Autoimmune encephalitis: what the radiologist needs to know.

Autoimmune encephalitis is a relatively novel nosological entity characterized by an immune-mediated damage of the central nervous system. While originally described as a paraneoplastic inflammatory phenomenon affecting limbic structures, numerous instances of non-paraneoplastic pathogenesis, as well as extra-limbic involvement, have been characterized. Given the wide spectrum of insidious clinical presentations ranging from cognitive impairment to psychiatric symptoms or seizures, it is crucial to raise awareness about this disease category. In fact, an early diagnosis can be dramatically beneficial for the prognosis both to achieve an early therapeutic intervention and to detect a potential underlying malignancy. In this scenario, the radiologist can be the first to pose the hypothesis of autoimmune encephalitis and refer the patient to a comprehensive diagnostic work-up - including clinical, serological, and neurophysiological assessments.In this article, we illustrate the main radiological characteristics of autoimmune encephalitis and its subtypes, including the typical limbic presentation, the features of extra-limbic involvement, and also peculiar imaging findings. In addition, we review the most relevant alternative diagnoses that should be considered, ranging from other encephalitides to neoplasms, vascular conditions, and post-seizure alterations. Finally, we discuss the most appropriate imaging diagnostic work-up, also proposing a suggested MRI protocol.

The role of EEG and neuroimaging in the diagnosis of non-convulsive status epilepticus in Subacute Encephalopathy with Seizures in Alcoholics (SESA syndrome): a case report and overview of the literature.

Epileptic seizures are frequently associated with liver dysfunction and alcoholism. Subacute encephalopathy with seizures in chronic alcoholics (SESA) is an underrecognized condition with peculiar clinical, EEG and neuroradiological features.We report the case of a 58-year-old man with previous alcohol use disorder (AUD) and acute-on chronic liver failure on alcohol-related cirrhosis, referred for urgent Orthotopic Liver Transplantation evaluation. The patient presented with delirium, aphasia and progressive deterioration of consciousness leading to intensive care unit admission. EEG showed slow activity with superimposed lateralized periodic discharges (LPDs) over the left temporo-occipital regions and ictal discharges with focal motor phenomena, consistent with focal status epilepticus. Antiseizure treatment with lacosamide and levetiracetam was administered with progressive improvement of consciousness.Brain MRI disclosed T2/FLAIR areas of hyperintensity in the left pulvinar and T2/FLAIR hyperintensity with corresponding DWI hyperintensity in the left hippocampal cortex, suggestive of post/peri-ictal excitotoxic changes with anatomical correspondence to focal LPDs distribution. SWI demonstrated decreased prominence of cortical veins in the left temporo-occipital region consistent with increased venous blood oxygenation in compensatory hyperperfusion.In conclusion, SESA should be suspected in the differential diagnosis of patients with AUD presenting with focal neurological deficits, seizures and focal EEG abnormalities. In this context, EEG and brain MRI represent useful tools with both diagnostic and prognostic value.

Short-term mild hyperventilation on intracranial pressure, cerebral autoregulation, and oxygenation in acute brain injury patients: a prospective observational study.

