title: Evaluation of the ERETIC method as an improved quantitative reference for 1H HR-MAS spectroscopy of prostate tissue.
abstract: The Electronic REference To access In vivo Concentrations (ERETIC) method was applied to (1)H HR-MAS spectroscopy. The accuracy, precision, and stability of ERETIC as a quantitative reference were evaluated in solution and human prostate tissue samples. For comparison, the reliability of 3-(trimethylsilyl)propionic-2,2,3,3-d(4) acid (TSP) as a quantitation reference was also evaluated. The ERETIC and TSP peak areas were found to be stable in solution over the short-term and long-term, with long-term relative standard deviations (RSDs) of 4.10% and 2.60%, respectively. Quantification of TSP in solution using the ERETIC peak as a reference and a calibrated, rotor-dependent conversion factor yielded results with a precision < or =2.9% and an accuracy error < or =4.2% when compared with the expected values. The ERETIC peak area reproducibility was superior to TSP's reproducibility, corrected for mass, in both prostate surgical and biopsy samples (4.53% vs. 21.2% and 3.34% vs. 31.8%, respectively). Furthermore, the tissue TSP peaks exhibited only 27.5% of the expected area, which would cause an overestimation of metabolite concentrations if used as a reference. The improved quantification accuracy and precision provided by ERETIC may enable the detection of smaller metabolic differences that may exist between individual tissue samples and disease states.
authors.affiliation: Department of Bioengineering, University of California Berkeley, USA.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Albers
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Butler
authors.forename: Iman
authors.initials: I
authors.lastname: Rahwa
authors.forename: Nguyen
authors.initials: N
authors.lastname: Bao
authors.forename: Kayvan R
authors.initials: KR
authors.lastname: Keshari
authors.forename: Mark G
authors.initials: MG
authors.lastname: Swanson
authors.forename: John
authors.initials: J
authors.lastname: Kurhanewicz
mesh_terms: D000465:Algorithms; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods* / Q000592:standards*; D008297:Male; D011467:Prostate / Q000378:metabolism*; D011522:Protons; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014481:United States
chemical_list: D011522:Protons