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Advanced signal-processing for ultra-fast magnetic resonance Spectroscopic Imaging, and Training

Final Activity Report Summary - FAST (Advanced Signal-processing for Ultra-Fast Magnetic Resonance Spectroscopic Imaging, and Training)

Magnetic Resonance Imaging (MRI) non-invasively visualises anatomy of a living subject by using the signal from the magnetic 1H nuclei of water in that subject. But MRI cannot visualise biochemistry. The latter requires MR Spectroscopy (MRS). Combining MRI and MRS results in MRS Imaging (MRSI). MRSI can non-invasively provide in vivo images of biochemistry using signals from magnetic nuclei in disease biomarkers (metabolites). FAST was multi-disciplinary, its expertise comprising medicine, biochemistry, chemistry, physics, data processing, informatics. Hence, FAST was imminently amenable to broad training of young researchers.

FAST's main tasks were:
1) MRSI Methodology,
2) Virtual Scanner,
3) MRS/MRSI Signal Processing,
4) Information System,
5) Diseases,
Metabolomics, 6) Training and Transfer of Knowledge.

Task 1 concerned methodology for making MRSI faster and more sensitive. This is highly relevant because the concen-trations of metabolites in living subjects are at best four orders of magnitude below that of water. In addition, the polari-sation of magnetic nuclei, which constitutes the basis of the MRSI signal, is low too. FAST reached its goals by: Hyper-polarising 13C and 15N nuclei which enhanced the signal-to-noise ratio (SNR) by up to four orders of magnitude; new methods (SPECIAL and semi-LASER) for manipulating magnetic nuclei at high magnetic field; ultrafast segmented centre-out echo-planar MRSI; rapid 31P MRSI; temperature-reading MRSI; micro-coils for MRS.

Task 2 concerned sophisticated quantum-mechanical simulation of metabolite signals. This is rapidly becoming an in-dispensable part of data processing so as to alleviate the effect of low SNR. The challenge is to simulate all conceivable manipulations of nuclei programmed in a scanner. FAST made a new, powerful simulation tool enabling handling of hetero-nuclear spin systems and pulse sequence generalization for the simulation of spatially or spectrally selective excitation. These algorithms are being integrated in its software package jMRUI, including a new graphical user interface for the clinic.

Task 3 concerned MRS/MRSI data processing which included semi-parametric estimation and signal processing. In the real world, data processing is hampered by the fact that the model function of the signal at hand is partly unknown. FAST successfully concentrated on: unknown spectral lineshape, metabolite-based wavelets, genetic algorithms for more stable solutions, processing ex vivo measured data, combining quantum-mechanics and parameter estimation. New algorithms are being plugged into FAST's software package jMRUI.

Task 4 concerned the Software Package jMRUI itself (1800 licensees in 2010) and was a major deliverable of FAST. It resulted from efforts of the entire FAST Network. jMRUI was completely redesigned as a plug-in platform with new functionalities and version 4.0 was released world-wide on 10-2009. Next, jMRUI 4.1 was enriched with more plug-ins, offering advanced functionalities such as a cutting-edge virtual scanner and plug-ins tuned to the clinic. This version will be released in March 2011. In addition, a prototype of a vocal interface was developed for hands-off clinical use, and a new jMRUI Website was designed.

Task 5. Naturally, application within FAST of MRS/MRSI to Diseases and Metabolomics was indispensable. The fol-lowing topics were studied with MRS/MRSI. Humans: Multiple sclerosis, differential diagnosis of glioblastomas and metastases, disturbed lipid metabolism in early diabetes, non-invasive prostate cancer detection. Animals: Brain glioblastoma and edema, model of Alzheimer's disease, lipid metabolism.

Task 6. The jMRUI constituted an outstanding vehicle for Training and Transfer of Knowledge. It was demoed in the Booths of Philips and Siemens at the most prominent Medical Imaging International Annual Conference ISMRM during 2007-2010, and again in 2011. JMRUI-user meetings were held at ISMRM in 2007-2009 and a jMRUI-course was given in 2010. 421 Researcher-months (f/m), 7 Training courses, 86 Peer Reviewed articles in journals, 192 Articles in Proceedings. Results are compiled on FAST's website: