Brain SPECT imaging in temporal lobe epilepsy

Summary Temporal lobe epilepsy is diagnosed by clinical symptoms and signs and by localization of an epileptogenic focus. A brain SPECT study of two patients with temporal lobe epilepsy, using^99mTc-HMPAO, was used to demonstrate a perfusion abnormality in the temporal lobe, while brain CT and MRI were non-contributory. The electroencephalogram, though abnormal, did not localize the diseased area. The potential role of the SPECT study in diagnosis and localization of temporal lobe epilepsy is discussed.     

Gangliogliomas: characteristic imaging findings and role in the temporal lobe epilepsy

Introduction  Ganglioglioma is an uncommon neoplasm of the central nervous system, most frequently seen in the temporal lobe, and usually associated with medically refractory epilepsy in children and young adults. Few reports have considered ganglioglioma-associated epileptogenicity arising in the temporal lobe. The purpose of our study was to define the imaging features of ganglioglioma in the temporal lobe and their relation to the seizure foci revealed by electrocorticograms. Materials and methods  We reviewed 24 patients with pathologically confirmed ganglioglioma in the temporal lobe. Results  Computed tomography (CT) images showed gangliogliomas to be isodense (91.7%), and on T1-weighted images (T1-WI) most gangliogliomas (79.2%) were isointense to the gray matter. A cystic lesion was seen in 14 of 24 of the gangliogliomas (58.3%). Mass effects were not seen in any of the ten tumors without cystic components. One patient showed tumor recurrence. Dual pathology was seen in two cases (8.3%). In 23 cases, epileptogenicity was confirmed in the tumors by intraoperative electrocorticogram. The remaining case had no epileptogenicity. Conclusion  A tumor presenting isointensity to gray matter on T1-WI without mass effects in the medial temporal lobe in a young patient with temporal lobe epilepsy (TLE) might be the characteristic imaging of temporal lobe ganglioglioma. However, such tumors are not always associated with epileptogenicity, even if a ganglioglioma is found in a patient with TLE. The seizure foci may be contralateral to the ganglioglioma. Therefore, we need to investigate the hippocampus, white matter abnormalities of the ipsilateral and contralateral anterior temporal lobe, and other focal lesions closely.     

Diffusion tensor imaging tractography parameters of limbic system bundles in temporal lobe epilepsy patients

Purpose:

To investigate changes in diffusion tensor imaging (DTI) measures in limbic system white matter of patients with temporal lobe epilepsy (TLE) using diffusion tensor tractography.

Materials and Methods:

DTI metrics including fractional anisotropy (FA), λ1, λ2, λ3, and trace (Tr) coefficients were obtained from tractography for bilateral fornix, superior and inferior cingulum fibers in 18 patients and 10 healthy controls. Hippocampal signal‐to‐noise ratio (SNR) quantitative analysis was performed in order to confirm the magnetic resonance imaging (MRI) hippocampal lesion presence or absence in TLE patients.

Results:

Nine patients presented unilateral hippocampal sclerosis (TLE+HS) and nine patients had no signal abnormalities on conventional MRI (TLE?HS). On the ipsilateral seizure side, all three investigated tracts showed significant DTI indices abnormalities in both patient groups when compared with controls, most marked on the inferior cingulum. Contralateral to the seizure side, the three tracts presented significant DTI parameters in only the TLE+HS group when compared with controls.

Conclusion:

The DTI abnormalities found in the TLE?HS group may suggest that in the inferior cingulum the structural integrity is more affected than in the fornix or superior cingulum white matter bundles. The eigenvalues taken separately add complementary information to the FA and Tr metrics and may be useful indices in better understanding the architectural reorganization of limbic system tracts in TLE patients without HS. J. Magn. Reson. Imaging 2012;36:561–568. © 2012 Wiley Periodicals, Inc.

