The objective of this study was to investigate the contrast-to-noise ratio (CNR) between cortical gray matter (GM) and subcortical white matter (WM) across the cortex in relation to the ability of ...3-dimensional fluid attenuated inversion recovery and 3-dimensional double inversion recovery to distinguish between cortical lesions (CLs) and juxtacortical lesions (JCs).
A total of 38 multiple sclerosis patients underwent magnetic resonance imaging. Two neuroradiologists scored CLs and JCs on magnetic resonance imaging in 9 cerebral areas. Lesions were marked as nonclassifiable (NCs) when blurred WM-GM boundary leads to inaccuracy of their discrimination. The CNR between WM and GM (CNRWM-GM) was evaluated across the cortical areas.
The CNRWM-GM varies across the cortex; the lower values were found in motor and sensorimotor areas where almost all NCs were localized. A strong negative correlation was found between CNRWM-GM and NCs.
Discrimination between CLs and JCs is affected from the sharp visualization of the WM-GM boundary, which is directly related to CNRWM-GM.
Diffusion-weighted imaging (DWI), perfusion-weighted imaging (PWI) and MR spectroscopy (MRS) provide useful data for tumor evaluation. To assess the contribution of these multimodal techniques in ...grading glial neoplasms, we compared the value of DWI, PWI and MRS in the evaluation of histologically proven high- and low-grade gliomas in a population of 105 patients.
Independently for each modality, the following variables were used to compare the tumors: minimum apparent diffusion coefficient (ADC) and maximum relative cerebral blood volume (rCBV) normalized values between tumor and healthy tissue, maximum Cho/Cr ratio and minimum NAA/Cr ratio in tumor, and scored lactate and lipid values in tumor. The Mann-Whitney and Wilcoxon tests were employed to compare DWI, PWI and MRS between tumor types. Logistic regression analysis was used to determine which parameters best increased the diagnostic accuracy in terms of sensitivity, specificity, and positive and negative predictive values. ROC curves were determined for parameters with high sensitivity and specificity to identify threshold values to separate high- from low-grade lesions.
Statistically significant differences were found for rCBV tumor/normal tissue ratio, and NAA/Cr ratio in tumor and Cho/Cr ratio in tumor between low- and high-grade tumors. The best performing single parameter for group classification was the normalized rCBV value; including all parameters, statistical significance was reached by rCBV tumor/normal tissue ratio, NAA/Cr tumor ratio and lactate. From the ROC curves, a high probability for a neoplasm to be a high-grade lesion was associated with a rCBV tumor/normal tissue ratio of >1.16 and NAA/Cr tumor ratio of <0.44.
Combining PWI and MRS with conventional MR imaging increases the accuracy of the attribution of malignancy to glial neoplasms. The best performing parameter was found to be the perfusion level.
Motor Imagery (MI) refers to mental simulation of a motor action without producing any overt movement. Previous studies showed that children with Unilateral Cerebral Palsy (UCP) are impaired in ...implicit MI, as demonstrated by the performance of Hand Laterality Judgment tasks. The aim of this study was to examine the specificity of explicit MI deficits in UCP children.
A group of UCP children (
= 10; aged 9-14) performed a mental chronometry task consisting in grasping an object and placing it into a container, or in imagining to perform the same action. As control, a group of typically developing (TD) children, matched by age, performed the same task. Movement durations for executed and imagined trials were recorded. A subgroup of 7 UCP children and 10 TD children also underwent a session of functional MRI to examine the activation of parieto-frontal areas typically associated to MI processes, during the imagination of reaching-grasping actions performed with the paretic hand.
Behavioral results revealed the existence of a correlation between executed and imagined movement durations both in TD and UCP groups. Moreover, the regression analysis in TD children showed that higher scores in mental chronometry tasks were positively correlated to increased bilateral activation of the intraparietal sulcus (IPS), superior parietal lobule (SPL), and dorsal premotor (PMd) cortex. A similar analysis revealed in the UCP group a positive correlation between a higher score in the mental chronometry task and bilateral activations of IPS, and to activation of contralesional, right PMd, and putamen during imagination of grasping movements.
These results provide new insights on the relationship between MI capacity and motor deficits in UCP children, suggesting the possibility of the use of explicit MI training to improve patient's upper limb motor functions.
