Incidental findings on brain MRI - i.e., brain abnormalities discovered in subjects recruited to research studies as healthy controls or unexpected findings in patients - has garnered significant attention in the literature recently. Suspicious brain abnormalities have been reported to occur in as many as 40% of research participants, with clinically significant findings occurring in 2-8% of children and adults. We surveyed members of the MRI research community to document protocols used for discovering and disclosing such findings in research subjects. The cohort comprised investigators who conduct both structural and functional MRI studies. 84% of the investigators (N=31 to date) who responded to the survey reported discoveries of incidental findings on their studies. Findings ranged in severity from those requiring routine follow-up to those requiring immediate or urgent follow-up, and were detected by both MD-trained and non-MD-trained research personnel, including PhD investigators, professional labor...

Functional Magnetic Resonance Imaging has become an important analytical tool to study neurodegenerative diseases. We used EPI-BOLD fMRI technique to acquire functional images of patients with familial essential tremor (FET) disorder and healthy control volunteers, during the same motor task activity. Functional images were used to produce brain activation maps of the patients and volunteers. These functional maps of the primary somatosensorial and motor cortexes of patients and control subjects were compared for functional differences. The averaged functional brain images of eight of each case are presented, it can be observed that there are differences in active zones. The results presented in this work show that there are differences in functional maps during motor task activation between control subjects and FET patients suggesting a cerebral functional reorganization or plasticity, that can be mapped with BOLD-fMRI.

It is well documented that gray matter (GM) and white matter (WM) volumes decrease with age, while CSF increases. Statistical Parametric Mapping (SPM) is a widely used method for automated segmentation of brain tissue on MRI images. SPM uses a material mixture model of the distribution of image intensities with initial estimates provided by apriori probablility maps. Tissue volumes are expressed relative to Intra-Cranial Cavity Volume (ICCV) to normalize across different sized brains. Whole brain images of 24 elderly subjects (81.8 +/-6.3 years, 12 men) were acquired with a Siemens 1.5T Magnetom Vision scanner using a 3D MPRAGE sequence (TR/TE1= 11.4s/4.4) with 160-192 sagittal slices yielding 1mm3 voxels. SPM segmentation estimated normalized tissue volume (%ICCV). Individual subject tissue volume results (GM, WM and CSF) and ICCV were correlated with age. Average tissue volumes were 39.3 GM, 30.0 WM and 30.6 CSF %ICCV, though individual results varied substantially. Visual inspection demonstrated that GM...

There have been reports in the literature over the past 20 years that some muscles are not homogeneously activated (i.e. activated as subvolumes) during tasks. During the same period of time magnetic resonance (MR) imaging T2 times have started to be used to measure muscle activity. Certain potential subvolume organizations of motor units could lead to greater variability of T2 time as task effort increases (Prior et al., 1999). Prior et al tested the preceding hypothesis, but did not find any statistically significant differences in whole muscle T2 time variance with increased effort although there was a tendency for variance to increase. The purpose of this study was to look for changes in whole muscle T2 time variance in leg muscles including one purportedly compartmentalized muscle, the lateral gastrocnemius (LG; Segal et al., 1991). Able-bodied subjects carried out concentric plantarflexion contractions against loads equal to 25% and 65% of maximal voluntary contraction (MVC). All subjects had pre and...

Fibromyalgia (FM) is a puzzling disease marked by arthralgia and reports of memory dysfunction. Although FMs have been dismissed as malingerers, recent fMRI data show they have heightened sensitivity to pain mediated by several brain regions (Gracely et al., 2002), and their memory function is similar to adults 20 years older (Park et al., 2001). Using fMRI, we investigated whether FMs have “old” brains, with neural recruitment patterns (bilateral frontal and more extensive activations) during a working memory (WM) task typical of older adults, rather than patterns (focused, primarily unilateral activations) typical of younger adults. FMs (n = 12) and age- and education-matched controls (n = 9) performed a verbal WM task that involved either maintaining letters in memory or reorganizing them alphabetically and then responding to a probe. We found neural activation differences for manipulation of items in WM between FMs and controls, although behavioral performance was equivalent in both WM conditions. Spec...