     

Transneuronal degeneration in patients with temporal lobe epilepsy: evaluation by MR imaging

The aim of this study was to assess the MR imaging findings of transneuronal degeneration of limbic system in the patients with temporal lobe epilepsy, and to detect the influence of surgery on the anatomy of the limbic system. Axial and coronal T1- and T2-weighted MR images were retrospectively analyzed in 34 patients with temporal lobe epilepsy, focusing on transneuronal degeneration. In 17 of the 34 patients, MR images were also analyzed after selective amygdalo-hippocampectomy. Atrophy of the fornix, mamillary body, mamillothalamic tract (MTT), and thalamus ipsilateral to the epileptic focus was demonstrated on MR images in 14.7, 17.6, 8.8, and 11.8% of the 34 patients, respectively. Focal hyperintensity of the thalamus was found on T2-weighted images in 8.8% of the 34 patients. In 17 patients who were evaluated before and after surgery, transneuronal degeneration was seen more frequently after surgery: fornix (11.8 vs 29.4%), mamillary body (11.8 vs 52.9%), MTT (5.9 vs 11.8%), and thalamus (11.8 vs 11.8%). Transneuronal degeneration of the limbic system is clearly demonstrated by MR imaging in patients with temporal lobe epilepsy, and surgical intervention induces transneuronal degeneration more frequently.     

MRI of the fornix and mamillary body in temporal lobe epilepsy

We performed MRI on 27 patients with clinically proven temporal lobe epilepsy (TLE), all with prior EEG lateralisation, and 10 volunteers, studied to evaluate disparity in size arising from biological variation (group 1). Three-dimensional spoiled GRASS (3DSPGR) sequences provided 2-mm contiguous sections of the limbic system, enabling assessment of the hippocampus (HC), fornix (FN) and mamillary body (MB). Measurements of FN and MB width were made from a workstation. Any percentage difference in size was computed. In 19 cases there was unilateral abnormality in the HC (group 2); in 18 and 19 cases respectively there was a smaller FN and MB on the same side as the abnormal HC. This percentage difference in size was significantly greater than that in group 1 in the FN and MB in 17 and 17 cases respectively. Comparison of percentage difference computations for FN and MB between groups 1 and 2 showed high statistical significance (P < 0.0002). In 5 patients with clinical TLE the HC was normal on MRI (group 3). Unequal FN and MB sizes were found in 4, significant in 2. Comparison of percentage difference computations for FN and MB showed statistical significance (P < 0.0005 and P < 0.0003 respectively). There was no case of discordance between the sides of hippocampal abnormality and the smaller FN or MB or between the sides of smaller FN and MB. The strong concordance between the changes in the HC and those in the FN and MB suggests that this combination will play an important role in the assessment of TLE and limbic system abnormality. Received: 12 March 1996 Accepted: 12 August 1996     

颞叶癫痫的功能MRI研究进展

颞叶癫■（TLE）是癫■中最常见的难治性类型,临床上对于药物难以控制的癫■,手术切除致■灶具有良好的治疗效果。随着MRI技术的迅速发展,功能磁共振成像（fMRI）在癫■研究中的优势越来越显著,尤其在癫■灶的定侧、定位方面明显优于常规MRI,具有更好的临床应用价值。fMRI对TLE脑网络、认知功能的研究,及在TLE病因、病理生理机制、治疗预后等方面的应用取得了诸多进展。     

A proposed modification of the Wada test for presurgical assessment in temporal lobe epilepsy

We report experience with a modification of the Wada test used before temporal lobe resection in patients with drug-resistant epilepsy. Our procedure consists of injection of amytal via a microcatheter into the anterior choroidal artery or the P2 segment of the posterior cerebral artery and simultaneous presentation of verbal and figural memory test material before, during and after the injection. Pros and cons of the modification and inherent shortcomings of the amytal test are discussed on the basis of the results in ten patients.     

Lateralisation with magnetic resonance spectroscopic imaging in temporal lobe epilepsy: an evaluation of visual and region-of-interest analysis of metabolite concentration images

We carried out spectroscopic imaging (MRSI) on nine consecutive patients with temporal lobe epilepsy being assessed for epilepsy surgery, and nine neurologically healthy, age-matched volunteers. A volume of interest (VOI) was angled along the temporal horns on axial and sagittal images, and symmetrically over the temporal lobes on coronal images. Images showing the concentrations of N-acetylaspartate (NAA) and of choline-containing compounds plus creatine and phosphocreatine (Cho + Cr) were used for lateralisation. We compared assessment by visual inspection and by signal analysis from regions of interest (ROI) in different positions, where side-to-side differences in NAA/(Cho + Cr) ratio were used for lateralisation. The NAA/(Cho + Cr) ratio from the different ROI was also compared with that in the brain stem to assess if the latter could be used as an internal reference, e. g., for identification of bilateral changes. The metabolite concentration images were found useful for lateralisation of temporal lobe abnormalities related to epilepsy. Visual analysis can, with high accuracy, be used routinely. ROI analysis is useful for quantifying changes, giving more quantitative information about spatial distribution and the degree of signal loss. There was a large variation in NAA/(Cho + Cr) values in both patients and volunteers. The brain stem may be used as a reference for identification of bilateral changes. Received: 19 July 2000/Accepted: 21 December 2000     

