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1.
Br J Neurosurg ; 37(6): 1544-1559, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36148501

RESUMO

PURPOSE: Functional MRI (fMRI) has well-established uses to inform risks and plan maximally safe approaches in neurosurgery. In the field of brain tumour surgery, however, fMRI is currently in a state of clinical equipoise due to debate around both its sensitivity and specificity. MATERIALS AND METHODS: In this review, we summarise the role and our experience of fMRI in neurosurgery for gliomas and metastases. We discuss nuances in the conduct and interpretation of fMRI that, based on our practise, most directly impact fMRI's usefulness in the neurosurgical setting. RESULTS: Illustrated examples in which fMRI in our hands directly influences the neurosurgical treatment of brain tumours include evaluating the probability and nature of functional risks, especially for language functions. These presurgical risk assessments, in turn, help to predict the resectability of tumours, select or deselect patients for awake surgery, indicate the need for neurophysiological monitoring and guide the optimal use of intra-operative stimulation mapping. A further emerging application of fMRI is in measuring functional adaptation of functional networks after (partial) surgery, of potential use in the timing of further surgery. CONCLUSIONS: In appropriately selected patients with a clearly defined surgical question, fMRI offers a valuable complementary tool in the pre-surgical evaluation of brain tumours. However, there is a great need for standards in the administration and analysis of fMRI as much as in the techniques that it is commonly evaluated against. Surprisingly little data exists that evaluates the accuracy of fMRI not just against complementary methods, but in terms of its ultimate clinical aim of minimising post-surgical morbidity.


Assuntos
Neoplasias Encefálicas , Glioma , Humanos , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/cirurgia , Mapeamento Encefálico/métodos , Vigília , Imageamento por Ressonância Magnética/métodos , Glioma/diagnóstico por imagem , Glioma/cirurgia
2.
J Neurooncol ; 153(3): 547-557, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34196915

RESUMO

INTRODUCTION: Despite evidence of correspondence with intraoperative stimulation, there remains limited data on MRI diffusion tractography (DT)'s sensitivity to predict morbidity after neurosurgical oncology treatment. Our aims were: (1) evaluate DT against subcortical stimulation mapping and performance changes during and after awake neurosurgery; (2) evaluate utility of early post-operative DT to predict recovery from post-surgical deficits. METHODS: We retrospectively reviewed our first 100 awake neurosurgery procedures using DT- neuronavigation. Intra-operative stimulation and performance outcomes were assessed to classify DT predictions for sensitivity and specificity calculations. Post-operative DT data, available in 51 patients, were inspected for tract damage. RESULTS: 91 adult brain tumor patients (mean 49.2 years, 43 women) underwent 100 awake surgeries with subcortical stimulation between 2014 and 2019. Sensitivity and specificity of pre-operative DT predictions were 92.2% and 69.2%, varying among tracts. Post-operative deficits occurred after 41 procedures (39%), but were prolonged (> 3 months) in only 4 patients (4%). Post-operative DT in general confirmed surgical preservation of tracts. Post-operative DT anticipated complete recovery in a patient with supplementary motor area syndrome, and indicated infarct-related damage to corticospinal fibers associated with delayed, partial recovery in a second patient. CONCLUSIONS: Pre-operative DT provided very accurate predictions of the spatial location of tracts in relation to a tumor. As expected, however, the presence of a tract did not inform its functional status, resulting in variable DT specificity among individual tracts. While prolonged deficits were rare, DT in the immediate post-operative period offered additional potential to monitor neurological deficits and anticipate recovery potential.


Assuntos
Imagem de Tensor de Difusão , Vigília , Mapeamento Encefálico , Craniotomia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
3.
Stereotact Funct Neurosurg ; 97(4): 255-265, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31618749

RESUMO

Selective laser amygdalohippocampotomy (SLAH) is a minimally invasive surgical treatment for medial temporal lobe epilepsy. Visual field deficits (VFDs) are a significant potential complication. The objective of this study was to determine the relationship between VFDs and potential mechanisms of injury to the optic radiations and lateral geniculate nucleus. We performed a retrospective cross-sectional analysis of 3 patients (5.2%) who developed persistent VFDs after SLAH within our larger series (n = 58), 15 healthy individuals and 10 SLAH patients without visual complications. Diffusion tractography was used to evaluate laser catheter penetration of the optic radiations. Using a complementary approach, we evaluated evidence for focal microstructural tissue damage within the optic radiations and lateral geniculate nucleus. Overablation and potential heat radiation were assessed by quantifying ablation and choroidal fissure CSF volumes as well as energy deposited during SLAH.SLAH treatment parameters did not distinguish VFD patients. Atypically high overlap between the laser catheter and optic radiations was found in 1/3 VFD patients and was accompanied by focal reductions in fractional anisotropy where the catheter entered the lateral occipital white matter. Surprisingly, lateral geniculate tissue diffusivity was abnormal following, but also preceding, SLAH in patients who subsequently developed a VFD (all p = 0.005).In our series, vision-related complications following SLAH, which appear to occur less frequently than following open temporal lobe -surgery, were not directly explained by SLAH treatment parameters. Instead, our data suggest that variations in lateral geniculate structure may influence susceptibility to indirect heat injury from transoccipital SLAH.