Current guidelines suggest a target of partial pressure of carbon dioxide (PaCO2) of 32-35 mmHg (mild hypocapnia) as tier 2 for the management of intracranial hypertension. However, the effects of mild hyperventilation on cerebrovascular dynamics are not completely elucidated. The aim of this study is to evaluate the changes of intracranial pressure (ICP), cerebral autoregulation (measured through pressure reactivity index, PRx), and regional cerebral oxygenation (rSO2) parameters before and after induction of mild hyperventilation. Single center, observational study including patients with acute brain injury (ABI) admitted to the intensive care unit undergoing multimodal neuromonitoring and requiring titration of PaCO2 values to mild hypocapnia as tier 2 for the management of intracranial hypertension. Twenty-five patients were included in this study (40% female), median age 64.7 years (Interquartile Range, IQR = 45.9-73.2). Median Glasgow Coma Scale was 6 (IQR = 3-11). After mild hyperventilation, PaCO2 values decreased (from 42 (39-44) to 34 (32-34) mmHg, p < 0.0001), ICP and PRx significantly decreased (from 25.4 (24.1-26.4) to 17.5 (16-21.2) mmHg, p < 0.0001, and from 0.32 (0.1-0.52) to 0.12 (-0.03-0.23), p < 0.0001). rSO2 was statistically but not clinically significantly reduced (from 60% (56-64) to 59% (54-61), p < 0.0001), but the arterial component of rSO2 (ΔO2Hbi, changes in concentration of oxygenated hemoglobin of the total rSO2) decreased from 3.83 (3-6.2) µM.cm to 1.6 (0.5-3.1) µM.cm, p = 0.0001. Mild hyperventilation can reduce ICP and improve cerebral autoregulation, with minimal clinical effects on cerebral oxygenation. However, the arterial component of rSO2 was importantly reduced. Multimodal neuromonitoring is essential when titrating PaCO2 values for ICP management.

Mild behavioral impairment as a potential marker of predementia risk states in motor neuron diseases.

BACKGROUND AND PURPOSE: Mild behavioral impairment (MBI) has been increasingly regarded as the neurobehavioral axis of predementia risk states, but a specific investigation of its detection as a potential marker of prodromal dementia in motor neuron diseases (MNDs) is still lacking. The aims of our study were therefore to explore MBI in MNDs both at onset and over the disease course, and to evaluate its relationship with baseline and longitudinal cognitive features. METHODS: Sixty MND patients with cognitive/behavioral, mood, and motor examinations were recruited and followed longitudinally for up to 15 months. Associations between baseline MBI symptoms and clinical features were tested using the Spearman correlation coefficient. Based on longitudinal data, relative deltas of variation for each cognitive measure were generated, and linear regression models were then used to evaluate the role of baseline MBI symptoms in predicting longitudinal rates of cognitive decline. RESULTS: At disease onset, the most impaired MBI domain was affective/emotional dysregulation, followed by impulse dyscontrol, apathy, and social inappropriateness. Greater MBI symptoms correlated with more severe baseline motor, cognitive/behavioral, and mood disturbances (p values from <0.001 to 0.05). Longitudinally, the greatest decline was observed in the affective/emotional dysregulation domain, followed by impulse dyscontrol, apathy, and social inappropriateness. Greater MBI symptoms at onset were significant predictors of more severe longitudinal cognitive decline in both amyotrophic lateral sclerosis (ALS)-specific and ALS-nonspecific functions (p values from <0.001 to 0.03). CONCLUSIONS: MBI represents a valuable clinical marker of incident cognitive decline in MNDs, and its evaluation has good potential for detecting dementia in its preclinical/prodromal phase.

Intravenous immunoglobulin bridging to rituximab in NMDAR encephalitis patients non-responders to first-line treatments.

BACKGROUND: The immunotherapy strategy for autoimmune encephalitis is based on several types and schedules of both first- and second-line drugs. Failing to respond to the latter prompts the use of non-conventional rescue therapies, with higher risks of severe adverse effects. We report on a protocol that entails the use of intravenous immunoglobulin cycles to bridge the 4-month period that the second-line drug rituximab needs to exert its full therapeutic effects. METHODS: Three patients with NMDAR encephalitis who were non-responders to first-line treatments entered the study. The protocol consisted of six monthly cycles of intravenous immunoglobulins (IVIG, 0.4 mg/kg/die for 5 days), starting 1 month after the last rituximab infusion (1000 mg at days 0 and 15). Brain MRI and [18F]-FDG-PET were performed at onset and at six and 18 months after onset. RESULTS: In the three patients, substantial improvements of disability or complete recovery were achieved, without modifications over the 30-to-50-month follow-up. No adverse events nor laboratory test abnormalities were recorded. Imaging findings paralleled the favorable disease courses. Brain [18F]-FDG-PET was more sensitive than MRI in detecting abnormalities. DISCUSSION: Our observations suggest that the herein-described protocol might be used in patients with NMDAR encephalitis at risk for poor prognosis in the mid-term when they need to shift to rituximab. [18F]-FDG-PET confirmed to be a sensitive tool to detect the minimal brain lesions that can underlie isolated cognitive and psychiatric symptoms.

