Lesion Overlap Research Articles

Investigating the structure-function relationship of the corticomotor system early after stroke using machine learning

BackgroundMotor outcomes after stroke can be predicted using structural and functional biomarkers of the descending corticomotor pathway, typically measured using magnetic resonance imaging and transcranial magnetic stimulation, respectively. However, the precise structural determinants of intact corticomotor function are unknown. Identifying structure–function links in the corticomotor pathway could provide valuable insight into the mechanisms of post-stroke motor impairment. This study used supervised machine learning to classify upper limb motor evoked potential status using MRI metrics obtained early after stroke. MethodsRetrospective data from 91 patients (49 women, age 35–97 years) with moderate to severe upper limb weakness within a week after stroke were included in this study. Support vector machine classifiers were trained using metrics from T1- and diffusion-weighted MRI to classify motor evoked potential status, empirically measured using transcranial magnetic stimulation. ResultsSupport vector machine classification of motor evoked potential status was 81% accurate, with false positives more common than false negatives. Important structural MRI metrics included diffusion anisotropy asymmetry in the supplementary and pre-supplementary motor tracts, maximum cross-sectional lesion overlap in the sensorimotor tract and ventral premotor tract, and mean diffusivity asymmetry in the posterior limbs of the internal capsule. InterpretationsMRI measures of corticomotor structure are good but imperfect predictors of corticomotor function. Residual corticomotor function after stroke depends on both the extent of cross-sectional macrostructural tract damage and preservation of white-matter microstructural integrity. Analysing the corticomotor pathway using a multivariable MRI approach across multiple tracts may yield more information than univariate biomarker analyses.

Normal-appearing naming-related functional activation in incidentally discovered low-grade gliomas: a single institution study.

Incidentally discovered low-grade gliomas (iLGGs) represent a rare neurological condition, which is associated with a good clinical status and usually preserved - or borderline - cognitive functions; only recently, knowledge has increased on their development and clinical features. Better understanding these aspects is fundamental to set up the most appropriate clinical protocol. We used fMRI to conduct an exploratory investigation of the effects of iLGG growth on the brain and the potential occurrence of early rearrangement in the functional network associated with object naming. We compared this group of 13 patients with an iLGG in the left hemisphere (maximum lesion overlap in the left inferior frontal gyrus and median tumor volume 12 cm3) and with preserved naming skills with that of a healthy control group. No significant differences were observed in the functional activations between the two groups, but a cluster in the controls vs. patients contrast mainly located in the right lateral visual cortex. As this region is unspecific for object naming and no significant changes emerged when checking for covariates, we concluded that iLGG growth did not affect the functional network and plasticity-related reorganization did not occur yet. We attributed this finding to iLGG features, such as small tumor size at the diagnosis and lack or minimal infiltration. These findings are preliminary, and we recommend future investigation to replicate them and test generalizability to other functional networks. Understanding the potential functional effects of iLGG growth is fundamental for the choice of the most appropriate treatment.

Does automated breast ultrasound (ABUS) add to breast tomosynthesis (DBT) in assessment of lesions in dense breasts?

BackgroundAs mammography has its known limitations in dense breast, additional imaging is usually needed. We aimed to evaluate the role of automated breast ultrasound in addition to tomosynthesis in detection and diagnosis of breast lesions in dense breasts. Seventy patients with dense breasts subjected to full-field digital mammography (FFDM) including digital breast tomosynthesis (DBT) and automated breast ultrasound (ABUS). Both studies were evaluated by two experienced radiologists to assess breast composition, mass characterization, asymmetry, calcification, axillary lymphadenopathy, extent of disease (EOD), skin thickening, retraction, architectural distortion, and BIRADS classification. All breast masses were interpreted as above described and then correlated with final pathological diagnosis.ResultsStudy included 70 females presenting with different types of breast lesions. Eighty-two masses were detected: 53 benign (n = 53/82), 29 malignant (n = 29/82). Histopathology of the masses was reached by core biopsy (n = 30), FNAC (n = 14), and excisional biopsy (n = 11). The rest of the masses (n = 27/82) were confirmed by their characteristic sonographic appearances; 20 cases of multiple bilateral anechoic simple cysts, 7 typical fibroadenomas showed stationary course on follow-up. As regards the final BIRADS score given for both modalities, tomosynthesis showed accuracy of 93.1% in characterization of malignant masses with accuracy of 94.3% in benign masses, on the other hand automated ultrasound showed 100% accuracy in characterization of malignant masses with 98.1% accuracy in benign masses.ConclusionAdding ABUS to tomosynthesis has proven a valuable imaging tool for characterization of breast lesions in dense breasts both as screening and diagnostic tool. They proved to be more sensitive and specific than digital mammography alone in showing tissue overlap, tumor characterization, lesion margins, extent, and multiplicity of malignant lesions.

