The Lateral Corticospinal Tract Sign: An MRI Marker for Amyotrophic Lateral Sclerosis.

Background Radially sampled averaged magnetization inversion-recovery acquisition (rAMIRA) imaging shows hyperintensity in the lateral corticospinal tract (CST) in patients with motor neuron diseases. Purpose To systematically determine the accuracy of the lateral corticospinal tract sign for detecting patients with amyotrophic lateral sclerosis (ALS) at rAMIRA MRI. Materials and Methods This study included prospectively acquired data from participants in ALS and other motor neuron disease imaging studies at the University Hospital Basel, Switzerland. All participants underwent 3-T axial two-dimensional rAMIRA imaging at four cervical intervertebral disk levels. The lateral CST sign was defined as spinal cord white matter hyperintensity dorsolateral to the anterior horns, with higher signal intensity than in the dorsal columns on axial rAMIRA images. Marker accuracy was assessed in a study data set and in an independent validation data set. Postmortem rAMIRA imaging and histopathologic analysis were performed in one participant who died during the study. Results Participants with ALS (study data set: 38 participants [mean age, 61 years; IQR, 15 years], 22 male participants; validation data set: 10 participants [mean age, 61 years; IQR, 21 years], seven male participants), post-polio syndrome (study data set: 25 participants [mean age, 68 years; IQR, 8 years], 12 male participants), spinal muscular atrophy (study data set: 10 participants [mean age, 43 years; IQR, 14 years], eight male participants; validation data set: five participants [mean age, 38 years; IQR, 19 years], two male participants), and healthy control participants (study data set: 60 participants [mean age, 57 years; IQR, 20 years], 36 male participants; validation data set: 10 participants [mean age, 44 years; IQR, 17 years], seven male participants) were included. The sensitivity and specificity of rAMIRA for ALS were 60% (23 of 38) and 97% (91 of 94) in the study data set and 100% (10 of 10) and 93% (14 of 15) in the validation data set, respectively. Histopathologic analysis showed distinct loss of myelinated axons in the localization of the hyperintensities observed at rAMIRA imaging performed in situ and after organ extraction. Conclusion The recently defined marker at rAMIRA MRI may be a promising tool for assessing upper motor neuron degeneration in the lateral CST in patients with ALS. Clinical trials registration no. NCT03561623, NCT05764434, NCT06137612 © RSNA, 2024 Supplemental material is available for this article.

Contrast-Enhancing Lesion Segmentation in Multiple Sclerosis: A Deep Learning Approach Validated in a Multicentric Cohort.

The detection of contrast-enhancing lesions (CELs) is fundamental for the diagnosis and monitoring of patients with multiple sclerosis (MS). This task is time-consuming and suffers from high intra- and inter-rater variability in clinical practice. However, only a few studies proposed automatic approaches for CEL detection. This study aimed to develop a deep learning model that automatically detects and segments CELs in clinical Magnetic Resonance Imaging (MRI) scans. A 3D UNet-based network was trained with clinical MRI from the Swiss Multiple Sclerosis Cohort. The dataset comprised 372 scans from 280 MS patients: 162 showed at least one CEL, while 118 showed no CELs. The input dataset consisted of T1-weighted before and after gadolinium injection, and FLuid Attenuated Inversion Recovery images. The sampling strategy was based on a white matter lesion mask to confirm the existence of real contrast-enhancing lesions. To overcome the dataset imbalance, a weighted loss function was implemented. The Dice Score Coefficient and True Positive and False Positive Rates were 0.76, 0.93, and 0.02, respectively. Based on these results, the model developed in this study might well be considered for clinical decision support.

Longitudinal visibility of MRI findings in living victims of strangulation.