Calcified brain metastases may be more frequent than normally considered.

OBJECTIVES: To verify the incidence of calcified brain metastases (CBM), illustrating the different presentation patterns and histology of primary tumor. METHODS: A series of 1002 consecutive brain computed tomography (CT) scans of patients with known primary tumors was retrospectively assessed. CBM were defined by the presence of calcification within intra-axial-enhancing lesions; identification of CBM was based on visual examination and ROI analysis (> 85 Hounsfield units). Also, calcifications in the primary tumor of all patients with brain metastases were evaluated. In CBM patients, we investigated the type of calcifications (punctate, nodular, cluster, ring, coarse), the histology of primary tumor, and if a previous RT was performed. RESULTS: Among 190 (18.9%) patients with brain metastatic disease, 34 presented with CBM (17.9%). Sixteen patients were previously treated with RT, while 18 presented calcifications ab initio (9.5% of all brain metastases). The majority of patients with CBM had a primitive lung adenocarcinoma (56%), followed by breast ductal invasive carcinoma (20%) and small cell lung carcinoma (11.8%). CBM were single in 44.1% of patients and multiple in 55.9%. With regard to the type of calcifications, the majority of CBM were punctate, without specific correlations between calcification type and histology of primary tumor. No patients with ab initio CBM had calcifications in primary tumor. CONCLUSION: In conclusion, our data show that CBM are more common than usually thought, showing an incidence of 9.5% ab initio in patients with brain metastases. This study underlines that neuroradiologists should not overlook intraparenchymal brain calcifications, especially in oncologic patients. KEY POINTS: • Among the differential diagnosis of brain intraparenchymal calcifications, metastases are considered uncommon and found predominantly in patients treated with radiotherapy (RT). • Our data show that CBM are more common than usually thought, showing an incidence of 9.5% ab initio in patients with brain metastases. • A proportion of intraparenchymal brain calcifications, especially in oncologic patients, might represent evolving lesions and neuroradiologists should not overlook them to avoid a delay in diagnosis and treatment.

An eleven-year history of Vanishing White Matter Disease in an adult patient with no cognitive decline and EIF2B5 mutations. A case report.

Vanishing White Matter Disease (VWMD) is a rare autosomal recessive leukoencephalopathy . The classical presentation is characterized by a severe cerebellar ataxia, spasticity, neurological deterioration with a chronic progressive course and episodes of acute neurological deterioration after stress conditions.We report a 52-year-old man with VWMD and atypical features who manifested two major events of transient aphasia eleven years apart with complete recovery in 48 hours. No cognitive decline was present. Brain MRI revealed typical aspects of VWMD including diffuse leukoencephalopathy with relative sparing of U-fibers. We identified the presence of c.592G>A (p.Glu198Lys) and c.1360 C>T (p.Pro454Ser) mutations in EIF2B5.

Age at symptom onset influences cortical thinning distribution and survival in amyotrophic lateral sclerosis.

