MRSI Data (mrsi + data)

Distribution by Scientific Domains

Selected Abstracts

High-field MRSI of the prostate using a transmit/receive endorectal coil and gradient modulated adiabatic localization

Jamie Near PhD
Abstract Purpose To demonstrate in vivo magnetic resonance spectroscopic imaging (MRSI) of the human prostate at 4.0T using a transmit/receive endorectal coil and a pulse sequence designed specifically for this application. Materials and Methods A solid, reusable endorectal probe was designed for both radiofrequency transmission and reception. Finite difference time domain (FDTD) simulations were performed to characterize the coil's electric field distribution, and temperature measurements were performed in a beef tissue phantom to determine the coil's safe operating limit. The localization by selective adiabatic refocusing (LASER) pulse sequence was implemented using six gradient modulated offset independent adiabatic (GOIA) pulses for very sharp, B1 -insensitive voxel localization. Results Based on the simulations and temperature measurements, the coil's safe operating limit was conservatively estimated to be 1.0W for 15 minutes. The transition width of the GOIA pulse selection profiles was only 6% of the bandwidth, compared with 22% for a specific absorption rate (SAR)-matched conventional adiabatic pulse. Using the coil and pulse sequence described here, MRSI data were successfully acquired from a patient with biopsy-proven prostate cancer, with a nominal voxel size of 0.34 cc in a scan time of 15 minutes. Conclusion This work demonstrates the safe and effective use of a transmit/receive endorectal coil for in vivo MRSI of the prostate. J. Magn. Reson. Imaging 2009;30:335,343. 2009 Wiley-Liss, Inc. [source]

Proton MR spectroscopic imaging of the medulla and cervical spinal cord,

Richard A.E. Edden PhD
Abstract Purpose To demonstrate the feasibility of quantitative, one-dimensional proton MR spectroscopic imaging (1D-MRSI) of the upper cervical spine and medulla at 3.0 Tesla. Materials and Methods A method was developed for 1D-point-resolved spectroscopy sequence (PRESS)-MRSI, exciting signal in five voxels extending from the pontomedullary junction to the level of the C3 vertebra, and performed in 10 healthy volunteers to generate control data. Results High-resolution 1D-MRSI data were obtained from all 10 subjects. Upper cervical spine concentrations of choline, creatine, and N-acetyl aspartate were estimated to be 2.8 0.5, 8.8 1.8, and 10.9 2.7 mM, respectively, while in the medulla they were 2.6 0.5, 9.1 1.7, and 10.8 0.9 mM. Conclusion Quantitative 1D-MRSI of the upper cervical spine has been shown to be feasible at 3.0 Tesla. J. Magn. Reson. Imaging 2007;26:1101,1105. 2007 Wiley-Liss, Inc. [source]

Novel methodology for the archiving and interactive reading of clinical magnetic resonance spectroscopic imaging

Jeffry R. Alger
Abstract Archiving clinical magnetic resonance spectroscopic imaging (MRSI) data and presenting the data to specialists (e.g., neuroradiologists, neurosurgeons, neurologists, neuro-oncologists, and MR scientists) who work in different physical locations is a practical problem of significance. This communication describes a novel solution. The study hypothesis was that it is possible to use widely available distributed computing techniques to create a clinical MRSI user interface addressable from any personal computer with a suitable network connection. A worldwide web MRSI archive and interface system was created that permits the user to interactively view individual MRSI voxel spectra with correlation to MR images and to parametric spectroscopic images. Web browser software (i.e., Netscape and Internet Explorer) permits users in various physical locations to access centrally archived MRSI data using a variety of operating systems and client workstations. The system was used for archiving and displaying more than 1000 clinical MRSI studies performed at the authors' institution. The system also permits MRSI data to be viewed via the Internet from distant locations worldwide. The study illustrates that widely available software operating within highly distributed electronic networks can be used for archiving and interactive reading of large amounts of clinical MRSI data. Magn Reson Med 48:411,418, 2002. 2002 Wiley-Liss, Inc. [source]

Cerebellar metabolic symmetry in essential tremor studied with 1H magnetic resonance spectroscopic imaging: Implications for disease pathology

Elan D. Louis MD
Abstract The pathological basis for essential tremor (ET) is not known; however, metabolic changes in the cerebellum can be observed in positron emission tomography (PET) and 1H magnetic resonance spectroscopic imaging (MRSI) studies. Tremor is relatively symmetric in ET, suggesting that underlying metabolic changes could be also symmetric. The degree of metabolic asymmetry in the cerebellum, however, has not yet been studied in ET, and knowledge about distribution and laterality of metabolic changes might shed some light on basic disease mechanisms. We measured brain metabolism (N -acetylaspartate[NAA]/creatine [tCR]) to obtain an asymmetry index for cerebellar cortical metabolism ET patients compared with that in controls. This index, a percentage, was calculated as |(value right , value left)|/(value right + value left) 100. Multislice 1H MRSI data were acquired for 20 patients and 11 controls. In ET patients, mean right and left cerebellar cortical NAA/tCR values were 1.61 0.42 and 1.55 0.38, respectively, compared with 1.81 0.62 and 1.87 0.49 in controls. The difference between right and left cerebellar cortical NAA/tCR was also calculated for each subject. In ET patients, the mean right-left difference was 0.14 0.11, compared with 0.32 0.27 in controls (P = 0.016). The mean cerebellar cortical asymmetry index was low in ET (8.8 6.1%), one-half of that in controls (17.0 13.7%, P = 0.027). These data suggest that pathological lesions in ET patients, which remain elusive, might be distributed similarly in each cerebellar cortex. Postmortem studies are needed to confirm these preliminary imaging results. 2004 Movement Disorder Society [source]

Quantification of prostate MRSI data by model-based time domain fitting and frequency domain analysis

Pieter Pels
Abstract This paper compares two spectral processing methods for obtaining quantitative measures from in vivo prostate spectra, evaluates their effectiveness, and discusses the necessary modifications for accurate results. A frequency domain analysis (FDA) method based on peak integration was compared with a time domain fitting (TDF) method, a model-based nonlinear least squares fitting algorithm. The accuracy of both methods at estimating the choline,+,creatine,+,polyamines to citrate ratio (CCP:C) was tested using Monte Carlo simulations, empirical phantom MRSI data and in vivo MRSI data. The paper discusses the different approaches employed to achieve the quantification of the overlapping choline, creatine and polyamine resonances. Monte Carlo simulations showed induced biases on the estimated CCP:C ratios. Both methods were successful in identifying tumor tissue, provided that the CCP:C ratio was greater than a given (normal) threshold. Both methods predicted the same voxel condition in 94% of the in vivo voxels (68 out of 72). Both TDF and FDA methods had the ability to identify malignant voxels in an artifact-free case study using the estimated CCP:C ratio. Comparing the ratios estimated by the TDF and the FDA, the methods predicted the same spectrum type in 17 out of 18 voxels of the in vivo case study (94.4%). Copyright 2006 John Wiley & Sons, Ltd. [source]