Assuntos
Tonsila do Cerebelo/cirurgia , Hipocampo/cirurgia , Terapia a Laser/efeitos adversos , Complicações Pós-Operatórias/etiologia , Técnicas Estereotáxicas/efeitos adversos , Transtornos da Visão/etiologia , Adolescente , Adulto , Idoso , Tonsila do Cerebelo/diagnóstico por imagem , Estudos Transversais , Epilepsia do Lobo Temporal/diagnóstico por imagem , Epilepsia do Lobo Temporal/cirurgia , Feminino , Seguimentos , Hipocampo/diagnóstico por imagem , Humanos , Terapia a Laser/tendências , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/diagnóstico por imagem , Psicocirurgia/efeitos adversos , Psicocirurgia/tendências , Estudos Retrospectivos , Fatores de Risco , Técnicas Estereotáxicas/tendências , Transtornos da Visão/diagnóstico por imagem , Campos Visuais/fisiologia , Adulto Jovem
4.
Brain Inj ; 33(7): 854-868, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30848964

RESUMO

The posterior cingulate cortex (PCC) and corpus callosum (CC) are susceptible to trauma, but injury often evades detection. PCC Metabolic disruption may predict CC white matter tract injury and the secondary cascade responsible for progression. While the time frame for the secondary cascade remains unclear in humans, the first 24 h (hyper-acute phase) are crucial for life-saving interventions. Objectives: To test whether Magnetic Resonance Imaging (MRI) markers are detectable in the hyper-acute phase and progress after traumatic brain injury (TBI) and whether alterations in these parameters reflect injury severity. Methods: Spectroscopic and diffusion-weighted MRI data were collected in 18 patients with TBI (within 24 h and repeated 7-15 days following injury) and 18 healthy controls (scanned once). Results: Within 24 h of TBI N-acetylaspartate was reduced (F = 11.43, p = 0.002) and choline increased (F = 10.67, p = 0.003), the latter driven by moderate-severe injury (F = 5.54, p = 0.03). Alterations in fractional anisotropy (FA) and axial diffusivity (AD) progressed between the two time-points in the splenium of the CC (p = 0.029 and p = 0.013). Gradual reductions in FA correlated with progressive increases in choline (p = 0.029). Conclusions: Metabolic disruption and structural injury can be detected within hours of trauma. Metabolic and diffusion parameters allow identification of severity and provide evidence of injury progression.


Assuntos
Lesões Encefálicas Traumáticas/diagnóstico por imagem , Corpo Caloso/diagnóstico por imagem , Giro do Cíngulo/diagnóstico por imagem , Substância Branca/diagnóstico por imagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Lesões Encefálicas Traumáticas/metabolismo , Corpo Caloso/lesões , Corpo Caloso/metabolismo , Imagem de Tensor de Difusão , Feminino , Substância Cinzenta/diagnóstico por imagem , Substância Cinzenta/metabolismo , Giro do Cíngulo/lesões , Giro do Cíngulo/metabolismo , Humanos , Processamento de Imagem Assistida por Computador , Espectroscopia de Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Neuroimagem , Substância Branca/metabolismo , Adulto Jovem
5.
J Neurosci ; 37(12): 3150-3159, 2017 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-28213445

RESUMO

Recent "representational" accounts suggest a key role for the hippocampus in complex scene perception. Due to limitations in scanner field strength, however, the functional neuroanatomy of hippocampal-dependent scene perception is unknown. Here, we applied 7 T high-resolution functional magnetic resonance imaging (fMRI) alongside a perceptual oddity task, modified from nonhuman primate studies. This task requires subjects to discriminate highly similar scenes, faces, or objects from multiple viewpoints, and has revealed selective impairments during scene discrimination following hippocampal lesions. Region-of-interest analyses identified a preferential response in the subiculum subfield of the hippocampus during scene, but not face or object, discriminations. Notably, this effect was in the anteromedial subiculum and was not modulated by whether scenes were subsequently remembered or forgotten. These results highlight the value of ultra-high-field fMRI in generating more refined, anatomically informed, functional accounts of hippocampal contributions to cognition, and a unique role for the human subiculum in discrimination of complex scenes from different viewpoints.SIGNIFICANCE STATEMENT There is increasing evidence that the human hippocampus supports functions beyond just episodic memory, with human lesion studies suggesting a contribution to the perceptual processing of navigationally relevant, complex scenes. While the hippocampus itself contains several small, functionally distinct subfields, examining the role of these in scene processing has been previously limited by scanner field strength. By applying ultra-high-resolution 7 T fMRI, we delineated the functional contribution of individual hippocampal subfields during a perceptual discrimination task for scenes, faces, and objects. This demonstrated that the discrimination of scenes, relative to faces and objects, recruits the anterior subicular region of the hippocampus, regardless of whether scenes were subsequently remembered or forgotten.