PURPOSE: The lifetime risk of developing amyotrophic lateral sclerosis (ALS) increases in the elderly, and greater age at symptom onset has been identified as a negative prognostic factor in the disease. However, the underlying neurobiological mechanisms are still poorly investigated. We hypothesized that older age at symptom onset would have been associated with greater extra-motor cortical damage contributing to worse prognosis, so we explored the relationship between age at symptom onset, cortical thinning (CT) distribution, and clinical markers of disease progression. METHODS: We included 26 ALS patients and 29 healthy controls with T1-weighted magnetic resonance imaging (MRI). FreeSurfer 6.0 was used to identify regions of cortical atrophy (CA) in ALS, and to relate age at symptom onset to CT distribution. Linear regression analyses were then used to investigate whether MRI metrics of age-related damage were predictive of clinical progression. MRI results were corrected using the Monte Carlo simulation method, and regression analyses were further corrected for disease duration. RESULTS: ALS patients exhibited significant CA mainly encompassing motor regions, but also involving the cuneus bilaterally and the right superior parietal cortex (p < 0.05). Older age at symptom onset was selectively associated with greater extra-motor (frontotemporal) CT, including pars opercularis bilaterally, left middle temporal, and parahippocampal cortices (p < 0.05), and CT of these regions was predictive of shorter survival (p = 0.004, p = 0.03). CONCLUSION: More severe frontotemporal CT contributes to shorter survival in older ALS patients. These findings have the potential to unravel the neurobiological mechanisms linking older age at symptom onset to worse prognosis in ALS.

Predictors of self-perceived health worsening over COVID-19 emergency in ALS.

INTRODUCTION: Factors influencing self-perceived health status over Corona Virus Disease 2019 (COVID-19) emergency in vulnerable populations, such as patients with chronic neurological diseases, are still unknown. In this work, we aimed at testing whether clinical care changes imposed by the quarantine, together with certain demographic and disease-specific features, might have determined a self-perceived worsening of health status in patients with amyotrophic lateral sclerosis (ALS). METHODS: A brief web-based questionnaire investigating self-perceived anxiety, depression, and motor worsening, as well as clinical care changes over COVID-19 emergency, was administered to ALS patients currently followed at San Martino Hospital. Ordinal and logistic regression analyses were applied to identify significant predictors of health status. RESULTS: Fifty-seven ALS patients completed the questionnaire. A total of 35.08% of cases reported anxiety symptoms, 36.84% depressive symptoms, and 35.08% reported worsening of motor symptoms. Significant predictors of anxiety symptoms severity included female gender, greater motor impairment, more aggressive disease course, and rehabilitation therapy suspension. The only significant predictor of depressive symptoms severity was a more aggressive disease course. Significant predictors of motor worsening were shorter disease duration and exams/visits cancelation. DISCUSSION: COVID-19 emergency and its management exerted a significant impact on self-perceived health status in patients with ALS, particularly in those cases in the earliest disease phases and with a more aggressive disease course. These findings have potential to improve personalized medicine strategies in the next phase.

Amygdalar nuclei and hippocampal subfields on MRI: Test-retest reliability of automated volumetry across different MRI sites and vendors.

BACKGROUND: The amygdala and the hippocampus are two limbic structures that play a critical role in cognition and behavior, however their manual segmentation and that of their smaller nuclei/subfields in multicenter datasets is time consuming and difficult due to the low contrast of standard MRI. Here, we assessed the reliability of the automated segmentation of amygdalar nuclei and hippocampal subfields across sites and vendors using FreeSurfer in two independent cohorts of older and younger healthy adults. METHODS: Sixty-five healthy older (cohort 1) and 68 younger subjects (cohort 2), from the PharmaCog and CoRR consortia, underwent repeated 3D-T1 MRI (interval 1-90 days). Segmentation was performed using FreeSurfer v6.0. Reliability was assessed using volume reproducibility error (ε) and spatial overlapping coefficient (DICE) between test and retest session. RESULTS: Significant MRI site and vendor effects (p â€‹< â€‹.05) were found in a few subfields/nuclei for the ε, while extensive effects were found for the DICE score of most subfields/nuclei. Reliability was strongly influenced by volume, as ε correlated negatively and DICE correlated positively with volume size of structures (absolute value of Spearman's r correlations >0.43, p â€‹< â€‹1.39E-36). In particular, volumes larger than 200 â€‹mm3 (for amygdalar nuclei) and 300 â€‹mm3 (for hippocampal subfields, except for molecular layer) had the best test-retest reproducibility (ε â€‹< â€‹5% and DICE â€‹> â€‹0.80). CONCLUSION: Our results support the use of volumetric measures of larger amygdalar nuclei and hippocampal subfields in multisite MRI studies. These measures could be useful for disease tracking and assessment of efficacy in drug trials.

