J Hartmann1, J Gellermann2,3, T Brandt1, M Schmidt1, S Pyatykh4, J Hesser4, O Ott1, R Fietkau1, C Bert1. 1. 1 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany. 2. 2 Department of Radiation Oncology, University Hospital Tübingen, Tübingen, Germany. 3. 3 Praxis/Zentrum für Strahlentherapie und Radioonkologie, Berlin, Germany. 4. 4 Medical Faculty Mannheim, Experimental Radiation Oncology, Heidelberg University, Mannheim, Germany.
Abstract
OBJECTIVE: The difference in the resonance frequency of water and methylene moieties of lipids quantifies in magnetic resonance spectroscopy the absolute temperature using a predefined calibration curve. The purpose of this study was the investigation of peak evaluation methods and the magnetic resonance spectroscopy sequence (point-resolved spectroscopy) parameter optimization that enables thermometry during deep hyperthermia treatments. MATERIALS AND METHODS: Different Lorentz peak-fitting methods and a peak finding method using singular value decomposition of a Hankel matrix were compared. Phantom measurements on organic substances (mayonnaise and pork) were performed inside the hyperthermia 1.5-T magnetic resonance imaging system for the parameter optimization study. Parameter settings such as voxel size, echo time, and flip angle were varied and investigated. RESULTS: Usually all peak analyzing methods were applicable. Lorentz peak-fitting method in MATLAB proved to be the most stable regardless of the number of fitted peaks, yet the slowest method. The examinations yielded an optimal parameter combination of 8 cm3 voxel volume, 55 millisecond echo time, and a 90° excitation pulse flip angle. CONCLUSION: The Lorentz peak-fitting method in MATLAB was the most reliable peak analyzing method. Measurements in homogeneous and heterogeneous phantoms resulted in optimized parameters for the magnetic resonance spectroscopy sequence for thermometry.
OBJECTIVE: The difference in the resonance frequency of water and methylene moieties of lipids quantifies in magnetic resonance spectroscopy the absolute temperature using a predefined calibration curve. The purpose of this study was the investigation of peak evaluation methods and the magnetic resonance spectroscopy sequence (point-resolved spectroscopy) parameter optimization that enables thermometry during deep hyperthermia treatments. MATERIALS AND METHODS: Different Lorentz peak-fitting methods and a peak finding method using singular value decomposition of a Hankel matrix were compared. Phantom measurements on organic substances (mayonnaise and pork) were performed inside the hyperthermia 1.5-T magnetic resonance imaging system for the parameter optimization study. Parameter settings such as voxel size, echo time, and flip angle were varied and investigated. RESULTS: Usually all peak analyzing methods were applicable. Lorentz peak-fitting method in MATLAB proved to be the most stable regardless of the number of fitted peaks, yet the slowest method. The examinations yielded an optimal parameter combination of 8 cm3 voxel volume, 55 millisecond echo time, and a 90° excitation pulse flip angle. CONCLUSION: The Lorentz peak-fitting method in MATLAB was the most reliable peak analyzing method. Measurements in homogeneous and heterogeneous phantoms resulted in optimized parameters for the magnetic resonance spectroscopy sequence for thermometry.
Authors: J Gellermann; W Wlodarczyk; A Feussner; H Fähling; J Nadobny; B Hildebrandt; R Felix; P Wust Journal: Int J Hyperthermia Date: 2005-09 Impact factor: 3.914
Authors: M Peller; R Löffler; A Baur; P Turner; S Abdel-Rahman; G Futschik; M Santl; W Hiddemann; M Reiser; R Issels Journal: Radiologe Date: 1999-09 Impact factor: 0.635
Authors: René F Verhaart; Zef Rijnen; Valerio Fortunati; Gerda M Verduijn; Theo van Walsum; Jifke F Veenland; Margarethus M Paulides Journal: Strahlenther Onkol Date: 2014-11 Impact factor: 3.621