The anesthetic approach for endovascular recanalization therapy depends on the lesion site in acute ischemic stroke

PurposeEndovascular therapy (EVT) of large-vessel occlusion in acute ischemic stroke (AIS) may be performed in general anesthesia (GA) or conscious sedation (CS). We intended to determine the contribution of ischemic cerebral lesion sites on the physician’s decision between GA and CS using voxel-based lesion symptom mapping (VLSM).MethodsIn a prospective local database, we sought patients with documented AIS and EVT. Age, stroke severity, lesion volume, vigilance, and aphasia scores were compared between EVT patients with GA and CS. The ischemic lesions were analyzed on CT or MRI scans and transformed into stereotaxic space. We determined the lesion overlap and assessed whether GA or CS is associated with specific cerebral lesion sites using the voxel-wise Liebermeister test.ResultsOne hundred seventy-nine patients with AIS and EVT were included in the analysis. The VLSM analysis yielded associations between GA and ischemic lesions in the left hemispheric middle cerebral artery territory and posterior circulation areas. Stroke severity and lesion volume were significantly higher in the GA group. The prevalence of aphasia and aphasia severity was significantly higher and parameters of vigilance lower in the GA group.ConclusionsThe VLSM analysis showed associations between GA and ischemic lesions in the left hemispheric middle cerebral artery territory and posterior circulation areas including the thalamus that are known to cause neurologic deficits, such as aphasia or compromised vigilance, in AIS-patients with EVT. Our data suggest that higher disability, clinical impairment due to neurological deficits like aphasia, or reduced alertness of affected patients may influence the physician’s decision on using GA in EVT.

Prevalence of acute dizziness and vertigo in cortical stroke.

In posterior circulation stroke, vertigo can be a presenting feature. However, whether isolated hemispheric strokes present with vertigo is less clear, despite a few single case reports in the literature. Here, (a) the prevalence of vertigo/dizziness in acute stroke is explored and (b) the cortical distribution of the lesions in relation to both the known vestibular cortex and the evolution of the symptoms, are considered. Structured interviews were conducted in 173 consecutive unselected patients admitted to the hyperacute stroke unit at the University College London Hospitals. The interview was used to evaluate whether the patient was suffering from dizziness and/or vertigo before the onset of the stroke and at the time of the stroke (acute dizziness/vertigo), and the nature of these symptoms. In all, 53 patients had cortical infarcts, of which 21 patients reported acute dizziness. Out of these 21, five patients reported rotational vertigo. Seventeen of the total 53 patients had lesions in known vestibular cortical areas distributed within the insular and parietal opercular cortices. The prevalence of vertigo in acute cortical strokes was 9%, with no single locus of lesion overlap. There is growing evidence supporting a lateralized vestibular cortex, with speculation that cortical strokes affecting the right hemisphere are more likely to cause vestibular symptoms than left hemispheric strokes. A trend was observed for this association, with the right hemisphere affected in four of five patients who reported spinning vertigo at the onset of the stroke.

Dorsal vagal nucleus involvement relates to QTc-prolongation after acute medullary infarction.