Ecological impact of isolated cognitive relapses in MS.

Isolated cognitive relapses (ICRs) are transient deficits in cognitive performance that are the only presentation of a multiple sclerosis (MS) relapse. Here, we evaluated the impact of ICRs on cognitive difficulties in daily activities (assessed with the Multiple Sclerosis Neuropsychological Screening Questionnaire, Informant Version (MSNQ-I)) to characterize ICRs' clinical relevance. We used 2-year-long retrospective data to compare 15 relapsing-remitting MS (RRMS) patients with ICRs with 57 RRMS patients presenting an asymptomatic gadolinium enhancing lesion (and no-ICRs). ICRs were associated not only with neuropsychological performance decline but also with an increase in the daily cognitive difficulties. These findings support the ecological relevance of ICRs.

A clinically feasible 7-Tesla protocol for the identification of cortical lesions in Multiple Sclerosis.

OBJECTIVES: The aim of this study was to evaluate the capability of sequences acquired on a 7-T MRI scanner, within times and anatomical coverage appropriate for clinical studies, to identify cortical lesions (CLs) in patients with Multiple Sclerosis (MS). Furthermore, we aimed to confirm the clinical significance of CL, testing the correlations between gray matter (GM) lesions and clinical scores. METHODS: A 7-T MRI protocol included 3D-T1-weighted and T2*-weighted sequences. Images were evaluated independently by three readers of different experience, and the number of CLs was recorded. Between-rater concordance was assessed calculating the intraclass correlation coefficient (ICC). Lin's concordance correlation coefficient was used to compare CL detection between sequences, while partial correlations and multivariable regression models were used to study the relationship between CL and clinical data. RESULTS: Forty MS patients (M/F, 17/23; 44.7 ± 12.6 years) were enrolled in this study, and CLs were identified in 35/40 subjects (87.5%). CL detection rate on 3D-T1-weighted images was significantly correlated with the detection rate on T2*-weighted images (r = 0.99; p < 0.001), with high concordance between readers (ICC ≥ 0.995). CLs were significantly correlated with both motor and cognitive scores (all with p ≤ 0.04). CONCLUSIONS: CL can be identified over the whole brain at 7-T in MS using a 3D-T1-weighted volume, acquired in a clinically feasible time and with comparable performance to that achievable using the T2*-weighted sequence. Based on the central role of CL in the development of clinical disability, we suggest that 3D-T1-weighted volume may play a role in the evaluation of CL in MS undergoing MRI on ultra-high-field scanners. KEY POINTS: • Cortical lesions can be identified in a clinically feasible time with a 7-T protocol, which includes a 3D-T1-weighted volume. • Cortical lesions correlated significantly with both motor and cognitive disability in MS patients. • Given their correlation with clinical disability, evaluation of a cortical lesion on a 7-T clinical protocol could help in the management of MS patients.

Degree of microstructural changes within T1-SE versus T1-GE hypointense lesions in multiple sclerosis: relevance for the definition of "black holes".

