title: Optimization of Single Voxel MR Spectroscopy Sequence Parameters and Data Analysis Methods for Thermometry in Deep Hyperthermia Treatments.
abstract: 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.
  
  
  
  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.
  
  
  
  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 cm3voxel volume, 55 millisecond echo time, and a 90° excitation pulse flip angle.
  
  
  
  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.affiliation: 1 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Hartmann
authors.affiliation: 2 Department of Radiation Oncology, University Hospital Tübingen, Tübingen, Germany.|3 Praxis/Zentrum für Strahlentherapie und Radioonkologie, Berlin, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Gellermann
authors.affiliation: 1 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Brandt
authors.affiliation: 1 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schmidt
authors.affiliation: 4 Medical Faculty Mannheim, Experimental Radiation Oncology, Heidelberg University, Mannheim, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Pyatykh
authors.affiliation: 4 Medical Faculty Mannheim, Experimental Radiation Oncology, Heidelberg University, Mannheim, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Hesser
authors.affiliation: 1 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Ott
authors.affiliation: 1 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Fietkau
authors.affiliation: 1 Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Bert
mesh_terms: D000818:Animals; D002138:Calibration; D003627:Data Interpretation, Statistical; D006979:Hyperthermia, Induced; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D019047:Phantoms, Imaging; D034421:Sus scrofa; D062125:Thermometry
keywords: MR spectroscopy; hyperthermia; noninvasive; phantom study; thermometry