Neuroimaging findings in 4342 hospitalized COVID-19 subjects: A multicenter report from the United States and Europe.

BACKGROUND AND PURPOSE: To determine the incidence of acute neuroimaging (NI) findings and comorbidities in the coronavirus disease of 2019 (COVID-19)-infected subjects in seven U.S. and four European hospitals. METHODS: This is a retrospective study of COVID-19-positive subjects with the following inclusion criteria: age >18, lab-confirmed COVID-19 infection, and acute NI findings (NI+) attributed to COVID-19 on CT or MRI brain. NI+ and comorbidities in total hospitalized COVID-19-positive (TN) subjects were assessed. RESULTS: A total of 37,950 COVID-19-positive subjects were reviewed and 4342 underwent NI. NI+ incidence in subjects with NI was 10.1% (442/4342) including 7.9% (294/3701) in the United States and 22.8% (148/647) in Europe. NI+ incidence in TN was 1.16% (442/37,950). In NI (4342), incidence of ischemic stroke was 6.4% followed by intracranial hemorrhage (ICH) (3.8%), encephalitis (0.5%), sinus venous thrombosis (0.2%), and acute disseminated encephalomyelitis (ADEM) (0.2%). White matter involvement was seen in 57% of NI+. Hypertension was the most common comorbidity (54%) before cardiac disease (28.8%) and diabetes mellitus (27.7%). Cardiac disease (p < .025), diabetes (p < .014), and chronic kidney disease (p < .012) were more common in the United States. CONCLUSION: This multicenter, multinational study investigated the incidence and spectrum of NI+ in 37,950 hospitalized adult COVID-19 subjects including regional differences in incidences of NI+, associated comorbidities, and other demographics. NI+ incidence in TN was 1.16% including 0.95% in the United States and 2.09% in Europe. ICH, encephalitis, and ADEM were common in Europe, while ischemic strokes were more common in the United States. In this cohort, incidence and distribution of NI+ helped characterize the neurological complications of COVID-19.

Cerebral perfusion using ASL in patients with COVID-19 and neurological manifestations: A retrospective multicenter observational study.

BACKGROUND AND PURPOSE: Cerebral hypoperfusion has been reported in patients with COVID-19 and neurological manifestations in small cohorts. We aimed to systematically assess changes in cerebral perfusion in a cohort of 59 of these patients, with or without abnormalities on morphological MRI sequences. METHODS: Patients with biologically-confirmed COVID-19 and neurological manifestations undergoing a brain MRI with technically adequate arterial spin labeling (ASL) perfusion were included in this retrospective multicenter study. ASL maps were jointly reviewed by two readers blinded to clinical data. They assessed abnormal perfusion in four regions of interest in each brain hemisphere: frontal lobe, parietal lobe, posterior temporal lobe, and temporal pole extended to the amygdalo-hippocampal complex. RESULTS: Fifty-nine patients (44 men (75%), mean age 61.2 years) were included. Most patients had a severe COVID-19, 57 (97%) needed oxygen therapy and 43 (73%) were hospitalized in intensive care unit at the time of MRI. Morphological brain MRI was abnormal in 44 (75%) patients. ASL perfusion was abnormal in 53 (90%) patients, and particularly in all patients with normal morphological MRI. Hypoperfusion occurred in 48 (81%) patients, mostly in temporal poles (52 (44%)) and frontal lobes (40 (34%)). Hyperperfusion occurred in 9 (15%) patients and was closely associated with post-contrast FLAIR leptomeningeal enhancement (100% [66.4%-100%] of hyperperfusion with enhancement versus 28.6% [16.6%-43.2%] without, p = 0.002). Studied clinical parameters (especially sedation) and other morphological MRI anomalies had no significant impact on perfusion anomalies. CONCLUSION: Brain ASL perfusion showed hypoperfusion in more than 80% of patients with severe COVID-19, with or without visible lesion on conventional MRI abnormalities.

Cerebral and cognitive modifications in retired professional soccer players: TC-FOOT protocol, a transverse analytical study.