Infarction of the medulla has been associated with prolongation of the QTc, severe arrhythmia, and sudden cardiac death, yet the precise anatomical substrate remains uncertain. We sought to determine the possible anatomical structures relating to QTc-prolongation in patients with acute medullary infarction. We included 12 subjects with acute ischemic medullary infarction on brain MRI, who presented within 4.5h from the last known well time, with a 90-day follow-up. For an unbiased lesion analysis, medullary infarcts were manually outlined on diffusion weighted MRI and co-registered with an anatomical atlas. Nine out of 12 had QTc-prolongation. Qualitative and semi-quantitative comparisons were made between infarct location and QTc-prolongation. Among patients with QTc-prolongation, the greatest degree of congruence of the infarct location was over the dorsal vagal nucleus (DVN, 8 out of 9). There was a significant correlation between the number of sections showing infarction of the DVN and presence of QTc-prolongation (r=.582, p=.047). Among patients without QTc-prolongation, the maximum lesion overlap included the medial aspect of the gigantocelluar reticular nucleus of the reticular formation. We found that the DVN is a key anatomical substrate related to QTc-prolongation. Further studies with more patients and high-resolution, volumetric MRI are needed to confirm our findings.

Characterizing subtypes and neural correlates of receptive aprosodia in acute right hemisphere stroke

IntroductionSpeakers naturally produce prosodic variations depending on their emotional state. Receptive prosody has several processing stages. We aimed to conduct lesion-symptom mapping to determine whether damage (core infarct or hypoperfusion) to specific brain areas was associated with receptive aprosodia or with impairment at different processing stages in individuals with acute right hemisphere stroke. We also aimed to determine whether different subtypes of receptive aprosodia exist that are characterized by distinctive behavioral performance patterns. MethodsTwenty patients with receptive aprosodia following right hemisphere ischemic stroke were enrolled within five days of stroke; clinical imaging was acquired. Participants completed tests of receptive emotional prosody, and tests of each stage of prosodic processing (Stage 1: acoustic analysis; Stage 2: analyzing abstract representations of acoustic characteristics that convey emotion; Stage 3: semantic processing). Emotional facial recognition was also assessed. LASSO regression was used to identify predictors of performance on each behavioral task. Predictors entered into each model included 14 right hemisphere regions, hypoperfusion in four vascular territories as measured using FLAIR hyperintense vessel ratings, lesion volume, age, and education. A k-medoid cluster analysis was used to identify different subtypes of receptive aprosodia based on performance on the behavioral tasks. ResultsImpaired receptive emotional prosody and impaired emotional facial expression recognition were both predicted by greater percent damage to the caudate. The k-medoid cluster analysis identified three different subtypes of aprosodia. One group was primarily impaired on Stage 1 processing and primarily had frontotemporal lesions. The second group had a domain-general emotion recognition impairment and maximal lesion overlap in subcortical areas. Finally, the third group was characterized by a Stage 2 processing deficit and had lesion overlap in posterior regions. ConclusionsSubcortical structures, particularly the caudate, play an important role in emotional prosody comprehension. Receptive aprosodia can result from impairments at different processing stages.

Factors associated with chemotherapy benefit in breast cancer patients with midrange Oncotype DX breast recurrence scores.

Chemotherapy for patients with hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative, node-negative breast cancer, and with midrange Oncotype DX breast recurrence scores (RS) still needs to be further individualized. To improve the treatment decision making, we aimed to develop a method that provides a single score based on multiple factors associated with chemotherapy benefit. We analyzed Surveillance, Epidemiology, and End Results registry data from 31,731 patients with hormone receptor-positive, HER2-negative, node-negative breast cancer and midrange RS characterized by sociodemographic (age and marital status) and clinicopathologic (tumor size, histologic grade, progesterone receptor status, broad histological classification, lesion laterality, and lesion overlap) features and stratified by RS ranges. For the entire sample and for each characteristic, overall survival was compared between patients who underwent chemotherapy and those who did not (or status unknown) within each RS stratum. There was no any association between chemotherapy and survival for patients with RS=11-15. However, for patients with RS=16-25, a chemotherapy benefit was associated with tumor size, histologic grade, progesterone receptor status, histological type, and lesion laterality. In addition, overlapping lesion of breast and married at diagnosis might provide additional predictive information of chemotherapy benefit when RS=21-25. A simple and effective algorithm was designed by combining these factors to output a novel and personalized chemotherapy benefit score to effectively identify patients with RS=16-25 who would most likely benefit from chemotherapy, which might facilitate improved treatment by providing individualized recommendations.