ABSTRACT
BACKGROUND AND PURPOSE
This study aims to investigate whether radiomic quantitative image features (IFs) from perfusion dynamic susceptibility contrast magnetic resonance imaging (DSC‐MRI) ...retain sufficient strength to predict O6‐methylguanine–DNA methyltransferase promoter methylation (MGMT_pm) in newly diagnosed glioblastoma (GB) patients.
METHODS
We retrospectively reviewed the perfusion DSC‐MRI of 59 patients with GB. Patients were classified into three groups: (1) unmethylated if MGMT_pm ≤ 9% (UM); (2) intermediate‐methylated if MGMT_pm ranged between 10% and 29% (IM); (3) methylated if MGMT_pm ≥ 30% (M). A total of 92 quantitative IFs were obtained from relative cerebral blood volume and relative cerebral blood flow maps. The Mann‐Whitney U‐test was applied to assess whether there were statistical differences in IFs between patient groups. Those IFs showing significant difference between two patient groups were termed relevant IFs (rIFs). rIFs were uploaded to a machine learning model to predict the MGMT_pm.
RESULTS
No rIFs were found between UM and IM groups. Fourteen rIFs were found among UM‐M, IM‐M, and (UM + IM)‐M groups. We built a multilayer perceptron deep learning model that classified patients as belonging to UM + IM and M group. The model performed well with 75% sensitivity, 85% specificity, and an area under the receiver‐operating curve of .84.
CONCLUSION
rIFs from perfusion DSC‐MRI are potential biomarkers in GBs with a ≥30% MGMT_pm. Otherwise, unmethylated and intermediate‐methylated GBs lack of rIFs. Five of 14 rIFs show sufficient strength to build an accurate prediction model of MGMT_pm.
Late recovery of consciousness in vegetative state is considered as an exceptional outcome and has been reported prevalently in patients who suffered a traumatic brain injury. In these patients, the ...benefits of prolonging the rehabilitation, aimed at the recovery of autonomy in basic everyday activities, has been demonstrated. Here, we describe the application of an intensive multi-professional rehabilitation program carried out on a young female patient, with exceptionally late recovery of consciousness, specifically, after 7 years of vegetative state due to severe brain hemorrhage. Neuropsychological and functional assessment was conducted before and after the end of the rehabilitation program. In addition, functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI)-based probabilistic tractography were performed. Two follow-up neuropsychological and functional assessments were also conducted 6 and 29 months after the conclusion of the program. Functional results showed an improvement, maintained over time, in walking with assistance, cognitive efficiency, visual acuity and visual field, dysarthria, and execution of activities of daily living. Moreover, functional and structural magnetic resonance imaging (MRI) data documented the existence of preserved neural networks involved in sensory, motor, and linguistic tasks, which in all likelihood support the recovery process. This report suggests the possibility of undertaking an intensive rehabilitation program in patients who remain for long periods in altered states of consciousness, in spite of early negative prognosis.
The aim of the present study was to determine whether Broca's area is involved in translating some aspects of arm gesture representations into mouth articulation gestures. In Experiment 1, we applied ...low-frequency repetitive transcranial magnetic stimulation over Broca's area and over the symmetrical loci of the right hemisphere of participants responding verbally to communicative spoken words, to gestures, or to the simultaneous presentation of the two signals. We performed also sham stimulation over the left stimulation loci. In Experiment 2, we performed the same stimulations as in Experiment 1 to participants responding with words congruent and incongruent with gestures. After sham stimulation voicing parameters were enhanced when responding to communicative spoken words or to gestures as compared to a control condition of word reading. This effect increased when participants responded to the simultaneous presentation of both communicative signals. In contrast, voicing was interfered when the verbal responses were incongruent with gestures. The left stimulation neither induced enhancement on voicing parameters of words congruent with gestures nor interference on words incongruent with gestures. We interpreted the enhancement of the verbal response to gesturing in terms of intention to interact directly. Consequently, we proposed that Broca's area is involved in the process of translating into speech aspects concerning the social intention coded by the gesture. Moreover, we discussed the results in terms of evolution to support the theory Corballis, M. C. (2002).
