Optic Radiation In Patients Research Articles

Injury of the optic radiation in patients with mild TBI: A DTT study.

ObjectivesWe investigated injuries of the optic radiations (ORs) in patients with mild traumatic brain injury (TBI) by using diffusion tensor tractography (DTT).MethodsFifty-two consecutive patients who complained of visual problems showed abnormal visual evoked potential (VEP) latency but no abnormality on conventional brain MRI after mild TBI, and fifty normal control subjects were recruited for this study. Subjects’ ORs were reconstructed using DTT, and three DTT parameters (fractional anisotropy [FA], apparent diffusion coefficient [ADC], and tract volume) were measured for each OR.ResultsMean FA value and tract volume of the OR were significantly lower in the patient group than in the control group (p < 0.05). However, there was no significant difference in the ADC values of the OR between the patient and control groups (p > 0.05). A weak negative correlation was detected between VEP latency and OR fiber number (r = 0.204, p < 0.05).ConclusionsDTT revealed that OR injuries were not detected on the conventional brain MRI scans of patients who complained of visual problems and had abnormal VEP latency after mild TBI. Our results suggest that DTT would be a useful technique for detecting OR injury in patients with mild TBI.

Combined machine learning and diffusion tensor imaging reveals altered anatomic fiber connectivity of the brain in primary open-angle glaucoma

Parameters derived from diffusion tensor imaging (DTI) have been found to be significantly altered in the optic tracts, optic nerves, and optic radiations in patients with primary open-angle glaucoma (POAG). In this study, DTI-derived parameters were further constructed into fiber connectivity, and we investigated anatomical fiber connectivity changes within and beyond the visual pathway in POAG patients. DTI and T1-weighted magnetic resonance images were acquired in 18 POAG patients and 26 healthy controls (HC). White matter tracts based on the Brodmann atlases (BA) were constructed using the deterministic fiber tracking method. The mean fractional anisotropy (FA), fiber number (FN), and mean fiber length (FL) were measured and then evaluated using two-sample t-tests between POAG and HC. The fiber connectivity between regions was taken as the features for classifying HC and POAG using a machine learning method known as naïve Bayesian classification. The mean FA decreased in connections between visual cortex BA17/BA18 and cortex BA23/BA25/BA35/BA36, while it increased in the connections between cortex BA3/BA7/BA9 and BA5/BA6/BA45/BA25 in POAG. Classification using fibers where a significant difference in FN had been identified produced better accuracy (ACC = 0.89) than using FA or FL (ACC = 0.77 and 0.75, respectively). The FN of individual fiber connections with higher accuracy and significant changes in POAG involved brain regions associated with vision (BA19), depression (BA10/BA46/BA25), and memory (BA29). These findings strengthen the hypothesis that POAG involves changes in anatomical connectivity within and beyond the visual pathway. Classification using the machine learning method reveals that mean FN has the potential to be used as a biomarker for detecting white matter microstructure changes in POAG.

Optic radiation injury in patients with aneurismal subarachnoid hemorrhage: A preliminary diffusion tensor imaging report.

Visual field defect is one of the various clinical manifestations in patients with subarachnoid hemorrhage (SAH). Little is known about the pathogenic mechanism of visual field defect in SAH. In the current study, we investigated the diffusion tensor imaging (DTI) finding of the optic radiation in patients with SAH following rupture of a cerebral artery aneurysm. We recruited 21 patients with aneurismal SAH (12 males, 9 females, mean age, 52.67 years; range, 41–68 years) who showed no definite lesion along the visual pathway. Twenty-one age-and sex-matched normal control subjects were also recruited. DTI data were acquired at an average of 5.9 weeks (range: 3–12 weeks) after onset and reconstruction of the optic radiation was performed using DTI-Studio software. The fractional anisotropy value, apparent diffusion coefficient value, and fiber number of the optic radiation were measured. The fractional anisotropy value of the optic radiation was significantly decreased, and the apparent diffusion coefficient value was significantly increased, in patients with aneurismal SAH than in normal control subjects. However, there was no significant difference in the fiber number of the optic radiation between patients with aneurismal SAH and normal control subjects. The decrement of fractional anisotropy value and increment of apparent diffusion coefficient value of the optic radiation in patients with aneurismal SAH suggest optic radiation injury. Therefore, we recommend a thorough evaluation for optic radiation injury in patient with aneurismal SAH.

