Marie-Curie Fellow Research & Training Network www.fast-mrs.eu C. Labadie (ER) Marie Curie Fellow (ER) of the FAST project :: partner 4, Leipzig, Germany Involved in the following tasks T2 Acquisition: T2 and T4 investigate and develop advanced, innovative ways of acquiring MRSI data, at the forefront of MR-methodology. This is a highly challenging task exploring uncharted paths. T4.1 Signal processing: MRSI signals contain a strong non-parametric part from macromolecules that perturbs the wanted, parametric, part from metabolites. This requires a semi-parametric approach which is still under development, worldwide. T5 eMRUI Software package: Hands-free use for Intra Operative MRSI (simulation of scanner noise). T7 Training: Weekly reviews with related records and document object identifiers (DOI). Pulse sequence programming training (in preparation). Research focus Macromolecule baseline: Application of the Cross-Regularized Inverse Laplace Transform of Short Echo Time STEAM Spectra Acquired with Variation of the Mixing Time The macromolecule baseline contained in short-echo-time magnetic resonance spectra of the human brain can be estimated by nulling metabolites with an inversion recovery preparation. The inverse Laplace transform (ILT) of a set of metabolite nulled STEAM spectra acquired at varying mixing times (TM) enables to establish a T1-map of the macromolecule baseline. The ILT is typically performed by regularizing the distribution of relaxation times (relaxogram), leading to a broad unimodal relaxogram when the SNR is low, as in the case of proton spectroscopy. An increase in resolution can be achieved by regularizing the frequency dimension (cross-regularization) instead of the relaxogram. We developed a method to combine the regularization of both the frequency dimension and of the relaxogram (2D-regularization).   Myelin Water Fraction: Estimation of the Myelin Water Fraction by Means of Cross-Regularized Inverse Laplace Transform of Look-Locker FLASH Images The T1 relaxogram (continuous distribution of relaxation times constants) of a slice of the brain of an healthy volunteer was computed by cross-regularized inverse Laplace transform (ILT) of 64 Look-Locker FLASH images measured at 4 Tesla with geometric sampling of the inversion recovery (TI 24.4 ms - 11.4 sec). The T1 relaxogram exhibits four T1 components respectively attributed to the water trapped in myelin (T1 ca. 168 ms), white matter (T1 ca. 1.17 sec), gray matter (T1 ca. 1.58 sec) and CSF (T1 ca. 4.06 sec). A histogram of the myelin water fraction (MWF), the intensity of the myelin water peak divided by the total water signal, reveals a bimodal distribution. Selecting a MWF threshold of ca. 0.07 effectively performs a segmentation of white (MWF 0.12 + 0.016) and gray matter (MWF 0.047 + 0.022).   Publications Cross-Regularized Inverse Laplace Transform C. Labadie, D. V. Ott, T. H. Jochimsen, J-H. Lee, H. E. Möller: Comparison of Myelin Water Fraction in Cross-Regularized T1-Relaxograms of Normal White Matter at 3T and 7T and of Normal-Appearing White Matter at 3T, ePoster, Proc. 17th Scientific Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM), Honolulu, Hawaii, USA, 18-24 April 2009. The myelin water fraction (MWF) measured by cross-regularized T1-relaxography exhibits an increase between 3T and 7T in the white matter of a healthy volunteer. The field dependency of MWF and T1 allowed an estimation of the exchange of water between myelin and the axonal space with a mean resident time of water in myelin of 666.4 ± 369.5 ms. A preliminary study of lesions and normal-appearing white matter in an MS-patient suggests a slight change in the bimodal distribution of MWF.   