Cognitive control, defined as the ability to suppress irrelevant information and actions in favor of more relevant ones, has been shown to become more efficient with age. In the present study we explore the neural basis of this development in a longitudinal functional MRI study of children aged 7 to 12 years. Subjects, who had previously participated in a study using a go nogo paradigm, participated in a second fMRI session using a similar task. The subjects’ task was to press a button to a string of targets, but inhibit their response to a non-target (25 to 30% of trials). The average time interval between the sessions was 2 yrs and the average age at time 1 was 9 yrs (7.2-10.3), and 11 yrs (9.2-12.9) at time 2. Behaviorally, subjects became more accurate and faster in detecting the target (p < 0.001) from time 1 to time 2, but there were a similar number of false alarms. The imaging results showed that the average MR signal change between time 1 and 2 was no different in motor cortex for the comparison o...

Typically, functional magnetic resonance imaging (fMRI) data is analyzed using statistical models that rely on linear time series methods. However, studies have shown that the blood-oxygenation-level-dependent (BOLD) contrast may not be a linear response to neural activation. Given that there is a nonlinear component to fMRI data, our understanding of the hemodynamic response may benefit by the use of nonlinear methods. Phase synchronization occurs when a relationship exists between two or more nonlinear oscillators and the instantaneous phases of these oscillators become locked. In order to investigate the occurrence of phase synchronization in fMRI studies, we acquired data on three normal volunteers for motor, visual, and language tasks and performed the standard analysis using SPM’99, which analyzes fMRI data according to the General Linear Model. After the activation maps were created for each of the tasks, we selected 4x4 clusters in the cluster centroids. We then performed the phase synchronization ...

19 Participants with developmental Specific Language Impairment (SLI) were examined by neuropsychological and quantitative magnetic resonance imaging (MRI) techniques. Measures of intelligence (IQ), language, and memory were obtained, and 3D MRI structural datasets were analysed for bilateral pathology using voxel-based morphometry (VBM). Each participant had been diagnosed with SLI during childhood, and had or was attending a special language unit. The participants ranged in age between 8 and 24 years, and none had any evidence of oro-motor dyspraxia. In addition, each had superior nonverbal compared to verbal IQ, and was impaired on a range of language tests, and on measures of episodic long term memory. To examine the reliability of the VBM findings, two age-matched SLI groups (N=10, & N=9) were formed. Using VBM, comparison of each group to its own control group (matched on age, sex, and nonverbal IQ) showed significant bilateral reductions in grey matter within the cerebellum, particularly around the ...

It has been argued that the longer lasting effects of low-frequency rTMS trains rely on post-synaptic inhibitory GABAergic synapses, but there remains some uncertainty whether an additional pathophysiological mechanism might support this post-synaptic inhibition. In this study, we investigated whether rTMS at 1 Hz administered for 12 minutes at 90% of motor threshold to the primary motor cortex would lead to any changes in cortical diffusivity of water protons by comparing a series of diffusion weighted MRI (DWI) scans acquired before and after the rTMS train. Impairments of water diffusivity can typically be seen in the acute stage of an ischemic insult or focal status epilepticus, and their reversibility has been shown. Preliminary analysis of the diffusion images shows only a minimally increased signal within the motor region in half of the subjects (3 out of 6). This minimal signal change was no longer present 15 minutes after the end of the rTMS train. The initial signal change in some subjects is not...

Background: Deception is a cognitive phenomenon with important practical implications. Existence of a correlation between the P-300 component of evoked brain potentials and deception suggests that the cognitive distinction between truth and lie could be associated with differences in local brain activity. The guilty knowledge task (GKT) has been used to simulate deception under laboratory and field conditions. Functional Magnetic Resonance Imaging (fMRI) allows high-resolution study of changes in regional cerebral blood flow (rCBF) during cognition. We used fMRI to identify brain regions differentially activated by deceptive and truthful responses on the GKT. Methods: fMRI was performed in 23 normal subjects during the GKT. The amplitude and location of fMRI signal during and after deceptive and truthful responses were recorded. After exclusion of five subjects for task errors and motion artifact, data was analyzed for rCBF differences between truthful and deceptive responses. Results: Increased rCBF was s...