Study of optic radiations in patients with primary open-angle glaucoma with diffusion tensor imaging

Objective: To study the alteration of the optic radiations in patients with primary open-angle glaucoma (POAG) by diffusion tensor imaging (DTI) and tractography, and to reveal the correlation between the DTI derived parameters and the severity of the disease. Methods: A total of 24 patients with POAG and 20 age- and gender-matched healthy controls were enrolled in this study from January 2011 to June 2013.All subjects underwent ophthalmoscopy, standard automatic perimetry, intraocular pressure measurement and MRI scanning.All the eyes of POAG patients were evaluated by Hodapp-Anderson-Parrish (HAP) system.Then the stages of bilateral eyes were added together to evaluate the disease severity.Tractography was used to measure the fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity (AD) of the optic radiations of these subjects.The results of the two groups were compared.Partial correlation was then used to reveal the correlation between these derived DTI parameters and the severity of POAG. Results: Compared with health controls, POAG patients showed significant decreased FA (t=-3.299, P=0.002) and AD (t=-2.485, P=0.013), increased RD (t=2.365, P=0.018) in optic radiation .The alteration of MD was not significant (t=0.719, P=0.454). Mean FA values of the optic radiations were negatively correlated with POAG stages (r=-0.643, P= 0.001), while mean RD values (r=0.570, P= 0.004) and mean MD values (r= 0.448, P= 0.028) were positively correlated with POAG stages.No correlation between AD values and severity of POAG was found. Conclusion: In the optic radiations of POAG patients, the FA values and AD values decrease, while RD values increase, indicating the fiber integrity changes.The alterations of FA, RD and MD are correlated with disease severity.

Diffusion tensor imaging of occult injury of optic radiation following optic neuritis in multiple sclerosis.

Multiple sclerosis (MS) is easily detected by routine magnetic resonance imaging (MRI). However, it is not possible to detect early or occult lesions in MS by routine MRI, and this may explain the inconsistency between the severity of the lesions found by MRI and the degree of clinical disability of patients with MS. The present study included 10 patients with relapsing-remitting MS and 10 healthy volunteers. Each patient underwent routine 3.0 T MRI, diffusion tensor imaging (DTI), and diffusion tensor tractography (DTT). Optic nerve and optic radiation were analyzed by DTI and DTT. The fractional anisotropy (FA), mean diffusivity (MD), λ//, and λ┴ values were measured. In the 10 patients with MS, 7 optic nerves were affected, and 13 optic nerves were not affected. Cranial MRI showed that optic nerve thickening and hyperintensity occurred in 2 patients with MS. In the directionally encoded color maps, a hypointensive green signal in the optic nerve was observed in 3 patients with MS. The FA values were significantly lower and the MD, λ//, and λ┴ values were significantly higher in the affected and unaffected optic nerves and optic radiations in patients with MS in comparison with controls (P<0.05). There were no significant differences in these values between the affected and unaffected optic nerves and optic radiation in patients with MS (P>0.05). Diffusion tensor imaging is sensitive in the detection of occult injury of the optic nerve and optic radiation following optic neuritis. Diffusion tensor imaging may be a useful tool for the early diagnosis, treatment and management of MS.

