fMRI reliability in subjects with stroke
ABSTRACT Functional MRI (fMRI) has become one of the most commonly used neuroimaging tools to assess the cortical effects associated with rehabilitation, learning, or disease recovery in subjects with stroke. Despite this, there has been no systematic study of the reliability of the fMR signal in this population. The purpose of this study was to examine the within- and between-session reliability of fMRI in cortical and cerebellar structures in subjects with stroke during a complex, continuous visual motor task performed with the less affected hand. Nine subjects with stroke underwent four testing trials during two sessions separated by three weeks. Subjects performed a drawing task using an MRI compatible joystick while in the MRI. Methods of analysis evaluated included: percent signal intensity change, active voxel count and a voxel by voxel stat value analysis within and between testing sessions. Reliability was determined with Interclass correlation coefficients (ICC) in the following regions of interest: primary motor (M1), primary sensory (S1), premotor cortex (PMC), medial cerebellum (MCB), and lateral cerebellum (LCB). Results indicate that intensity change has superior reliability to the other methods of analysis (Average ICC across brain regions and trials: intensity change: 0.73, voxel count: 0.58, voxel by voxel: 0.67) and that generally with any analysis method, within-session reliability was higher than between-session, as indicated by higher ICC values across brain regions. Overall, when comparing between-session results, moderate to good reliability was obtained with intensity change (ICC: M1: 0.52, S1: 0.80, SMA: 0.78, PMC: 0.94, MCB: 0.86, and LCB: 0.59). These results show good reliability in subjects with stroke when performing a continuous motor task. These findings give confidence for interpreting fMRI test/retest research in subjects with stroke.
Full-textDOI: · Available from: Michael Robert Borich, Jan 02, 2015
- SourceAvailable from: Mukesh Dhamala
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- "Three ROIs were defined anatomically as follows: the M1 as the area extending from the anterior bank of the central sulcus to the anterior edge of the precentral gyrus (Dassonville et al., 2001; Kimberley et al., 2008b,c), the PMC as the area between M1 and the sulcus nearest the coronal plane through the anterior commissure, bounded inferiorly by the inferior edge of the frontal lobe (Dassonville et al., 2001), and the SMA as the medial region of the hemispheres superior to the dorsal bank of the cingulated sulcus along the same anterior-posterior extent as the PM (Dassonville et al., 2001; Kimberley et al., 2008a,c). "
ABSTRACT: Coherent network oscillations (< 0.1 Hz) linking distributed brain regions are commonly observed in the brain during both rest and task conditions. What oscillatory network exists and how network oscillations change in connectivity strength, frequency and direction when going from rest to explicit task are topics of recent inquiry. Here, we study network oscillations within the sensorimotor regions of able-bodied individuals using hemodynamic activity as measured by functional near-infrared spectroscopy (fNIRS). Using spectral interdependency methods, we examined how the supplementary motor area (SMA), the left premotor cortex (LPMC) and the left primary motor cortex (LM1) are bound as a network during extended resting state (RS) and between-tasks resting state (btRS), and how the activity of the network changes as participants execute left, right and bilateral hand (LH, RH and BH) finger movements. We found: (i) power, coherence and Granger causality spectra had significant peaks within the frequency band (0.01-0.04 Hz) during RS whereas the peaks shifted to a bit higher frequency range (0.04- 0.08 Hz) during btRS and finger movement tasks, (ii) there was significant bidirectional connectivity between all the nodes during RS and unidirectional connectivity from the LM1 to SMA and LM1 to LPMC during btRS, and (iii) the connections from SMA to LM1 and from LPMC to LM1 were significantly modulated in LH, RH and BH finger movements relative to btRS. The unidirectional connectivity from SMA to LM1 just before the actual task changed to the bidirectional connectivity during LH and BH finger movement. The unidirectionality could be associated with movement suppression and the bidirectionality with for preparation, sensorimotor update and controlled execution. These results underscore that fNIRS is an effective tool for monitoring spectral signatures of brain activity, which may serve as an important precursor before monitoring the recovery progress following brain injury.Frontiers in Systems Neuroscience 02/2014; 8:13. DOI:10.3389/fnsys.2014.00013