OBJECTIVES: To retrospectively evaluate the different performances of T1-SE and T1-GE sequences in detecting hypointense lesions in multiple sclerosis (MS), to quantify the degree of microstructural damage within lesions and to correlate them with patient clinical status. METHODS: Sixty clinically isolated syndrome (CIS) and MS patients underwent brain magnetic resonance imaging (MRI) on 1.5-T and 3-T scanners. We identified T2 fluid-attenuated inversion recovery hyperintense lesions with no hypointense signal on T1-SE/T1-GE (a), hypointense lesions only on T1-GE (b), and hypointense lesions on both T1-SE and T1-GE sequences (c). We compared mean lesion number (LN) and volume (LV) identified on T1-SE and T1-GE sequences, correlating them with Expanded Disability Status Scale (EDSS); fractional anisotropy (FA) and mean diffusivity (MD) values inside each lesion type were extracted and normal-appearing white matter (NAWM). RESULTS: Thirty-five patients were female. Mean age was 39.2 (± 7.8); median EDSS was 3 (± 2). There were 23 CIS, 21 relapsing-remitting (RR), and 16 progressive MS. T1-GE and T1-SE LN and LV were significantly different (p < 0.001), both correlating with EDSS. Both FA and MD metrics resulted significantly different among the three lesion groups and NAWM (p < 0.001). FA and MD values extracted from (b) and (c) showed statistically significant differences (p < 0.001), while for (a) and (b), the differences were not significant (p = 0.31 for FA and p = 0.62 for MD). CONCLUSION: T1-SE hypointense lesions demonstrated a more pronounced degree of microstructural damage. T1-weighted sequence type must be more carefully evaluated in clinical and research settings. KEY POINTS: • T1-weighted spin-echo (T1-SE) images detect chronic hypointense lesions (so called black holes) associated with more severe microstructural changes. • In the last years, three-dimensional (3D) T1-weighted gradient-echo (T1-GE) sequences are often utilized in lieu of T1-SE acquisition, more so at 3 T or higher fields. • T1-weighted sequence type must be more carefully evaluated in clinical and research settings in the definition of "black holes" in MS, in order to avoid the overestimation of the effective severe tissue damage.

Brain microvascular occlusive disorder in COVID-19: a case report.

We describe the case of a COVID-19 patient with severely impaired consciousness after sedation hold, showing magnetic resonance imaging (MRI) findings of (i) acute bilateral supratentorial ischemic lesions involving the fronto-parietal white matter and the corpus callosum and (ii) multiple diffuse susceptibility weighted imaging (SWI) hypointense foci, infra and supratentorial, predominantly bithalamic, suggestive of microhemorrhage or alternatively microthrombi. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) RNA was detected in the cerebrospinal fluid. Our findings suggest the occurrence of vascular damage, predominantly involving microvessels. The underlying mechanisms, which include direct and indirect penetration of the virus to the central nervous system and systemic cardiorespiratory complications, are yet to be elucidated, and a direct correlation with SARS-CoV-2 infection remains uncertain.

Composite MRI measures and short-term disability in patients with clinically isolated syndrome suggestive of MS.

BACKGROUND: The use of composite magnetic resonance imaging (MRI) measures has been suggested to better explain disability in patients with multiple sclerosis (MS). However, little is known about the utility of composite scores at the earliest stages of the disease. OBJECTIVE: To investigate whether, in patients with clinically isolated syndrome (CIS), a composite MRI measure, rather than the single metrics, would explain conversion to MS and would better correlate with disability at baseline and at 1 year of follow-up. METHODS: Corticospinal tract (CST), corpus callosum (CC) and optic radiation (OR) volume, fractional anisotropy (FA), and mean diffusivity (MD) values were measured in 27 CIS patients and 24 healthy controls (HCs). Z-scores of FA, MD, and tract volume measures were calculated in patients, based on the corresponding measures obtained from HCs, and then combined in a composite score for each tract. Correlations between Z-scores at baseline and both the Expanded Disability Status Scale (EDSS) at baseline and at follow-up (FU-EDSS) were investigated. RESULTS: Only CST, CC, and OR composite scores as well as the CST volume were significantly associated with FU-EDSS ( p = 0.005, p = 0.007, p = 0.020, and p = 0.010, respectively). CONCLUSION: The combination of MRI measures rather than the individual metrics better captured the association between tissue damage in both the CC, OR and CST and short-term follow-up disability.