Assuntos
Mapeamento Encefálico/métodos , Hipocampo/fisiologia , Aumento da Imagem/métodos , Imageamento por Ressonância Magnética/métodos , Rede Nervosa/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Adolescente , Adulto , Tomada de Decisões/fisiologia , Feminino , Humanos , Masculino , Adulto Jovem
6.
NMR Biomed ; 31(3)2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29315915

RESUMO

Abnormally high levels of the 'oncometabolite' 2-hydroxyglutarate (2-HG) occur in many grade II and III gliomas, and correlate with mutations in the genes of isocitrate dehydrogenase (IDH) isoforms. In vivo measurement of 2-HG in patients, using magnetic resonance spectroscopy (MRS), has largely been carried out at 3 T, yet signal overlap continues to pose a challenge for 2-HG detection. To combat this, several groups have proposed MRS methods at ultra-high field (≥7 T) where theoretical increases in signal-to-noise ratio and spectral resolution could improve 2-HG detection. Long echo time (long-TE) semi-localization by adiabatic selective refocusing (semi-LASER) (TE = 110 ms) is a promising method for improved 2-HG detection in vivo at either 3 or 7 T owing to the use of broad-band adiabatic localization. Using previously published semi-LASER methods at 3 and 7 T, this study directly compares the detectability of 2-HG in phantoms and in vivo across nine patients. Cramér-Rao lower bounds (CRLBs) of 2-HG fitting were found to be significantly lower at 7 T (6 ± 2%) relative to 3 T (15 ± 7%) (p = 0.0019), yet were larger at 7 T in an IDH wild-type patient. Although no increase in SNR was detected at 7 T (77 ± 26) relative to 3 T (77 ± 30), the detection of 2-HG was greatly enhanced through an improved spectral profile and increased resolution at 7 T. 7 T had a large effect on pairwise fitting correlations between γ-aminobutyric acid (GABA) and 2-HG (p = 0.004), and resulted in smaller coefficients. The increased sensitivity for 2-HG detection using long-TE acquisition at 7 T may allow for more rapid estimation of 2-HG (within a few spectral averages) together with other associated metabolic markers in glioma.


Assuntos
Glutaratos/metabolismo , Espectroscopia de Ressonância Magnética , Adulto , Neoplasias Encefálicas/metabolismo , Colina/metabolismo , Creatina/metabolismo , Feminino , Glioma/metabolismo , Humanos , Isocitrato Desidrogenase/metabolismo , Masculino , Pessoa de Meia-Idade , Adulto Jovem
7.
J Neurol Neurosurg Psychiatry ; 88(12): 1017-1025, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28710324

RESUMO

State-of-the-art glioma treatment aims to maximise neuro-oncological benefit while minimising losses in quality of life. Optimising this balance remains hindered by our still limited understanding of information processing in the human brain. To help understand individual differences in functional outcomes following neuro-oncological treatment, we review mounting evidence demonstrating the fundamental role that white matter connections play in complex human behaviour. We focus on selected fibre tracts whose destruction is recognised to elicit predictable behavioural deficits and consider specific indications for non-invasive diffusion MRI tractography, the only existing method to map these fibre tracts in vivo, in the selection and planning of neuro-oncological treatments. Despite remaining challenges, longitudinal tract imaging, in combination with intraoperative testing and neuropsychological evaluation, offers unique opportunities to refine our understanding of human brain organisation in the quest to predict and ultimately reduce the quality of life burden of both surgical and non-surgical first-line neuro-oncological therapies.


