Keith S. Cover

How do brain tumors alter functional connectivity? A magnetoencephalography study

This study was undertaken to test the hypothesis that brain tumors interfere with normal brain function by disrupting functional connectivity of brain networks.

Accelerating regional atrophy rates in the progression from normal aging to Alzheimer’s disease

We investigated progression of atrophy in vivo, in Alzheimer’s disease (AD), and mild cognitive impairment (MCI). We included 64 patients with AD, 44 with MCI and 34 controls with serial MRI examinations (interval 1.8u2009±u20090.7xa0years). A nonlinear registration algorithm (fluid) was used to calculate atrophy rates in six regions: frontal, medial temporal, temporal (extramedial), parietal, occipital lobes and insular cortex. In MCI, the highest atrophy rate was observed in the medial temporal lobe, comparable with AD. AD patients showed even higher atrophy rates in the extramedial temporal lobe. Additionally, atrophy rates in frontal, parietal and occipital lobes were increased. Cox proportional hazard models showed that all regional atrophy rates predicted conversion to AD. Hazard ratios varied between 2.6 (95% confidence interval (CI) = 1.1–6.2) for occipital atrophy and 15.8 (95% CIu2009=u20093.5–71.8) for medial temporal lobe atrophy. In conclusion, atrophy spreads through the brain with development of AD. MCI is marked by temporal lobe atrophy. In AD, atrophy rate in the extramedial temporal lobe was even higher. Moreover, atrophy rates also accelerated in parietal, frontal, insular and occipital lobes. Finally, in nondemented elderly, medial temporal lobe atrophy was most predictive of progression to AD, demonstrating the involvement of this region in the development of AD.

Multiple sclerosis patients show a highly significant decrease in alpha band interhemispheric synchronization measured using MEG.

MEG data were acquired from a group of relapsing-remitting multiple sclerosis (MS) patients and a group of healthy controls, using an eyes-closed no-task condition. An interhemispheric coherence measure (IHCM), reflecting the synchronization between the left and right hemispheres, showed a decrease in the patients, particularly in the alpha band. No comparable differences were seen in the alpha band power or its distribution over the head. The observed difference is in agreement with a reduced long-range connectivity in the brains of MS patients. The IHCM was found to be reproducible in controls over a period of more than 15 months. Further studies should investigate whether MEG derived synchronization measures may be useful as markers for MS disease load.

Detection of very high correlation in the alpha band between temporal regions of the human brain using MEG.

It is generally believed that alpha band (8-12 Hz) electric and magnetic activity in the area of the left and right temporal regions in the human brain are at best poorly correlated. There are no previous reports of very high alpha band correlation between left and right temporal regions by magnetoencephalography (MEG) or electroencephalography (EEG). We present whole head magnetoencephalography (MEG) results that demonstrate that, for temporal channels in the majority of healthy subjects tested, the alpha band signals are highly to very highly correlated and are antiparallel in direction. A correlation as high as -0.97 was found for a limited time in one subject. We suggest that the correlation found may be the consequence of strong direct or indirect coupling between homologue areas in left and right temporal regions rather than a common source. The correlation may provide a valuable index of loss of connectivity in the brain due to disease as well providing valuable insight to brain function and deserves further investigation.

Using color intensity projections to visualize air flow in operating theaters with the goal of reducing infections

Infection following neurosurgery is all too common. One possible source of infection is the transportation of dust and other contaminates into the open wound by airflow within the operating theatre. While many modern operating theatres have a filtered, uniform and gentle flow of air cascading down over the operating table from a large area fan in the ceiling, many obstacles might introduce turbulence into the laminar flow including lights, equipment and personal. Schlieren imaging - which is sensitive to small disturbances in the laminar flow such as breathing and turbulence caused by air warmed by a hand at body temperature – was used to image the air flow due to activities in an operating theatre. Color intensity projections (CIPs) were employed to reduce the workload of analyzing the large amount of video data. CIPs – which has been applied to images in angiography, 4D CT, nuclear medicine and astronomy – summarizes the changes over many gray scale images in a single color image in a way which most interpreters find intuitive. CIPs uses the hue, saturation and brightness of the color image to encode the summary. Imaging in an operating theatre showed substantial disruptions to the airflow due to equipment such as the lighting. When these disruptions are combined with such minor factors as heat from the hand, reversal of the preferred airflow patterns can occur. These reversals of preferred airflow patterns have the potential to transport contaminates into the open wound. Further study is required to understand both the frequency of the reversed airflow patterns and the impact they may have on infection rates.