发作间期SPECT对难治性颞叶癫痫的诊断价值

目的:探讨难治性颞叶癫痫(TLE)单光子发射计算机断层(SPECT)的影像特征及定位诊断价值.方法:选择35例经临床手术证实的难治性TLE,术前均行发作间期SPECT脑血流灌注显像和常规MRI扫描.以临床定位结果做对照,观察难治性TLE的SPECT影像改变,分析发作间期脑血流灌注显像定位诊断颞叶致痫灶的临床应用价值.结果:难治性颞叶癫痫SPECT的影像特征为致痫灶侧前颞叶内侧和/或外侧皮质的血流灌注减低,对侧前颞叶的内侧皮质可出现轻度的灌注减低.常合并与患侧同侧的一处或以上脑区的灌注减低.SPECT致痫灶定位诊断的阳性率达77.14％00(27/35),尤其能检出52.94％ (9/17) MRI阴性TLE的致痫灶.结论:发作间期SPECT脑血流灌注显像能丰富难治性TLE的定位诊断信息,提高定位MRI阴性TLE患者致痫灶的比例.     

难治性颞叶癫痫的分子影像学研究与病理对照

目的:对照难治性颞叶癫痫(TLE)手术病理资料,探讨联合单光子发射计算机断层(SPECT)和质子磁共振波谱(1 H-MRS)两种分子影像学技术对TLE定位的临床价值。方法:选择29例经手术病理证实的单侧TLE。所有患者术前均行SPECT发作间期脑血流(CBF)灌注显像、常规磁共振(MRI)扫描和1 H-MRS成像。将两种分子影像学技术,发作间期CBF灌注显像和1 H-MRS,对TLE的定位表现与病理结果进行对比分析。结果:病理改变最常见的是海马硬化和皮质发育不良,共27例(93.10%),此两种改变伴随出现于16例中(55.17%)。对于双重病理TLE,MRI、SPECT定位阳性率均为100%(16/16),MRS为87.50%(14/16)。对于单纯性海马硬化,MRI为阴性,SPECT仅为14.29%(1/7),而MRS高达57.14%(4/7)。对于单纯性皮质发育不全,MRS为阴性,MRI为50.00%(2/4),而SPECT高达75.00%(3/4)。联合应用SPECT和MRS对TLE定位率高达86.20%(25/29),尤其是对MRI阴性的患者,两种技术联合能发现54.55%(6/11)TLE的致痫灶。结论:联合SPECT发作间期脑血流灌注显像和1 H-MRS两种分子影像学技术能为难治性TLE提供更为全面和准确的定位诊断信息,可进一步提高定位MRI阴性TLE患者致痫灶的比例。     

颞叶癫的DTI研究进展

癫间是一组由大脑神经元异常放电所引起的以短暂中枢神经系统功能失常为特征的慢性脑部疾患,颞叶癫间是最常见的局灶性癫间类型,扩散张量成像是近些年迅速发展起来的磁共振新技术,可以反映颞叶癫间病人脑组织内微结构和功能的异常,对于帮助临床定位癫间病灶,研究致间灶与周围脑区的解剖结构连接等具有较显著的优势.     