Assuntos
Neoplasias Encefálicas/diagnóstico por imagem , Encéfalo/crescimento & desenvolvimento , Imagem de Tensor de Difusão/métodos , Glioma/diagnóstico por imagem , Neoplasias do Sistema Nervoso/diagnóstico por imagem , Substância Branca/diagnóstico por imagem , Humanos , Recuperação de Função Fisiológica
8.
Cereb Cortex ; 25(11): 4584-95, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26009613

RESUMO

Short-term (STM) and long-term memory (LTM) have largely been considered as separate brain systems reflecting fronto-parietal and medial temporal lobe (MTL) functions, respectively. This functional dichotomy has been called into question by evidence of deficits on aspects of working memory in patients with MTL damage, suggesting a potentially direct hippocampal contribution to STM. As the hippocampus has direct anatomical connections with the thalamus, we tested the hypothesis that damage to thalamic nuclei regulating cortico-cortical interactions may contribute to STM deficits in patients with hippocampal dysfunction. We used diffusion-weighted magnetic resonance imaging-based tractography to identify anatomical subdivisions in patients with MTL epilepsy. From these, we measured resting-state functional connectivity with detailed cortical divisions of the frontal, temporal, and parietal lobes. Whereas thalamo-temporal functional connectivity reflected LTM performance, thalamo-prefrontal functional connectivity specifically predicted STM performance. Notably, patients with hippocampal volume loss showed thalamic volume loss, most prominent in the pulvinar region, not detected in patients with normal hippocampal volumes. Aberrant thalamo-cortical connectivity in the epileptic hemisphere was mirrored in a loss of behavioral association with STM performance specifically in patients with hippocampal atrophy. These findings identify thalamo-cortical disruption as a potential mechanism contributing to STM deficits in the context of MTL damage.


Assuntos
Lesões Encefálicas/complicações , Lesões Encefálicas/patologia , Córtex Cerebral/fisiopatologia , Transtornos da Memória/etiologia , Memória de Curto Prazo/fisiologia , Lobo Temporal/patologia , Tálamo/fisiopatologia , Adolescente , Adulto , Estudos de Coortes , Imagem de Difusão por Ressonância Magnética , Epilepsia do Lobo Temporal/patologia , Epilepsia do Lobo Temporal/fisiopatologia , Epilepsia do Lobo Temporal/cirurgia , Feminino , Hipocampo/irrigação sanguínea , Hipocampo/patologia , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Vias Neurais/irrigação sanguínea , Vias Neurais/patologia , Testes Neuropsicológicos , Oxigênio/sangue , Adulto Jovem
9.
J Neurosci ; 34(14): 4920-8, 2014 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-24695711

RESUMO

In the healthy human brain, evidence for dissociable memory networks along the anterior-posterior axis of the hippocampus suggests that this structure may not function as a unitary entity. Failure to consider these functional divisions may explain diverging results among studies of memory adaptation in disease. Using task-based and resting functional MRI, we show that chronic seizures disrupting the anterior medial temporal lobe (MTL) preserve anterior and posterior hippocampal-cortical dissociations, but alter signaling between these and other key brain regions. During performance of a memory encoding task, we found reduced neural activity in human patients with unilateral temporal lobe epilepsy relative to age-matched healthy controls, but no upregulation of fMRI signal in unaffected hippocampal subregions. Instead, patients showed aberrant resting fMRI connectivity within anterior and posterior hippocampal-cortical networks, which was associated with memory decline, distinguishing memory-intact from memory-impaired patients. Our results highlight a critical role for intact hippocampo-cortical functional communication in memory and provide evidence that chronic injury-induced functional reorganization in the diseased MTL is behavioral inefficient.


Assuntos
Epilepsia do Lobo Temporal/complicações , Hipocampo/fisiopatologia , Transtornos da Memória/etiologia , Transtornos da Memória/patologia , Rede Nervosa/fisiopatologia , Adolescente , Adulto , Mapeamento Encefálico , Feminino , Hipocampo/irrigação sanguínea , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Pessoa de Meia-Idade , Rede Nervosa/irrigação sanguínea , Testes Neuropsicológicos , Oxigênio/sangue , Descanso , Estatística como Assunto , Estatísticas não Paramétricas , Adulto Jovem
10.
Epilepsia ; 56(1): 101-13, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25489630

