[Show abstract][Hide abstract] ABSTRACT: To evaluate perfusion, diffusion, and spectroscopy values in enhancing and non-enhancing lesions for patients with newly diagnosed gliomas of different grades.
Sixty-seven patients with newly diagnosed glioma were entered into the study 20 grade II, 26 grade III and 21 grade IV. MR data were acquired at 1.5T and included diffusion weighted images (59/67 patients), dynamic perfusion weighted images (30/67 patients) and 3D H-1 MR spectroscopy (64/67 patients). Enhancing and non-enhancing lesions were delineated by a neuroradiologist and applied to maps of relative cerebral blood volume (rCBV), apparent diffusion coefficient (ADC), relative anisotropy (RA) and metabolite intensities.
The median rCBV within enhancing regions of grade IV gliomas was significantly elevated relative to enhancing regions in grade III gliomas and normal brain. ADC was elevated relative to normal brain, but was not significantly different between grades or between enhancing and non-enhancing regions. The RA was higher in the non-enhancing region of grade IV gliomas relative to grade II and grade III. Levels of lactate plus lipid were significantly elevated in grade IV relative to grade II and grade III gliomas. Both enhancing and non-enhancing regions in grade IV gliomas showed significant correlations between CBV, ADC and choline levels.
The data were consistent with grade IV gliomas having higher membrane turnover, increased cell density and increased vascularity within enhancing lesions. Analysis of the correlations among parameters within grade IV gliomas suggested that high vascularity (high rCBV) was correlated with increased cellularity (low ADC) and increased membrane turnover (high choline) in these lesions. The non-enhancing region of grades II and III gliomas had MR parameters consistent with increased cellularity and/or membrane turnover.
NMR in Biomedicine 07/2006; 19(4):463-75. · 3.45 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Brain atrophy reflects the net result of irreversible and destructive pathological processes in multiple sclerosis (MS). The gross morphological changes can be accurately quantified using standard magnetic resonance imaging (MRI) acquisitions and various image analysis tools. The current methods used to assess whole-brain atrophy in patients with MS can be classified into 2 groups based on their reliance on segmentation and registration. Segmentation-based methods employed to measure whole-brain atrophy in MS include the brain parenchymal fraction, the index of brain atrophy, the whole-brain ratio, the brain to intracranial capacity ratio, fuzzy connectedness/Udupa's method, 3DVIEWNIX, the Alfano method, and SIENAX. Current registration-based methods used to measure whole-brain atrophy in MS include the brain boundary shift integral, SIENA, statistical parametric mapping, template-driven seg mentation, and voxel-based morphometry. Most of the methods presented here are sensitive to subtle changes in brain structures and have been successfully applied to MS as measures of whole-brain atrophy. Yet comparative studies of these methods are limited and are complicated by the lack of a gold standard for image acquisition, a segmentation algorithm, an image analysis method, or a reproducibility measure. Overall, the measure of whole-brain atrophy from MRI contributes to an appreciation of the dynamics of MS pathology and its relationship to the clinical course of MS. Determination of the relative reproducibility, precision, sensitivity, and validity of these methods will promote the use of whole-brain atrophy measures as components of comprehensive MRI-based outcome assessment in MS clinical trials.
Journal of Neuroimaging 08/2004; 14(3 Suppl):11S-19S. · 1.41 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The determination of the form of prion disease and early diagnosis are important for prognostic, public health, and epidemiologic reasons.
To describe a patient with sporadic Creutzfeldt-Jakob disease (sCJD) who had a clinical history and initial electroencephalogram and magnetic resonance imaging findings consistent with variant CJD (vCJD).
Results of a repeated electroencephalogram were suggestive of sCJD, and a subsequent brain biopsy confirmed this diagnosis.
This case cautions against relying solely on T2- and diffusion-weighted pulvinar hyperintensity and clinical features to differentiate between vCJD and sCJD, and further supports established diagnostic criteria for vCJD.
[Show abstract][Hide abstract] ABSTRACT: We herein present a methodology for standardized and clinically applicable measurement of T1 relaxation maps with high resolution and volumetric coverage by using the commercially available 3D spoiled gradient-echo sequence. The reproducibility of the T1 metrics derived from these maps and their sensitivity to distinguish between control participants and patients with multiple sclerosis are evaluated.
Axial view 3D RF spoiled data sets with two flip angles were acquired at 1.5 T to generate the T1 maps, with all other imaging parameters (27/6 ms [TR/TE]; field of view, 180 x 240 x 186 mm(3); matrix, 192 x 256 x 124) kept identical between the two acquisitions. T1 maps were collected from 20 normal control participants and 32 patients with multiple sclerosis. An automated and operator-independent method was developed to segment the relaxation maps and define T1 metrics.
We showed that the metrics derived from these maps to represent tissue characteristics were highly reproducible (coefficient of variation, approximately 1% to 4%) and were significantly different between normal control participants and patients with multiple sclerosis (P <.001) for the small cohort of patients in this study.
The commercially accessible 3D spoiled gradient-echo sequence can be used to generate T1 relaxation maps with high resolution and volumetric coverage. The metrics derived from the relaxation maps are reproducible and have been shown to be sensitive to qualitative and quantitative differences between subgroups of patients with multiple sclerosis and control participants, with strong statistical significance. The use of a commercially available sequence enables the standardization and comparison of T1 metrics across different multiple sclerosis centers.
American Journal of Neuroradiology 01/2003; 24(1):58-67. · 3.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The goal of this study was to determine whether presurgical metabolite levels measured by 3D MR Spectroscopic Imaging (MRSI) can accurately detect viable cancer within human brain tumor masses. A total of 31 patients (33 exams, 39 pathology correlations) with brain tumors were studied prior to surgical biopsy and/or resection. The 3D MRSI was obtained with a spatial resolution of 0.2 to 1 cc throughout the majority of the mass and adjacent brain tissue using PRESS-CSI localization. Levels of choline, creatine and NAA were estimated from the locations of the resected tissue and normalized to normal appearing brain tissue. The data were correlated with subsequent histologic analysis of the biopsy tissue samples. Although there were large variations in the metabolite ratios, all regions of confirmed cancer demonstrated significant choline levels and a mean choline/NAA ratio of 5.84 + 2.58 with the lowest value being 1.3. This lowest value is greater than 4 standard deviations above the mean (0.52 +/- 0.13) found in 8 normal volunteers. The choline signal intensities in confirmed cancers were significantly elevated compared to normal appearing brain tissue with a mean ratio of 1.71 +/- 0.69. Spectra with no significant metabolite levels were observed in the non-enhancing necrotic core of the tumor masses. The results of this study indicate that 3D MRSI of brain tumors can detect abnormal metabolite levels in regions of viable cancer and grades and can differentiate cancer from necrosis and/or normal brain tissue.
Magnetic Resonance Imaging 02/2001; 19(1):89-101. · 2.06 Impact Factor