Conventional and advanced imaging in neuromyelitis optica

Neuromyelitis optica spectrum disorder: pathophysiological approach

Aim: To review the main pathological findings of Neuromyelitis Optica Spectrum Disorder (NMOSD) associated with the presence of autoantibodies to aquaporin-4 (AQP4) as well as the mechanisms of astrocyte dysfunction and demyelination. Methods: An comprehensive search of the literature in the field was carried out using the database of The National Center for Biotechnology Information from . Systematic searches were performed until July 2022. Results: NMOSD is an inflammatory and demyelinating disease of the central nervous system mainly in the areas of the optic nerves and spinal cord, thus explaining mostly the clinical findings. Other areas affected in NMOSD are the brainstem, hypothalamus, and periventricular regions. Relapses in NMOSD are generally severe and patients only partially recover. NMOSD includes clinical conditions where autoantibodies to aquaporin-4 (AQP4-IgG) of astrocytes are detected as well as similar clinical conditions where such antibodies are not detected. AQP4 are channel-forming integral membrane proteins of which AQ4 isoforms are able to aggregate in supramolecular assemblies termed orthogonal arrays of particles (OAP) and are essential in the regulation of water homeostasis and the adequate modulation of neuronal activity and circuitry. AQP4 assembly in orthogonal arrays of particles is essential for AQP4-IgG pathogenicity since AQP4 autoantibodies bind to OAPs with higher affinity than for AQP4 tetramers. NMOSD has a complex background with prominent roles for genes encoding cytokines and cytokine receptors. AQP4 autoantibodies activate the complement-mediated inflammatory demyelination and the ensuing damage to AQP4 water channels, leading to water influx, necrosis and axonal loss. Conclusions: NMOSD as an astrocytopathy is a nosological entity different from multiple sclerosis with its own serological marker: immunoglobulin G-type autoantibodies against the AQP4 protein which elicits a complement-dependent cytotoxicity and neuroinflammation. Some patients with typical manifestations of NMSOD are AQP4 seronegative and myelin oligodendrocyte glycoprotein positive. Thus, the detection of autoantibodies against AQP4 or other autoantibodies is crucial for the correct treatment of the disease and immunosuppressant therapy is the first choice.

Radiological approach to non-compressive myelopathies

Background

Myelopathy, a pathological condition related to the spinal cord can broadly be categorized into compressive and non-compressive aetiologies. Magnetic resonance imaging remains the modality of choice when suspecting non-compressive myelopathy as it helps to localize the affected segment and exclude compression as the cause of myelopathy. This review deals with the imaging approach for non-compressive myelopathies.

Main body

Demyelinating disorders are the most common cause of non-compressive myelopathy and often show confounding features. Other causes include inflammatory, ischemic, metabolic, and neoplastic disorders. Non-compressive myelopathy can broadly be classified into acute and non-acute onset which can further be categorized according to the distribution of the signal abnormalities, including length of cord involvement, specific tract involvement, enhancement pattern, and the region of the spinal cord that is affected.

Conclusions

Imaging plays a critical role in the evaluation of clinically suspected cases of myelopathy and MR imaging (with or without contrast) remains the preferred modality. Compressive causes must be excluded as a cause of myelopathy. Despite a multitude of causes, the most common imaging appearance is a nonspecific T2 hyperintense signal in the spinal cord, and thus, a pragmatic diagnostic approach along with appropriate clinical and biochemical correlation is essential for arriving at an accurate diagnosis.

18 F-FDG PET/CT Appearance of Radiation-Induced Delayed Transverse Myelitis

ABSTRACT

Delayed-onset radiation-induced myelitis is a rare but serious complication of radiation exposure to the spinal cord. In this report, we describe the 18 F-FDG PET/CT findings of radiation-induced myelitis in a patient with carcinoma of buccal mucosa treated with external beam radiotherapy.

Etiological and Radiological Spectrum of Longitudinal Myelitis: A Hospital-Based Study in North East India

Introduction  An inflammatory lesion of the spinal cord where three or more than three vertebral segments of the cord is involved is called longitudinal extensive myelitis (LETM). It has several varied causes out of which neuromyelitis optica (NMO) and its spectrum disorder have received a distinct entity. Various radiological and clinical features help us to suspect an etiology which then further guides us into the treatment protocol and prognosis of the patients.