C. Labadie, J-H. Lee, S. Jarchow, W. D. Rooney, C. S. Springer, H. E. Möller: Detection of the Myelin Water Fraction in 4 Tesla Longitudinal Relaxation Data by Cross-Regularized Inverse Laplace Transform, Poster 2243, Proc. 16th Scientific Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM), Toronto, Canada, 3-9 May 2008. The multiexponential analysis of normal brain 1H2O inversion recovery data, geometrically sampled starting at ca. 40 ms, reveals the presence of a small relaxographic peak at T1 = ca. 200 ms. This corresponds to 0.12 fraction of the total white matter water signal. It is attributed to the myelin water fraction (MWF), and suggests that water exchange in the human brain is sufficiently slow to enable the observation of water compartmentalization in longitudinal relaxation. In gray matter, the MWF represents ca. 0.05 of its total water and the peak is positioned at the same T1 value as in white matter.   C. Labadie, J-H. Lee, H. E. Möller: Estimation of the Inversion-Pulse Efficiency in the Context of Multi-Exponential Analysis of Spin-Lattice Relaxation, Poster 1418, Proc. 16th Scientific Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM), Toronto, Canada, 3-9 May 2008. A CONTIN-based procedure to estimate the inversion-pulse efficiency in the context of multi-exponential longitudinal relaxation is proposed and compared to a mono-exponential three-parameter NLLS fit. Simulations using continuous T1 distributions show that the three-parameter NLLS fit underestimates the efficiency when a small T1 peak is present below 400 ms. Such underestimation of the efficiency is apparent in the white matter of the human brain at 4 Tesla. The novel procedure enables to adequately estimate the inversion-pulse efficiency necessary to perform a reliable multi-exponential analysis of spinlattice relaxation.   C. Labadie, S. Jarchow, H. E. Möller: Estimation of Fractional Contributions of White and Gray Matter by Cross-Regularized Inverse Laplace Transform, Poster, Proc. 15th Scientific Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM), Berlin, Germany, 19-25 May 2007. A Look-Locker train of inversion recovery images was processed with a cross-regularized ILT that takes advantage of pixel connectedness to leave the T1 distribution relatively unconstrained thus permitting to observe minor changes in the white and gray matter mixture. A detailed analysis of the T1 distribution enables to estimate the fractional contributions of white matter, gray matter and CSF. The resulting segmentation does not require prior neuro-anatomical knowledge.   S. Jarchow, C. Labadie, H. Möller: Characterization of Macromolecular Components by Cross-Regularized Inverse Laplace Transform of Human Proton MR-Spectroscopy at 3 Tesla, oral scientific presentation, Proc. 22nd Annual Meeting of the European Society for Magnetic Resonance in Medicine and Biology (ESMRMB), p. 269, Basel, Switzerland, 15-18 September 2005. The use of metabolite nulled spectra may be hampered by T1 differences and distributions, thus limiting investigations to macromolecular peaks up-field of NAA (M1-M4). We recently applied a novel cross-regularized inverse Laplace transform (ILT) to MRS data acquired at various mixing times that computes a two-dimensional map as a function of PPM and log(T1). In this work we introduce a further post-processing step to separate the macromolecular components from the metabolites.   C. Labadie, H. Möller, S. Jarchow: Cross-Regularisation of the Frequency Domain Enables High-Resolution Inverse Laplace Transform of the Human Brain Single Voxel Spectroscopy at 3 Tesla, oral scientific presentation, Proc. 13th Scientific Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM), p. 56, Miami Beach, Florida, USA, 7-13 May 2005. The separation of metabolites and macromolecules relies on macromolecule basis sets provided as prior-knowledge for quantitation procedures. An alternate approach based on the inverse Laplace transform (ILT) of STEAM spectra acquired at variable TE or TM is proposed to estimate the proton density distributions as a function of T2 or T1. An improved ILT cross-regularisation of the frequency domain was successfully applied to 3 Tesla data from parietal white matter of a human volunteer.   