Initial experiences with magnetic resonance imaging (MRI) of living strangulation victims demonstrated additional findings of internal injuries compared to the standard clinical forensic examination. However, existing studies on the use of MRI for this purpose mostly focused on the first 48 h after the incident. The aims of this study were (a) to evaluate the longitudinal visibility of MRI findings after violence against the neck by performing two MRI examinations within 12 days and a minimum of four days between both MRI scans and (b) to assess which MRI sequences were most helpful for the detection of injuries. Twenty strangulation victims participated in this study and underwent one (n = 8) or two (n = 12) MRI scans. The first MRI examination was conducted during the first five days, the second five to 12 days after the incident. Two blinded radiologists assessed the MRI data and looked for lesions in the structures of the neck. In total, 140 findings were reported in the 32 MRI examinations. Most of the findings were detected in the thyroid and the muscles of the neck. T2-weighted SPACE with fat suppression, T1-weighted TSE and T1-weighted MPRAGE were rated as the most helpful MRI sequences. Subjects who showed findings in the initial scan also demonstrated comparable results in the second scan, which was performed on average 8.4 days after the incident. Our results show that even up to 12 days after the incident, the criminal proceeding of strangulation cases may greatly profit from the information provided by an MRI examination of the neck in addition to the standard clinical forensic examination.

Atherosclerosis and depression: is carotid intima-media thicker in patients with depression compared to matched control individuals? A systematic review and meta-analysis.

OBJECTIVE: To investigate if there is an association between atherosclerosis and depression by using as imaging biomarker the carotid intima media thickness (cIMT), a surrogate marker for atherosclerosis. METHODS: PubMed/Medline, Embase and Cochrane databases were comprehensively searched to identify studies investigating the association between cIMT and depression. The results were pooled using a random-effects statistical model, appropriate for the expected high heterogeneity. Sensitivity and subgroup analyses were conducted where data was available. RESULTS: Overall, 22 and 13 studies met inclusion criteria for the qualitative and the quantitative synthesis, respectively, with a total of 4466 patients and 21,635 control participants. Results showed that cIMT is significantly higher in the depression, compared to the control groups with an overall mean difference of 0.07 mm (95% CI 0.04-0.10, p < 0.01). Subgroup analysis showed that diabetes could present as a confounding factor in patients with depression and an increased cIMT. CONCLUSIONS: This study confirms a significantly increased cIMT in patients with depression, compared with controls and suggests a possible bidirectional link between atherosclerosis and depression. An early screening of cardiovascular disease in individuals suffering with depression should be considered.

Association of Spinal Cord Atrophy and Brain Paramagnetic Rim Lesions With Progression Independent of Relapse Activity in People With MS.

BACKGROUND AND OBJECTIVES: Progression independent of relapse activity (PIRA) is a crucial determinant of overall disability accumulation in multiple sclerosis (MS). Accelerated brain atrophy has been shown in patients experiencing PIRA. In this study, we assessed the relation between PIRA and neurodegenerative processes reflected by (1) longitudinal spinal cord atrophy and (2) brain paramagnetic rim lesions (PRLs). Besides, the same relationship was investigated in progressive MS (PMS). Last, we explored the value of cross-sectional brain and spinal cord volumetric measurements in predicting PIRA. METHODS: From an ongoing multicentric cohort study, we selected patients with MS with (1) availability of a susceptibility-based MRI scan and (2) regular clinical and conventional MRI follow-up in the 4 years before the susceptibility-based MRI. Comparisons in spinal cord atrophy rates (explored with linear mixed-effect models) and PRL count (explored with negative binomial regression models) were performed between: (1) relapsing-remitting (RRMS) and PMS phenotypes and (2) patients experiencing PIRA and patients without confirmed disability accumulation (CDA) during follow-up (both considering the entire cohort and the subgroup of patients with RRMS). Associations between baseline MRI volumetric measurements and time to PIRA were explored with multivariable Cox regression analyses. RESULTS: In total, 445 patients with MS (64.9% female; mean [SD] age at baseline 45.0 [11.4] years; 11.2% with PMS) were enrolled. Compared with patients with RRMS, those with PMS had accelerated cervical cord atrophy (mean difference in annual percentage volume change [MD-APC] -1.41; p = 0.004) and higher PRL load (incidence rate ratio [IRR] 1.93; p = 0.005). Increased spinal cord atrophy (MD-APC -1.39; p = 0.0008) and PRL burden (IRR 1.95; p = 0.0008) were measured in patients with PIRA compared with patients without CDA; such differences were also confirmed when restricting the analysis to patients with RRMS. Baseline volumetric measurements of the cervical cord, whole brain, and cerebral cortex significantly predicted time to PIRA (all p ≤ 0.002). DISCUSSION: Our results show that PIRA is associated with both increased spinal cord atrophy and PRL burden, and this association is evident also in patients with RRMS. These findings further point to the need to develop targeted treatment strategies for PIRA to prevent irreversible neuroaxonal loss and optimize long-term outcomes of patients with MS.

