Diffusion-weighted imaging helps differentiate multiple sclerosis and neuromyelitis optica-related acute optic neuritis

MRI signs helpful in the differentiation of patients with anterior ischaemic optic neuropathy and optic neuritis

BACKGROUND/AIMS

The aim of this study was to identify specific MRI characteristics of anterior ischaemic optic neuropathy (AION) and optic neuritis (ON) that would aid in the differentiation between these two diagnoses.

METHODS

We retrospectively analysed a consecutive case series including all patients with an MRI study of brain and orbit and the clinical diagnosis of either ON or AION. We examined the scans for restricted diffusion of the optic nerve, optic sheath diameter, enhancement and location of enhancement of the optic nerve and distribution of the white matter lesions.

RESULTS

Fifty patients met the inclusion criteria. We found an accuracy of 0.98 for the discrimination between AION and ON based solely on parameters extracted from MRI data. Dominance analysis to determine the most influential parameters showed that the enhancement pattern of the optic nerve and distribution of the white matter lesions had the biggest impact on the classification and led to a discrimination accuracy of 0.9 when used alone.

CONCLUSION

In patients with an inconclusive clinical diagnosis, optic nerve enhancement pattern and distribution of white matter lesions can aid in the diagnosis and differentiation between AION and ON. Diffusion-weighted imaging did not add significant information to the diagnosis or help to differentiate between the two conditions.

Autoimmune disease of head and neck, imaging, and clinical review

Autoimmune disease of the head and neck (H&N) could be primary or secondary to systemic diseases, medications, or malignancies. Immune-mediated diseases of the H&N are not common in daily practice of radiologists; the diagnosis is frequently delayed because of the non-specific initial presentation and lack of familiarity with some of the specific imaging and clinical features. In this review, we aim to provide a practical diagnostic approach based on the specific radiological findings for each disease. We hope that our review will help radiologists expand their understanding of the spectrum of the discussed disease entities, help them narrow the differential diagnosis, and avoid unnecessary tissue biopsy when appropriate based on the specific clinical scenarios.

Comparison of 1.5 Tesla and 3.0 Tesla Magnetic Resonance Imaging in the Evaluation of Acute Demyelinating Optic Neuritis

BACKGROUND

Optic neuritis (ON) is the most common optic neuropathy in young adults. MRI is reported to have a high sensitivity for ON. Higher signal strengths of MRI may enhance resolution and lead to better detection of ON. We sought to compare the sensitivity of 3.0 Tesla (T) MRI to that of 1.5 T MRI in detecting acute demyelinating ON.

METHODS

A retrospective chart review was performed on patients with a clinical diagnosis of optic neuritis at Mayo Clinic Health System from January 2010 to April 2020. Among 1,850 patients identified, 126 patients met the eligibility criteria. Exclusion criteria comprised questionable or alternative diagnosis, diagnosis of ON before the study period, eye examinations performed elsewhere, or absence of fat-saturated head and orbits MRIs performed locally within 30 days of symptom onset. Gadolinium contrast enhancement, T2 hyperintensity, and the radiologic diagnosis of ON were recorded by a neuro-radiologist who was masked to the clinical history and the magnet strength of the MRI.

RESULTS

Fifty-three patients (42.1%) had 3.0 T MRI, and 73 patients (57.9%) had 1.5 T MRI. Overall, 88.9% (112/126) of patients were determined to have a positive MRI for ON. The radiographic sensitivity for ON was higher in the 3.0 T group compared with the 1.5 T group (98.1% vs 82.2%, respectively [P = 0.004]). The frequency of gadolinium enhancement was found to be greater in the 3 T group compared with the 1.5 T group (98.1% vs 76.7%, respectively [P < 0.001]). T2 hyperintensity was also more often seen in the 3.0 T group compared with the 1.5 T group (88.7% vs 68.5%, respectively [P = 0.01]).

CONCLUSIONS

3.0 T MRI is more sensitive than 1.5 T MRI in detecting ON. This finding suggests that 3.0 T MRI is a preferred imaging modality for the confirmation of ON.