INTRODUCTION: Soccer is the most popular sport in the world. This contact sport carries the risk of exposure to repeated head impacts in the form of subconcussions, defined as minimal brain injuries following head impact, with no symptom of concussion. While it has been suggested that exposure to repetitive subconcussive events can result in long-term neurophysiological modifications, and the later development of chronic traumatic encephalopathy, the consequences of these repeated impacts remain controversial and largely unexplored in the context of soccer players. METHODS AND ANALYSIS: This is a prospective, single-centre, exposure/non-exposure, transverse study assessing the MRI and neuropsychological abnormalities in professional retired soccer players exposed to subconcussive impacts, compared with high-level athletes not exposed to head impacts. The primary outcome corresponds to the results of MRI by advanced MRI techniques (diffusion tensor, cerebral perfusion, functional MRI, cerebral volumetry and cortical thickness, spectroscopy, susceptibility imaging). Secondary outcomes are the results of the neuropsychological tests: number of errors and time to complete tests. We hypothesise that repeated subconcussive impacts could lead to morphological lesions and impact on soccer players' cognitive skills in the long term. ETHICS AND DISSEMINATION: Ethics approval has been obtained and the study was approved by the Comité de Protection des Personnes (CPP) No 2021-A01169-32. Study findings will be disseminated by publication in a high-impact international journal. Results will be presented at national and international imaging meetings. TRIAL REGISTRATION NUMBER: NCT04903015.

18 F-FDOPA and MRI Findings in a Case of Multiple Sclerosis.

ABSTRACT: A 39-year-old woman with no significant medical history underwent a brain MRI because of headaches and dysarthria having lasted 3 weeks. A tumor lesion was suspected. PET imaging was decided. She underwent FDG and FDOPA PET, leading to the diagnosis of low-grade glioma. Three months later, a new imaging assessment was organized. It showed a decrease in the hypermetabolism of the lesion and the appearance of a second lesion questioning the diagnosis. Further assessment led to the conclusion of a multiple sclerosis. This case illustrates that FDOPA PET uptake should be interpreted with caution in patients with suspected primary brain tumors.

MRI dedicated to the emergency department for diplopia or dizziness: a cost-effectiveness analysis.

OBJECTIVES: The purpose of this study was to compare the costs and organizational benefits of diagnostic workup without and with MRI dedicated to the ED. METHODS: We conducted a prospective observational uncontrolled before-after study in one ED of a university hospital in France from July 1, 2018, and January 3, 2020. We included all consecutive patients presenting with dizziness or diplopia. The main outcomes were the clinical decision time of ED physicians and the total costs for each strategy. Outcomes were compared using propensity score with inverse probability weighting in the 2 arms and an incremental cost-effectiveness ratio (ICER) was calculated. RESULTS: Among the 199 patients during the "before" period (average age: 60.4 years ± 17.6): 112 men (57%), and 181 during the "after" period (average age, 54.8 years ± 18.5): 107 men (59%), the average costs were €2701 (95% CI 1918; 3704) and €2389 (95% CI: €1627; 3280) per patient, respectively. The average time to clinical decision was 9.8 h (95% CI: 8.9 10.7) in the group "before" and 7.7 h (95% CI: 7.1; 8.4) in the group "after" (ICER: €151 saved for a reduction of 1 h in clinical decision time). The probabilistic sensitivity analysis estimated a 71% chance that the MRI dedicated to ED was dominant (less costly and more effective). CONCLUSION: Easy access to MRI in the ED for posterior circulation stroke-like symptoms must be considered a relevant approach to help physicians for an appropriate and rapid diagnostic with reduction of costs. TRIAL REGISTRATION: NCT03660852 KEY POINTS: • A dedicated MRI in the ED for diplopia or dizziness may be considered an efficient strategy improving diagnostic performance, reducing physicians' decision time, and decreasing hospital costs. • This strategy supports clinical decision-making with early treatment and management of patients with posterior circulation-like symptoms in the ED. • There is 71% chance that the MRI dedicated to ED was dominant (less costly and more effective) compared with a strategy without dedicated MRI.

Evolution of Neuroimaging Findings in Severe COVID-19 Patients with Initial Neurological Impairment: An Observational Study.

