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DCE-MRI Data (dce-mri + data)
Selected AbstractsImproved bolus arrival time and arterial input function estimation for tracer kinetic analysis in DCE-MRIJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2009Anup Singh PhD Abstract Purpose To develop a methodology for improved estimation of bolus arrival time (BAT) and arterial input function (AIF) which are prerequisites for tracer kinetic analysis of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) data and to verify the applicability of the same in the case of intracranial lesions (brain tumor and tuberculoma). Materials and Methods A continuous piecewise linear (PL) model (with BAT as one of the free parameters) is proposed for concentration time curve C(t) in T1 -weighted DCE-MRI. The resulting improved procedure suggested for automatic extraction of AIF is compared with earlier methods. The accuracy of BAT and other estimated parameters is tested over simulated as well as experimental data. Results The proposed PL model provides a good approximation of C(t) trends of interest and fit parameters show their significance in a better understanding and classification of different tissues. BAT was correctly estimated. The automatic and robust estimation of AIF obtained using the proposed methodology also corrects for partial volume effects. The accuracy of tracer kinetic analysis is improved and the proposed methodology also reduces the time complexity of the computations. Conclusion The PL model parameters along with AIF measured by the proposed procedure can be used for an improved tracer kinetic analysis of DCE-MRI data. J. Magn. Reson. Imaging 2009;29:166,176. © 2008 Wiley-Liss, Inc. [source] Noncompartmental kinetic analysis of DCE-MRI data from malignant tumors: Application to glioblastoma treated with bevacizumabMAGNETIC RESONANCE IN MEDICINE, Issue 2 2010Ruediger E. Port Abstract Dynamic contrast enhanced MRI contrast agent kinetics in malignant tumors are typically complex, requiring multicompartment tumor models for adequate description. For consistent comparisons among tumors or among successive studies of the same tumor, we propose to estimate the total contrast agent,accessible volume fraction of tumor, including blood plasma, vpe, and an average transfer rate constant across all tumor compartments, Ktrans.av, by fitting a three-compartment tumor model and then calculating the area under the tumor impulse-response function (= vpe) and the ratio area under the tumor impulse response function over mean residence time in tumor (= Ktrans.av). If the duration of dynamic contrast enhanced MRI was too short to extrapolate the tumor impulse-response function to infinity with any confidence, then conditional parameters v and Ktrans.av* should be calculated from the available incomplete impulse response function. Median decreases of 33% were found for both v and Ktrans.av* in glioblastoma patients (n = 16) 24 hours after the administration of bevacizumab (P < 0.001). Median total contrast-enhancing tumor volume was reduced by 18% (P < 0.0001). The combined changes of tumor volume, v, and Ktrans.av* suggest a reduction of true vpe, possibly accompanied by a reduction of true Ktrans.av. The proposed method provides estimates of a scale and a shape parameter to describe contrast agent kinetics of varying complexity in a uniform way. Magn Reson Med, 2010. © 2010 Wiley-Liss, Inc. [source] An automated method for nonparametric kinetic analysis of clinical DCE-MRI data: Application to glioblastoma treated with bevacizumabMAGNETIC RESONANCE IN MEDICINE, Issue 5 2010Gregory Z. Ferl Abstract Here, we describe an automated nonparametric method for evaluating gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) kinetics, based on dynamic contrast-enhanced,MRI scans of glioblastoma patients taken before and after treatment with bevacizumab; no specific model or equation structure is assumed or used. Tumor and venous blood concentration-time profiles are smoothed, using a robust algorithm that removes artifacts due to patient motion, and then deconvolved, yielding an impulse response function. In addition to smoothing, robustness of the deconvolution operation is assured by excluding data that occur prior to the plasma peak; an exhaustive analysis was performed to demonstrate that exclusion of the prepeak plasma data does not significantly affect results. All analysis steps are executed by a single R script that requires blood and tumor curves as the sole input. Statistical moment analysis of the Impulse response function yields the area under the curve (AUC) and mean residence time (MRT). Comparison of deconvolution results to fitted Tofts model parameters suggests that and AUC of the Impulse response function closely approximate fractional clearance from plasma to tissue (Ktrans) and fractional interstitial volume (ve) . Intervisit variability is shown to be comparable when using the deconvolution method (11% [] and 13%[AUC]) compared to the Tofts model (14%[Ktrans] and 24%[ve]). AUC and both exhibit a statistically significant decrease (P < 0.005) 1 day after administration of bevacizumab. Magn Reson Med 63:1366,1375, 2010. © 2010 Wiley-Liss, Inc. [source] Blood,spinal cord barrier permeability in experimental spinal cord injury: dynamic contrast-enhanced MRINMR IN BIOMEDICINE, Issue 3 2009David M. Cohen Abstract After a primary traumatic injury, spinal cord tissue undergoes a series of pathobiological changes, including compromised blood,spinal cord barrier (BSCB) integrity. These vascular changes occur over both time and space. In an experimental model of spinal cord injury (SCI), longitudinal dynamic contrast-enhanced MRI (DCE-MRI) studies were performed up to 56 days after SCI to quantify spatial and temporal changes in the BSCB permeability in tissue that did not show any visible enhancement on the post-contrast MRI (non-enhancing tissue). DCE-MRI data were analyzed using a two-compartment pharmacokinetic model. These studies demonstrate gradual restoration of BSCB with post-SCI time. However, on the basis of DCE-MRI, and confirmed by immunohistochemistry, the BSCB remained compromised even at 56 days after SCI. In addition, open-field locomotion was evaluated using the 21-point Basso,Beattie,Bresnahan scale. A significant correlation between decreased BSCB permeability and improved locomotor recovery was observed. Copyright © 2008 John Wiley & Sons, Ltd. [source] A method for interleaved acquisition of a vascular input function for dynamic contrast-enhanced MRI in experimental rat tumoursNMR IN BIOMEDICINE, Issue 3 2004Dominick J. O. McIntyre Abstract Dynamic contrast-enhanced MRI is widely used for the evaluation of the response of experimental rodent tumours to antitumour therapy, particularly for the newly developing antiangiogenic and antivascular agents. However, standard models require a time-course for the plasma concentration of contrast agent (usually referred to as the arterial input function) to calculate the transfer constant Ktrans from the dynamic time-course data. Ideally, the plasma concentration time-course should be measured during each experiment to obtain the most accurate measure of Ktrans. This is technically difficult in rodents, so assumed values are generally used. A method is presented here using interleaved acquisitions from a tail coil to obtain the plasma concentration simultaneously with DCE-MRI data obtained from a solenoid coil around the tumour. The SNR of the resulting vascular input function data is high compared with methods using a volume coil to acquire plasma concentrations from the aorta and vena cava. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||