Adding the Optic Nerve in Multiple Sclerosis Diagnostic Criteria: A Longitudinal, Prospective, Multicenter Study

BACKGROUND AND OBJECTIVES: The optic nerve is not one of the areas of the CNS that can be used to demonstrate dissemination in space (DIS) within the 2017 McDonald criteria for the diagnosis of multiple sclerosis (MS). Objectives were (1) to assess whether optic nerve-MRI (ON-MRI), optical coherence tomography (OCT), and visual evoked potentials (VEP) detect optic nerve involvement in clinically isolated syndrome (CIS) and (2) to evaluate the contribution of the optic nerve topography to the current diagnostic criteria in a prospective, multicenter cohort. METHODS: MAGNIMS centers were invited to provide prospective data on patients with CIS who underwent a visual assessment with at least 2 of 3 investigations (ON-MRI, OCT, or VEP) within 6 months of onset. Modified DIS criteria were constructed by adding the optic nerve topography, defined by each investigation separately and any combination of them, as the fifth area of the CNS. A risk assessment analysis and the performance of the different DIS criteria were analyzed using the diagnosis of MS according to the 2017 McDonald criteria as the primary outcome and new T2 lesions and/or a second relapse as the secondary outcome. RESULTS: We included 157 patients with CIS from 5 MAGNIMS centers; 60/157 (38.2%) patients presented with optic neuritis. Optic nerve involvement on ON-MRI was found in 40.2% patients at study entry and in 72.5% of those with optic neuritis.At follow-up (mean 27.9 months, SD 14.5), 111/157 patients (70.7%) were diagnosed with MS according to the 2017 McDonald criteria. Fulfilling either 2017 DIS or any modified DIS criteria conferred a similar high risk for reaching primary and secondary outcomes. The modified DIS criteria had higher sensitivity (92.5% [with ON-MRI] vs 88.2%), but slightly lower specificity (80.0% [with GCIPL IEA ≥4 µm] vs 82.2%), with overall similar accuracy (86.6% [with ON-MRI] vs 86.5%) than 2017 DIS criteria. Consistent results were found for secondary outcomes. DISCUSSION: In patients with CIS, the presence of an optic nerve lesion defined by MRI, OCT, or VEP is frequently detected, especially when presenting with optic neuritis. Our study supports the addition of the optic nerve as a fifth topography to fulfill DIS criteria.

Does Functional Imaging Play a Role in Pre-Operative Diagnosis of Brain Tumours?

Although there is a large variability in the neural organization of language function between individuals, there is an ongoing debate about functional imaging as a standard procedure in the preoperative setting of brain tumors. Brain mapping of the language centers differs from individual to individual in multilingual patients and changes in its architecture may occur as a result of neuroplasticity induced by a mass lesion. This article discusses the role of functional imaging in the preoperative setting.

Prospective Assessment of Cerebral Microbleeds with Low-Field Magnetic Resonance Imaging (0.55 Tesla MRI).