BACKGROUND AND OBJECTIVES: Cerebral complications related to the COVID-19 were documented by brain MRIs during the acute phase. The purpose of the present study was to describe the evolution of these neuroimaging findings (MRI and FDG-PET/CT) and describe the neurocognitive outcomes of these patients. METHODS: During the first wave of the COVID-19 outbreak between 1 March and 31 May 2020, 112 consecutive COVID-19 patients with neurologic manifestations underwent a brain MRI at Strasbourg University hospitals. After recovery, during follow-up, of these 112 patients, 31 (initially hospitalized in intensive care units) underwent additional imaging studies (at least one brain MRI). RESULTS: Twenty-three men (74%) and eight women (26%) with a mean age of 61 years (range: 18-79) were included. Leptomeningeal enhancement, diffuse brain microhemorrhages, acute ischemic strokes, suspicion of cerebral vasculitis, and acute inflammatory demyelinating lesions were described on the initial brain MRIs. During follow-up, the evolution of the leptomeningeal enhancement was discordant, and the cerebral microhemorrhages were stable. We observed normalization of the vessel walls in all patients suspected of cerebral vasculitis. Four patients (13%) demonstrated new complications during follow-up (ischemic strokes, hypoglossal neuritis, marked increase in the white matter FLAIR hyperintensities with presumed vascular origin, and one suspected case of cerebral vasculitis). Concerning the grey matter volumetry, we observed a loss of volume of 3.2% during an average period of approximately five months. During follow-up, the more frequent FDG-PET/CT findings were hypometabolism in temporal and insular regions. CONCLUSION: A minority of initially severe COVID-19 patients demonstrated new complications on their brain MRIs during follow-up after recovery.

Evaluation of neuroradiology emergency MRI interpretations: low discrepancy rates between on-call radiology residents' preliminary interpretations and neuroradiologists' final reports.

OBJECTIVES: To evaluate the performance of on-call radiology residents in interpreting alone brain and spine MRI studies performed after hours, to describe their mistakes, and to identify influencing factors that increased the occurrence of errors. METHODS: A total of 328 MRI examinations performed during a 13-month period (from December 1, 2019, to January 1, 2021) were prospectively included. Discrepancies between the preliminary interpretation of on-call radiology residents and the final reports of attending neuroradiologists were noted and classified according to a three-level score: level 1 (perfect interpretation or minor correction), level 2 (important correction without immediate change in patient management), or level 3 (major correction with immediate change in patient management). Categorical data were compared using Fisher's exact test. RESULTS: The overall discrepancy rate (level-2 and level-3 errors) was 16%; the rate of major discrepancies (only level-3 errors) was 5.5%. The major-discrepancy rate of second-year residents, when compared with that of senior residents, was significantly higher (p = 0.02). Almost all of the level-3 errors concerned cerebrovascular pathology. The most common level-2 errors involved undescribed aneurysms. We found no significant difference in the major-discrepancy rate regarding time since the beginning of the shift. CONCLUSIONS: The great majority of examinations were correctly interpreted. The rate of major discrepancies in our study was comparable to the data in the literature, and there was no adverse clinical outcome. The level of residency has an effect on the rate of serious errors in residents' reports. KEY POINTS: • The rate of major discrepancies between preliminary MRI interpretations by on-call radiology residents and final reports by attending neuroradiologists is low, and comparable to discrepancy rates reported for head CT interpretations. • The youngest residents made significantly more serious errors when compared to senior residents. • There was no adverse clinical outcome in patient morbidity as a result of an initial misdiagnosis.

Neuroimaging in patients with COVID-19: a neuroradiology expert group consensus.

Neurological and neuroradiological manifestations in patients with COVID-19 have been extensively reported. Available imaging data are, however, very heterogeneous. Hence, there is a growing need to standardise clinical indications for neuroimaging, MRI acquisition protocols, and necessity of follow-up examinations. A NeuroCovid working group with experts in the field of neuroimaging in COVID-19 has been constituted under the aegis of the Subspecialty Committee on Diagnostic Neuroradiology of the European Society of Neuroradiology (ESNR). The initial objectives of this NeuroCovid working group are to address the standardisation of the imaging in patients with neurological manifestations of COVID-19 and to give advice based on expert opinion with the aim of improving the quality of patient care and ensure high quality of any future clinical studies. KEY POINTS: • In patients with COVID-19 and neurological manifestations, neuroimaging should be performed in order to detect underlying causal pathology. • The basic MRI recommended protocol includes T2-weighted, FLAIR (preferably 3D), and diffusion-weighted images, as well as haemorrhage-sensitive sequence (preferably SWI), and at least for the initial investigation pre and post-contrast T1 weighted-images. • 3D FLAIR should be acquired after gadolinium administration in order to optimise the detection of leptomeningeal contrast enhancement.

