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MRI Analysis (mri + analysis)
Selected AbstractsFerucarbotran expands area treated by radiofrequency ablation in rabbit liversJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 7pt2 2008Tatsuya Miyake Abstract Background and Aim:, Several studies have examined the factors involved with expansion of the coagulation volume following radiofrequency ablation (RFA). Ferucarbotran contains superparamagnetic iron oxide that generates heat in a radiofrequency electric field and may have an effect on the area affected by RFA. We attempted to determine whether ferucarbotran administration expands radiofrequency-ablated volume using a rabbit model. Methods:, A total of 15 male Japanese white rabbits (16 weeks old) were used and divided into three groups of five each. A 1-mL saline solution was given intravenously into a dorsal ear vein in the control group, whereas 1 mL ferucarbotran solution (0.016 mL/kg bodyweight) was given to the common-dose group and 1 mL of a twofold concentrated ferucarbotran solution (0.032 mL/kg bodyweight) was given to the high-dose group. RFA was performed with a cool-tip electrode 4 h after the administration and immediately thereafter the rabbits were killed, and the volume of the ablated area measured using magnetic resonance imaging (MRI). Following the MRI analysis, the rabbit's livers were resected, and the maximum short axis diameter of the ablated area in each was measured. Results:, None of the rabbits died during the RFA procedure. The volume of the ablated area estimated on MR images in the ferucarbotran-administered groups was larger than that in the control group. Further, our macroscopic assessment showed that the maximum short axis diameter had a tendency to increase with ferucarbotran administration. Conclusion:, Ferucarbotran may expand the area treated by RFA. [source] Clinical,Magnetic Resonance Imaging Correlations in Multiple SclerosisJOURNAL OF NEUROIMAGING, Issue 2005Robert Zivadinov MD ABSTRACT Conventional magnetic resonance imaging (MRI) has routinely been used to improve the accuracy of multiple sclerosis (MS) diagnosis and monitoring, detect the effects of diseasemodifying therapy, and refine the utility of clinical assessments. However, conventional MRI measures, such as the use of lesion volume and count of gadolinium-enhancing and T2 lesions, have insufficient sensitivity and specificity to reveal the true degree of pathological changes occurring in MS. Newer metrics of MRI analysis, including T1-weighted hypointense lesions (black holes) and central nervous system (CNS) atrophy measures, are able to capture a more global picture of the range of tissue alterations caused by inflammation, demyelination, axonal loss, and neurodegeneration. There is mounting evidence that these MRI measures correlate well with existing and developing neurological impairment and disability. In so doing, these MRI techniques can help elucidate the mechanisms underlying the pathophysiology and natural history of MS. The current understanding is that T1 black holes and CNS atrophy more accurately reflect the neurodegenerative and destructive components of the MS disease process. Therefore, the shortand long-term studies that aim to measure the degree and severity of the neurodegenerative MS disease process should incorporate these MRI metrics as part of their standard routine MRI protocols. [source] Focal Cortical Dysplasia: Improving Diagnosis and Localization With Magnetic Resonance Imaging Multiplanar and Curvilinear ReconstructionJOURNAL OF NEUROIMAGING, Issue 3 2002Maria Augusta Montenegro MD ABSTRACT Objective. To establish the contribution of multiplanar reconstruction (MPR) and curvilinear reformatting (CR) to the MRI investigation of focal cortical dysplasia (FCD). Methods. From a group of patients with intractable frontal lobe epilepsy, we selected patients with neuroimaging diagnosis of FCD. The diagnosis of FCD was based on the neuroimaging findings after a three step evaluation, always in the same order: (a) plain MRI films, (b) MPR, and (c) CR. After the selection of patients, the process of reviewing all the images in the three stages described above was performed by one of us, who did not take part on the selection of patients nor on the initial evaluation, and who was blind to the clinical and EEG findings of the patients. For data analysis, we first assessed the contribution of the additional findings of MPR analysis compared to the results of the evaluation using only plain MRI films, as is usually done in routine practice. Second, we assessed the contribution of CR to the findings of plain MRI films plus MPR. After completing the multistep evaluation, we all went back to review the plain MRI films with knowledge of lesion topography, in order to identify possible subtle features associated with FCD. Results. Seventeen patients met the inclusion criteria. Twelve had imaging diagnosis of FCD and were included in the second step of this project. Plain films of high resolution MRI showed the lesion in 6 (50%) of the 12 patients. By adding MPR to the plain MRI films, we identified lesions in all 12 patients. Furthermore, we found that MPR provided a better lesion localization and ascertainment of its relationship to other cerebral structures in 5 of 6 (83%) patients who had a lesion identified on plain films. By adding CR to the plain MRI films plus MPR analysis, we observed that (a) CR also allowed the identification of the dysplastic