Alterations of the optic pathway between unilateral and bilateral optic nerve damage in multiple sclerosis as revealed by the combined use of advanced diffusion kurtosis imaging and visual evoked potentials

ObjectivesWe investigated changes in the optic tract and optic radiation in patients with multiple sclerosis (MS) by comparing unilateral and bilateral optic nerve damage assessed based on visual evoked potentials (VEPs) using advanced diffusion MR metrics. MethodsIn 21 MS patients, diffusion MRI was performed. Maps of fractional anisotropy, apparent diffusion coefficient (ADC), and mean kurtosis (MK) were computed. On the basis of the P100 latency in VEPs, the MS patients were divided into three groups: bilateral (n=7), unilateral (n=7), and no abnormality (n=7). Their optic tracts and optic radiations were analyzed with diffusion MRI-based fiber tracking. We also investigated the correlations between diffusion parameters and VEPs (n=21). ResultsIn the optic tract, the diffusion changes in each of the three groups showed step-like changes. The diffusion changes in the optic radiations of the unilateral group were similar to those in the normal VEP group. Only the bilateral group showed significantly higher ADC and lower MK relative to the other two groups (P<0.05, Steel–Dwass multiple-comparison test). A significant positive correlation between VEP latency and ADC and a significant negative correlation between VEP latency and MK were observed (P<0.01, Spearman's correction). ConclusionsWe first evaluated the relationship between VEPs and DKI and concluded that the lateral geniculate nucleus may compensate for unilateral damage in the pre-geniculate optic pathway via neural plasticity.

Diffusion tensor imaging of optic nerve and optic radiation in primary chronic angle-closure glaucoma using 3T magnetic resonance imaging.

To evaluate the value of quantitative diffusion tensor imaging (DTI) in assessing the axonal and myelin damage of the optic nerves and optic radiations in patients with chronic primary angle-closure glaucoma (PACG) by using high-field magnetic resonance (MR) imaging (3T). Twenty patients with bilateral chronic PACG and twenty age- and sex matched disease-free control subjects were enrolled. Conventional MRI and DTI were performed on all subjects using 3T MR scanner. Mean diffusivity (MD), fractional anisotropy (FA), axial diffusivities (AD) and radial diffusivities (RD) of each optic nerve and each optic radiation were measured by using post-processing software of DTI studio 2.3, and then compared between left eyes and right eyes and between patients group and control group. The paired-sample t- test were used. There was no abnormality in the shape and signal intensity of the optic nerves and optic radiations in patients group and control group on the conventional MRI. No significant differences were observed in the FA, MD, AD and RD between the right and left optic nerves and optic radiations within patients group and control group (P>0.05). The optic nerves and optic radiations of patients with chronic PACG, as compared with control subjects, had significantly higher MD, AD, RD and significantly lower FA (P<0.05). The diffusivity of optic nerves and optic radiations in chronic PACG group showed abnormal and diffusivity parameters could be used markers of axonal and myelin injury in glaucoma.

Damage to the Optic Radiation in Patients With Mild Traumatic Brain Injury.

There are known limitations of conventional computed tomography and magnetic resonance imaging in detecting neural injury in patients with mild traumatic brain injury (TBI). Diffusion tensor imaging (DTI) provides a method to further assess cerebral injury in this patient population. We report 2 patients with mild TBI who showed injury of the optic radiation (OR) as demonstrated by DTI. Two patients who complained of visual field loss after mild TBI and 9 age-matched normal control subjects were recruited for this study. Peripheral field defects were detected with automated perimetry in both patients. Regarding the configuration of OR, the total volume of OR was decreased in the right OR of both patients compared with controls; in contrast, the left ORs were divided into 2 parts in both patients. The voxel numbers of both ORs in both patients were more than 2 standard deviations lower than that of normal control subjects. The apparent diffusion coefficient value of the right OR in patient 2 was more than 2 standard deviations higher than that of normal controls. We demonstrated injury of the OR using DTI in 2 patients who showed visual field defects after mild TBI.

Cerebral glucose metabolism in the striate cortex positively correlates with fractional anisotropy values of the optic radiation in patients with glaucoma.