Cerebral mucormycosis: neuroimaging findings and histopathological correlation.

INTRODUCTION: Mucormycosis are infections caused by molds of the order Mucorales. These opportunistic infections are rare, difficult to diagnose, and have a poor prognosis. We aimed to describe common radiographic patterns that may help to diagnose cerebral mucormycosis and search for histopathological correlations with imaging data. METHODS: We studied the radiological findings (CT and MRI) of 18 patients with cerebral mucormycosis and four patients' histopathological findings. RESULTS: All patients were immunocompromised and/or diabetic. The type of lesions depended on the infection's dissemination pathway. Hematogenous dissemination lesions were most frequently abscesses (59 lesions), cortical, cortical-subcortical, or in the basal ganglia, with a halo aspect on DWI for lesions larger than 1.6 cm. Only seven lesions were enhanced after contrast injection, with different presentations depending on patients' immune status. Ischemia and hemorrhagic areas were also seen. Vascular lesions were represented by stenosis and thrombosis. Direct posterior extension lesions were bi-fronto basal hypodensities on CT and restricted diffusion without enhancement on MRI. A particular extension, perineural spread, was seen along the trigeminal nerve. Histopathological analysis found endovascular lesions with destruction of vessel walls by Mucorales, microbleeds around vessels, as well as acute and chronic inflammation. CONCLUSIONS: MRI is the critical exam for cerebral mucormycosis. Weak ring enhancement and reduced halo diffusion suggest the diagnosis of fungal infections. Involvement of the frontal lobes should raise suspicion of mucormycosis (along with aspergillosis). The perineural spread can be considered a more specific extension pathway of mucormycosis.

Abnormal MRI findings of the orbital or visual pathways in patients with severe COVID-19: Observations from the French multicenter COVID-19 cohort.

OBJECTIVES: COVID-19 is a multisystemic disease. Ophthalmological abnormalities are relatively rare among COVID-19-infected patients. The aim of our study was to report orbital and visual pathways MRI findings in a nationwide multicenter cohort of patients with severe COVID-19. METHODS: This IRB-approved retrospective multi-center study included participants presenting with severe COVID-19, who underwent brain MRI from March 4th to May 1st 2020. Two neuroradiologists ("blinded"), blinded to all data, individually analyzed morphological MRIs focusing on the orbits and the visual pathways. A second consensus reading session was performed in the case of disagreement between both readers. Clinical and ophthalmological data were compared to MRI findings. Descriptive statistical analysis and interobserver agreement for MRI reading using non-weighted Cohen kappa statistics were performed. RESULTS: 129 participants (43 [33%] women and 86 [67%] men, mean age 63 ± 14 years) were included in the study. 17/129 (13%) patients had abnormal MRI findings of the orbit or visual pathways. 11/17 (65%) patients had a FLAIR-WI hyperintense optic disc. 6/17 (35%) patients had abnormal signal of at least one of the visual pathway structures: 6/6 (100%) of the optic nerve, 1/6 (17%) of the optic chiasm, 2/6 (33%) of the optic tract and 1/6 (17%) of the optic radiations. CONCLUSIONS: Our study showed that a substantial number of patients with severe COVID-19 presented with abnormal MRI findings of the orbit or visual pathways, which might lead to potentially severe visual impairment.

Inferior Colliculus's Hypermetabolism: A New Finding on Brain FDG PET and Perfusion MRI in a Patient With COVID-19.

ABSTRACT: We present the case of a 64-year-old man presenting an episode of confusion during SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection with a positive oropharyngeal swab polymerase chain reaction test. He was hospitalized for dyspnea related to pneumonia demonstrated on chest CT. FDG PET performed after the confusion phase, but still in the COVID-19 (coronavirus disease 2019)-positive phase, showed high glucose metabolism of the inferior colliculi. Morphological MRI was normal. The first-pass perfusion MRI shows hyperperfusion of the inferior colliculi, corresponding to FDG PET hypermetabolism.