RESUMO

OBJECTIVES: Patients with temporal lobe epilepsy (TLE) experience significant deficits in category-related object recognition and naming following standard surgical approaches. These deficits may result from a decoupling of core processing modules (e.g., language, visual processing, and semantic memory), due to "collateral damage" to temporal regions outside the hippocampus following open surgical approaches. We predicted that stereotactic laser amygdalohippocampotomy (SLAH) would minimize such deficits because it preserves white matter pathways and neocortical regions that are critical for these cognitive processes. METHODS: Tests of naming and recognition of common nouns (Boston Naming Test) and famous persons were compared with nonparametric analyses using exact tests between a group of 19 patients with medically intractable mesial TLE undergoing SLAH (10 dominant, 9 nondominant), and a comparable series of TLE patients undergoing standard surgical approaches (n=39) using a prospective, nonrandomized, nonblinded, parallel-group design. RESULTS: Performance declines were significantly greater for the patients with dominant TLE who were undergoing open resection versus SLAH for naming famous faces and common nouns (F=24.3, p<0.0001, η2=0.57, and F=11.2, p<0.001, η2=0.39, respectively), and for the patients with nondominant TLE undergoing open resection versus SLAH for recognizing famous faces (F=3.9, p<0.02, η2=0.19). When examined on an individual subject basis, no SLAH patients experienced any performance declines on these measures. In contrast, 32 of the 39 patients undergoing standard surgical approaches declined on one or more measures for both object types (p<0.001, Fisher's exact test). Twenty-one of 22 left (dominant) TLE patients declined on one or both naming tasks after open resection, while 11 of 17 right (nondominant) TLE patients declined on face recognition. SIGNIFICANCE: Preliminary results suggest (1) naming and recognition functions can be spared in TLE patients undergoing SLAH, and (2) the hippocampus does not appear to be an essential component of neural networks underlying name retrieval or recognition of common objects or famous faces.


Assuntos
Tonsila do Cerebelo/cirurgia , Epilepsia do Lobo Temporal/cirurgia , Hipocampo/cirurgia , Transtornos da Linguagem/prevenção & controle , Terapia a Laser/métodos , Transtornos da Memória/prevenção & controle , Reconhecimento Psicológico , Cirurgia Assistida por Computador/métodos , Adulto , Face , Lateralidade Funcional , Humanos , Idioma , Transtornos da Linguagem/etiologia , Terapia a Laser/efeitos adversos , Imageamento por Ressonância Magnética , Transtornos da Memória/etiologia , Pessoa de Meia-Idade , Testes Neuropsicológicos , Reconhecimento Visual de Modelos , Técnicas Estereotáxicas , Resultado do Tratamento , Adulto Jovem
12.
Brain ; 136(Pt 10): 3151-62, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24014519

RESUMO

Voltage-gated potassium channel complex antibodies, particularly those directed against leucine-rich glioma inactivated 1, are associated with a common form of limbic encephalitis that presents with cognitive impairment and seizures. Faciobrachial dystonic seizures have recently been reported as immunotherapy-responsive, brief, frequent events that often predate the cognitive impairment associated with this limbic encephalitis. However, these observations were made from a retrospective study without serial cognitive assessments. Here, we undertook the first prospective study of faciobrachial dystonic seizures with serial assessments of seizure frequencies, cognition and antibodies in 10 cases identified over 20 months. We hypothesized that (i) faciobrachial dystonic seizures would show a differential response to anti-epileptic drugs and immunotherapy; and that (ii) effective treatment of faciobrachial dystonic seizures would accelerate recovery and prevent the development of cognitive impairment. The 10 cases expand both the known age at onset (28 to 92 years, median 68) and clinical features, with events of longer duration, simultaneously bilateral events, prominent automatisms, sensory aura, and post-ictal fear and speech arrest. Ictal epileptiform electroencephalographic changes were present in three cases. All 10 cases were positive for voltage-gated potassium channel-complex antibodies (346-4515 pM): nine showed specificity for leucine-rich glioma inactivated 1. Seven cases had normal clinical magnetic resonance imaging, and the cerebrospinal fluid examination was unremarkable in all seven tested. Faciobrachial dystonic seizures were controlled more effectively with immunotherapy than anti-epileptic drugs (P = 0.006). Strikingly, in the nine cases who remained anti-epileptic drug refractory for a median of 30 days (range 11-200), the addition of corticosteroids was associated with cessation of faciobrachial dystonic seizures within 1 week in three and within 2 months in six cases. Voltage-gated potassium channel-complex antibodies persisted in the four cases with relapses of faciobrachial dystonic seizures during corticosteroid withdrawal. Time to recovery of baseline function was positively correlated with time to immunotherapy (r = 0.74; P = 0.03) but not time to anti-epileptic drug administration (r = 0.55; P = 0.10). Of 10 cases, the eight cases who received anti-epileptic drugs (n = 3) or no treatment (n = 5) all developed cognitive impairment. By contrast, the two who did not develop cognitive impairment received immunotherapy to treat their faciobrachial dystonic seizures (P = 0.02). In eight cases without clinical magnetic resonance imaging evidence of hippocampal signal change, cross-sectional volumetric magnetic resonance imaging post-recovery, after accounting for age and head size, revealed cases (n = 8) had smaller brain volumes than healthy controls (n = 13) (P < 0.001). In conclusion, faciobrachial dystonic seizures can be prospectively identified as a form of epilepsy with an expanding phenotype. Immunotherapy is associated with excellent control of the frequently anti-epileptic drug refractory seizures, hastens time to recovery, and may prevent the subsequent development of cognitive impairment observed in this study.


