title: Development and Optimisation of Radial Techniques for Sodium Magnetic Resonance Imaging
creator: Nielles-Vallespin, Sonia
subject: ddc-530
subject: 530 Physics
description: The goal of this work was to provide techniques and hardware for 23Na MRI of the human brain, heart and muscle in a clinical scanner at 1.5T. For this purpose, radiofrequency (RF) coils were developed and a transmit/receive switch was adapted to 16.84 MHz. A 3D radial gradient echo (GRE) sequence was implemented, with a minimum echo time TEmin = 0.07ms for 1H and 0.2ms for 23Na, allowing to detect both the short (T2= 0.5ms) and the long (T2= 12-25ms) components of the 23Na NMR signal for total 23Na content evaluation. A gridding reconstruction algorithm with a Kaiser-Bessel window and a rho filter was implemented and optimised for both 23Na and 1H MRI. At an acquisition time Tacq= 10min and a nominal resolution Dx= 4mm, the signal-to-noise ratio SNR of the in-vivo 23Na 3D radial images was twofold higher than in standard cartesian GRE MRI (TEmin= 2ms). In the radial images blurring due to T2 signal decay during data acquisition was observed, reducing the resolution by approximately a factor of two. Both cartesian and radial GRE methods were compared at 1.5T and 4T. An SNR increase of SNR(4T)/SNR(1.5T) ~4 was measured in-vivo. In brain tumour patients, a 20% 23Na MRI signal increase in the tumour region was detected. A contrast-to-noise ratio CNR = 23% between healthy tissue and tumour achieved with the 3D radial was 20% higher than the CNR of the cartesian sequence. In patients with a 23Na channel disfunction, a 23Na MRI signal increase of ~10% was measured. This method allows for the detection of changes in the intracellular 23Na concentration and may provide a new tool to non-invasively evaluate tissue vitality.
date: 2004
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/5262/1/Nielles_Vallespin_S.pdf
identifier: DOI:10.11588/heidok.00005262
identifier: urn:nbn:de:bsz:16-opus-52622
identifier:   Nielles-Vallespin, Sonia  (2004) Development and Optimisation of Radial Techniques for Sodium Magnetic Resonance Imaging.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/5262/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng