Diagnostic accuracy of double inversion recovery (DIR) in detection of cortical gray matter lesions in patients with MS

Background Conventional imaging techniques have a low sensitivity for detection of cortical and deep grey matter lesions in MS which hinder accurate assessment of the total lesion burden. Aim of this work was to assess the diagnostic accuracy of double inversion recovery (DIR) sequence in the detection of cortical grey matter lesions in MS patients. Results Forty MS patients were prospectively included in this study. Imaging was performed using Philips Ingenia 1.5 T device. The sensitivity, specificity, PPV, NPV and accuracy of DIR sequence in detection of cortical grey matter lesions were 60%, 100%, 100%, 55.6% and 73.3%, respectively. The sensitivity, specificity, positive and negative predictive values as well as accuracy of Flair sequence were 50%, 100%, 100%, 50% and 66.7%, respectively. The sensitivity, specificity, positive and negative predictive values as well as accuracy of T2 sequence in the detection of cortical grey matter lesions were 22.5%, 100%, 100%, 39.2% and 48.3%, respectively. Conclusions Detection rate of cortical gray matter lesions was significantly higher on DIR sequence than on T2 and Flair sequences.

Neuroanatomical Moderators of the Impact of Mild Behavioral Impairment on Cognition

Older adults with mild behavioral impairment (MBI), or the presence of late-life neuropsychiatric symptoms, have a unique cognitive phenotype. However, the neural correlates associated with MBI-related cognitive changes is not well understood. The goal of this study is to examine if specific regions of the brain moderate the relationship between the presence of MBI and performance on tasks of cognition. Data from the National Alzheimer’s Coordinating Center was utilized for this study. Participants (N=1,451) were included in our analyses if they were cognitively healthy or had mild cognitive impairment (MCI). Multiple domains of cognitive performance were evaluated. The neuroanatomical regions included hippocampus, caudal anterior cingulate (ACC), rostral ACC, entorhinal, and parahippocampal gray matter volume; and caudal ACC, rostral ACC, entorhinal, and parahippocampal mean cortical thickness. Hippocampal, entorhinal, and parahippocampal cortical gray matter volume moderated the relationship between MBI and performance on tasks of episodic memory. Left rostral ACC cortical gray matter volume and entorhinal and parahippocampal mean cortical thickness moderated the relationship between MBI and performance on language tasks. Hippocampi cortical gray matter volume also moderated the relationship between MBI and performance on processing speed tasks. Persons with smaller brain sizes in these areas were more negatively affected in these cognitive domains if they had MBI. These results suggest that the association between smaller brain volumes and cognition was stronger among persons with MBI. These findings suggest that older adults with MBI may perform worse on these tasks due to neurodegeneration that is present.

Aberrant modularity and lower resiliency of structural covariance network in first-episode antipsychotic-naive psychoses

Objective: Structural brain alterations are consistently observed in schizophrenia. However, divergent findings suggest that often-observed regions exist within a network of susceptible regions. We conducted structural covariance analysis of multiple morphometric features of 358 regions from 79 first-episode anti-psychotic-naive psychosis patients (FEAP) and 68 healthy controls to investigate network differences. Methods: Using graph theoretic methods, we investigated structural covariance network of Freesurfer-derived cortical gray matter volumes, thickness, curvature, and surface area using the Brain Connectivity Toolbox within MATLAB, compared network modularity using the Community Detection Toolbox within MATLAB, and examined the resilience of the network using simulated attacks. Results: FEAP showed decreased heterogeneity of cortical volumes compared to controls which was driven by decreased heterogeneity of cortical thickness but not surface area. Reduced morphological heterogeneity was associated with less differentiated community structure in FEAP compared to controls. FEAP patients, in general, showed less resilient networks that were more vulnerable to attacks on fewer nodes compared to healthy subjects. Conclusions: Our findings of decreased heterogeneity may be associated with FEAP-related pathology since the impact of illness chronicity and treatment are minimized. Contribution of cortical thickness but not surface area covariance network suggests that neurodevelopmental processes affecting the thickness rather than the surface area may be pathophysiologically more significant.