PURPOSE: Accurate detection of cerebral microbleeds (CMBs) on susceptibility-weighted (SWI) magnetic resonance imaging (MRI) is crucial for the characterization of many neurological diseases. Low-field MRI offers greater access at lower costs and lower infrastructural requirements, but also reduced susceptibility artifacts. We therefore evaluated the diagnostic performance for the detection of CMBs of a whole-body low-field MRI in a prospective cohort of suspected stroke patients compared to an established 1.5 T MRI. METHODS: A prospective scanner comparison was performed including 27 patients, of whom 3 patients were excluded because the time interval was >1 h between acquisition of the 1.5 T and 0.55 T MRI. All SWI sequences were assessed for the presence, number, and localization of CMBs by two neuroradiologists and additionally underwent a Likert rating with respect to image impression, resolution, noise, contrast, and diagnostic quality. RESULTS: A total of 24 patients with a mean age of 74 years were included (11 female). Both readers detected the same number and localization of microbleeds in all 24 datasets (sensitivity and specificity 100%; interreader reliability Ï° = 1), with CMBs only being observed in 12 patients. Likert ratings of the sequences at both field strengths regarding overall image quality and diagnostic quality did not reveal significant differences between the 0.55 T and 1.5 T sequences (p = 0.942; p = 0.672). For resolution and contrast, the 0.55 T sequences were even significantly superior (p < 0.0001; p < 0.0003), whereas the 1.5 T sequences were significantly superior (p < 0.0001) regarding noise. CONCLUSION: Low-field MRI at 0.55 T may have similar accuracy as 1.5 T scanners for the detection of microbleeds and thus may have great potential as a resource-efficient alternative in the near future.

A Multicenter Longitudinal MRI Study Assessing LeMan-PV Software Accuracy in the Detection of White Matter Lesions in Multiple Sclerosis Patients.

BACKGROUND: Detecting new and enlarged lesions in multiple sclerosis (MS) patients is needed to determine their disease activity. LeMan-PV is a software embedded in the scanner reconstruction system of one vendor, which automatically assesses new and enlarged white matter lesions (NELs) in the follow-up of MS patients; however, multicenter validation studies are lacking. PURPOSE: To assess the accuracy of LeMan-PV for the longitudinal detection NEL white-matter MS lesions in a multicenter clinical setting. STUDY TYPE: Retrospective, longitudinal. SUBJECTS: A total of 206 patients with a definitive MS diagnosis and at least two follow-up MRI studies from five centers participating in the Swiss Multiple Sclerosis Cohort study. Mean age at first follow-up = 45.2 years (range: 36.9-52.8 years); 70 males. FIELD STRENGTH/SEQUENCE: Fluid attenuated inversion recovery (FLAIR) and T1-weighted magnetization prepared rapid gradient echo (T1-MPRAGE) sequences at 1.5 T and 3 T. ASSESSMENT: The study included 313 MRI pairs of datasets. Data were analyzed with LeMan-PV and compared with a manual "reference standard" provided by a neuroradiologist. A second rater (neurologist) performed the same analysis in a subset of MRI pairs to evaluate the rating-accuracy. The Sensitivity (Se), Specificity (Sp), Accuracy (Acc), F1-score, lesion-wise False-Positive-Rate (aFPR), and other measures were used to assess LeMan-PV performance for the detection of NEL at 1.5 T and 3 T. The performance was also evaluated in the subgroup of 123 MRI pairs at 3 T. STATISTICAL TESTS: Intraclass correlation coefficient (ICC) and Cohen's kappa (CK) were used to evaluate the agreement between readers. RESULTS: The interreader agreement was high for detecting new lesions (ICC = 0.97, Pvalue < 10-20 , CK = 0.82, P value = 0) and good (ICC = 0.75, P value < 10-12 , CK = 0.68, P value = 0) for detecting enlarged lesions. Across all centers, scanner field strengths (1.5 T, 3 T), and for NEL, LeMan-PV achieved: Acc = 61%, Se = 65%, Sp = 60%, F1-score = 0.44, aFPR = 1.31. When both follow-ups were acquired at 3 T, LeMan-PV accuracy was higher (Acc = 66%, Se = 66%, Sp = 66%, F1-score = 0.28, aFPR = 3.03). DATA CONCLUSION: In this multicenter study using clinical data settings acquired at 1.5 T and 3 T, and variations in MRI protocols, LeMan-PV showed similar sensitivity in detecting NEL with respect to other recent 3 T multicentric studies based on neural networks. While LeMan-PV performance is not optimal, its main advantage is that it provides automated clinical decision support integrated into the radiological-routine flow. EVIDENCE LEVEL: 4 TECHNICAL EFFICACY: Stage 2.