It has recently become clear that glaucoma is not only an ocular disease, but involves central visual pathways as well. The purpose of this study was to examine functional and structural alterations in the brains of glaucoma patients. Case-control study in a hospital. A total of 32 glaucoma patients and 19 healthy controls. All participants underwent positron emission tomography with (18)F-fluorodeoxyglucose, diffusion-tensor magnetic resonance imaging, and the 30-2 program of the Humphrey Visual Field Analyzer. Fractional anisotropy values of the optic radiation were compared between the two groups by defining regions of interests. Cerebral glucose metabolism was compared using statistical parametric mapping software. The correlation coefficients were calculated between the average of the total deviation of hemivisual fields of both eyes, fractional anisotropy values of the contralateral optic radiation and glucose metabolism in the contralateral striate cortex. Fractional anisotropy values in the bilateral optic radiations were significantly lower in patients with glaucoma. A significant glucose hypometabolism in the bilateral striate cortex was also observed in the glaucoma group. Regression analyses for glaucoma patients demonstrated that the average of the total deviation of hemivisual fields significantly correlated with both fractional anisotropy value of the contralateral optic radiation and glucose metabolism in the contralateral striate cortex. Moreover, there were significant correlations between fractional anisotropy values of the optic radiation and ipsilateral striatal glucose metabolism. We observed structural alterations in the bilateral optic radiations and glucose hypometabolism in the bilateral striate cortex of glaucoma patients.

Diffusion tensor magnetic resonance imaging in the diagnosis of visual pathway neurodegeneration in glaucoma

To study the state of visual pathways in patients with glaucoma by means of diffusion tensor magnetic resonance imaging (DT-MRI). DT-MRI was performed in 16 patients: 12 patients with POAG of different stages and 4 controls. Fractional anisotropy (FA) and its longitudinal variation (FA) determined by an original software (Fractional Anisotropy Analyzer) were used to assess the state of the lateral geniculate body and optic radiation. All patients also underwent optical coherence tomography (OCT) of the retina and optic nerve head, Heindelberg retinal tomography (HRT), and Humphrey standard automated perimetry (SAP). There was a significant decrease in FA values in glaucoma patients as compared with the control group (medians of 0.74 and 0.77 respectively, p < 0.01). Moderate and strong correlations of AFA with glaucoma stage as well as morphometric (GCC Average, GLV, FLV, and RNFL Average provided by OCT, rim area provided by HRT) and functional parameters (MD and PSD provided by SAP) of the retina and optic nerve head were also established. Reduced fractional anisotropy of the lateral geniculate body and optic radiation in patients with glaucoma may be considered an indicator of axonal degeneration at the level of the visual centers. DT-MRI in vivo helps to determine whether or not the neurodegenerative process spreads to the central nervous system as glaucoma progresses.

Optic radiation damage in multiple sclerosis is associated with visual dysfunction and retinal thinning--an ultrahigh-field MR pilot study.

To investigate posterior visual pathway damage in multiple sclerosis using ultrahigh-field magnetic resonance imaging (MRI) at 7 Tesla (7 T), and to determine its correlation with visual disability and retinal fibre layer (RNFL) damage detectable by optic coherence tomography (OCT). We studied 7 T MRI, OCT, functional acuity contrast testing (FACT), and visually evoked potentials (VEP, n = 16) in 30 patients (including 26 relapsing-remitting MS and four clinically isolated syndrome patients) and 12 healthy controls to quantify RNFL thickness, optic radiation lesion volume, and optic radiation thickness. Optic radiation lesion volume was associated with thinning of the optic radiation (p < 0.001), delayed VEP (p = 0.031), and visual disability indicated by FACT (p = 0.020). Furthermore, we observed an inverse correlation between optic radiation lesion volume and RNFL thickness (p < 0.001), including patients without previous optic neuritis (p < 0.001). Anterior visual pathway damage, but also (subclinical) optic radiation integrity loss detectable by 7 T MRI are common findings in MS that are mutually affected. Given the association between optic radiation damage, visual impairment, and increased VEP latency in this exploratory study of a limited sample size, clinicians should be aware of acute lesions within the optic radiation in patients with (bilateral) visual disturbances. • Focal destruction of the optic radiation is detectable by 7 T MRI. • Focal optic radiation damage is common in MS. • Optic radiation damage is associated with RNFL thinning, detectable by OCT. • Optic radiation damage is associated with delayed VEP and visual dysfunction. • RNFL thickness in non-optic neuritis eyes correlates with optic radiation demyelination.