Materials and Methods  A retrospective study performed in a referral center in North East India in 15 months. Thirty-two patients of LETM were enrolled based on clinical and radiological available data. An attempt was made to classify the various etiologies and correlate with their radiological findings.

Results  The most common etiology noted was NMO seen in 7 patients (21.8%) followed by tuberculosis (TB) (18.7%) and post-infection myelitis (18.7%). Other etiology seen was acute disseminated encephalomyelitis (6.24%), spinal cord infarct (3.12%), radiation myelitis (6.24%), Japanese encephalitis sequalae (3.12%), systemic lupus erythematosus (3.12%), and remained undiagnosed in six patients (18.7%). Radiologically, cervico-dorsal spine was most common location in NMO (71%) whereas dorsolumbar in TB (50%). The lesion was predominantly central in both NMO (100%) and TB (80%) as compared with the other causes of LETM. It was noted that more than 50% of the transverse area of the cord was involved in both NMO (71%) and TB (50%), but < 50% involvement were more common in the post-infectious and others causes of LETM.

Conclusion  LETM has a various differential diagnosis, infection need to be kept in mind while ruling out NMO. Radiological features can suggest or help differentiate the various etiologies of LETM but NMO and infection like TB almost has the same features except for a different cord site predilection.

Pediatric Spinal Cord Diseases

Spinal cord diseases in pediatric patients are highly variable in terms of presentation, pathology, and prognosis. Not only do they differ with respect to each other but so too with their adult equivalents. Some of the most common diseases are autoimmune (ie, multiple sclerosis, acute disseminated encephalomyelitis, and acute transverse myelitis), congenital (ie, dysraphism with spina bifida, split cord malformation, and tethered cord syndrome), tumor (ie, juvenile pilocytic astrocytoma, ependymoma, and hem-angioblastoma), and vascular (ie, cavernous malformations, arteriovenous malformations, and dural arteriovenous fistulas) in nature. These each require their own niche treatment paradigm and prognosis. Furthermore, presentation of different spinal cord diseases in children can be difficult to discern without epidemiologic and imaging data. Interpretation of these data is crucial to facilitating a timely and accurate diagnosis. Correspondingly, the aim of this review was to highlight the most pertinent features of the most common spinal cord diseases in the pediatric population.

The role of MRI and CT of the brain in first episodes of psychosis and behavioural abnormality

AIM

To investigate whether computed tomography (CT)/magnetic resonance imaging (MRI) brain imaging is associated with detection of structural causes of a first episode of psychosis (FEP) or first episode of behavioural abnormality (FEB) in the paediatric population, as this has not been previously documented in the literature.

MATERIALS AND METHODS

Individuals with FEP/FEB but no neurological signs referred to a tertiary children's centre for cerebral MRI or CT were reviewed retrospectively. Individuals were evaluated independently with one technique (CT or MRI) only.

RESULTS

Thirty-four consecutive cerebral MRI and six consecutive CT examinations were identified between 2017 and 2020. No patients were identified as having an organic cause for the psychosis at MRI or CT. Four patients (9%) had incidental findings on MRI, unrelated to the psychosis, such as prominent perivascular spaces, hypoplastic transverse sinus, and sinonasal mucosal wall thickening. No abnormal findings were seen on CT. There was therefore no obvious difference between MRI and CT imaging in detecting organic disease potentially responsible for FEP.

CONCLUSION

Routine structural MRI or CT of the brain is unlikely to reveal disease leading to a significant change in management. MRI demonstrated only a few incidental findings, unrelated to the child's clinical history. Therefore, routine brain structural imaging of FEP/FEB in paediatric patients without focal neurology may not be routinely required. If imaging is requested, then there is no significant difference between CT and MRI in detecting clinically significant lesions.