Spontaneous infarction of lumbar roots, vertebrae and paravertebral muscles.

Ischemic injury to the lumbosacral nerve roots and plexus is a rare condition resulting from thrombosis of one or several lumbar arteries. As the arterial supply of the spine presents great variations between subjects, the clinical presentation of lumbar thrombosis is highly variable depending on the relative involvement of nerve roots, bones or muscles. Diagnosis can be challenging, especially in the acute phase, as different structures can be simultaneously involved. The identification of an enlarged vessel centered in the area of tissue damage can help with the final diagnosis. We present the case of a 59-year-old woman who presented with spontaneous incomplete cauda equina syndrome due to diffuse lumbar nerve root infarction. On imaging, acute lumbar artery thrombosis was confirmed, and in addition to nerve roots, adjacent vertebral and paraspinal muscle infarctions were also present.

Ocular MRI Findings in Patients with Severe COVID-19: A Retrospective Multicenter Observational Study.

Coronavirus disease 2019 (COVID-19) may affect various organs. This case series reports nine patients (one of nine [11%] women and eight of nine [89%] men; mean age ± standard deviation, 56 years ± 13) with globe MRI abnormalities obtained from a multicenter cohort of 129 patients presenting with severe COVID-19 from March 4, 2020, to May 1, 2020. Nine of 129 (7%) patients had one or several nodules of the posterior pole that were hyperintense at fluid-attenuated inversion-recovery imaging. All patients had nodules in the macular region, eight of nine (89%) had bilateral nodules, and two of nine (22%) had nodules outside the macular region. Screening of these patients might improve the management of potentially severe ophthalmologic manifestations of the virus. See also the editorial by Kirsch in this issue. © RSNA, 2021 Online supplemental material is available for this article.

Signal changes in enhanced T1-weighted images related to gadolinium retention: A three-time-point imaging study.

BACKGROUND AND PURPOSE: Concern has grown about the finding of gadolinium deposits in the brain after administering gadolinium-based contrast agents (GBCAs). The mechanism is unclear, and related questions remain unanswered, including the stability over time. Therefore, we conducted a three-time-point study to explore T1-weighted (W) signal changes in the dentate nucleus (DN) and globus pallidus (GP), after the first, fifth, and tenth injections of either a macrocyclic agent (gadoterate meglumine) or a linear agent (gadobenate dimeglumine). MATERIALS AND METHODS: For this retrospective, multicenter, longitudinal study, two groups of 18 (gadoterate meglumine) and 19 (gadobenate dimeglumine) patients were identified. The evolution of the signal over time was analyzed using DN/pons (DN/P) and GP/thalamus (GP/T) ratios. RESULTS: DN/P and GP/T ratios tended to increase after the fifth administration of gadobenate dimeglumine, following by a downward trend. A trend in a decrease in DN/P and GP/T ratios were found after the fifth and tenth administrations of gadoterate meglumine. CONCLUSION: After exposure to gadobenate dimeglumine, the signal intensity (SI) tended to increase after the fifth injection owing to gadolinium accumulation, however, a SI increase was not found after the tenth administration supporting the hypothesis of a slow elimination of the previously retained gadolinium (wash-out effect) from the brain or of a change in form (by dechelation), causing the signal to fade. No increasing SI was found in the DN and GP after exclusive exposure to gadoterate meglumine, thus confirming its stability. We found, instead, a trend for a significative gadolinium elimination over time.

Cerebrospinal Fluid Features in Patients With Coronavirus Disease 2019 and Neurological Manifestations: Correlation with Brain Magnetic Resonance Imaging Findings in 58 Patients.