Virtual brain grafting: Enabling whole brain parcellation in the presence of large lesions

Brain atlases and templates are at the heart of neuroimaging analyses, for which they facilitate multimodal registration, enable group comparisons and provide anatomical reference. However, as atlas-based approaches rely on correspondence mapping between images they perform poorly in the presence of structural pathology. Whilst several strategies exist to overcome this problem, their performance is often dependent on the type, size and homogeneity of any lesions present. We therefore propose a new solution, referred to as Virtual Brain Grafting (VBG), which is a fully-automated, open-source workflow to reliably parcellate magnetic resonance imaging (MRI) datasets in the presence of a broad spectrum of focal brain pathologies, including large, bilateral, intra- and extra-axial, heterogeneous lesions with and without mass effect.The core of the VBG approach is the generation of a lesion-free T1-weighted image, which enables further image processing operations that would otherwise fail. Here we validated our solution based on Freesurfer recon-all parcellation in a group of 10 patients with heterogeneous gliomatous lesions, and a realistic synthetic cohort of glioma patients (n = 100) derived from healthy control data and patient data.We demonstrate that VBG outperforms a non-VBG approach assessed qualitatively by expert neuroradiologists and Mann-Whitney U tests to compare corresponding parcellations (real patients U(6,6) = 33, z = 2.738, P < .010, synthetic-patients U(48,48) = 2076, z = 7.336, P < .001). Results were also quantitatively evaluated by comparing mean dice scores from the synthetic-patients using one-way ANOVA (unilateral VBG = 0.894, bilateral VBG = 0.903, and non-VBG = 0.617, P < .001). Additionally, we used linear regression to show the influence of lesion volume, lesion overlap with, and distance from the Freesurfer volumes of interest, on labeling accuracy.VBG may benefit the neuroimaging community by enabling automated state-of-the-art MRI analyses in clinical populations using methods such as FreeSurfer, CAT12, SPM, Connectome Workbench, as well as structural and functional connectomics. To fully maximize its availability, VBG is provided as open software under a Mozilla 2.0 license (https://github.com/KUL-Radneuron/KUL_VBG).

Brain Magnetic Resonance Imaging Characteristics of Anti-Leucine-Rich Glioma-Inactivated 1 Encephalitis and Their Clinical Relevance: A Single-Center Study in China.

Objective: To characterize the magnetic resonance imaging (MRI) features of anti-leucine-rich glioma-inactivated 1 (LGI1) encephalitis and explore their clinical relevance.Methods: Patients with anti-LGI1 encephalitis who underwent MRI at our center were included in this study. Baseline and follow-up MRI characteristics were evaluated, and relationships between lesion location and clinical symptoms were analyzed. The extent of signal abnormalities within the lesion overlap region was measured and correlated with modified Rankin Scale scores and serum antibody titer.Results: Seventy-six patients were enrolled, of which 57 (75%) were classified as MR positive. Brain lesions were located in medial temporal lobe (MTL) (89%) and basal ganglia (BG) (28%). Hippocampus and amygdala were lesion hubs with more than 50% lesion overlap. BG lesions were found in 30% of patients with faciobrachial dystonic seizure (FBDS) and only 7% of patients without FBDS (p = 0.013). Meanwhile, MTL lesions were more commonly observed in patients with memory impairment (70 vs. 0%, p = 0.017). MRI features included hyperintensity and edema at baseline, as well as hypointensity and atrophy at follow-up. Correlations between signal intensity of lesion hubs (including hippocampus and amygdala) and modified Rankin Scale scores were found on T2 (r = 0.414, p < 0.001) and diffusion-weighted imaging (r = 0.456, p < 0.001).Conclusion: MTL and BG are two important structures affected by anti-LGI1 encephalitis, and they are associated with distinctive symptoms. Our study provided evidence from Chinese patients that BG lesions are more commonly observed in patients with FBDS, potentially suggesting BG localization. Furthermore, in addition to supporting diagnosis, MRI has the potential to quantify disease severity.