MRI Prognostic Factors in Multiple Sclerosis, Neuromyelitis Optica Spectrum Disorder, and Myelin Oligodendrocyte Antibody Disease

Several MRI measures have been developed in the last couple of decades, providing a number of imaging biomarkers that can capture the complexity of the pathological processes occurring in multiple sclerosis (MS) brains. Such measures have provided more specific information on the heterogeneous pathologic substrate of MS-related tissue damage, being able to detect, and quantify the evolution of structural changes both within and outside focal lesions. In clinical practise, MRI is increasingly used in the MS field to help to assess patients during follow-up, guide treatment decisions and, importantly, predict the disease course. Moreover, the process of identifying new effective therapies for MS patients has been supported by the use of serial MRI examinations in order to sensitively detect the sub-clinical effects of disease-modifying treatments at an earlier stage than is possible using measures based on clinical disease activity. However, despite this has been largely demonstrated in the relapsing forms of MS, a poor understanding of the underlying pathologic mechanisms leading to either progression or tissue repair in MS as well as the lack of sensitive outcome measures for the progressive phases of the disease and repair therapies makes the development of effective treatments a big challenge. Finally, the role of MRI biomarkers in the monitoring of disease activity and the assessment of treatment response in other inflammatory demyelinating diseases of the central nervous system, such as neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte antibody disease (MOGAD) is still marginal, and advanced MRI studies have shown conflicting results. Against this background, this review focused on recently developed MRI measures, which were sensitive to pathological changes, and that could best contribute in the future to provide prognostic information and monitor patients with MS and other inflammatory demyelinating diseases, in particular, NMOSD and MOGAD.

Role of Structural, Metabolic, and Functional MRI in Monitoring Visual System Impairment and Recovery

The visual system, consisting of the eyes and the visual pathways of the brain, receives and interprets light from the environment so that we can perceive the world around us. A wide variety of disorders can affect human vision, ranging from ocular to neurologic to systemic in nature. While other noninvasive imaging techniques such as optical coherence tomography and ultrasound can image particular sections of the visual system, magnetic resonance imaging (MRI) offers high resolution without depth limitations. MRI also gives superior soft-tissue contrast throughout the entire pathway compared to computed tomography. By leveraging different imaging sequences, MRI is uniquely capable of unveiling the intricate processes of ocular anatomy, tissue physiology, and neurological function in the human visual system from the microscopic to macroscopic levels. In this review we discuss how structural, metabolic, and functional MRI can be used in the clinical assessment of normal and pathologic states in the anatomic structures of the visual system, including the eyes, optic nerves, optic chiasm, optic tracts, visual brain nuclei, optic radiations, and visual cortical areas. We detail a selection of recent clinical applications of MRI at each position along the visual pathways, including the evaluation of pathology, plasticity, and the potential for restoration, as well as its limitations and key areas of ongoing exploration. Our discussion of the current and future developments in MR ocular and neuroimaging highlights its potential impact on our ability to understand visual function in new detail and to improve our protection and treatment of anatomic structures that are integral to this fundamental sensory system. LEVEL OF EVIDENCE 3:   TECHNICAL EFFICACY STAGE 3:  .

MRI characteristics of MOG-Ab associated disease in adults: An update

Our knowledge of the radiological spectrum of myelin oligodendrocyte glycoprotein antibody associated disease (MOGAD) is growing rapidly. An update on the radiological features of the disease, and its evolution is thus necessary. Magnetic resonance imaging (MRI) has an increasingly important role in the differential diagnosis of MOGAD particularly from aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder (AQP4-NMOSD), and multiple sclerosis (MS). Differentiating these conditions is of prime importance because the management is different between the three inflammatory diseases, and thus could prevent further attack-related disability. Therefore, identifying the MRI features suggestive of MOGAD has diagnostic and prognostic implications. We herein review optic nerve, spinal cord and the brain MRI findings from MOGAD adult patients, and compare them to AQP4-NMOSD and MS.

The quest for high spatial resolution diffusion-weighted imaging of the human brain in vivo

Diffusion-weighted imaging, a contrast unique to MRI, is used for assessment of tissue microstructure in vivo. However, this exquisite sensitivity to finer scales far above imaging resolution comes at the cost of vulnerability to errors caused by sources of motion other than diffusion motion. Addressing the issue of motion has traditionally limited diffusion-weighted imaging to a few acquisition techniques and, as a consequence, to poorer spatial resolution than other MRI applications. Advances in MRI imaging methodology have allowed diffusion-weighted MRI to push to ever higher spatial resolution. In this review we focus on the pulse sequences and associated techniques under development that have pushed the limits of image quality and spatial resolution in diffusion-weighted MRI.

