Optimization of Single Voxel MR Spectroscopy Sequence Parameters and Data Analysis Methods for Thermometry in Deep Hyperthermia Treatments. (August 2017)

• Record Type: Journal Article
• Authors: Hartmann, J.; Gellermann, J.; Brandt, T.; Schmidt, M.; Pyatykh, S.; Hesser, J.; Ott, O.; Fietkau, R.; Bert, C.
• Is Part Of: Technology in cancer research & treatment. Volume 16:Number 4(2017:Aug.)
• Page Start: 470
• Page End: 481
• Publication Date: 2017-08
• Subjects: thermometry -- MR spectroscopy -- hyperthermia -- noninvasive -- phantom study; Oncology -- Periodicals; Cancer -- Diagnosis -- Periodicals; Cancer -- Treatment -- Technological innovations -- Periodicals; 616.994
• DOI: 10.1177/1533034616656310
• Languages: English
• ISSNs: 1533-0346

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 cm 3 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.