Neural mechanisms of foreign accent syndrome: Lesion and network analysis

BackgroundForeign accent syndrome (FAS) is a rare acquired speech disorder wherein an individual’s spoken accent is perceived as “foreign.” Most reported cases involve left frontal brain lesions, but it is known that various other lesions can also cause FAS. To determine whether heterogeneous FAS-causing lesions are localized to a common functional speech network rather than to a single anatomical site, we employed a recently validated image analysis technique known as “lesion network mapping.” MethodsWe identified 25 published cases of acquired neurogenic FAS without aphasia, and mapped each lesion volume onto a reference brain. We next identified the network of brain regions functionally connected to each FAS lesion using a connectome dataset from normative participants. Network maps were then overlapped to identify common network sites across the lesions. ResultsClassical lesion overlap analysis showed heterogeneity in lesion anatomical location, consistent with prior reports. However, at least 80% of lesions showed network overlap in the bilateral lower and middle portions of the precentral gyrus and in the medial frontal cortex. The left lower portion of the precentral gyrus is suggested to be the location of lesions causing apraxia of speech (AOS), and the middle portion is considered to be a larynx-specific motor area associated with the production of vowels and stop/nasal consonants and with the determination of pitch accent. ConclusionsThe lesions that cause FAS are anatomically heterogeneous, but they share a common functional network located in the bilateral posterior region of the frontal lobe. This network specifically includes not only the lower portion of the central gyrus, but also its middle region, which is referred to as the larynx motor cortex and is known to be associated with phonation. Our findings suggest that disrupted networks in FAS might be anatomically different from those in AOS.

Normal-appearing white matter structural integrity in incidentally discovered low-grade gliomas: a single institution study.

Incidentally discovered low-grade gliomas (iLGGs) are poorly reported in the literature and little is still known about their effects on white-matter structure. In this study, we investigated whether iLLG growth in either hemisphere could affect main white-matter association tracts and cortico-spinal tract. We retrospectively analyzed white-matter integrity in a group of 18 patients with iLGG having a mostly preserved cognitive status [1]. We identified two groups of patients, 13 having iLGG in left hemisphere (LH) and five in right hemisphere (RH) and maximum lesion overlap in inferior frontal gyrus and in medial frontal areas, respectively. A group of healthy controls (N.=20) was included. We carried out a univariate analysis of variance to inspect potential effect of interaction between hemisphere harboring the lesion (i.e., LH or RH) and hemisphere taken into account on number of streamlines and fractional anisotropy (FA) of reconstructed white-matter tracts. The sole significant interaction concerned left arcuate fasciculus, with patients with iLGG in LH having a lower number of streamlines than healthy controls; interaction involving FA was not significant for any of the fascicles. Lack of any other significant findings indicates overall preserved white matter. iLGG size and growth pattern could explain why white-matter status did not markedly differ with respect to the healthy controls. Findings therefore support evidence that iLGGs represent the earlier phase in natural history of LGGs and are discussed in a clinical perspective and in support to safe early surgery.

Reversible Cerebral Vasoconstriction Syndrome Combined with Posterior Encephalopathy Syndrome, and Transient Splenial Lesion after Delivery

The postpartum period is generally considered to be increased risk of various cerebral disorders, such as reversible cerebral vasoconstriction syndrome (RCVS), posterior reversible encephalopathy syndrome (PRES), and eclampsia. They manifest as an isolated syndrome or overlapped. Emergent diagnosis and appropriate treatment are mandatory because of the risk of permanent cerebral damage. Here, we report a case presenting with the overlap of RCVS, PRES, and transient splenial lesion of corpus callosum after delivery.

Identification of neural networks preferentially engaged by epileptogenic mass lesions through lesion network mapping analysis