MRI signs of CNS demyelinating diseases

The differential diagnosis of the central nervous system (CNS) demyelinating diseases can be greatly facilitated by visualization and appreciation of pathognomonic radiological signs, visualized on magnetic resonance imaging (MRI) sequences. Given the distinct therapeutic approaches for each of these diseases, a decisive and reliable diagnosis in patients presenting with demyelination-associated symptoms is of crucial value. Multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) are major examples of such conditions, each possessing a number of MRI signs, closely associated with the disorder. This pictorial review aims to describe seventeen pathognomonic MRI signs associated with several CNS demyelinating disorders including MS, NMOSD, myelin oligodendrocyte glycoprotein-associated disease, Baló's concentric sclerosis, metachromatic leukodystrophy, progressive multifocal leukoencephalopathy, and neurosarcoidosis.

Neuromyelitis optica

Neuromyelitis optica (NMO; also known as Devic syndrome) is a clinical syndrome characterized by attacks of acute optic neuritis and transverse myelitis. In most patients, NMO is caused by pathogenetic serum IgG autoantibodies to aquaporin 4 (AQP4), the most abundant water-channel protein in the central nervous system. In a subset of patients negative for AQP4-IgG, pathogenetic serum IgG antibodies to myelin oligodendrocyte glycoprotein, an antigen in the outer myelin sheath of central nervous system neurons, are present. Other causes of NMO (such as paraneoplastic disorders and neurosarcoidosis) are rare. NMO was previously associated with a poor prognosis; however, treatment with steroids and plasma exchange for acute attacks and with immunosuppressants (in particular, B cell-depleting agents) for attack prevention has greatly improved the long-term outcomes. Recently, a number of randomized controlled trials have been completed and the first drugs, all therapeutic monoclonal antibodies, have been approved for the treatment of AQP4-IgG-positive NMO and its formes frustes.

The spectrum of immune-mediated and inflammatory lesions of the brainstem: Clues to diagnosis

The presentation of a patient with brainstem symptoms and signs invokes a number of common and less common differential diagnoses, and accurate diagnosis can be challenging. We review the major immune-mediated and inflammatory syndromes that can affect the brainstem including multiple sclerosis, neuromyelitis optica spectrum disorder, neuro-Behçet disease, chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids, neurosarcoidosis, Susac syndrome, and the histiocytic disorders. We focus on clinical features and MRI clues that help to distinguish among the different brainstem conditions. Accurate diagnosis is important to guide appropriate treatment and limit neurologic disability.

Neuromyelitis Optica Spectrum Disorder: A Case Report of Effective Combination Immunosuppressant, Corticosteroids, and Therapeutic Plasma Exchange

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease that causes severe demyelination, especially in the optic nerve and spinal cord with typical clinical manifestations of acute optic neuritis and transverse myelitis. The symptoms can occur simultaneously or separated by a variable period. NMOSD is associated with serum aquaporin antibodies 4 immunoglobulin G (AQP4-IgG).

CASE PRESENTATION

We report a case of a 22-year-old male with complaints of weakness of all four limbs, impaired vision, urinary incontinence, and dyspnea. The Expanded Disability Status Scale (EDSS) was nine. Spinal magnetic resonance imaging (MRI) showed longitudinal extensive transversal myelitis. The brain MRI showed a normal impression, whereas the brain magnetic resonance spectroscopy (MRS) examination showed a description of the mild demyelination process. The serum antibody AQP4 (AQP4-IgG) results were seronegative, the cerebrospinal fluid examination was normal, and the oligoclonal band was negative. The ophthalmoscopic examination found bilateral papillary atrophy but optical coherence tomography (OCT) was still normal. Somatosensory evoked potential and visual evoked potential examinations were abnormal. The patient was diagnosed with NMOSD and was given combination immunosuppressant therapy, corticosteroids, and therapeutic plasma exchange. The patient experienced significant improvement with EDSS decreased to six.

CONCLUSION

In the case of relapsing NMOSD patient, combination therapy of immunosuppressant's, corticosteroids, and TPE was used. There were significant improvements from EDSS nine to six.