Assuntos
Anticorpos/uso terapêutico , Transtornos Cognitivos/prevenção & controle , Convulsões/tratamento farmacológico , Adulto , Idoso , Idoso de 80 Anos ou mais , Eletroencefalografia/métodos , Feminino , Humanos , Encefalite Límbica/tratamento farmacológico , Encefalite Límbica/fisiopatologia , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Fenótipo , Estudos Prospectivos , Convulsões/imunologia , Convulsões/fisiopatologia , Resultado do Tratamento
13.
BMC Psychiatry ; 14: 159, 2014 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-24885374

RESUMO

BACKGROUND: The Whitehall II (WHII) study of British civil servants provides a unique source of longitudinal data to investigate key factors hypothesized to affect brain health and cognitive ageing. This paper introduces the multi-modal magnetic resonance imaging (MRI) protocol and cognitive assessment designed to investigate brain health in a random sample of 800 members of the WHII study. METHODS/DESIGN: A total of 6035 civil servants participated in the WHII Phase 11 clinical examination in 2012-2013. A random sample of these participants was included in a sub-study comprising an MRI brain scan, a detailed clinical and cognitive assessment, and collection of blood and buccal mucosal samples for the characterisation of immune function and associated measures. Data collection for this sub-study started in 2012 and will be completed by 2016. The participants, for whom social and health records have been collected since 1985, were between 60-85 years of age at the time the MRI study started. Here, we describe the pre-specified clinical and cognitive assessment protocols, the state-of-the-art MRI sequences and latest pipelines for analyses of this sub-study. DISCUSSION: The integration of cutting-edge MRI techniques, clinical and cognitive tests in combination with retrospective data on social, behavioural and biological variables during the preceding 25 years from a well-established longitudinal epidemiological study (WHII cohort) will provide a unique opportunity to examine brain structure and function in relation to age-related diseases and the modifiable and non-modifiable factors affecting resilience against and vulnerability to adverse brain changes.


Assuntos
Envelhecimento/patologia , Encéfalo/patologia , Transtornos Cognitivos/patologia , Imageamento por Ressonância Magnética/métodos , Neuroimagem/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Cognição , Feminino , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
14.
Neuropsychologia ; 194: 108783, 2024 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-38161052

RESUMO

Prior univariate functional magnetic resonance imaging (fMRI) studies in humans suggest that the anteromedial subicular complex of the hippocampus is a hub for scene-based cognition. However, it is possible that univariate approaches were not sufficiently sensitive to detect scene-related activity in other subfields that have been implicated in spatial processing (e.g., CA1). Further, as connectivity-based functional gradients in the hippocampus do not respect classical subfield boundary definitions, category selectivity may be distributed across anatomical subfields. Region-of-interest approaches, therefore, may limit our ability to observe category selectivity across discrete subfield boundaries. To address these issues, we applied searchlight multivariate pattern analysis to 7T fMRI data of healthy adults who undertook a simultaneous visual odd-one-out discrimination task for scene and non-scene (including face) visual stimuli, hypothesising that scene classification would be possible in multiple hippocampal regions within, but not constrained to, anteromedial subicular complex and CA1. Indeed, we found that the scene-selective searchlight map overlapped not only with anteromedial subicular complex (distal subiculum, pre/para subiculum), but also inferior CA1, alongside posteromedial (including retrosplenial) and parahippocampal cortices. Probabilistic overlap maps revealed gradients of scene category selectivity, with the strongest overlap located in the medial hippocampus, converging with searchlight findings. This was contrasted with gradients of face category selectivity, which had stronger overlap in more lateral hippocampus, supporting ideas of parallel processing streams for these two categories. Our work helps to map the scene, in contrast to, face processing networks within, and connected to, the human hippocampus.


Assuntos
Mapeamento Encefálico , Hipocampo , Adulto , Humanos , Mapeamento Encefálico/métodos , Hipocampo/diagnóstico por imagem , Córtex Cerebral , Percepção Visual , Cognição , Imageamento por Ressonância Magnética/métodos
15.
Brain ; 135(Pt 8): 2350-7, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22669081

