{"id":{"repo_id":"heid-diss","oai_identifier":"oai:archiv.ub.uni-heidelberg.de:5262"},"canonical_url":"https://search.dev.ndltd.org/etd/heid-diss/oai:archiv.ub.uni-heidelberg.de:5262","repository":{"repo_id":"heid-diss","name":"Universität Heidelberg","base_url":"http://archiv.ub.uni-heidelberg.de/volltextserver/cgi/oai2"},"display":{"title":"Development and Optimisation of Radial Techniques for Sodium Magnetic Resonance Imaging","abstract":"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.","abstract_html":"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.","abstract_has_math":false,"creators":["Nielles-Vallespin, Sonia"],"institution":"Universität Heidelberg","degree_name":null,"degree_level":"thesis.doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":["Schad, Lothar R."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2004,"date_issued":"2004-12-22","date_published":"2004-12-22","updated_at":"2026-07-24T02:30:04Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://www.ub.uni-heidelberg.de/archiv/5262","outbound_label":"Repository record","outbound_source":"source_url"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Schad, Lothar R."]},{"key":"dc:creator","label":"Author","values":["Nielles-Vallespin, Sonia"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:publisher","label":"Institution","values":["Universitätsbibliothek Heidelberg"]},{"key":"dc:type","label":"Dc Type","values":["doctoralThesis"]},{"key":"thesis:degree_level","label":"Degree Level","values":["thesis.doctoral"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Universität Heidelberg"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["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.","Das Ziel dieser Arbeit war die Bereitstellung von Techniken und Hardware für die 23Na-MRT des menschlichen Gehirns, Herzens und Muskels an einem klinischen Tomographen bei 1.5T. Zu diesem Zweck wurden Hochfrequenz-(HF)-spulen entwickelt und Sende-Empfangsweichen auf 16.84MHz angepasst. Eine radiale 3D Gradientenecho-(GRE)-sequenz wurde mit einer minimalen Echozeit von TEmin= 0.07ms für 1H und 0.2ms für 23Na implementiert, um sowohl die kurze (T2= 0.5ms) als auch die lange (T2= 12-25ms) Komponente des 23Na NMR Signals bei der Messung des gesamten Natriumgehalts zu detektieren. Ein Gridding Rekonstruktionsalgorithmus mit einem rho-Filter und einem Kaiser-Bessel-Fenster wurde implementiert und sowohl für 23Na als auch für 1H MRT optimiert. Bei einer Gesamtmesszeit von Tacq= 10min und einer nominellen Auflösung von Dx= 4mm wurde ein zweifach höheres Signal-zu-Rausch Verhältnis SNR in in-vivo 23Na Radialbildern beobachtet als in konventionellen cartesischen 3D GRE Daten. In den Radialbildern wurden aufgrund des T2-Signalzerfalls während der Datenaufnahme Unschärfen beobachtet, die die Auflösung um einen Faktor von ungefähr zwei reduzierten. Sowohl cartesische als auch radiale GRE-Methoden wurden bei 1.5T und 4T miteinander verglichen. Eine Zunahme des SNR von SNR(4T)/SNR(1.5T) ~4 wurde in-vivo gemessen. In Hirntumorpatienten wurde eine 20%ige Zunahme des 23Na MR Signals in der Tumorregion detektiert. Das Kontrast-zu-Rausch Verhältnis CNR= 23% zwischen gesundem Gewebe und Tumor gemessen mit der 3D Radialtechnik war 20% grösser als das CNR der cartesischen Sequenz. In Patienten mit einer Disfunktion der Natriumkanle der Zelle wurde eine 23Na Signalerhöhung von 10% gemessen. Diese Methode erlaubt es, Änderungen der intrazellulären 23Na Konzentration zu detektieren und könnte ein neues Werkzeug zur nichtinvasiven Evaluation der Gewebevitalität darstellen."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Development and Optimisation of Radial Techniques for Sodium Magnetic Resonance Imaging","Entwicklung und Optimierung von RadialTechniken für die Natrium-Magnetresonanzbildgebung"]}]}],"canonical_facts":{"dc:contributor":["Schad, Lothar R."],"dc:creator":["Nielles-Vallespin, Sonia"],"dc:description.abstract":["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.","Das Ziel dieser Arbeit war die Bereitstellung von Techniken und Hardware für die 23Na-MRT des menschlichen Gehirns, Herzens und Muskels an einem klinischen Tomographen bei 1.5T. Zu diesem Zweck wurden Hochfrequenz-(HF)-spulen entwickelt und Sende-Empfangsweichen auf 16.84MHz angepasst. Eine radiale 3D Gradientenecho-(GRE)-sequenz wurde mit einer minimalen Echozeit von TEmin= 0.07ms für 1H und 0.2ms für 23Na implementiert, um sowohl die kurze (T2= 0.5ms) als auch die lange (T2= 12-25ms) Komponente des 23Na NMR Signals bei der Messung des gesamten Natriumgehalts zu detektieren. Ein Gridding Rekonstruktionsalgorithmus mit einem rho-Filter und einem Kaiser-Bessel-Fenster wurde implementiert und sowohl für 23Na als auch für 1H MRT optimiert. Bei einer Gesamtmesszeit von Tacq= 10min und einer nominellen Auflösung von Dx= 4mm wurde ein zweifach höheres Signal-zu-Rausch Verhältnis SNR in in-vivo 23Na Radialbildern beobachtet als in konventionellen cartesischen 3D GRE Daten. In den Radialbildern wurden aufgrund des T2-Signalzerfalls während der Datenaufnahme Unschärfen beobachtet, die die Auflösung um einen Faktor von ungefähr zwei reduzierten. Sowohl cartesische als auch radiale GRE-Methoden wurden bei 1.5T und 4T miteinander verglichen. Eine Zunahme des SNR von SNR(4T)/SNR(1.5T) ~4 wurde in-vivo gemessen. In Hirntumorpatienten wurde eine 20%ige Zunahme des 23Na MR Signals in der Tumorregion detektiert. Das Kontrast-zu-Rausch Verhältnis CNR= 23% zwischen gesundem Gewebe und Tumor gemessen mit der 3D Radialtechnik war 20% grösser als das CNR der cartesischen Sequenz. In Patienten mit einer Disfunktion der Natriumkanle der Zelle wurde eine 23Na Signalerhöhung von 10% gemessen. Diese Methode erlaubt es, Änderungen der intrazellulären 23Na Konzentration zu detektieren und könnte ein neues Werkzeug zur nichtinvasiven Evaluation der Gewebevitalität darstellen."],"dc:format.medium":["application/pdf"],"dc:publisher":["Universitätsbibliothek Heidelberg"],"dc:title":["Development and Optimisation of Radial Techniques for Sodium Magnetic Resonance Imaging","Entwicklung und Optimierung von RadialTechniken für die Natrium-Magnetresonanzbildgebung"],"dc:type":["doctoralThesis"],"thesis:degree_level":["thesis.doctoral"],"thesis:institution_name":["Universität Heidelberg"]},"updated_at":"2026-07-24T02:30:04Z"}