Alteration of fractional anisotropy and mean diffusivity in glaucoma: novel results of a meta-analysis of diffusion tensor imaging studies.

ObjectivesWe hypothesized that a meta-analysis of existing studies may help to reveal significant changes on diffusion tensor imaging (DTI) in patients with glaucoma. Therefore, a meta-analysis was utilized to investigate the possibility that DTI can detect white matter damage in patients with glaucoma.MethodsThe study design and report adhered to the PRISMA Statement guidelines. DTI studies that compared glaucoma patients and controls were surveyed using PubMed, Web of Science and EMBASE (January 2008 to September 2013). Stata was used to analyze the decrease in fractional anisotropy (FA) and increase in mean diffusivity (MD) in the optic nerve and optic radiation in patients with glaucoma.ResultsEleven DTI studies were identified through a comprehensive literature search, and 10 independent DTI studies of glaucoma patients were eligible for the meta-analysis. A random effects model revealed a significant FA reduction in the optic nerve and optic radiation, as well as a significant MD increase in the tracts. A heterogeneity analysis suggested that FA may be related to glaucoma severity.ConclusionsOur findings revealed that the optic nerve and optic radiation were vulnerable regions in patients with glaucoma and that FA may be correlated with glaucoma severity and age. Furthermore, this study suggests that magnetic resonance imaging in patients with glaucoma may help to provide objective evidence to aid in the diagnosis and management of glaucoma.

Direct electrical stimulation of the optic radiation in patients with covered eyes

Direct electrical stimulation (DES) of the optic radiation (OR) during an awake tumor resection has been repeatedly reported. In all cases, visual function monitoring was performed in patients with open eyes which were looking at a picture. We report a new modification of the standard method, OR stimulation in patient with closed and covered eyes. To the best of our knowledge, this method was not presented before. According to our first experience, this methodology may be in some cases a potentially more sensitive form of neuromonitoring than the OR stimulation in patients with open eyes, as the phosphenes elicited by DES may be more distinct in patients with covered eyes. The technique is discussed, and a literature review on intraoperative identification of the OR is presented as well. However, a future prospective study is needed to confirm the relevance of our finding.

Diffusion Tensor Imaging Findings of Optic Radiation in Patients with Putaminal Hemorrhage

Objectives: Little is known about optic radiation (OR) injury in intracerebral hemorrhage (ICH). We attempted to investigate OR injury in patients with ICH by diffusion tensor imaging (DTI). Methods: Forty-three consecutive patients with putaminal hemorrhage and 40 normal healthy control subjects were recruited. DTI data were acquired at the beginning of rehabilitation (average 34 days after onset). DTI-Studio software was used to reconstruct the OR. Fractional anisotropies (FA) and fiber numbers of the ORs were measured. FA values and fiber numbers of affected ORs were described as abnormal when they were more than 2.5 SD lower than those of normal controls. Results: Thirty (70%) of the 43 patients showed an OR abnormality in the affected hemisphere. In 13 (30%) patients, the affected OR was disrupted or nonreconstructable. On the other hand, of the 20 patients with preserved OR integrity, 14 (33%) had a low FA value and 3 (7%) a low FA and fiber number. The other 13 (30%) of the 43 patients had no abnormal OR findings. Conclusion: Seventy percent of patients showed any abnormality of OR in the affected hemisphere on DTI. This result suggests that patients with putaminal hemorrhage are at high risk of OR injury.