Free water elimination improves test-retest reproducibility of diffusion tensor imaging indices in the brain: A longitudinal multisite study of healthy elderly subjects.

Free water elimination (FWE) in brain diffusion MRI has been shown to improve tissue specificity in human white matter characterization both in health and in disease. Relative to the classical diffusion tensor imaging (DTI) model, FWE is also expected to increase sensitivity to microstructural changes in longitudinal studies. However, it is not clear if these two models differ in their test-retest reproducibility. This study compares a bi-tensor model for FWE with DTI by extending a previous longitudinal-reproducibility 3T multisite study (10 sites, 7 different scanner models) of 50 healthy elderly participants (55-80 years old) scanned in two sessions at least 1 week apart. We computed the reproducibility of commonly used DTI metrics (FA: fractional anisotropy, MD: mean diffusivity, RD: radial diffusivity, and AXD: axial diffusivity), derived either using a DTI model or a FWE model. The DTI metrics were evaluated over 48 white-matter regions of the JHU-ICBM-DTI-81 white-matter labels atlas, and reproducibility errors were assessed. We found that relative to the DTI model, FWE significantly reduced reproducibility errors in most areas tested. In particular, for the FA and MD metrics, there was an average reduction of approximately 1% in the reproducibility error. The reproducibility scores did not significantly differ across sites. This study shows that FWE improves sensitivity and is thus promising for clinical applications, with the potential to identify more subtle changes. The increased reproducibility allows for smaller sample size or shorter trials in studies evaluating biomarkers of disease progression or treatment effects. Hum Brain Mapp 38:12-26, 2017. © 2016 Wiley Periodicals, Inc.

Radiation dose to the operator during fluoroscopically guided spine procedures.

PURPOSE: Fluoroscopy is widely used to guide diagnostic and therapeutic spine procedures. The purpose of this study was to quantify radiation incident on the operator (operator Air Kerma) during a wide range of fluoroscopy-guided spine procedures and its correlation with the amount of radiation incident on the patient (Kerma Area Product-KAP). METHODS: We retrospectively included 57 consecutive fluoroscopically guided spine procedures. KAP [Gy cm2] and total fluoroscopy time were recorded for each procedure. An electronic dosimeter recorded the operator Air Kerma [µGy] for each procedure. Operator Air Kerma for each procedure, correlation between KAP and operator Air Kerma, and between KAP and fluoroscopy time was obtained. RESULTS: Operator Air Kerma was widely variable across procedures, with median value of 6.4 µGy per procedure. Median fluoroscopy time and median KAP per procedure were 2.6 min and 4.7 Gy cm2, respectively. There was correlation between operator Air Kerma and KAP (r 2 = 0.60), with a slope of 1.6 µGy Air Kerma per unit Gy cm2 KAP incident on the patient and between fluoroscopy time and KAP (r 2 = 0.63). CONCLUSION: Operator Air Kerma during individual fluoroscopy-guided spine procedures can be approximated from the commonly and readily available information of the total amount of radiation incident on the patient, measured as KAP.

Spinal cord arteriovenous shunts of the ventral (anterior) sulcus: anatomical, clinical, and therapeutic considerations.