Subcortical structural abnormalities in female neuromyelitis optica patients with neuropathic pain

Neuromyelitis optica (NMO) is a disease characterised by severe relapses of optic neuritis and longitudinally extensive transverse myelitis and it has a strong female predilection. Pain is one of the most typical symptom in NMO. However, few studies have been conducted to examine the neuropathic pain mechanism of NMO patients or gender-specific effects using magnetic resonance imaging technique. A total of 38 female patients with NMO, 28 with pain (NMOWP) and 10 without pain (NMOWoP), were classified using the Brief Pain Inventory (BPI); 22 healthy females were also recruited. We used the FSL Image Registration and Segmentation Toolbox (FIRST) for subcortical region volumes quantifications, and voxel-based morphometry analysis for cortical gray matter (GM) volume, to examine the brain morphology in NMOWP patients. In addition, correlation test between structural measurements of NMO patients and clinical indexes was also performed. The results showed: 1) no significant differences in cortical GM density between the NMOWP and NMOWoP groups; 2) significantly smaller hippocampus and pallidum volumes in the NMOWP group compared with the NMOWoP group; 3) significant negative correlation between the average BPI and volumes of the accumbens nucleus and thalamus in NMO patients. These results revealed that structural abnormality exists in NMO female patients who have pain, with significant implications for our understanding of the brain morphology in NMO patients with pain.

Posterior reversible encephalopathy syndrome with isolated infratentorial involvement: A case report

Posterior reversible encephalopathy syndrome (PRES) is a clinical and radiological entity of acute neurological symptoms associated with characteristic MRI finding. Vasogenic edema in the white matter of parieto-occipital regions is the classical MRI findings. Spinal cord involvement in PRES is extremely rare and frequently underrecognized condition. Recently, a variant-type PRES with isolated involvement of infratentorial structures is getting more attention. Herein, we present a case of hypertensive emergency and associated radiological features of PRES with isolated involvement of the brain stem, cerebellum, and spinal cord.

Quantitative radiomic biomarkers for discrimination between neuromyelitis optica spectrum disorder and multiple sclerosis

BACKGROUND

Precise diagnosis and early appropriate treatment are of importance to reduce neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) morbidity. Distinguishing NMOSD from MS based on clinical manifestations and neuroimaging remains challenging.

PURPOSE

To investigate radiomic signatures as potential imaging biomarkers for distinguishing NMOSD from MS, and to develop and validate a diagnostic radiomic-signature-based nomogram for individualized disease discrimination.

STUDY TYPE

Retrospective, cross-sectional study.

SUBJECTS

Seventy-seven NMOSD patients and 73 MS patients.

FIELD STRENGTH/SEQUENCE

3T/T₂ -weighted imaging.

ASSESSMENT

Eighty-eight patients and 62 patients were respectively enrolled in the primary and validation cohorts. Quantitative radiomic features were automatically extracted from lesioned regions on T₂ -weighted imaging. A least absolute shrinkage and selection operator analysis was used to reduce the dimensionality of features. Finally, we constructed a radiomic nomogram for disease discrimination.

STATISTICAL TESTS

Features were compared using the Mann-Whitney U-test with a nonnormal distribution. We depicted the nomogram on the basis of the results of the logistic regression using the rms package in R. The Hmisc package was used to investigate the performance of the nomogram via Harrell's C-index.

RESULTS

A total of 273 quantitative radiomic features were extracted from lesions. A multivariable analysis selected 11 radiomic features and five clinical features to be included in the model. The radiomic signature (P < 0.001 for both the primary and validation cohorts) showed good potential for building a classification model for disease discrimination. The area under the receiver operating characteristic curve was 0.9880 for the training cohort and 0.9363 for the validation cohort. The nomogram exhibited good discrimination, a concordance index of 0.9363, and good calibration in the primary cohort. The nomogram showed similar discrimination, concordance (0.9940), and calibration in the validation cohort.

DATA CONCLUSION

The diagnostic radiomic-signature-based nomogram has potential utility for individualized disease discrimination of NMOSD from MS in clinical practice.

LEVEL OF EVIDENCE

4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1113-1121.