Global Cortical Atrophy Is Associated with an Unfavorable Outcome in Stroke Patients on Oral Anticoagulation.

INTRODUCTION: Measures of cerebral small vessel disease (cSVD), such as white matter hyperintensities (WMH) and cerebral microbleeds (CMB), are associated with an unfavorable clinical course in stroke patients on oral anticoagulation (OAC) for atrial fibrillation (AF). Here, we investigated whether similar findings can be observed for global cortical atrophy (GCA). METHODS: Registry-based prospective observational study of 320 patients treated with OAC following AF stroke. Patients underwent magnetic resonance imaging (MRI) allowing assessment of GCA. Using the simplified visual Pasquier scale, the severity of GCA was categorized as follows: 0: no atrophy, 1: mild atrophy; 2: moderate atrophy, and 3: severe atrophy. Using adjusted logistic and Cox regression analysis, we investigated the association of GCA using a composite outcome measure, comprising: (i) recurrent acute ischemic stroke (IS); (ii) intracranial hemorrhage (ICH); and (iii) death. RESULTS: In our time to event analysis after adjusting for potential confounders (i.e., WMH, CMB, age, sex, diabetes, arterial hypertension, coronary heart disease, hyperlipidemia, and antiplatelet use), GCA was associated with an increased risk for the composite outcome in all three degrees of atrophy (grade 1: aHR 3.95, 95% CI 1.34-11.63, p = 0.013; grade 2: aHR 3.89, 95% CI 1.23-12.30, p = 0.021; grade 3: aHR 4.16, 95% CI 1.17-14.84, p = 0.028). CONCLUSION: GCA was associated with our composite outcome also after adjusting for other cSVD markers (i.e., CMB, WMH) and age, indicating that GCA may potentially serve as a prognostic marker for stroke patients with atrial fibrillation on oral anticoagulation.

Quantifying the Effects of Structured Reporting on Report Turnaround Times and Proofreading Workload in Neuroradiology.

RATIONALE AND OBJECTIVES: To assess the effects of a change from free text reporting to structured reporting on resident reports, the proofreading workload and report turnaround times in the neuroradiology daily routine. MATERIALS AND METHODS: Our neuroradiology section introduced structured reporting templates in July 2019. Reports dictated by residents during dayshifts from January 2019 to March 2020 were retrospectively assessed using quantitative parameters from report comparison. Through automatic analysis of text-string differences between report states (i.e. draft, preliminary and final report), Jaccard similarities and edit distances of reports following read-out sessions as well as after report sign-off were calculated. Furthermore, turnaround times until preliminary and final report availability to clinicians were investigated. Parameters were visualized as trending line graphs and statistically compared between reporting standards. RESULTS: Three thousand five hundred thirty-eight reports were included into analysis. Mean Jaccard similarity of resident drafts and staff-reviewed final reports increased from 0.53 ± 0.37 to 0.79 ± 0.22 after the introduction of structured reporting (p < .001). Both mean overall edits on draft reports by residents following read-out sessions (0.30 ± 0.45 vs. 0.09 ± 0.29; p < .001) and by staff radiologists during report sign-off (0.17 ± 0.28 vs. 0.12 ± 0.23, p < .001) decreased. With structured reporting, mean turnaround time until preliminary report availability to clinicians decreased by 20.7 minutes (246.9 ± 207.0 vs. 226.2 ± 224.9; p < .001). Similarly, final reports were available 35.0 minutes faster on average (558.05 ± 15.1 vs. 523.0 ± 497.3; p = .002). CONCLUSION: Structured reporting is beneficial in the neuroradiology daily routine, as resident drafts require fewer edits in the report review process. This reduction in proofreading workload is likely responsible for lower report turnaround times.