INTRODUCTION: Ventral sulcus spinal cord arteriovenous shunts (SCAVS) are rare vascular lesions that are located outside the spinal cord, are exclusively vascularized by the anterior spinal axis, and drain exclusively through the anterior spinal vein. We report the anatomical, clinical, and neuro-radiological features of SCAVS managed by our team. METHODS: We conducted a retrospective study of patients with SCAVSs evaluated by the senior author of this report (GR) between 1981 and 2014. Data were collected by reviewing clinical notes and by a systematic analysis of spinal angiograms and MRI. RESULTS: Among 358 patients, we identified 8 patients (3 women) with ventral sulcus spinal cord arteriovenous shunts. Mean age was 30.5 years. Six patients presented with progressive neurological symptoms, and two with acute neurological symptoms related to hematomyelia. Three shunts were located in the cervical cord, four in the thoracic cord, and one at the conus medullaris; there were two nidus type A-V shunts (AVMs) and six fistula type A-V shunts (AVFs). Seven patients were treated by endovascular therapy with glue embolization. Embolization led to anatomical cure in 5 cases, and a significant reduction of shunt volume and flow of more than 75% in 2 cases. In none of the cases we observed permanent morbidity. CONCLUSIONS: AVS of the ventral sulcus of the spinal cord are rare. Recognition of these lesions and precise localization of the anatomical space in which they are located, may allow a better understanding of their pathophysiology and clinical manifestations and guide proper therapeutic decisions.

Longitudinal reproducibility of default-mode network connectivity in healthy elderly participants: A multicentric resting-state fMRI study.

To date, limited data are available regarding the inter-site consistency of test-retest reproducibility of functional connectivity measurements, in particular with regard to integrity of the Default Mode Network (DMN) in elderly participants. We implemented a harmonized resting-state fMRI protocol on 13 clinical scanners at 3.0T using vendor-provided sequences. Each site scanned a group of 5 healthy elderly participants twice, at least a week apart. We evaluated inter-site differences and test-retest reproducibility of both temporal signal-to-noise ratio (tSNR) and functional connectivity measurements derived from: i) seed-based analysis (SBA) with seed in the posterior cingulate cortex (PCC), ii) group independent component analysis (ICA) separately for each site (site ICA), and iii) consortium ICA, with group ICA across the whole consortium. Despite protocol harmonization, significant and quantitatively important inter-site differences remained in the tSNR of resting-state fMRI data; these were plausibly driven by hardware and pulse sequence differences across scanners which could not be harmonized. Nevertheless, the tSNR test-retest reproducibility in the consortium was high (ICC=0.81). The DMN was consistently extracted across all sites and analysis methods. While significant inter-site differences in connectivity scores were found, there were no differences in the associated test-retest error. Overall, ICA measurements were more reliable than PCC-SBA, with site ICA showing higher reproducibility than consortium ICA. Across the DMN nodes, the PCC yielded the most reliable measurements (≈4% test-retest error, ICC=0.85), the medial frontal cortex the least reliable (≈12%, ICC=0.82) and the lateral parietal cortices were in between (site ICA). Altogether these findings support usage of harmonized multisite studies of resting-state functional connectivity to characterize longitudinal effects in studies that assess disease progression and treatment response.

Resting-state functional connectivity and motor imagery brain activation.

Motor imagery (MI) relies on the mental simulation of an action without any overt motor execution (ME), and can facilitate motor learning and enhance the effect of rehabilitation in patients with neurological conditions. While functional magnetic resonance imaging (fMRI) during MI and ME reveals shared cortical representations, the role and functional relevance of the resting-state functional connectivity (RSFC) of brain regions involved in MI is yet unknown. Here, we performed resting-state fMRI followed by fMRI during ME and MI with the dominant hand. We used a behavioral chronometry test to measure ME and MI movement duration and compute an index of performance (IP). Then, we analyzed the voxel-matched correlation between the individual MI parameter estimates and seed-based RSFC maps in the MI network to measure the correspondence between RSFC and MI fMRI activation. We found that inter-individual differences in intrinsic connectivity in the MI network predicted several clusters of activation. Taken together, present findings provide first evidence that RSFC within the MI network is predictive of the activation of MI brain regions, including those associated with behavioral performance, thus suggesting a role for RSFC in obtaining a deeper understanding of neural substrates of MI and of MI ability. Hum Brain Mapp 37:3847-3857, 2016. © 2016 Wiley Periodicals, Inc.