-41. [PMID: 18514917 DOI: 10.1016/j.brainresrev.2008.04.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2008] [Revised: 04/24/2008] [Accepted: 04/25/2008] [Indexed: 10/22/2022]
Abstract
Diffusion-weighted magnetic resonance imaging (DW-MRI) is a novel noninvasive technique probing the Brownian motion of water molecules. It has already proved very useful in the early identification of cerebral ischemia in human patients. Although a wide spectrum of peri-ictal, postictal or interictal DW-MRI abnormalities are recently being increasingly identified, clinicians are often in a dilemma about their significance in epilepsy. This article briefly reviews the whole dynamic ADC fluctuations and the implications of hypothetical pathophysiological evolution of effected zones in prolonged seizures or status epilepticus (SE) and their potential clinical applications in epilepsy.
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Affiliation(s)
- Jin-Tai Yu
- Department of Neurology, Qingdao Municipal Hospital, Affiliated Hospital of Qingdao University Medical College, Shandong Province, PR China
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Abstract
Diffusion-based imaging is an advanced MRI technique that is sensitive to the movement of water molecules, providing additional information on the micro-structural arrangement of tissue. Qualitative and quantitative analysis of peri, post and interictal diffusion images can aid the localization of seizure foci. Diffusion tensor tractography is an extension of diffusion-based imaging, and can provide additional information about white matter pathways. Both techniques are able to increase understanding of the effects of epilepsy on the structural organization of the brain, and can be used to optimize presurgical planning of patients with epilepsy. This review focuses on the basis, applications, limitations, and future directions of diffusion imaging in epilepsy. Literature search strategy: We searched Pubmed using the terms "diffusion MRI or diffusion tensor MRI or tractography and epilepsy."
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Affiliation(s)
- Mahinda Yogarajah
- Department of Clinical and Experimental Epilepsy and National Society for Epilepsy, Institute of Neurology, University College London, Queen Square, London, United Kingdom
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Müller MJ, Greverus D, Dellani PR, Weibrich C, Wille PR, Scheurich A, Stoeter P, Fellgiebel A. Functional implications of hippocampal volume and diffusivity in mild cognitive impairment. Neuroimage 2005; 28:1033-42. [PMID: 16084115 DOI: 10.1016/j.neuroimage.2005.06.029] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2005] [Revised: 06/13/2005] [Accepted: 06/23/2005] [Indexed: 11/22/2022] Open
Abstract
Hippocampal atrophy has been related to mild cognitive impairment (MCI) and early Alzheimer disease (AD), but the diagnostic significance of cross-sectionally determined hippocampal volumes is still ambiguous. Diffusion-Tensor-Imaging (DTI) in MCI patients revealed an association of microstructural changes in hippocampal areas with verbal memory decline. MRI volumetry and DTI were combined to investigate 18 MCI patients attending a memory clinic, and 18 carefully age- and gender-matched healthy controls. Neuropsychological testing, high resolution T1-weighted volume MRI scans, and DTI scans with regions-of-interest in hippocampal areas were applied. Left hippocampal volume was significantly lower (-11%, P = 0.02) in MCI patients than in control subjects. No significant differences were found for the right hippocampus (-4%). Mean diffusivity (MD) was significantly elevated in MCI patients vs. controls in left (+10%, P = 0.002) and right hippocampal areas (+13%, P = 0.02). Hippocampal volume and MD values were not significantly correlated. Combining left hippocampal volume and MD measures showed that lower left hippocampal volumes were associated with poor verbal memory performance particularly when co-occurring with high MD values. No comparable associations could be found regarding the right hippocampal formation and with respect to non-verbal memory function. The results demonstrate that microstructural abnormalities as revealed by DTI are very sensitive early indicators of hippocampal dysfunction. The combination of macro- and microstructural parameters in hippocampal areas could be promising in early detection of neurodegenerative processes.
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Affiliation(s)
- Matthias J Müller
- Department of Psychiatry, Untere Zahlbacher Str. 8, D-55131 Mainz, Germany.
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