RESUMO

Magnetic resonance imaging methods that measure interregional brain signalling at rest have been advanced as powerful tools to probe organizational properties of functional networks. In drug-resistant temporal lobe epilepsy, resting functional magnetic resonance imaging studies have primarily employed region of interest approaches that preclude a comprehensive evaluation of large-scale functional interactions. In line with the distributed nature of structural damage in this condition, we set out to quantify connectivity across the entire range of resting networks. Furthermore, we assessed whether connectivity is driven by co-localized structural pathology. We obtained resting state, diffusion tensor and anatomical imaging data in 35 patients with temporal lobe epilepsy and 20 healthy subjects on a 3 T scanner. Resting state networks were identified using independent component analysis, which allows an objective whole-brain quantification of functional connectivity. We performed group comparisons before and after correcting for voxel-wise grey matter density. In addition, we identified voxel-wise associations between resting connectivity and white matter coherence indexed by fractional anisotropy. Compared with controls, patients showed altered (typically reduced) functional connectivity between the hippocampus, anterior temporal, precentral cortices and the default mode and sensorimotor networks. Reduced network integration of the hippocampus was explained by variations in grey matter density, while functional connectivity of the parahippocampus, and frontal and temporal neocortices showed atypical associations with white matter coherence within pathways carrying connections of these regions. Our multimodal imaging study suggests that in temporal lobe epilepsy, cortical atrophy and microstructural white matter damage impact functional resting connectivity.


Assuntos
Imagem de Tensor de Difusão , Eletroencefalografia , Epilepsia do Lobo Temporal/patologia , Epilepsia do Lobo Temporal/fisiopatologia , Rede Nervosa/fisiologia , Descanso/fisiologia , Adulto , Imagem de Tensor de Difusão/métodos , Eletroencefalografia/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Rede Nervosa/patologia , Adulto Jovem
16.
Neuroimage ; 63(1): 611-21, 2012 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-22743195

RESUMO

Several studies have sought to test the neurodevelopmental hypothesis of schizophrenia through analysis of cortical gyrification. However, to date, results have been inconsistent. A possible reason for this is that gyrification measures at the centimeter scale may be insensitive to subtle morphological changes at smaller scales. The lack of consistency in such studies may impede further interpretation of cortical morphology as an aid to understanding the etiology of schizophrenia. In this study we developed a new approach, examining whether millimeter-scale measures of cortical curvature are sensitive to changes in fundamental geometric properties of the cortical surface in schizophrenia. We determined and compared millimeter-scale and centimeter-scale curvature in three separate case-control studies; specifically two adult groups and one adolescent group. The datasets were of different sizes, with different ages and gender-spreads. The results clearly show that millimeter-scale intrinsic curvature measures were more robust and consistent in identifying reduced gyrification in patients across all three datasets. To further interpret this finding we quantified the ratio of expansion in the upper and lower cortical layers. The results suggest that reduced gyrification in schizophrenia is driven by a reduction in the expansion of upper cortical layers. This may plausibly be related to a reduction in short-range connectivity.


Assuntos
Envelhecimento/patologia , Córtex Cerebral/patologia , Bases de Dados Factuais , Imageamento por Ressonância Magnética/métodos , Esquizofrenia/patologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Variações Dependentes do Observador , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Adulto Jovem
17.
Neuroimage ; 57(1): 167-181, 2011 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-21473920

RESUMO

Diffusion imaging of post mortem brains has great potential both as a reference for brain specimens that undergo sectioning, and as a link between in vivo diffusion studies and "gold standard" histology/dissection. While there is a relatively mature literature on post mortem diffusion imaging of animals, human brains have proven more challenging due to their incompatibility with high-performance scanners. This study presents a method for post mortem diffusion imaging of whole, human brains using a clinical 3-Tesla scanner with a 3D segmented EPI spin-echo sequence. Results in eleven brains at 0.94 × 0.94 × 0.94 mm resolution are presented, and in a single brain at 0.73 × 0.73 × 0.73 mm resolution. Region-of-interest analysis of diffusion tensor parameters indicate that these properties are altered compared to in vivo (reduced diffusivity and anisotropy), with significant dependence on post mortem interval (time from death to fixation). Despite these alterations, diffusion tractography of several major tracts is successfully demonstrated at both resolutions. We also report novel findings of cortical anisotropy and partial volume effects.


Assuntos
Artefatos , Autopsia , Mapeamento Encefálico/métodos , Encéfalo/fisiopatologia , Imagem de Difusão por Ressonância Magnética/métodos , Anisotropia , Humanos , Interpretação de Imagem Assistida por Computador/métodos , Fixação de Tecidos
18.
Clin Neuroradiol ; 31(1): 245-256, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32274518