Lesion network mapping (LNM) has been applied to true lesions (e.g., cerebrovascular lesions in stroke) to identify functionally connected brain networks. No previous studies have utilized LNM for analysis of intra-axial mass lesions. Here, we implemented LNM for identification of potentially vulnerable epileptogenic networks in mass lesions causing medically-refractory epilepsy (MRE). Intra-axial brain lesions were manually segmented in patients with MRE seen at our institution (EL_INST). These lesions were then normalized to standard space and used as seeds in a high-resolution normative resting state functional magnetic resonance imaging template. The resulting connectivity maps were first thresholded (pBonferroni_cor < 0.05) and binarized; the thresholded binarized connectivity maps were subsequently summed to produce overall group connectivity maps, which were compared with established resting-state networks to identify potential networks prone to epileptogenicity. To validate our data, this approach was also applied to an external dataset of epileptogenic lesions identified from the literature (EL_LIT). As an additional exploratory analysis, we also segmented and computed the connectivity of institutional non-epileptogenic lesions (NEL_INST), calculating voxel-wise odds ratios (VORs) to identify voxels more likely to be functionally-connected with EL_INST versus NEL_INST. To ensure connectivity results were not driven by anatomical overlap, the extent of lesion overlap between EL_INST, and EL_LIT and NEL_INST was assessed using the Dice Similarity Coefficient (DSC, lower index ~ less overlap). Twenty-eight patients from our institution were included (EL_INST: 17 patients, 17 lesions, 10 low-grade glioma, 3 cavernoma, 4 focal cortical dysplasia; NEL_INST: 11 patients, 33 lesions, all brain metastases). An additional 23 cases (25 lesions) with similar characteristics to the EL_INST data were identified from the literature (EL_LIT). Despite minimal anatomical overlap of lesions, both EL_INST and EL_LIT showed greatest functional connectivity overlap with structures in the Default Mode Network, Frontoparietal Network, Ventral Attention Network, and the Limbic Network—with percentage volume overlap of 19.5%, 19.1%, 19.1%, and 12.5%, respectively—suggesting them as networks consistently engaged by epileptogenic mass lesions. Our exploratory analysis moreover showed that the mesial frontal lobes, parahippocampal gyrus, and lateral temporal neocortex were at least twice as likely to be functionally connected with the EL_INST compared to the NEL_INST group (i.e. Peak VOR > 2.0); canonical resting-state networks preferentially engaged by EL_INSTs were the Limbic and the Frontoparietal Networks (Mean VOR > 1.5). In this proof of concept study, we demonstrate the feasibility of LNM for intra-axial mass lesions by showing that ELs have discrete functional connections and may preferentially engage in discrete resting-state networks. Thus, the underlying normative neural circuitry may, in part, explain the propensity of particular lesions toward the development of MRE. If prospectively validated, this has ramifications for patient counseling along with both approach and timing of surgery for lesions in locations prone to development of MRE.

652The effect of varying irrigation flow rate during irrigated radiofrequency ablation on optimising lesion shape

Abstract Funding Acknowledgements Investigator Sponsored Research grant from Boston Scientific Introduction Irrigated catheters are the standard tool for radiofrequency (RF) ablation in the left atrium and ventricles. However, pathological studies of irrigated RF lesions show a "tear-drop" shape, with the widest diameter some depth below the endocardial surface and relative endocardial sparing. This requires overlap of lesions to achieve contiguity at the endocardial surface. There has been little investigation into the effect of altering irrigation rate on lesion shape and volume. Purpose To test the hypothesis that varying the irrigation flow rate would optimise lesion shape by minimising endocardial sparing while maintaining lesion depth. Methods In an ex vivo animal heart model, irrigated ablation lesions were performed in porcine ventricular tissue at 30W using an Intellatip MiFi OI catheter with 5 different irrigation protocols: A. fixed rate (30ml/min); B. continuous reduction (30 to 2ml/min over 30s); C. continuous increase (2 to 30ml/min over 30s); D. stepwise reduction (30ml/min (10s) to 16ml/min (10s) to 2ml/min (10s)); E. stepwise increase (2ml/min (10s) to 16ml/min (10s) to 30ml/min (10s). Contact force (10g) and ablation duration (30s) were constant. Steam pops during ablation were recorded. Tissue sections were stained with triphenyltetrazolium chloride (TTC) after ablation to allow accurate measurement of lesion boundaries. Surface diameter, lesion depth, maximum diameter, and depth at maximum diameter were measured using Vernier Calipers to calculate lesion volume. Pictures of lesions were analysed further by ImageJ software to measure the degree of endocardial sparing. The optimal protocol was further tested against fixed-rate irrigation at 20W – 40W. Results 10-20 lesions were performed for each irrigation protocol. Of the 4 experimental protocols, continuous reduction (protocol B) resulted in the most optimal lesion shape (Figure). With this protocol, endocardial sparing area was significantly reduced compared to fixed-rate irrigation (1.61 vs. 2.64mm2, P &amp;lt; 0.0001), with a trend towards an increase in surface diameter (9.25 vs. 8.46mm, P = 0.08). There was no significant difference in lesion depth (5.35 vs. 4.77mm), lesion volume (374 vs. 332mm3) or maximum diameter (10.3 vs. 10.8mm). Steam pop occurred in 1 of 20 (5%) lesions in each of protocols A and B. Significantly reduced endocardial sparing with preserved volume/depth was consistent for continuous reduction when compared to fixed-rate irrigation across power settings of 20W (17ml/min), 30 W (17ml/min or 30ml/min) and 40W (30ml/min) (P &amp;lt; 0.0001). Conclusions Continuous reduction in irrigation flow rate from 30 to 2ml/min during irrigated RF ablation results in reduced endocardial sparing with preserved lesion depth and volume when compared to fixed-rate irrigation across power settings of 20 – 40W. This may allow for greater lesion spacing while maintaining endocardial contiguity and merits further investigation to improve irrigated RF ablation efficiency. Abstract Figure