Color intensity projections with hue cycling for intuitive and compressed presentation of motion in medical imaging modalities

Color intensity projections (CIPs) has been employed to improve the accuracy and reduce the workload of interpreting a series of grayscale images by summarizing the grayscale images in a single color image. CIPs – which has been applied to grayscale images in angiography, 4D CT, nuclear medicine and astronomy – uses the hue, saturation and brightness of the color image to encode the summary information. In CIPs, when a pixel has the same value over the grayscale images, the corresponding pixel in the color image has the identical grayscale color. The arrival time of a signal at each pixel, such as the arrival time of contrast in angiography, is often encoded in the hue (red-yellow-green-light blue-blue-purple) of the corresponding pixel in the color image. In addition, the saturation and brightness of each pixel in the color image encodes the amplitude range and amplitude maximum of the corresponding pixel in the grayscale images. In previous applications of CIPs the hue has been limited to less than one cycle over the color image to avoid the aliasing due to a hue corresponding to more than one arrival time. However, sometimes in applications such as angiography and astronomy, in some instances the aliasing due to increasing the number of cycles of hue over the color image is tolerable as it increases the resolution of arrival time. Key to applying hue cycling effectively is interpolating several grayscale images between each pair of grayscale images. Ideally, the interpreter is allowed to adjust the amount of hue cycling in realtime to find the best setting for each particular CIPs image. CIPs with hue cycling should be a valuable tool in many fields where interpreting a series of grayscale images is required.

P1-302: Accelerating regional atrophy rates in the progression from normal aging to Alzheimer's disease

Background: To assess regional lobar atrophy rates, as well as investigate the risk of progression to dementia in initially non-demented elderly, based on these regional atrophy rates. Methods: We included 64 patients with Alzheimer’s (AD), 44 patients with Mild Cognitive Impairment (MCI), and 34 controls, with repeated MR imaging including volumetric imaging (interval 1.8 0.7y). Fluid, a non-linear matching algorithm, was applied to measure longitudinal regional atrophy rates in 6 regions: frontal, medial temporal, remaining part temporal, parietal, occipital, and insular lobe. Results: ANOVA for repeated measures with region as within subjects factor, diagnosis as between subjects factor, and age and sex as covariates, showed significant main effects of diagnosis (p 0.001), and region (p 0.001; figure), and an interaction between diagnosis and region (p 0.001). For MCI patients, the highest atrophy rates were observed in the medial temporal lobe, where atrophy rates were comparable to those of AD patients. With progression of the disease, atrophy spread throughout the brain, as AD patients showed even higher atrophy rates in the remaining part of the temporal lobe. Atrophy rates in the frontal, parietal and occipital lobes were additionally increased in comparison to patients with MCI. Subsequently Cox proportional hazard models, adjusted for age and sex, showed that all regional atrophy rates predicted conversion to AD. Hazard ratio’s varied between 2.6 (95% confidence interval, CI (1.1 6.2)) for occipital lobe, and 15.8 (95% CI (3.5 71.8)) for the medial temporal lobe. When evaluated simultaneously in a stepwise model, medial temporal lobe atrophy rate was the only predictor. Conclusions: These data illustrate how atrophy spreads through the brain with the progression of AD. In MCI, the temporal lobe shows the greatest atrophy rate. In AD patients, the medial temporal lobe shows an atrophy rate comparable to MCI, while the remaining part of the temporal lobe demonstrates an even higher rate of atrophy. Moreover, atrophy also accelerates in parietal, frontal, insular and occipital lobes. Finally, in non-demented elderly medial temporal lobe atrophy was most predictive of progression to AD, demonstrating the importance of this region in the early detection of AD. P1-303 PHASE I STUDY OF THE F-LABELLED BENZOTHIAZOLE DERIVATIVE [F]AH110690 AS A BIOMARKER OF ALZHEIMER’S DISEASE– RELATED BRAIN AMYLOIDOSIS