Magnetic resonance imaging findings in a patient with seropositive neuromyelitis optica

We present the case of a 23-year-old female with a subacute history of complex additive neurology which consisted of progressive unilateral visual impairment and subsequent blindness of the right eye, in conjunction with distal lower motor neuron symptoms of weakness and sensory loss from T4 level down. Special investigations performed, included serology and an urgent magnetic resonance imaging (MRI) of the brain and spinal cord, which exhibited a diffuse demyelinating disease of the brain and spinal cord without the typical features of multiple sclerosis (MS) and laboratory findings, which were positive for the AQP-4 antibody, confirming the diagnosis of neuromyelitis optica (NMO). Pulsed methylprednisolone was initiated urgently with good effect and immunosuppression with cyclophosphamide was added after the exclusion of additional pathology. She experienced a complete resolution of her weakness and sensory impairment upon discharge; however, her unilateral visual loss remained. The recent advances in the identification of autoimmune biomarkers and the widening spectrum of imaging findings in NMO necessitate that the clinician and radiologist keep abreast of the current diagnostic tools and criteria that distinguish NMO from other demyelinating conditions.

Differentiating Neuromyelitis Optica-Related and Multiple Sclerosis-Related Acute Optic Neuritis Using Conventional Magnetic Resonance Imaging Combined With Readout-Segmented Echo-Planar Diffusion-Weighted Imaging

PURPOSE

In clinical practice, acute optic neuritis (ON) associated with the development of neuromyelitis optica (NMO) after the first attack is often indistinguishable from that associated with multiple sclerosis (MS). We aimed to determine the optimal combination of features derived from conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging using readout-segmented echo-planar imaging (RESOLVE-DWI) for the differentiation of these conditions.

MATERIALS AND METHODS

Orbital conventional MRI and RESOLVE-DWI were performed using a 3.0-T scanner on 54 patients with acute ON (26 NMO-related and 28 MS-related). The features detected by conventional MRI (including laterality, the enhancement pattern, and the extent and position of involvement) and the apparent diffusion coefficient (ADC) measurements were retrospectively compared between the NMO-related and MS-related groups. A multivariate logistic regression analysis was used to identify the most significant variables, and receiver operating characteristic curve analyses were performed to determine the ability of a combined diagnostic model based on the qualitative and quantitative characteristics identified in this study to differentiate the 2 conditions.

RESULTS

The multivariate logistic regression analyses indicated that the presence of chiasm involvement and lower ADC values were significantly associated with NMO-related acute ON compared with MS-related acute ON (P = 0.037 and 0.008, respectively). The diagnostic criterion of chiasm involvement or "ADC < 791 × 10 mm/s and chiasm involvement" had the highest specificity (96.9%), and "ADC < 791 × 10 mm/s or chiasm involvement" showed the optimal sensitivity (77.8%) for differentiating NMO-related from MS-related acute ON.

CONCLUSIONS

Conventional MRI RESOLVE-DWI is helpful for differentiating NMO-related acute ON from MS-related acute ON. The combination of the ADC value chiasm involvement appears to be effective for discriminating these 2 types of acute ON.

Location, length, and enhancement: systematic approach to differentiating intramedullary spinal cord lesions

Purpose

Intramedullary spinal cord abnormalities are often challenging to diagnose. Spinal cord biopsy is a high-risk procedure with the potential to cause permanent neurological injury. Magnetic resonance imaging is the modality of choice for diagnosis and preoperative assessment of patients with spinal cord abnormalities. The radiologist’s ability to narrow the differential diagnosis of spinal cord abnormalities has the potential to save patients from invasive approaches for diagnosis and also guide appropriate management.

Approach/methods

This article will provide a systematic approach to the evaluation of intramedullary spinal cord lesions—with emphasis on location, length and segment distribution, and enhancement pattern—to help narrow the differential diagnosis. In doing so, we will review various spinal cord pathologies, including demyelinating and metabolic conditions, neoplasms, and vascular lesions.

Summary/conclusion

Although intramedullary spinal cord abnormalities can be a challenge for the radiologist, a systematic approach to the differential diagnosis with a focus on lesion location, cord length and segment involvement, as well as enhancement pattern, can greatly help narrow the differential diagnosis, if not synch the diagnosis. This strategy will potentially obviate the need for an invasive approach to diagnosis and help guide treatment.

Teaching points

• Imaging diagnosis of intramedullary spinal cord lesions could obviate cord biopsy.