C. Labadie, S. Jarchow: Cross-Regularised Relaxographic Imaging, ePoster, Proc. 12th Scientific Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM), p. 2707, Kyoto, Japan, 15-21 Mai 2004. A novel cross-regularization of relaxographic imaging provides an increased resolution of the continuous distribution of longitudinal relaxation times with a doped phantom. The shape of the transversal relaxation peaks was investigated in the context of pig knee cartilage in various angles to the static field and subjected to a small pressure of 50 kPa. The cross-regularization was able to resolve peak features that are otherwise smoothed away by the general-purpose regularization.   Relaxographic Imaging C. Labadie, J-H. Lee, G. Vetek, C.S. Springer: Relaxographic Imaging, Article, Journal of Magnetic Resonance Series B, Vol. 105, pp. 99-112, 1994.   C. Labadie, D. Gounot, Y. Mauss, B. Dumitresco: Data sampling in MR relaxation, Article, Magnetic Resonance Materials in Physics, Biology and Medicine (MAGMA), Vol. 2, pp. 383-385, 1994.   C. Labadie, J-H. Lee, G. Vetek, I. Palyka, C.S. Springer: Longitudinal Relaxographic Imaging with Ultra-fast Sampling, Oral scientific presentation, Proc. 11th Annual Scientific Meeting and Exhibition of the Society of Magnetic Resonance in Medicine (held jointly with the 9th Annual Congress of the ESMRMB), Vol. 1, p. 887, Berlin, 8-14 August 1992.   C. Labadie, T.M. Button, W.D. Rooney, J-H. Lee, C.S. Springer: Relaxographic Imaging, Poster, Proc. 10th Annual Scientific Meeting and Exhibition of the Society of Magnetic Resonance in Medicine, Work in Progress, p. 1218, San Francisco, 10-16 August 1992.   Relaxographic Analysis J-H. Lee, C. Labadie, C.S. Springer, G.S. Harbison: Two-Dimensional Inverse Laplace Transform NMR: Altered Relaxation Times Allow Detection of Exchange Correlation, Article, Journal of the American Chemical Society, Vol. 115, pp. 7761-7764, 1993.   J-H. Lee, C. Labadie, C. Labadie, G. Vetek, C.S. Springer: Relaxographic Discrimination of Water Spaces in Cell Suspensions, Oral scientific presentation, Proc. 12th Annual Scientific Meeting and Exhibition of the Society of Magnetic Resonance in Medicine, Vol. 1, p. 140, New York, 14-20 August 1993.   J-H. Lee, C. Labadie, C.S. Springer: Relaxographic Analysis of 23Na Resonances, Poster talk, Proc. 11th Annual Scientific Meeting and Exhibition of the Society of Magnetic Resonance in Medicine (held jointly with the 9th Annual Congress of the ESMRMB), Vol. 2, p. 2214, Berlin, 8-14 August 1992.   J-H. Lee, Y. Seo, M. Murakami, C. Labadie, C.S. Springer: SR-Free Discrimination of Compartmental 23Na Resonances by Relaxographic Analysis : Erythrocyte Suspensions, Poster, Proc. 11th Annual Scientific Meeting and Exhibition of the Society of Magnetic Resonance in Medicine (held jointly with the 9th Annual Congress of the ESMRMB), Work in Progress, p. 2222, Berlin, 8-14 August 1992.   Diffusion Tensor Imaging S. Jarchow, C. Labadie: Diffusion Tensor Imaging Auswertung Courseware, eLearning Courseware, Prinzip der Diffusion Tensor Berechnung, MATLAB Umsetzung, Beispiele, Präsentation, Uniklinikum Jena, 26. Februar 2004.   S. Jarchow, R. Schlösser, I. Nenadic, S. Köhler, E. Sinsel, G. Wagner, C. Labadie, I. Krumbein, C. Fitzek, J. Reichenbach, H. Sauer: Optimized Voxel-Based Group Analysis of Diffusion Tensor Imaging by Means of Barycentric Linear Anisotropy, Abstract und Posterpräsentation, Deutsche Gesellschaft für Klinische Neurophysiologie und funktionelle Bildgebung, 49. Jahrestagung der DGKN, Jena, 15-19 September 2004.   Functional Magnetic Resonance Imaging G. Cros, F. Hennel, N. Bolo, F. Girard, F. Hodé, C. Labadie, J.F. Nédélec, J.P. Macher, M. Décorps: Visualisation of Vein Effect in Functional Imaging using Phase Gradient Methods, Poster, Proc. 1st Symposium on Magnetic Resonance Applied to Psychiatry, Mapping Brain Function, p. 43, Rouffach, France, 29-30 September 1994.

Marie-Curie Research & Training Network Advanced Signal-Processing for Ultra-Fast Magnetic Resonance Marie Curie fellows   C. Labadie (ER)   Partner 4 - Leipzig   Contact   Weekly reviews   Links Marie Curie actions