BACKGROUND: Neurological manifestations are common in patients with coronavirus disease 2019 (COVID-19), but little is known about pathophysiological mechanisms. In this single-center study, we examined neurological manifestations in 58 patients, including cerebrospinal fluid (CSF) analysis and neuroimaging findings. METHODS: The study included 58 patients with COVID-19 and neurological manifestations in whom severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse-transcription polymerase chain reaction screening and on CSF analysis were performed. Clinical, laboratory, and brain magnetic resonance (MR) imaging data were retrospectively collected and analyzed. RESULTS: Patients were mostly men (66%), with a median age of 62 years. Encephalopathy was frequent (81%), followed by pyramidal dysfunction (16%), seizures (10%), and headaches (5%). CSF protein and albumin levels were increased in 38% and 23%, respectively. A total of 40% of patients displayed an elevated albumin quotient, suggesting impaired blood-brain barrier integrity. CSF-specific immunoglobulin G oligoclonal band was found in 5 patients (11%), suggesting an intrathecal synthesis of immunoglobulin G, and 26 patients (55%) presented identical oligoclonal bands in serum and CSF. Four patients (7%) had a positive CSF SARS-CoV-2 reverse-transcription polymerase chain reaction. Leptomeningeal enhancement was present on brain MR images in 20 patients (38%). CONCLUSIONS: Brain MR imaging abnormalities, especially leptomeningeal enhancement, and increased inflammatory markers in CSF are frequent in patients with neurological manifestations related to COVID-19, whereas SARS-CoV-2 detection in CSF remained scanty.

Cerebral vasculitis of medium-sized vessels as a possible mechanism of brain damage in COVID-19 patients.

BACKGROUND AND PURPOSE: Cerebral complications related to COVID-19 were recently reported, and the underlying mechanisms of brain damage remain uncertain, probably multifactorial. Among various hypotheses suggested, a possible vasculitis was issued but never confirmed. Herein, we aimed to describe brain MRIs focused on the intracranial vessel wall in a population of COVID-19 patients with neurologic manifestations. MATERIALS AND METHODS: Between March 1 and May 31, 2020, 69 consecutive COVID-19 patients with neurologic manifestations underwent a brain MRI allowing the study of the intracranial vessel wall at Strasbourg University hospitals and were retrospectively included. During the same period, 25 consecutive patients, without suspicion of SARS-CoV-2 infection, underwent a brain MRI urgently, with the same imaging protocols. A vasculitis seemed likely when imaging demonstrated vessel wall thickening with homogeneous and concentric enhancement. RESULTS: Among the 69 COVID-19 patients included, 11 (16%) presented arterial vessel wall thickening with homogeneous and concentric enhancement, compatible with cerebral vasculitis. These neuroimaging findings were not found among the 25 patients without SARS-CoV-2 infection, and the difference was statistically significant (p = 0.03). Middle cerebral arteries, basilar artery, and posterior cerebral arteries were the most frequent vessels involved. For nine of them, imaging demonstrated ischemic or hemorrhagic complications. CONCLUSION: Cerebral vasculitis of medium-sized vessels seems to be one of the mechanisms at the origin of brain damage related to COVID-19.

Critical illness-associated cerebral microbleeds for patients with severe COVID-19: etiologic hypotheses.

BACKGROUND AND PURPOSE: During the COVID-19 outbreak, the presence of extensive white matter microhemorrhages was detected by brain MRIs. The goal of this study was to investigate the origin of this atypical hemorrhagic complication. METHODS: Between March 17 and May 18, 2020, 80 patients with severe COVID-19 infections were admitted for acute respiratory distress syndrome to intensive care units at the University Hospitals of Strasbourg for whom a brain MRI for neurologic manifestations was performed. 19 patients (24%) with diffuse microhemorrhages were compared to 18 control patients with COVID-19 and normal brain MRI. RESULTS: The first hypothesis was hypoxemia. The latter seemed very likely since respiratory failure was longer and more pronounced in patients with microhemorrhages (prolonged endotracheal intubation (p = 0.0002), higher FiO2 (p = 0.03), increased use of extracorporeal membrane oxygenation (p = 0.04)). A relevant hypothesis, the role of microangiopathy, was also considered, since patients with microhemorrhages presented a higher increase of the D-Dimers (p = 0.01) and a tendency to more frequent thrombotic events (p = 0.12). Another hypothesis tested was the role of kidney failure, which was more severe in the group with diffuse microhemorrhages (higher creatinine level [median of 293 µmol/L versus 112 µmol/L, p = 0.04] and more dialysis were introduced in this group during ICU stay [12 versus 5 patients, p = 0.04]). CONCLUSIONS: Blood-brain barrier dysfunction secondary to hypoxemia and high concentration of uremic toxins seems to be the main mechanism leading to critical illness-associated cerebral microbleeds, and this complication remains to be frequently described in severe COVID-19 patients.