. Princeton, NJ: Princeton University Press proposing spoken language as evolved from an ancient communication system using arm gestures.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The present fMRI study was aimed at assessing the cortical areas active when individuals observe non-object-directed actions (mimed, symbolic, and meaningless), and when they imagine performing those ...same actions. fMRI signal increases in common between action observation and motor imagery were found in the premotor cortex and in a large region of the inferior parietal lobule. While the premotor cortex activation overlapped that previously found during the observation and imagination of object-directed actions, in the parietal lobe the signal increase was not restricted to the intraparietal sulcus region, known to be active during the observation and imagination of object-directed actions, but extended into the supramarginal and angular gyri. When contrasting motor imagery with the observation of non-object-directed actions, signal increases were found in the mesial frontal and cingulate cortices, the supramarginal gyrus, and the inferior frontal gyrus. The opposite contrast showed activation virtually limited to visual areas. In conclusion, the present data define the common circuit for observing and imagining non-object-directed actions. In addition, they show that the representation of non-object-directed actions include parietal regions not found to be involved in coding object-directed actions.
Abstract The eponym “Tapia’s syndrome” indicates an associated unilateral vocal cord and tongue paralysis secondary to a peripheral involvement of the recurrent laryngeal branch and the hypoglossal ...nerve. Although mainly observed as a complication of surgery or anaesthesia, it can rarely occur secondary to infectious or neoplastic causes. We are presenting a case of a teen-ager with Tapia’s syndrome who had been seeking medical assistance for episodes of loss of consciousness and was diagnosed with a high-grade peripheral B-cell lymphoma, an association not previously described. This syndrome should be remembered even outside the surgical contest for its highly localising value.
Background
Quantification of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) kinetic parameters (KPs) requires a determination of native tissue T1. Two approaches are adopted: (i) ...tissue T1-maps are acquired; and (ii) an a priori T1 value (fT1) is fixed for all patients (fT1-approach). Although it is more attractive, the fT1-approach might bias the results of KP calculations due to tissue T1 variability.
Purpose
To quantify the tissue T1 variability of recurrent high-grade glioma (HGG) and the error in KP estimation when the fT1-approach is adopted.
Material and Methods
We reviewed the postoperative MRI scans of 28 patients with recurrent HGG after radiochemotherapy. MRI study included T1-maps from multiple-dynamic multiple-echo imaging, DCE-MRI, and contrast enhanced T1-weighted images. KPs were calculated using T1-map and fT1-approach.
Results
The tissue T1 variability of recurrent HGG was relevant. The absolute error in KP estimation, as a function of the deviation of fT1 from the true value, was 8% every 100 ms. The difference between the KPs obtained with fT1-approach from fT1 values of 1300, 1390, and 1500 ms and their reference values were mostly within the 95% confidence interval (± 1.96 standard deviation). Conversely, using fT1 values of 900, 1200, 1600, and 1900 ms causes a significant error in KP estimation (P<0.05).
Conclusion
Recurrent HGG is characterized by a substantial T1 variability. Although the fT1-approach does not account for this variability, it results in a minor effect on the KP estimations provided the fT1 value is in the range of 1300–1500 ms.
ABSTRACT
BACKGROUND AND PURPOSE
The aim of this study was to evaluate the differences in dynamic contrast‐enhanced (DCE) magnetic resonance imaging (MRI) perfusion estimates of high‐grade brain ...gliomas (HGG) due to the use of an input function (IF) obtained respectively from arterial (AIF) and venous (VIF) approaches by two different commercially available software applications.
METHODS
This prospective study includes 20 patients with pathologically confirmed diagnosis of high‐grade gliomas. The data source was processed by using two DCE dedicated commercial packages, both based on the extended Toft model, but the first customized to obtain input function from arterial measurement and the second from sagittal sinus sampling. The quantitative parametric perfusion maps estimated from the two software packages were compared by means of a region of interest (ROI) analysis. The resulting input functions from venous and arterial data were also compared.
RESULTS
No significant difference has been found between the perfusion parameters obtained with the two different software packages (P‐value < .05). The comparison of the VIFs and AIFs obtained by the two packages showed no statistical differences.
CONCLUSIONS
Direct comparison of DCE‐MRI measurements with IF generated by means of arterial or venous waveform led to no statistical difference in quantitative metrics for evaluating HGG. However, additional research involving DCE‐MRI acquisition protocols and post‐processing would be beneficial to further substantiate the effectiveness of venous approach as the IF method compared with arterial‐based IF measurement.
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