Diffusion tensor imaging of the optic radiations after optic neuritis

Trans-synaptic degeneration could exacerbate neurodegeneration in multiple sclerosis (MS). We aimed to assess whether anterograde trans-synaptic degeneration could be identified in the primary visual pathway in vivo. Diffusion tensor imaging (DTI) was used to assess the optic radiations in 15 patients with previous optic nerve inflammation and 9 healthy volunteers. A probabilistic atlas of the optic radiations was created from healthy diffusion tractography data. Lengthwise profiles for DTI parameters (axial [λ(||) ], radial [λ(⟂) ] and mean diffusivity [MD], fractional anisotropy [FA] and the angle of deviation of the principal eigenvector [α]) were analyzed for patients and controls. Patients also underwent multifocal visual evoked potential (mfVEP) assessments to characterize the latency and amplitude of cortical potentials. Correlations were performed between mfVEP latency and amplitude in the left and right visual hemi-fields and DTI parameters in the contra-lateral optic radiations. Patients displayed a significant decrease in λ(||) within the body of both optic radiations, which significantly correlated with loss of mfVEP amplitude. Abnormal λ(⟂) and FA were detected bilaterally throughout the optic radiations in patients but the abnormality was not associated with amplitude reduction or latency prolongation of the mfVEP. An abnormal α value was observed in the left optic radiations of patients, and the α value in the body of the optic radiations also correlated with mfVEP amplitude loss. The assocation between bilateral DTI abnormalities within the optic radiations and loss of afferent electrical activity could indicate anterograde trans-synaptic degeneration occurs following optic neuritis.

Directional diffusivity changes in the optic nerve and optic radiation in optic neuritis

Optic neuritis (ON) is defined as an inflammation of the optic nerve and provides a useful model for studying the effects of inflammatory demyelination of white matter. The aim of this study was to assess the diffusion changes in both the optic nerve and optic radiation in patients with acute and chronic ON using diffusion tensor (DT) MRI. 33 patients with idiopathic demyelinating optic neuritis (IDON) and 33 gender- and age-matched healthy controls were examined with DT-MRI and with T(1) and T(2) weighted MRI. Compared with controls, both first-episode and recurrent patients with IDON in the acute stage showed significantly increased radial diffusivity (λ(⊥)) and decreased mean fractional anisotropy (FA) in the affected nerves. Reduced FA, increased λ(⊥), mean diffusivity (MD) and axial diffusivity (λ(∥)) were determined in patients with subacute IDON. We found no significant difference in the directional diffusivity of optic radiation in patients whose disease had lasted less than 1 year compared with healthy controls. However, significant changes in the FA and λ(⊥) of the optic radiation were detected in patients with disease duration of more than 1 year. These results show the great potential and capacity of DT-MRI measures as useful biomarkers and indicators for the evaluation of myelin injury in the visual pathway.

Optic Nerve and Optic Radiation Neurodegeneration in Patients with Glaucoma: In Vivo Analysis with 3-T Diffusion-Tensor MR Imaging

To evaluate, with high-field-strength diffusion-tensor (DT) magnetic resonance (MR) imaging, the axonal architecture of the optic nerves and optic radiations in patients with glaucoma and determine whether DT MR imaging-derived parameters correlate with disease severity. The study was approved by the institutional review board. All participants provided written informed consent. Sixteen patients with primary open-angle glaucoma were examined. Glaucoma severity was clinically assessed with use of a six-stage system based on static threshold visual field parameters. Ten healthy individuals served as control subjects. DT MR imaging was performed with a 3-T MR unit. Mean diffusivity (MD) and fractional anisotropy (FA) maps were automatically created. Regions of interest were positioned on the MD and FA maps, and mean MD and mean FA values were calculated for each optic nerve and each optic radiation. The optic radiations and optic nerves of patients with glaucoma, as compared with control subjects, had significantly higher MD and significantly lower FA. The mean MD values for the optic nerves and the glaucoma stages varied consistently (r = 0.8087, P < .0001). A negative correlation between mean FA for the optic nerves and glaucoma stage (r = -0.7464, P < .0001) was observed. Glaucoma is a complex neurologic disease that affects optic nerves and optic radiations. The finding that DT MR imaging-derived MD and FA in the optic nerves correlate with glaucoma severity suggests that these parameters could serve as complementary indicators of disease severity.

