title: Quantification of low fat contents: a comparison of MR imaging and spectroscopy methods at 1.5 and 3 T.
abstract: Magnetic resonance spectroscopy (MRS) has long been considered the golden standard for non-invasive measurement of tissue fat content. With improved techniques for fat/water separation, imaging has become an alternative to MRS for fat quantification. Several imaging models have been proposed, but their performance relative to MRS at very low fat contents is yet not fully established. In this work, imaging and spectroscopy were compared at 1.5 T and 3 T in phantoms with 0-3% fat fraction (FF). We propose a multispectral model with individual a priori R(2) relaxation rates for water and fat, and a common unknown R(2)' relaxation. Magnitude and complex image reconstructions were also compared. Best accuracy was obtained with the imaging method at 1.5 T. At 3 T, the FFs were underestimated due to larger fat-water phase shifts. Agreement between measured and true FF was excellent for the imaging method at 1.5 T (imaging: FF(meas)=0.98 FF(true)-0.01%, spectroscopy: FF(meas)=0.77 FF(true)+0.08%), and fair at 3 T (imaging: FF(meas)=0.91 FF(true)-0.19%, spectroscopy: FF(meas)=0.79 FF(true)+0.02%). The imaging method was able to quantify FFs down to approx. 0.5%. We conclude that the suggested imaging model is capable of fat quantification with accuracy and precision similar to or better than spectroscopy and offers an improvement vs. a model with a common R(2)* relaxation only.
authors: Medical Radiation Physics, Dept. of Clinical Sciences Malmö, Lund University, Skåne University Hospital Malmö, Sweden. sven.mansson@med.lu.se
authors: Sven
authors: S
authors: Månsson
authors: Pernilla
authors: P
authors: Peterson
authors: Edvin
authors: E
authors: Johansson
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism / Q000473:pathology*; D003198:Computer Simulation; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015233:Models, Statistical; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water