Brain cortical alterations in COVID-19 patients with neurological symptoms.

Background: Growing evidence suggests that the central nervous system is affected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), since infected patients suffer from acute and long-term neurological sequelae. Nevertheless, it is currently unknown whether the virus affects the brain cortex. The purpose of this study was to assess the cortical gray matter volume, the cortical thickness, and the cortical surface area in a group of SARS-CoV-2 infected patients with neurological symptoms compared to healthy control subjects. Additionally, we analyzed the cortical features and the association with inflammatory biomarkers in the cerebrospinal fluid (CSF) and plasma. Materials and methods: Thirty-three patients were selected from a prospective cross-sectional study cohort during the ongoing pandemic (August 2020-April 2021) at the university hospitals of Basel and Zurich (Switzerland). The group included patients with different neurological symptom severity (Class I: nearly asymptomatic/mild symptoms, II: moderate symptoms, III: severe symptoms). Thirty-three healthy age and sex-matched subjects that underwent the same MRI protocol served as controls. For each anatomical T1w MPRAGE image, regional cortical gray matter volume, thickness, and surface area were computed with FreeSurfer. Using a linear regression model, cortical measures were compared between groups (patients vs. controls; Class I vs. II-III), with age, sex, MRI magnetic field strength, and total intracranial volume/mean thickness/total surface area as covariates. In a subgroup of patients, the association between cortical features and clinical parameters was assessed using partial correlation adjusting for the same covariates. P-values were corrected using a false discovery rate (FDR). Results: Our findings revealed a lower cortical volume in COVID-19 patients' orbitofrontal, frontal, and cingulate regions than in controls (p < 0.05). Regional gray matter volume and thickness decreases were negatively associated with CSF total protein levels, the CSF/blood-albumin ratio, and CSF EN-RAGE levels. Conclusion: Our data suggest that viral-triggered inflammation leads to neurotoxic damage in some cortical areas during the acute phase of a COVID-19 infection in patients with neurological symptoms.

Severe Neuro-COVID is associated with peripheral immune signatures, autoimmunity and neurodegeneration: a prospective cross-sectional study.

Growing evidence links COVID-19 with acute and long-term neurological dysfunction. However, the pathophysiological mechanisms resulting in central nervous system involvement remain unclear, posing both diagnostic and therapeutic challenges. Here we show outcomes of a cross-sectional clinical study (NCT04472013) including clinical and imaging data and corresponding multidimensional characterization of immune mediators in the cerebrospinal fluid (CSF) and plasma of patients belonging to different Neuro-COVID severity classes. The most prominent signs of severe Neuro-COVID are blood-brain barrier (BBB) impairment, elevated microglia activation markers and a polyclonal B cell response targeting self-antigens and non-self-antigens. COVID-19 patients show decreased regional brain volumes associating with specific CSF parameters, however, COVID-19 patients characterized by plasma cytokine storm are presenting with a non-inflammatory CSF profile. Post-acute COVID-19 syndrome strongly associates with a distinctive set of CSF and plasma mediators. Collectively, we identify several potentially actionable targets to prevent or intervene with the neurological consequences of SARS-CoV-2 infection.

Impact of type of oral anticoagulants in patients with cerebral microbleeds after atrial fibrillation-related ischemic stroke or TIA: Results of the NOACISP-LONGTERM registry.