RESUMO

PURPOSE: Functional magnetic resonance imaging (fMRI) has an established role in neurosurgical planning; however, ambiguity surrounds the comparative value of resting and task-based fMRI relative to anatomical localization of the sensorimotor cortex. This study was carried out to determine: 1) how often fMRI adds to prediction of motor risks beyond expert neuroradiological review, 2) success rates of presurgical resting and task-based sensorimotor mapping, and 3) the impact of accelerated resting fMRI acquisitions on network detectability. METHODS: Data were collected at 2 centers from 71 patients with a primary brain tumor (31 women; mean age 41.9 ± 13.9 years) and 14 healthy individuals (6 women; mean age 37.9 ± 12.7 years). Preoperative 3T MRI included anatomical scans and resting fMRI using unaccelerated (TR = 3.5 s), intermediate (TR = 1.56 s) or high temporal resolution (TR = 0.72 s) sequences. Task fMRI finger tapping data were acquired in 45 patients. Group differences in fMRI reproducibility, spatial overlap and success frequencies were assessed with t­tests and χ2-tests. RESULTS: Radiological review identified the central sulcus in 98.6% (70/71) patients. Task-fMRI succeeded in 100% (45/45). Resting fMRI failed to identify a sensorimotor network in up to 10 patients; it succeeded in 97.9% (47/48) of accelerated fMRIs, compared to only 60.9% (14/23) of unaccelerated fMRIs ([Formula: see text](2) = 17.84, p < 0.001). Of the patients 12 experienced postoperative deterioration, largely predicted by anatomical proximity to the central sulcus. CONCLUSION: The use of fMRI in patients with residual or intact presurgical motor function added value to uncertain anatomical localization in just a single peri-Rolandic glioma case. Resting fMRI showed high correspondence to task localization when acquired with accelerated sequences but offered limited success at standard acquisitions.


Assuntos
Neoplasias Encefálicas , Glioma , Córtex Sensório-Motor , Adulto , Mapeamento Encefálico , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/cirurgia , Feminino , Glioma/diagnóstico por imagem , Glioma/cirurgia , Humanos , Imageamento por Ressonância Magnética , Masculino , Reprodutibilidade dos Testes , Córtex Sensório-Motor/diagnóstico por imagem
19.
Neuroimage Clin ; 30: 102689, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34215157

RESUMO

Large individual differences in how brain networks respond to treatment hinder efforts to personalise treatment in neurological conditions. We used a brain network fingerprinting approach to longitudinally track re-organisation of complementary phonological and semantic language networks in 19 patients before and after brain-tumour surgery. Patient task fingerprints were individually compared to normal networks established in 17 healthy controls. Additionally, pre- and post-operative patient fingerprints were directly compared to assess longitudinal network adaptations. We found that task networks remained stable over time in healthy controls, whereas treatment induced reorganisation in 47.4% of patient fluency networks and 15.8% of semantic networks. How networks adapted after surgery was highly unique; a subset of patients (10%) showed 'normalisation' while others (21%) developed newly atypical networks after treatment. The strongest predictor of adaptation of the fluency network was the presence of clinically reported language symptoms. Our findings indicate a tight coupling between processes disrupting performance and neural network adaptation, the patterns of which appear to be both task- and individually-unique. We propose that connectivity fingerprinting offers potential as a clinical marker to track adaptation of specific functional networks across treatment interventions over time.


Assuntos
Idioma , Imageamento por Ressonância Magnética , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Humanos , Individualidade , Vias Neurais/diagnóstico por imagem
20.
Front Neurol ; 12: 779495, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34956059

RESUMO

Objective: To evaluate declarative memory outcomes in medically refractory epilepsy patients who underwent either a highly selective laser ablation of the amygdalohippocampal complex or a conventional open temporal lobe resection. Methods: Post-operative change scores were examined for verbal memory outcome in epilepsy patients who underwent stereotactic laser amygdalohippocampotomy (SLAH: n = 40) or open resection procedures (n = 40) using both reliable change index (RCI) scores and a 1-SD change metric. Results: Using RCI scores, patients undergoing open resection (12/40, 30.0%) were more likely to decline on verbal memory than those undergoing SLAH (2/40 [5.0%], p = 0.0064, Fisher's exact test). Patients with language dominant procedures were much more likely to experience a significant verbal memory decline following open resection (9/19 [47.4%]) compared to laser ablation (2/19 [10.5%], p = 0.0293, Fisher's exact test). 1 SD verbal memory decline frequently occurred in the open resection sample of language dominant temporal lobe patients with mesial temporal sclerosis (8/10 [80.0%]), although it rarely occurred in such patients after SLAH (2/14, 14.3%) (p = 0.0027, Fisher's exact test). Memory improvement occurred significantly more frequently following SLAH than after open resection. Interpretation: These findings suggest that while verbal memory function can decline after laser ablation of the amygdalohippocampal complex, it is better preserved when compared to open temporal lobe resection. Our findings also highlight that the dominant hippocampus is not uniquely responsible for verbal memory. While this is at odds with our simple and common heuristic of the hippocampus in memory, it supports the findings of non-human primate studies showing that memory depends on broader medial and lateral TL regions.

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