Comparison of manual tracing versus a semiautomatic radial measurement method in temporal lobe MRI volumetry for pharmacoresistant epilepsy

Introduction The aim of this study was to test a modified radial semiautomated volumetry technique (radial divider technique, RDT) versus the manual volumetry technique (MVT) for proportionality of temporal subvolumes in 30 patients with drug-resistant temporal lobe epilepsy. Methods Included in the study were 30 patients (15 female, 15 male; mean age 39.6 years) with pharmacoresistant epilepsy (mean duration 26.6 years). MRI studies were performed preoperatively on a 1.5-T scanner. All image processing steps and volume measurements were performed using ANALYZE software. The volumes of six subregions were measured bilaterally; these included the superior temporal gyrus (STG), middle + inferior temporal gyrus (MITG), fusiform gyrus (FG), parahippocampal gyrus (PHG), amygdala (AM), and hippocampus (HP). Linear regression was used to investigate the relationship between the comparable subvolumes obtained with MVT and RDT. Results Very high correlations (R ² >0.95) between RDT and MVT were observed for the STG + MITG and the STG + MITG + FG, but low correlations for the PHG subvolumes and the combined PHG + HP + AM subvolumes. These observations were independent of the side of the pathology and of hemisphere. Conclusion The two measurement techniques provided highly reliable proportional results. This series in a homogeneous group of TLE patients suggests that the much quicker RDT is suitable for determining the volume of temporolateral and laterobasal temporal lobe compartments, of both the affected and the non-affected side and the right and left hemisphere. C.-A. Mueller and J. Scorzin contributed equally to this work.     

Sequential 123I-iododexetimide scans in temporal lobe epilepsy: comparison with neuroimaging scans (MR imaging and 18F-FDG PET imaging)

Purpose Muscarinic acetylcholine receptors (mAChRs) play an important role in the generation of seizures. Single-photon emission computed tomography (SPECT) with ¹²³I-iododexetimide (IDEX) depicts tracer uptake by mAChRs. Our aims were to: (a) determine the optimum time for interictal IDEX SPECT imaging; (b) determine the accuracy of IDEX scans in the localisation of seizure foci when compared with video EEG and MR imaging in patients with temporal lobe epilepsy (TLE); (c) characterise the distribution of IDEX binding in the temporal lobes and (d) compare IDEX SPECT and ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in identifying seizure foci.Methods We performed sequential scans using IDEX SPECT imaging at 0, 3, 6 and 24 h in 12 consecutive patients with refractory TLE undergoing assessment for epilepsy surgery. Visual and region of interest analyses of the mesial, lateral and polar regions of the temporal lobes were used to compare IDEX SPECT, FDG PET and MR imaging in seizure onset localisation.Results The 6-h IDEX scan (92%; =0.83, p=0.003) was superior to the 0-h (36%; =0.01, p>0.05), 3-h (55%; =0.13, p>0.05) and 24-h IDEX scans in identifying the temporal lobe of seizure origin. The 6-h IDEX scan correctly predicted the temporal lobe of seizure origin in two patients who required intracranial EEG recordings to define the seizure onset. Reduced ligand binding was most marked at the temporal pole and mesial temporal structures. IDEX SPECT was superior to interictal FDG PET (75%; =0.66, p=0.023) in seizure onset localisation. MR imaging was non-localising in two patients in whom it was normal and in another patient in whom there was bilateral symmetrical hippocampal atrophy.Conclusion The 6-h IDEX SPECT scan is a viable alternative to FDG PET imaging in seizure onset localisation in TLE.     

1H MR spectroscopy in histopathological subgroups of mesial temporal lobe epilepsy

The aim of the study was to analyze the lateralizing value of proton magnetic resonance spectroscopy (¹H MRS) in histopathologically different subgroups of mesial temporal lobe epilepsies (MTLE) and to correlate results with clinical, MRI and seizure outcome data. A group of 35 patients who underwent resective epilepsy surgery was retrospectively studied. Hippocampal ¹H MR spectra were evaluated. Metabolite concentrations were obtained using LCModel and NAA/Cr, NAA/Cho, NAA/(Cr+Cho), Cho/Cr ratios and coefficients of asymmetry were calculated. MRI correctly lateralized 89% of subjects and ¹H MRS 83%. MRI together with ¹H MRS correctly lateralized 100% of patients. Nineteen subjects had “classical” hippocampal sclerosis (HS), whereas the remaining 16 patients had “mild” HS. Nineteen patients had histopathologically proven malformation of cortical development (MCD) in the temporal pole; 16 subjects had only HS. No difference in ¹H MRS findings was found between patients in different histopathological subgroups of MTLE. Our results support the hypothesis that ¹H MRS abnormalities do not directly reflect histopathological changes in MTLE patients. Subjects with non-lateralized ¹H MRS abnormalities did not have a worse postoperative seizure outcome. We found no significant impact of contralateral ¹H MRS abnormality on post-surgical seizure outcome.     