Increased Sodium Concentration in Substantia Nigra in Early Parkinson's Disease: A Preliminary Study With Ultra-High Field (7T) MRI

Pathophysiology of idiopathic Parkinson's disease (iPD) is complex and still misunderstood. At a time when treatments with disease-modifying potential are being developed, identification of early markers of neurodegeneration is essential. Intracerebral sodium accumulation could be one of them. Indeed, it may be in relation to the mitochondrial dysfunction that early exists in iPD. For the first time, we used brain sodium (23Na) MRI to explore sodium concentration changes that have already been reported to be related to neurodegeneration in other diseases. We prospectively included 10 iPD patients (mean age 52.2 ± 5.9 years-old) with motor symptoms that started <36 months before inclusion and 12 healthy subjects (mean age 53 ± 6.4 years-old). Patients were scanned in OFF medication state by using proton (1H) and 23Na MRI at 7T. We then extracted quantitative Total Sodium Concentration (TSC) from five regions of interest known to be early impaired in iPD [substantia nigra (SN), putamen, caudate nucleus, pallidum, thalamus] and in one region supposed to be relatively spared in the first stages of the disease [cortical gray matter (neocortex)]. Potential atrophy in these structures was also investigated with 1H MRI. Relative to healthy subjects, iPD patients showed higher TSC in the SN (43.73 ± 4.64 vs. 37.72 ± 5.62, p = 0.006 after Bonferroni correction). A trend of increase in sodium concentrations was found within the pallidum (45.80 ± 4.19 vs. 41.07 ± 4.94, p = 0.017), putamen (48.65 ± 4.58 vs. 43.66 ± 5.04, p = 0.041) and the cortical gray matter (56.34 ± 3.92 vs. 50.81 ± 5.50, p = 0.021). No significant brain atrophy was found in patients compared to controls. Thus, alteration of sodium homeostasis in the SN in the absence of atrophy could be considered as a potential early marker of cellular dysfunction in iPD.

Effects of Thresholding on Voxel-Wise Correspondence of Breath-Hold and Resting-State Maps of Cerebrovascular Reactivity

Functional magnetic resonance imaging for presurgical brain mapping enables neurosurgeons to identify viable tissue near a site of operable pathology which might be at risk of surgery-induced damage. However, focal brain pathology (e.g., tumors) may selectively disrupt neurovascular coupling while leaving the underlying neurons functionally intact. Such neurovascular uncoupling can result in false negatives on brain activation maps thereby compromising their use for surgical planning. One way to detect potential neurovascular uncoupling is to map cerebrovascular reactivity using either an active breath-hold challenge or a passive resting-state scan. The equivalence of these two methods has yet to be fully established, especially at a voxel level of resolution. To quantitatively compare breath-hold and resting-state maps of cerebrovascular reactivity, we first identified threshold settings that optimized coverage of gray matter while minimizing false responses in white matter. When so optimized, the resting-state metric had moderately better gray matter coverage and specificity. We then assessed the spatial correspondence between the two metrics within cortical gray matter, again, across a wide range of thresholds. Optimal spatial correspondence was strongly dependent on threshold settings which if improperly set tended to produce statistically biased maps. When optimized, the two CVR maps did have moderately good correspondence with each other (mean accuracy of 73.6%). Our results show that while the breath-hold and resting-state maps may appear qualitatively similar they are not quantitatively identical at a voxel level of resolution.