• Evaluation of cord lesions should focus on location, length, and enhancement pattern.

• In demyelination, the degree of cross-sectional involvement is a distinguishing feature.

White Matter Diseases with Radiologic-Pathologic Correlation

White matter diseases include a wide spectrum of disorders that have in common impairment of normal myelination, either by secondary destruction of previously myelinated structures (demyelinating processes) or by primary abnormalities of myelin formation (dysmyelinating processes). The pathogenesis of many white matter diseases remains poorly understood. Demyelinating disorders are the object of this review and will be further divided into autoimmune, infectious, vascular, and toxic-metabolic processes. Autoimmune processes include multiple sclerosis and related diseases: tumefactive demyelinating lesions, Balo concentric sclerosis, Marburg and Schilder variants, neuromyelitis optica (Devic disease), acute disseminated encephalomyelitis, and acute hemorrhagic leukoencephalopathy (Hurst disease). Infectious processes include Lyme disease (neuroborreliosis), progressive multifocal leukoencephalopathy, and human immunodeficiency virus (HIV) encephalopathy. Vascular processes include different types of small-vessel disease: arteriolosclerosis, cerebral amyloid angiopathy, cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), primary angiitis of the central nervous system, Susac syndrome, and neurolupus. Toxic-metabolic processes include osmotic myelinolysis, methotrexate leukoencephalopathy, and posterior reversible encephalopathy syndrome. The imaging spectrum can vary widely from small multifocal white matter lesions to confluent or extensive white matter involvement. Understanding the pathologic substrate is fundamental for understanding the radiologic manifestations, and a systematic approach to the radiologic findings, in correlation with clinical and laboratory data, is crucial for narrowing the differential diagnosis. (©)RSNA, 2016.

Enhancing Brain Lesions during Acute Optic Neuritis and/or Longitudinally Extensive Transverse Myelitis May Portend a Higher Relapse Rate in Neuromyelitis Optica Spectrum Disorders

BACKGROUND AND PURPOSE

Neuromyelitis optica spectrum disorders are inflammatory demyelinating disorders with optic neuritis and/or longitudinally extensive transverse myelitis episodes. We now know that neuromyelitis optica spectrum disorders are associated with antibodies to aquaporin-4, which are highly concentrated on astrocytic end-feet at the blood-brain barrier. Immune-mediated disruption of the blood-brain barrier may manifest as contrast enhancement on brain MR imaging. We aimed to delineate the extent and frequency of contrast enhancement on brain MR imaging within 1 month of optic neuritis and/or longitudinally extensive transverse myelitis attacks and to correlate contrast enhancement with outcome measures.

MATERIALS AND METHODS

Brain MRIs of patients with neuromyelitis optica spectrum disorders were evaluated for patterns of contrast enhancement (periependymal, cloudlike, leptomeningeal, and so forth). The Fisher exact test was used to evaluate differences between the proportion of contrast enhancement in patients who were seropositive and seronegative for aquaporin-4 antibodies. The Mann-Whitney test was used to compare the annualized relapse rate and disease duration between patients with and without contrast enhancement and with and without seropositivity.

RESULTS

Brain MRIs of 77 patients were evaluated; 59 patients (10 males, 49 females) were scanned within 1 month of optic neuritis and/or longitudinally extensive transverse myelitis attacks and were included in the analysis. Forty-eight patients were seropositive, 9 were seronegative, and 2 were not tested for aquaporin-4 antibodies. Having brain contrast enhancement of any type during an acute attack was significantly associated with higher annualized relapse rates (P = .03) and marginally associated with shorter disease duration (P = .05). Having periependymal contrast enhancement was significantly associated with higher annualized relapse rates (P = .03).

CONCLUSIONS

Brain MRIs of patients with neuromyelitis optica spectrum disorders with contrast enhancement during an acute relapse of optic neuritis and/or longitudinally extensive transverse myelitis are associated with increased annual relapse rates.