Uncinate fasciculus fiber tracking in mesial temporal lobe epilepsy. Initial findings

In temporal lobe epilepsy (TLE) due to hippocampal sclerosis (HS), ictal discharge spread to the frontal and insulo-perisylvian cortex is commonly observed. The implication of white matter pathways in this propagation has not been investigated. We compared diffusion tensor imaging (DTI) measurements along the uncinate fasciculus (UF), a major tract connecting the frontal and temporal lobes, in patients and controls. Ten right-handed patients referred for intractable TLE due to a right HS were investigated on a 1.5-T MR scanner including a DTI sequence. All patients had interictal fluorodeoxyglucose PET showing an ipsilateral temporal hypometabolism associated with insular and frontal or perisylvian hypometabolism. The controls consisted of ten right-handed healthy subjects. UF fiber tracking was performed, and its fractional anisotropy (FA) values were compared between patients and controls, separately for the right and left UF. The left-minus-right FA UF asymmetry index was computed to test for intergroup differences. Asymmetries were found in the control group with right-greater-than-left FA. This asymmetrical pattern was lost in the patient group. Right FA values were lower in patients with right HS versus controls. Although preliminary, these findings may be related to the preferential pathway of seizure spread from the mesial temporal lobe to frontal and insulo-perisylvian areas.     

Monoamine oxidase B single-photon emission tomography with [123I]Ro 43-0463: imaging in volunteers and patients with temporal lobe epilepsy

Imaging of monoamine oxidase of subtype B (MAO B) is of interest in various neurological diseases. In the past non-invasive assessment of MAO B has only been possible with positron emission tomography (PET) ligands. Given the limited availability of PET, a single-photon emission tomography (SPET) ligand would be desirable. In this study SPET imaging with the new MAO B inhibitor [¹²³I]Ro 43-0463 was performed in five volunteers and nine patients with temporal lobe epilepsy (TLE). In two volunteers a second study was performed 12 h following blockade with deprenyl. In the TLE patients the tracer was administered as bolus (n = 4) or as prolonged infusion (n = 5). The regional uptake pattern correlated well with the known distribution of MAO B. In the two blocking studies ligand uptake was substantially reduced compared with baseline. In the TLE patients increased uptake was found in the ipsilateral mesial temporal lobe and, surprisingly, in the ipsilateral putamen. This study indicates the potential of the new SPET ligand [¹²³I]Ro 43-0463 to map MAO B concentration in the human brain. The new finding of increased MAO B in the putamen of TLE patients needs further studies to elucidate its exact pathophysiology. Received 2 October and in revised form 29 December 1997     

难治性颞叶癫痫海马和同侧前颞叶MRI特征及其与临床相关性

目的：探讨难治性颞叶癫痫海马硬化（HS）与同侧前颞叶 MRI特征及其与临床的相关性。方法：搜集经影像学或病理诊断为难治性颞叶癫痫 HS的34例患者的临床和影像资料,其中25例行手术治疗。34例中女15例,男19例,平均年龄（22．4±8．2）岁。观察海马及同侧前颞叶 MRI征象,根据海马及前颞叶 MRI 征象将34例分为同侧前颞叶正常组与前颞叶异常组,后者再分为同时出现灰白质分界模糊和颞叶萎缩组与仅出现一种征象组两亚组,比较各组间临床特征的差异。结果：34例中,22例（64．7％）出现 HS及同侧前颞叶异常,12例同侧颞叶正常。前颞叶异常组首次癫痫发作年龄低于前颞叶正常组（t＝－3．438,P＝0．002）,病程时间比前颞叶正常组长（t＝2．453,P＝0．020）。前颞叶同时出现灰白质分界模糊和颞叶萎缩组与仅存在一种征象组间临床特征无统计学差异。结论：难治性颞叶癫痫伴有前颞叶异常的颞叶癫痫多数首次发病年龄小,病程长,MRI特征与临床病情具有紧密的相关性,对于手术侧别选择意义重大。     

FMRI contributions to addressing autobiographical memory impairment in temporal lobe pathology