Resting State Functional Connectivity Is Associated With Motor Pathway Integrity and Upper-Limb Behavior in Chronic Stroke

Background. Resting state functional connectivity (RSFC) is a developmental priority for stroke recovery. Objective. To determine whether (1) RSFC differs between stroke survivors based on integrity of descending motor pathways; (2) RSFC is associated with upper-limb behavior in chronic stroke; and (3) the relationship between interhemispheric RSFC and upper-limb behavior differs based on descending motor pathway integrity. Methods. A total of 36 people with stroke (aged 64.4 ± 11.1 years, time since stroke 4.0 ± 2.8 years) and 25 healthy adults (aged 67.3 ± 6.7 years) participated in this study. RSFC was estimated from electroencephalography (EEG) recordings. Integrity of descending motor pathways was ascertained using transcranial magnetic stimulation to determine motor-evoked potential (MEP) status and magnetic resonance imaging to determine lesion overlap and fractional anisotropy of the corticospinal tract (CST). For stroke participants, upper-limb motor behavior was assessed using the Fugl-Meyer test, Action Research Arm Test and grip strength. Results. β-Frequency interhemispheric sensorimotor RSFC was greater for MEP+ stroke participants compared with MEP− (P = .020). There was a significant positive correlation between β RSFC and upper-limb behavior (P = .004) that appeared to be primarily driven by the MEP+ group. A hierarchical regression identified that the addition of β RSFC to measures of CST integrity explained greater variance in upper-limb behavior (R2 change = 0.13; P = .01). Conclusions. This study provides insight to understand the role of EEG-based measures of interhemispheric network activity in chronic stroke. Resting state interhemispheric connectivity was positively associated with upper-limb behavior for stroke survivors where residual integrity of descending motor pathways was maintained.

The diagnostic value of MR spectroscopy versus DWI-MRI in therapeutic planning of suspicious multi-centric cerebral lesions

BackgroundA broad spectrum of non-neoplastic lesions can radiologically mimic cerebral neoplasms. Magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), and diffusion-weighted imaging (DWI) are the most extensively used for enabling lesional characterization of different brain disorders. We aimed to assess the diagnostic value of MRS versus DWI in the diagnosis and therapeutic planning of multicentric cerebral focal lesions and in our retrospective study, we enrolled 64 patients with 100 brain lesions who underwent pre- and post-contrast MRI, MRS, and DWI. Diagnoses supplied by the histopathology and follow up clinical results as a gold standard. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy were calculated.ResultsConventional MRI poorly differentiates multiple cerebral lesions with 89.33% sensitivity, 44.4% specificity, and 78% accuracy. MRS results revealed statistical significance for differentiating neoplastic from non-neoplastic lesions as regards Cho/Cr, Cho/NAA, and NAA/Cr ratios (M ± SD) with P < 0.001 (significant), and there is statistical significance for neoplastic lesion differentiation when Cho/NAA and Ch/Cr ratios measured in the pre-lesional areas outside the tumor margin. DWI showed mixed diffusion changes in most of the studied lesions and the measured ADC values ranges showed overlap in neoplastic and non-neoplastic lesions, P value = 0.236* (insignificant).ConclusionMRS was found to be a more accurate diagnostic tool than DWI with ADC measurements in the differentiation and therapeutic planning of multicentric cerebral focal lesions.