Optical Coherence Tomography and Magnetic Resonance Imaging in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder

Irreversible disability in multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) is largely attributed to neuronal and axonal degeneration, which, along with inflammation, is one of the major pathological hallmarks of these diseases. Optical coherence tomography (OCT) is a non-invasive imaging tool that has been used in MS, NMOSD, and other diseases to quantify damage to the retina, including the ganglion cells and their axons. The fact that these are the only unmyelinated axons within the central nervous system (CNS) renders the afferent visual pathway an ideal model for studying axonal and neuronal degeneration in neurodegenerative diseases. Structural magnetic resonance imaging (MRI) can be used to obtain anatomical information about the CNS and to quantify evolving pathology in MS and NMOSD, both globally and in specific regions of the visual pathway including the optic nerve, optic radiations and visual cortex. Therefore, correlations between brain or optic nerve abnormalities on MRI, and retinal pathology using OCT, may shed light on how damage to one part of the CNS can affect others. In addition, these imaging techniques can help identify important differences between MS and NMOSD such as disease-specific damage to the visual pathway, trans-synaptic degeneration, or pathological changes independent of the underlying disease process. This review focuses on the current knowledge of the role of the visual pathway using OCT and MRI in patients with MS and NMOSD. Emphasis is placed on studies that employ both MRI and OCT to investigate damage to the visual system in these diseases.

Paediatric brainstem: A comprehensive review of pathologies on MR imaging

The brainstem is a midline structure formed by the midbrain, pons and medulla and is a home for various vital neurological centres of the human body. A diverse spectrum of disease entities can involve the brainstem, which includes infections, metabolic disorders, demyelination, vascular conditions, neurodegenerative disorders and tumours. Brainstem involvement can be primary or secondary, i.e., as part of systemic disorders. Due to the overlapping clinical presentation and symptomatology, imaging plays a decisive role in the detection, localisation and characterisation of brainstem pathologies. Magnetic resonance imaging (MRI) is the modality of choice and the use of advanced MR techniques such as diffusion-weighted imaging and spectroscopy can be especially helpful in providing a tenable diagnoses. This article is a compilation of the MR imaging manifestations of a spectrum of common and uncommon brainstem pathologies that can be encountered in the paediatric age group.

Teaching Points

• The paediatric brainstem can be afflicted by many pathologies that may overlap clinico-radiologically.

• MRI is the best modality for the localisation and diagnosis of brainstem pathologies.

• Diffusion-weighted imaging is useful in the diagnosis of vascular and metabolic disorders.

• Occasionally, demyelination and neoplasms can be indistinguishable on imaging.

Abnormal Spinal Cord Magnetic Resonance Signal: Approach to the Differential Diagnosis

T2-hyperintense signal abnormalities within the spinal cord on magnetic resonance imaging can evoke a broad differential diagnosis and can present a diagnostic dilemma. Here, we review and provide a succinct and relevant differential diagnosis based on imaging patterns and anatomical or physiopathologic correlation. Clues and imaging pearls are provided focusing on inflammatory, infectious, demyelinating, vascular, and metabolic involvement of the spinal cord.

Use of Advanced Magnetic Resonance Imaging Techniques in Neuromyelitis Optica Spectrum Disorder

Brain parenchymal lesions are frequently observed on conventional magnetic resonance imaging (MRI) scans of patients with neuromyelitis optica (NMO) spectrum disorder, but the specific morphological and temporal patterns distinguishing them unequivocally from lesions caused by other disorders have not been identified. This literature review summarizes the literature on advanced quantitative imaging measures reported for patients with NMO spectrum disorder, including proton MR spectroscopy, diffusion tensor imaging, magnetization transfer imaging, quantitative MR volumetry, and ultrahigh-field strength MRI. It was undertaken to consider the advanced MRI techniques used for patients with NMO by different specialists in the field. Although quantitative measures such as proton MR spectroscopy or magnetization transfer imaging have not reproducibly revealed diffuse brain injury, preliminary data from diffusion-weighted imaging and brain tissue volumetry indicate greater white matter than gray matter degradation. These findings could be confirmed by ultrahigh-field MRI. The use of nonconventional MRI techniques may further our understanding of the pathogenic processes in NMO spectrum disorders and may help us identify the distinct radiographic features corresponding to specific phenotypic manifestations of this disease.