Background: Cerebral microbleeds (CMBs) may have a differential impact on clinical outcome in stroke patients with atrial fibrillation (AF) treated with different types of oral anticoagulation (OAC). Methods: Observational single-center study on AF-stroke-patients treated with OAC. Magnetic-resonance-imaging was performed to assess CMBs. Outcome measures consisted of recurrent ischemic stroke (IS), intracranial hemorrhage (ICH), death, and their combined analysis. Functional disability was assessed by mRS. Using adjusted logistic regression and Cox proportional-hazards models, we assessed the association of the presence of CMBs and OAC type (vitamin K antagonists [VKAs] vs. direct oral anticoagulants [DOACs]) with clinical outcome. Results: Of 310 AF-stroke patients treated with OAC [DOACs: n = 234 (75%); VKAs: n = 76 (25%)], CMBs were present in 86 (28%) patients; of these, 66 (77%) received DOACs. In both groups, CMBs were associated with an increased risk for the composite outcome: VKAs: HR 3.654 [1.614; 8.277]; p = 0.002; DOACs: HR 2.230 [1.233; 4.034]; p = 0.008. Patients with CMBs had ~50% higher absolute rates of the composite outcome compared to the overall cohort, with a comparable ratio between treatment groups [VKAs 13/20(65%) vs. DOACs 19/66(29%); p < 0.01]. The VKA-group had a 2-fold higher IS [VKAs:4 (20%) vs. DOACs:6 (9%); p = 0.35] and a 10-fold higher ICH rate [VKAs: 3 (15%) vs. DOACs: 1 (1.5%); p = 0.038]. No significant interaction was observed between type of OAC and presence of CMBs. DOAC-patients showed a significantly better functional outcome (OR 0.40 [0.17; 0.94]; p = 0.04). Conclusions: In AF-stroke patients treated with OAC, the presence of CMBs was associated with an unfavorable composite outcome for both VKAs and DOACs, with a higher risk for recurrent IS than for ICH. Strokes were numerically higher under VKAs and increased in the presence of CMBs. Clinical trial registration: http://www.clinicaltrials.gov, Unique identifier: NCT03826927.

Brain atrophy measurement over a MRI scanner change in multiple sclerosis.

BACKGROUND: A change in MRI hardware impacts brain volume measurements. The aim of this study was to use MRI data from multiple sclerosis (MS) patients and healthy control subjects (HCs) to statistically model how to adjust brain atrophy measures in MS patients after a major scanner upgrade. METHODS: We scanned 20 MS patients and 26 HCs before and three months after a major scanner upgrade (1.5 T Siemens Healthineers Magnetom Avanto to 3 T Siemens Healthineers Skyra Fit). The patient group also underwent standardized serial MRIs before and after the scanner change. Percentage whole brain volume changes (PBVC) measured by Structural Image Evaluation using Normalization of Atrophy (SIENA) in the HCs was used to estimate a corrective term based on a linear model. The factor was internally validated in HCs, and then applied to the MS group. RESULTS: Mean PBVC during the scanner change was higher in MS than HCs (-4.1 ± 0.8 % versus -3.4 ± 0.6 %). A fixed corrective term of 3.4 (95% confidence interval: 3.13-3.67)% was estimated based on the observed average changes in HCs. Age and gender did not have a significant influence on this corrective term. After adjustment, a linear mixed effects model showed that the brain atrophy measures in MS during the scanner upgrade were not anymore associated with the scanner type (old vs new scanner; p = 0.29). CONCLUSION: A scanner change affects brain atrophy measures in longitudinal cohorts. The inclusion of a corrective term based on changes observed in HCs helps to adjust for the known and unknown factors associated with a scanner upgrade on a group level.

Potential of Stroke Imaging Using a New Prototype of Low-Field MRI: A Prospective Direct 0.55 T/1.5 T Scanner Comparison.