Visual system involvement in patients with Friedreich's ataxia

Optic neuropathy is common in mitochondrial disorders, but poorly characterized in Friedreich's ataxia (FRDA), a recessive condition caused by lack of the mitochondrial protein frataxin. We investigated 26 molecularly confirmed FRDA patients by studying both anterior and posterior sections of the visual pathway using a new, integrated approach. This included visual field testing and optical coherence tomography (OCT), pattern visual evoked potentials (P-VEPs) and diffusion-weighted imaging. The latter was used to study optic radiation by calculating water apparent diffusion coefficients (ADC). All patients suffered optic nerve involvement with their disorder. Different patterns of visual field defects were observed and a variably reduced retinal nerve fiber layer thickness was seen by OCT in all cases. P-VEPs were abnormal in approximately half of the patients. Decreased visual acuity and temporal optic disc pallor were present in advanced stages of the disease, but only five patients were symptomatic. Two of these patients suffered a sudden loss of central vision, mimicking Leber's hereditary optic neuropathy (LHON), and of the other three symptomatic patients two were noted to be compound heterozygotes. ADC values of optic radiations in patients were significantly higher than controls (P < 0.01). Retinal nerve fiber layer thickness at OCT and P-VEPs correlated with age at onset and ICARS total score. ADC values correlated with age at onset, disease duration, GAA triplet expansion size, ICARS total score and P-VEPs. Visual pathway involvement is found consistently in FRDA, being previously underestimated, and we here document that it also involves the optic radiations. Occasional LHON-like cases may occur. However, optic neuropathy in FRDA substantially differs from classic mitochondrial optic neuropathies implying a different pathophysiology of visual system degeneration in this mitochondrial disease.

Optic radiation changes after optic neuritis detected by tractography‐based group mapping

Postmortem data suggest that trans-synaptic degeneration occurs in the lateral geniculate nucleus after optic nerve injury. This study investigated in vivo the optic radiations in patients affected by optic neuritis using fast marching tractography (FMT), a diffusion magnetic resonance imaging (MRI) fiber tracking method, and group mapping techniques, which allow statistical comparisons between subjects. Seven patients, 1 year after isolated unilateral optic neuritis, and ten age and gender-matched controls underwent whole-brain diffusion tensor MR imaging. The FMT algorithm was used to generate voxel-scale connectivity (VSC) maps in the optic radiations in each subject in native space. Group maps of the left and right optic radiations were created in the patient and control group in a standardized reference frame using statistical parametric mapping (SPM99). The reconstructed optic radiations in the patient group were localized more laterally in the posterior part of the tracts and more inferiorly than in the control group. Patients showed reduced VSC values in both tracts compared with controls. These findings suggest that the group mapping techniques might be used to assess changes in the optic radiations in patients after an episode of optic neuritis. The changes we have observed may be secondary to the optic nerve damage.

Frequent involvement of the optic radiations in patients with acute isolated optic neuritis: by R.S.L. Hornabrook, D.H. Miller, M.R. Newton, et al. Neurology 42:77–79, 1992

Frequent involvement of the optic radiations in patients with acute isolated optic neuritis: by R.S.L. Hornabrook, D.H. Miller, M.R. Newton, et al. Neurology 42:77–79, 1992