Raphe Nuclei Echogenicity and Diameter of Third Ventricle in Schizophrenia Measured by Transcranial Sonography

Introduction: Serotonergic system hyperactivity at 5-HT2A receptors on glutamate neurons in the cerebral cortex is one of the pathways that is theoretically linked to psychosis. In addition to neurotransmitter dysfunction, volumetric studies revealed loss of cortical gray matter and ventricular enlargement in patients with schizophrenia, although there is no case-control research on patients with schizophrenia in order to evaluate echogenicity of RN or DTV. To address these issues, the present study assessed midbrain raphe nuclei (RN) as the main source of brain serotonin and diameter of third ventricle (DTV) as an index of atrophy by transcranial sonography (TCS) in a group of patients with schizophrenia. Methods: 30 patients with schizophrenia and 30 controls were assessed by TCS for RN echogenicity and DTV. TCS was done through temporal bone window via a phased-array ultrasound using 2.5 MHz transducer in depth of 14-16 cm. RN echogenicity assessed by a semi-quantitative visual scale and DTV was measured in thalamic plane. Results: 23 patients (76.5%) and 15 (50 %) controls showed hypoechogenicity of RN which was marginally significant (p=0.06). DTV was in average larger in the patient’s group (0.388 cm vs 0.234 cm, p<0.001). Conclusion: Increased DTV in the patients with schizophrenia is consistent with previous neuroimaging findings. However, marginally lower echogenicity of midbrain RN on TCS in schizophrenia is a new finding that supports the serotonin hypothesis of schizophrenia.

Evaluation of Early Cerebral Atrophy in Mild Cognitive Impairment with Positive Amyloid PET using MRIVolumetric Measurement

Objective: To identify early cerebral atrophy by using magnetic resonance imaging (MRI) volumetric measurement to distinguish mild cognitive impairment (MCI) from normal aging. Materials and Methods: A retrospective study in 29 Alzheimer’s disease (AD) patients (mean 75.6±7.3 years), 11 MCI patients (mean 68.8±3.9 years), and 27 healthy control (HC) subjects (mean 69.3±4.7 years) was performed with analysis of neurological and neuropsychiatric test, and underwent 3T MRI with high-resolution 3D-T1W. Quantitative volumetric analysis of brain including surface area, cortical gray matter volume, cortical thickness, and hippocampal subfields was performed by using FreeSurfer software. Results: The diminishment of cortical gray matter volume and cortical thickness were involved in most of brain regions, predominantly in temporal lobe with statistical significance in AD compared with MCI and HC. Comparison between amyloid positron emission tomography (PET) positive MCI subjects and HC has statistically significant difference in most regions of hippocampal subfield. The highest accuracy of 90.01% with sensitivity of 50% and specificity of 100% were found at subiculum. A comparison between amyloid PET positive MCI subjects and amyloid PET negative MCI subjects revealed significant differences at right molecular layer, right/average GC-ML-DG, right CA2/3, right CA4, and average CA4 with good accuracy, sensitivity, and specificity. Conclusion: The present study confirmed improved sensitivity of MRI volumetric measurement with hippocampal subfield analysis to identify early stage of AD in MCI patients, at least compared with positive amyloid PET MCI. Study with higher number of subjects using this method to discriminate MCI and normal aging control would provide benefits as the screening tool in older population. Keywords: Hippocampal subfield; Volumetric analysis; Alzheimer’s disease; Mild cognitive impairment

https://www.immunologyresearchjournal.com/articles/association-of-lupus-anticoagulant-with-brain-atrophy-in-gulf-war-illness-gwi.html

Separate lines of research have documented brain atrophy and evidence of autoimmune mechanisms in Gulf War Illness (GWI), including the presence of lupus anticoagulant (LAC), in veterans with GWI. Here we evaluated the possible association of LAC and brain volume in veterans with GWI. The presence of LAC was determined using Silica Clotting Time and dilute Russell’s Viper Venom Time assays. MRI data was acquired using a Philips 3T MR scanner from which total gray matter, total cortical gray matter, total subcortical gray matter, and total cerebral white matter were derived. The results demonstrated a statistically significant reduction of brain volume in all regions tested in GWI veterans with positive LAC, as compared to those without LAC. These findings add to the literature implicating autoimmune mechanisms in GWI and point to the presence of prothrombotic antiphospholipid antibodies as contributing to brain atrophy in GWI.