Episodic autobiographical memory (AM) allows one, through the recollection of sensory-perceptual details, thoughts and feelings, to become aware of an event as belonging to one’s own past as well as being able to project into one’s future. Because AM provides a sense of self-continuity, contributes to the integrity of the self, and helps predicting future experiences, any deficit of AM may have debilitating consequences for everyday life functioning. Understanding AM failure and the underlying neural mechanisms has the potential to shed light on brain reorganization mechanisms and engagement of compensatory processes. Functional magnetic resonance imaging (fMRI) provides the most promising imaging method to tackle these issues. We reviewed evidence from the few studies that used fMRI to investigate the functionality of the residual tissue, the neural reorganization and compensatory mechanisms in patients with neurological conditions due to impaired medial temporal lobe. Overall, these studies highlight the importance of the left hippocampus, which when atrophied and not functional leads to AM deficits but its residual functionality may support relatively normal AM recollection. When damaged hippocampal tissue is not functional, other brain regions (e.g., the medial prefrontal cortex) may be involved to compensate impairment, but they appear generally ineffective to support detailed episodic recollection.     

Does technetium-99m bicisate image local brain metabolism in late ictal temporal lobe epilepsy?

Ictal increase in regional cerebral blood flow as judged by single-photon emission tomography (SPET) is a common phenomenon during focal epileptic seizures. Up to 2 min postictally, regional hyperperfusion is a consistent finding with technetium-99m hexamethylpropylene amine oxime (HMPAO) in temporal lobe epilepsy. A new ^99mTc-labelled lipophilic cerebral blood flow imaging agent, bicisate, has considerably longer radiochemical stability and yields better image quality than ^99mTc-HMPAO. In this report, we present the case of a 21-year-old female patient with temporal lobe complex partial seizures. Magnetic resonance imaging revealed right hippocampal sclerosis. A dose of 550 MBq of ^99mTc-bicisate was injected 35 s after the onset of a seizure during intracranial EEG-videotelemetry. At the moment of injection, subdural EEG demonstrated the beginning of late ictal discharges and postictal suppression in the right temporomesial areas. Late ictal SPET images showed marked right fronto-temporo-parietal hypoactivity. The interictal SPET study clearly showed right frontotemporal hypoactivity. These preliminary data suggest that ^99mTc-bicisate shows late ictal/early postictal hypoactivity which might represent the primary change in neuronal metabolism rather than the secondary change in cerebral blood flow. Correspondence to: J.T. Kuikka     

颞叶癫痫在3T与7TMRI上的影像对比及与病理对照分析

目的 比较颞叶癫痫致痫灶3 T和7 T MR成像差异,并与病理结果对照分析,以确定7 T MRI在呈现、检测病变以及精确定位诊断中的意义。方法 共纳入2014年1月—2017年12月期间确诊的34例颞叶癫痫病人[男18例,女16例;平均年龄(27±8)岁]及5名正常对照（男3名,女2名;平均年龄27岁）,均行术前3 T和7 T MR扫描,全部病人均获术后病理结果。由2名高年资放射科医师对术前影像和病理结果进行对照分析,并对病理为海马硬化（HS）者的海马内部结构进行评分。采用配对t检验对3 T和7 T MRI上双侧海马内部结构评分进行比较。结果 病理诊断为HS者24例,其中20例在3 T及7 T MRI上诊断明确,4例MRI术前诊断欠明确。3 T 和7 T MRI上,患侧海马内部结构评分均低于正常侧（P<0.001）。7 T MRI上海马内部结构评分均高于3 T MRI（P<0.05）。局灶性皮质发育不良（FCD）6例（FCD Ia 2例、FCDIIIa 3例、FCDIIId 1例）。颞叶FCD Ia在3 T 及7 T MRI上均未发现,FCDIIIa及FCDIIId海马区病灶在3 T MRI及7 T MRI上均清楚显示。海马、颞叶占位4例（节细胞胶质瘤2例,脑膜瘤1例,左侧杏仁体部分区域胶质细胞增生1例）在3 T和7 T MRI均清楚显示。对5例正常对照脑部结构的显示,7 T MRI优于3 T MRI。结论 典型病灶在3 T及7 T MRI均可发现,7 T MRI对海马内部精细结构的显示优于3T MRI;不典型病灶7 T MRI能够更好地显示解剖精细结构,但有些病灶如FCD Ia提高场强后仍无法分辨。