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- "Currently, studies of test-retest stability of BOLD-fMRI in individuals with clinical disorders have been limited. Mixed results have been observed with some showing decreased stability in certain clinical disorders such as epilepsy and schizophrenia (Chiarelli et al., 2007a; Fernandez et al., 2003; Manoach et al., 2001) while others have seen greater stability in aphasic stroke patients who have recovered (Kimberley et al., 2008). In this study we observed a significant reduction in the stability of all calibrated BOLD fMRI measures, except for M, in HIV+ patients compared to HIV− controls (Table 3). "
ABSTRACT: Subject performance, scanner hardware, or biological factors can affect single session neuroimaging measures. Stability studies using calibrated blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI) have been performed in health but not disease. We utilized calibrated BOLD-fMRI to determine the effects of HIV on neurovascular coupling. Six clinically stable HIV-infected patients (HIV+) and 10 seronegative controls (HIV-) were scanned at two separate sessions approximately 3 months apart. Both mild hypercapnia (5% CO(2)) exposure and a visual functional activation task were performed. Intraclass correlation coefficients (ICC) and inter-subject variance were determined for calibrated BOLD-fMRI measures (baseline cerebral blood flow (CBF), functional CBF, BOLD, and cerebral metabolic rate of oxygen consumption (CMRO(2)) changes) for HIV+ and HIV- subjects. The two groups did not differ in age, sex, or education. HIV+ subjects had lower mean baseline CBF (p<0.04, Cohen's d=-1.07) and functional BOLD responses (p<0.001, Cohen's d=-2.47) and a trend towards a decrease in mean functional CBF responses (p=0.07, Cohen's d=-0.92) despite similar mean functional CMRO(2) changes (p=0.71, Cohen's d=0.19). The stability of each calibrated BOLD-fMRI measure, as assessed by ICC, was significantly lower for HIV+ subjects. In addition, HIV+ participants had greater inter-subject variability for baseline CBF (p<0.02), functional BOLD (p<0.001), CBF (p<0.001), and CMRO(2) (p<0.002) responses. Our results demonstrate that calibrated BOLD-fMRI measures have excellent stability within healthy controls. In contrast, these values have greater variability in clinically stable HIV+ subjects and may reflect alterations in coupling between CBF and CMRO(2) with disease.NeuroImage 10/2010; 54(3):2156-62. DOI:10.1016/j.neuroimage.2010.09.081 · 6.36 Impact Factor
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- "While a causal link between cerebral reorganization and functional recovery has yet to be firmly established, brain imaging studies in chronic stroke patients have shown plastic changes, including enhanced bilateral activation of the sensorimotor cortex, increased activity in secondary or higher order sensorimotor areas, and recruitment of additional cortical areas during performance of a hand sensorimotor task (Weiller, 1998). Functional magnetic resonance imaging (fMRI) in particular has been described as a reliable method for assessing stroke patients (Kimberley et al., 2008). Nevertheless, the chronic stroke literature lacks functional integration studies examining functional reorganization of motor systems through assessment of altered connectivity between motor related areas. "
ABSTRACT: The aim of this study was to investigate functional reorganization of motor systems by probing connectivity between motor related areas in chronic stroke patients using functional magnetic resonance imaging (fMRI) in conjunction with a novel MR-compatible hand-induced, robotic device (MR_CHIROD). We evaluated data sets obtained from healthy volunteers and right-hand-dominant patients with first-ever left-sided stroke > or =6 months prior and mild to moderate hemiparesis affecting the right hand. We acquired T1-weighted echo planar and fluid attenuation inversion recovery MR images and multi-level fMRI data using parallel imaging by means of the GeneRalized Autocalibrating Partially Parallel Acquisitions (GRAPPA) algorithm on a 3 T MR system. Participants underwent fMRI while performing a motor task with the MR_CHIROD in the MR scanner. Changes in effective connectivity among a network of primary motor cortex (M1), supplementary motor area (SMA) and cerebellum (Ce) were assessed using dynamic causal modeling. Relative to healthy controls, stroke patients exhibited decreased intrinsic neural coupling between M1 and Ce, which was consistent with a dysfunctional M1 to Ce connection. Stroke patients also showed increased SMA to M1 and SMA to cerebellum coupling, suggesting that changes in SMA and Ce connectivity may occur to compensate for a dysfunctional M1. The results demonstrate for the first time that connectivity alterations between motor areas may help counterbalance a functionally abnormal M1 in chronic stroke patients. Assessing changes in connectivity by means of fMRI and MR_CHIROD might be used in the future to further elucidate the neural network plasticity that underlies functional recovery in chronic stroke patients.NeuroImage 04/2009; 47 Suppl 2:T90-7. DOI:10.1016/j.neuroimage.2009.03.007 · 6.36 Impact Factor