Structural integrity of white matter tracts as a predictor of acute ischemic stroke outcome.

Clinical assessment scores in acute ischemic stroke are only moderately correlated with lesion volume since lesion location is an important confounding factor. Many studies have investigated gray matter indicators of stroke severity, but the understanding of white matter tract involvement is limited in the early phase after stroke. This study aimed to measure and model the involvement of white matter tracts with respect to 24-h post-stroke National Institutes of Health Stroke Scale (NIHSS). A total of 96 patients (50 females, mean age 66.4 ± 14.0 years, median NIHSS 5, interquartile range: 2-9.5) with follow-up fluid-attenuated inversion recovery magnetic resonance imaging data sets acquired one to seven days after acute ischemic stroke onset due to proximal anterior circulation occlusion were included. Lesions were semi-automatically segmented and non-linearly registered to a common reference atlas. The lesion overlap and tract integrity were determined for each white matter tract in the AALCAT atlas and used to model NIHSS outcomes using a supervised linear-kernel support vector regression method, which was evaluated using leave-one-patient-out cross validation. The support vector regression model using the tract integrity and tract lesion overlap measurements predicted the 24-h NIHSS score with a high correlation value of r = 0.7. Using the tract overlap and tract integrity feature improved the modeling accuracy of NIHSS significantly by 6% (p < 0.05) compared to using overlap measures only. White matter tract integrity and lesion load are important predictors for clinical outcome after an acute ischemic stroke as measured by the NIHSS and should be integrated for predictive modeling.

Multiple Lesions Detection of Fundus Images Based on Convolution Neural Network Algorithm With Improved SFLA

In order to effectively solve the problem of interlaced overlap in the fundus image lesions, large and small blood vessels packed densely and severely affected by light, and to achieve multi-label classification of fundus images. In this paper, a single population leapfrog optimization convolutional neural network algorithm (SFCNN) is proposed to detect and classify various fundus lesions. The algorithm uses the efficient search ability of the shuffled frog leaping algorithm to optimize the weight initialization and back propagation of the convolutional neural network. In order to deal with the problem of fundus image classification in the big data environment, the novel grouping optimization strategy is presented to effectively combine Spark platform and SFCNN algorithm to achieve large-scale fundus image classification and detection of multiple lesions. The experiment of the detection of fundus image lesions shows that the accuracy rate of SFCNN is better improved in both single lesion detection and overall detection, compared with other algorithms.

An Analysis of Clinical Outcome and Tractography following Bilateral Anterior Capsulotomy for Depression

Introduction: Bilateral anterior capsulotomy (BAC) is an effective surgical procedure for patients with treatment-resistant major depression (TRMD). In this work, we analyze the connectivity of the BAC lesions to identify connectivity “fingerprints” associated with clinical outcomes in patients with TRMD. Methods: We performed a retrospective study of ten patients following BAC surgery. These patients were divided into “responders” and “non-responders” based on the relative change in the Beck depression inventory (BDI) score after surgery. We generated the dorsolateral prefrontal associative (DLPFC) pathways and the ventromedial prefrontal limbic (vmPFC) pathways going through the anterior limb of the internal capsule and analyzed if the overlap of the BAC lesions with these pathways was associated with either outcome. Finally, we used the BAC lesions of our patients to generate group-averaged connectivity “fingerprints” associated with either outcome. Results: Six patients were responders (≥50% improvement in BDI), four patients were non-responders (<50% improvement). No significant impairments were found in most neuropsychological tests after surgery. The overlap analysis showed that in the responder group, there was less involvement of the DLPFC pathways than the vmPFC pathways (p = 0.001). Conversely, in the non-responder group, there was no significant difference between the involvement of both pathways (p = 0.157). The responder and non-responder connectivity fingerprint showed significant connections with the vmPFC limbic areas. However, the non-responder connectivity fingerprint also showed stronger connectivity to associative areas including the DLPFC and lateral orbitofrontal cortices. Conclusions: The optimum outcome following BAC surgery in this cohort was associated with interruption of vmPFC pathways and the relative preservation of DLPFC pathways.