Gray Matter Volume Reduction Is Associated with Cognitive Impairment in Neuromyelitis Optica

BACKGROUND AND PURPOSE

Whether gray matter impairment occurs in neuromyelitis optica is a matter of ongoing debate, and the association of gray matter impairment with cognitive deficits remains largely unknown. The purpose of this study was to investigate gray matter volume reductions and their association with cognitive decline in patients with neuromyelitis optica.

MATERIALS AND METHODS

This study included 50 patients with neuromyelitis optica and 50 sex-, age-, handedness-, and education-matched healthy subjects who underwent high-resolution structural MR imaging examinations and a battery of cognitive assessments. Gray matter volume and cognitive differences were compared between the 2 groups. The correlations of the regional gray matter volume with cognitive scores and clinical variables were explored in the patients with neuromyelitis optica.

RESULTS

Compared with healthy controls (635.9 ± 51.18 mL), patients with neuromyelitis optica (602.8 ± 51.03 mL) had a 5.21% decrease in the mean gray matter volume of the whole brain (P < .001). The significant gray matter volume reduction in neuromyelitis optica affected the frontal and temporal cortices and the right thalamus (false discovery rate correction, P < .05). The regional gray matter volumes in the frontal and temporal cortices were negatively correlated with disease severity in patients with neuromyelitis optica (Alphasim correction, P < .05). Patients with neuromyelitis optica had impairments in memory, information processing speed, and verbal fluency (P < .05), which were correlated with gray matter volume reductions in the medial prefrontal cortex and thalamus (Alphasim correction, P < .05).

CONCLUSIONS

Gray matter volume reduction is present in patients with neuromyelitis optica and is associated with cognitive impairment and disease severity in this group.

Acquired pathology of the pediatric spine and spinal cord

Pediatric spine pathology poses a diagnostic challenge for radiologists. Acquired spine pathology often yields nonspecific signs and symptoms in children, especially in the younger age groups, and diagnostic delay can carry significant morbidity. This review is focused on some of the more common diagnostic dilemmas we face when attempting to evaluate and diagnose acquired pediatric spine anomalies in daily practice. An understanding of some of the key differentiating features of these disease processes in conjunction with pertinent history, physical exam, and advanced imaging techniques can indicate the correct diagnosis.

Differentiating neuromyelitis optica from other causes of longitudinally extensive transverse myelitis on spinal magnetic resonance imaging

BACKGROUND

Although spinal magnetic resonance imaging (MRI) findings of neuromyelitis optica (NMO) have been described, there is limited data available that help differentiate NMO from other causes of longitudinally extensive transverse myelitis (LETM).

OBJECTIVE

To investigate the spinal MRI findings of LETM that help differentiate NMO at the acute stage from multiple sclerosis (MS) and other causes of LETM.

METHODS

We enrolled 94 patients with LETM into our study. Bright spotty lesions (BSL), the lesion distribution and location were evaluated on axial T2-weighted images. Brainstem extension, cord expansion, T1 darkness and lesion enhancement were noted. We also reviewed the brain MRI of the patients during LETM.

RESULTS

Patients with NMO had a greater amount of BSL and T1 dark lesions (p < 0.001 and 0.003, respectively). The lesions in NMO patients were more likely to involve greater than one-half of the spinal cord's cross-sectional area; to enhance and be centrally-located, or both centrally- and peripherally-located in the cord. Of the 62 available brain MRIs, 14 of the 27 whom were NMO patients had findings that may be specific to NMO.

CONCLUSIONS

Certain spinal cord MRI features are more commonly seen in NMO patients and so obtaining brain MRI during LETM may support diagnosis.

A simplified algorithm for diagnosis of spinal cord lesions

Neuroimaging is indispensable for evaluation of Myelopathy not only for localization but also for etiologic determination. MRI is the preferred examination for further characterization of the majority of these conditions. These include traumatic, inflammatory, infections, compressive and neoplastic conditions. This article provides an overview of a variety of pathologies that afflict the spinal cord in an easy to understand format. Their respective imaging manifestations on MRI and differential diagnoses are focused in this review. Early diagnosis and treatment of Myelopathy is critical in preventing or arresting neurological morbidity.