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Functional magnetic resonance imaging (fMRI) was used to map cortical areas that control eye blinking. T2*-weighted asymmetric spin-echo MRI (or BOLD-blood oxygen level dependent-MRI) was used to detect changes caused by focal variations in blood oxygenation. Six normal volunteers and two cases of dry eye (less than 5-mm Schirmer's test) entered the study.(More)
BACKGROUND AND PURPOSE Our objective was to develop a method to correct for the effect of partial volume averaging (PVA) in the CT measurement of contrast enhancement in small arteries, and to validate a dynamic contrast-enhanced CT method for the measurement of regional cerebral blood flow (rCBF). METHODS Contrast-enhanced CT scans of tubes of known(More)
BACKGROUND AND PURPOSE We have developed a dynamic CT method to measure absolute cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT). In this study we evaluated the ability of CT-derived functional maps to detect infarction in a rabbit model of focal cerebral ischemia. METHODS Sequential dynamic CT studies were performed at(More)
RATIONALE AND OBJECTIVES Deconvolution-based software can be used to calculate quantitative maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) from first-pass computed tomography perfusion (CTP) datasets. The application of this software requires the user to select multiple input variables. The purpose of this study(More)
We introduce a fast technique, based on the principles of the 2D Look-Locker T1 measurement scheme, to rapidly acquire the data for accurate maps of T1 in three dimensions. The acquisition time has been shortened considerably by segmenting the acquisition of the k(y) phase encode lines. Using this technique, the data for a 256 x 128 x 32 volumetric T1(More)
In a porcine ischemic stroke model, we sought to compare the acute predicted infarct core volume (PIV) defined by CT perfusion (CTP)-hemodynamic parameters and MR-diffusion-weighted imaging (MR-DWI)/apparent diffusion coefficient (ADC), with the true infarct core volume (TIV) as defined by histology. Ten Duroc-cross pigs had a CTP scan prior to injection of(More)
We have previously reported that exposure of rats to low-field (0.15 T) magnetic resonance imaging (MRI) increases blood-brain barrier (BBB) permeability. However, a number of investigators have failed to observe this effect when high-field MRI (1.5 T or higher) is used. Therefore, we investigated whether or not we would observe changes using our technique(More)
Based on the temporal distributions of clustered segments in the time series of the ten Dow Jones US (DJUS) economic sector indices, we calculated their cross and also over 11 corresponding segments within the present financial crisis. From these cross-correlation matrices, we constructed minimal spanning trees (MSTs) of the US economy at the sector level.(More)
The inclusion of dynamic contrast-enhanced computed tomography (CT) or CT perfusion (CTP) scan into the imaging workup for acute stroke patients is widespread. Along with vessel occlusion status from CT angiography, CTP provides pathophysiological information a non-contrast CT cannot provide during the hyperacute stages of cerebral ischemia. Measurement of(More)
We investigated the practical clinical utility of the CT perfusion (CTP) cerebral blood volume (CBV) parameter for differentiating salvageable from non-salvageable tissue in acute ischemic stroke (AIS). Fifty-five patients with AIS were imaged within 6 h from onset using CTP. Admission CBV defect (CBVD) volume was outlined using previously established gray(More)