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.

Diagnostic implications of MOG/AQP4 antibodies in recurrent optic neuritis

The present study aimed to detect myelin oligodendrocyte glycoprotein (MOG) and aquaporin-4 (AQP4) antibodies in serum specimens of patients with recurrent optic neuritis (RON) through establishing 293 cells with stable expression of MOG and the complete genomic sequence as the substrate using a cell-based assay (CBA). Furthermore, the clinical features of MOG antibody-positive recurrent optic neuritis (MOG-RON) were assessed. A total of 43 RON patients admitted to Beijing Tongren Hospital from December 2014 to May 2015 were enrolled, including 11 males and 32 females. The serum was collected from all patients, and the MOG and AQP4 antibodies were detected via the CBA. According to the results, the 43 patients were divided into four groups, namely the MOG antibody-positive group (n=11), the AQP4 antibody-positive group (n=20), the MOG/AQP4 antibody-positive group (n=1) and the MOG/AQP4 antibody-negative group (n=11). Clinical data were collected and all patients were followed up for 6 months, with parameters observed including the visual acuity, visual field and ocular fundus. The differences in the demographics, clinical features, characteristics of imaging examination, vision at onset and visual function recovery at 6 months after treatment were compared among the different groups. The characteristics of MOG antibody-positive RON were summarized. Of the 43 RON patients, 2.33% was both MOG and AQP4 antibody-positive, 27.91% were MOG antibody-positive. Compared with the AQP4-RON patients, there were relatively less MOG-RON patients (63.6 vs. 95.0%) and the canal segment and intracranial segment of the optic canal were less involved (P<0.05). The visual acuity at onset of MOG-RON was not inferior to that of AQP4-RON, and the visual recovery degree of MOG-RON was better (P<0.05). MOG antibody may be detected in the serum of certain RON patients, which have unique and different characteristics from AQP4 antibody-positive RON patients, so it may be used as a prognostic biomarker for RON. Furthermore, MOG antibody is present in the serum of patients with neuromyelitis optica spectrum disorders and may be a potential biomarker for these conditions.

Role of coronal high-resolution diffusion-weighted imaging in acute optic neuritis: a comparison with axial orientation

PURPOSE

Through a comparison with the axial orientation, we aimed to evaluate the role of coronal high-resolution diffusion-weighted imaging (DWI) in acute optic neuritis based on diagnostic accuracy and the reproducibility of apparent diffusion coefficient (ADC) measurements.

METHODS

Orbital DWI, using readout-segmented, parallel imaging, and 2D navigator-based reacquisition (RESOLVE-DWI), was performed on 49 patients with acute vision loss. The coronal (thickness = 3 mm) and axial (thickness = 2 mm) diffusion images were evaluated by two neuroradiologists retrospectively. The sensitivity, specificity, and accuracy were calculated through diagnostic test; the inter- and intra-observer reliabilities were assessed with a weighted Cohen's kappa test. In addition, the agreement of ADC measurement among observers was evaluated by the intra-class correlation coefficient (ICC), coefficient of variation (CV), and Bland-Altman plots. Comparison of ADC values was also performed by unpaired t test.

RESULTS

Among the 49 patients, 47 clinically positive optic nerves and 51 clinically negative optic nerves were found. The sensitivity, specificity, and accuracy were 85.1/87.2%, 90.2/94.12%, and 87.8/90.8%, respectively, for coronal RESOLVE-DWI and 83.0/85.1%, 66.7/76.5%, and 75.5/79.6%, respectively, for axial RESOLVE-DWI. The inter-observer kappa values were 0.710 and 0.806 for axial and coronal RESOLVE-DWI, respectively, and the intra-observer kappa values were 0.822 and 0.909, respectively (each P < 0.0001). Regarding the reproducibility of ADC measurements on axial and coronal RESOLVE-DWI, the ICCs among observers were 0.846 and 0.941, respectively, and the CV values were 7.046 and 4.810%, respectively. Bland-Altman plots revealed smaller inter-observer variability on coronal RESOLVE-DWI. ADC values were significantly lower in positive group (each P < 0.0001).

CONCLUSION

Higher specificity and better reproducibility of ADC measurements were found for coronal RESOLVE-DWI, which demonstrated the feasibility of the use of coronal RESOLVE-DWI to examine acute optic neuritis patients.