Objectives: Ischemic stroke is a leading cause of mortality and acquired disability worldwide and thus plays an enormous health-economic role. Imaging of choice is computed-tomographic (CT) or magnetic resonance imaging (MRI), especially diffusion-weighted (DW) sequences. However, MR imaging is associated with high costs and therefore has a limited availability leading to low-field-MRI techniques increasingly coming into focus. Thus, the aim of our study was to assess the potential of stroke imaging with low-field MRI. Material and Methods: A scanner comparison was performed including 27 patients (17 stroke cohort, 10 control group). For each patient, a brain scan was performed first with a 1.5T scanner and afterwards with a 0.55T scanner. Scan protocols were as identical as possible and optimized. Data analysis was performed in three steps: All DWI/ADC (apparent diffusion coefficient) and FLAIR (fluid attenuated inversion recovery) sequences underwent Likert rating with respect to image impression, resolution, noise, contrast, and diagnostic quality and were evaluated by two radiologists regarding number and localization of DWI and FLAIR lesions in a blinded fashion. Then segmentation of lesion volumes was performed by two other radiologists on DWI/ADC and FLAIR. Results: DWI/ADC lesions could be diagnosed with the same reliability by the most experienced reader in the 0.55T and 1.5T sequences (specificity 100% and sensitivity 92.9%, respectively). False positive findings did not occur. Detection of number/location of FLAIR lesions was mostly equivalent between 0.55T and 1.5T sequences. No significant difference (p = 0.789−0.104) for FLAIR resolution and contrast was observed regarding Likert scaling. For DWI/ADC noise, the 0.55T sequences were significantly superior (p < 0.026). Otherwise, the 1.5T sequences were significantly superior (p < 0.029). There was no significant difference in infarct volume and volume of infarct demarcation between the 0.55T and 1.5T sequences, when detectable. Conclusions: Low-field MRI stroke imaging at 0.55T may not be inferior to scanners with higher field strengths and thus has great potential as a low-cost alternative in future stroke diagnostics. However, there are limitations in the detection of very small infarcts. Further technical developments with follow-up studies must show whether this problem can be solved.

Association of Brain Atrophy With Disease Progression Independent of Relapse Activity in Patients With Relapsing Multiple Sclerosis.

Importance: The mechanisms driving neurodegeneration and brain atrophy in relapsing multiple sclerosis (RMS) are not completely understood. Objective: To determine whether disability progression independent of relapse activity (PIRA) in patients with RMS is associated with accelerated brain tissue loss. Design, Setting, and Participants: In this observational, longitudinal cohort study with median (IQR) follow-up of 3.2 years (2.0-4.9), data were acquired from January 2012 to September 2019 in a consortium of tertiary university and nonuniversity referral hospitals. Patients were included if they had regular clinical follow-up and at least 2 brain magnetic resonance imaging (MRI) scans suitable for volumetric analysis. Data were analyzed between January 2020 and March 2021. Exposures: According to the clinical evolution during the entire observation, patients were classified as those presenting (1) relapse activity only, (2) PIRA episodes only, (3) mixed activity, or (4) clinical stability. Main Outcomes and Measures: Mean difference in annual percentage change (MD-APC) in brain volume/cortical thickness between groups, calculated after propensity score matching. Brain atrophy rates, and their association with the variables of interest, were explored with linear mixed-effect models. Results: Included were 1904 brain MRI scans from 516 patients with RMS (67.4% female; mean [SD] age, 41.4 [11.1] years; median [IQR] Expanded Disability Status Scale score, 2.0 [1.5-3.0]). Scans with insufficient quality were excluded (n = 19). Radiological inflammatory activity was associated with increased atrophy rates in several brain compartments, while an increased annualized relapse rate was linked to accelerated deep gray matter (GM) volume loss. When compared with clinically stable patients, patients with PIRA had an increased rate of brain volume loss (MD-APC, -0.36; 95% CI, -0.60 to -0.12; P = .02), mainly driven by GM loss in the cerebral cortex. Patients who were relapsing presented increased whole brain atrophy (MD-APC, -0.18; 95% CI, -0.34 to -0.02; P = .04) with respect to clinically stable patients, with accelerated GM loss in both cerebral cortex and deep GM. No differences in brain atrophy rates were measured between patients with PIRA and those presenting relapse activity. Conclusions and Relevance: Our study shows that patients with RMS and PIRA exhibit accelerated brain atrophy, especially in the cerebral cortex. These results point to the need to recognize the insidious manifestations of PIRA in clinical practice and to further evaluate treatment strategies for patients with PIRA in clinical trials.