lesion in all patients, (b) CR improved lesion localization in one patient, and (c) CR provided a better visualization of the lesion extent in 4 patients (33%), showed a larger lesion in 3, and demonstrated that part of the area suspected as abnormal was more likely volume averaging in 2. Conclusion. MPR and CR analysis add to the neuroimaging evaluation of FCD by improving the lesion diagnosis and localization. CR helps to establish the extent of the lesion more precisely, allowing the visualization of some areas not shown on high resolution MRI and MPR. These techniques are complementary and do not replace the conventional wisdom of MRI analysis. [source] Evaluation of a method to map tibiofemoral contact points in the normal knee using MRIJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2004Jennifer M. Scarvell Abstract A technique using magnetic resonance imaging (MRI) is proposed for analysis of knee motion that is practical in the clinical situation. T1 weighted fast spin echo (FSE) and spoiled gradient echo (GE) sequences were compared to image both knees at 15° intervals from 0° to 90° flexion, while unloaded and loaded. The medial and lateral tibiofemoral contact points were mapped reliably using both FSE sequences and GE sequences with intra-class correlation(2,1) of 0.96 (CI 99% = 0.94,0.97) and 0.94 (CI 99% = 0.91,0.97), respectively. Results were consistent with the current literature on knee motion: the medial and lateral tibiofemoral contact pathways were different (F1.80 = 253.9, p < 0.0001) reflecting the longitudinal rotation of the knee, the loaded and unloaded knees were not different in the healthy knee (F1.80 = 0.007, p = 0.935), and the left and right knee were consistent for each individual (F1.80 = 0.005, p = 0.943). Therefore, right to left differences may be attributed to pathology. MRI analysis of knee kinematics as described by this technique of tibiofemoral contact point mapping provides a robust and reliable method of recording the tibiofemoral contact pattern of the knee. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] Twenty-five pitfalls in the analysis of diffusion MRI data,NMR IN BIOMEDICINE, Issue 7 2010Derek K. Jones Abstract Obtaining reliable data and drawing meaningful and robust inferences from diffusion MRI can be challenging and is subject to many pitfalls. The process of quantifying diffusion indices and eventually comparing them between groups of subjects and/or correlating them with other parameters starts at the acquisition of the raw data, followed by a long pipeline of image processing steps. Each one of these steps is susceptible to sources of bias, which may not only limit the accuracy and precision, but can lead to substantial errors. This article provides a detailed review of the steps along the analysis pipeline and their associated pitfalls. These are grouped into 1 pre-processing of data; 2 estimation of the tensor; 3 derivation of voxelwise quantitative parameters; 4 strategies for extracting quantitative parameters; and finally 5 intra-subject and inter-subject comparison, including region of interest, histogram, tract-specific and voxel-based analyses. The article covers important aspects of diffusion MRI analysis, such as motion correction, susceptibility and eddy current distortion correction, model fitting, region of interest placement, histogram and voxel-based analysis. We have assembled 25 pitfalls (several previously unreported) into a single article, which should serve as a useful reference for those embarking on new diffusion MRI-based studies, and as a check for those who may already be running studies but may have overlooked some important confounds. While some of these problems are well known to diffusion experts, they might not be to other researchers wishing to undertake a clinical study based on diffusion MRI. Copyright © 2010 John Wiley & Sons, Ltd. [source] RNAi-mediated reversible opening of the blood-brain barrierTHE JOURNAL OF GENE MEDICINE, Issue 8 2008Matthew Campbell Abstract Background The blood-brain barrier (BBB) contains tight junctions (TJs) which reduce the space between adjacent endothelial cells lining the fine capillaries of the microvasculature of the brain to form a selective and regulatable barrier. Methods Using a hydrodynamic approach, we delivered siRNA targeting the TJ protein claudin-5 to the endothelial cells of the BBB in mice. Results We have shown a significant decrease in claudin-5 mRNA levels 24 and 48 hours post-delivery of siRNA, with levels of protein expression decreasing up to 48 hours post-injection compared to uninjected, phosphate-buffered saline (PBS)-injected and non-targeting siRNA-injected mice. We observed increased permeability at the BBB to molecules up to 742 Da, but not 4400 Da, using tracer molecule perfusion and MRI analysis. To illustrate the functional efficacy of size-selective and transient barrier opening, we have shown that enhanced delivery of the small neuropeptide thyrotropin-releasing hormone (TRH) (MW 360 Da) to the brains of mice 48 hours post-injection of siRNA targeting claudin-5 significantly modifies behavioural output. Conclusions These data demonstrate that it is now possible to transiently and size-selectively open the BBB in mice, allowing in principle the delivery of a wide range of agents for the establishment and treatment of experimental mouse models of neurodegenerative, neuropsychiatric and malignant diseases. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||