Evaluation of the ERETIC method as an improved quantitative reference for 1H HR-MAS spectroscopy of prostate tissue

Authors

  • Mark J. Albers,

    1. Department of Bioengineering, University of California Berkeley and University of California San Francisco, San Francisco, California
    2. Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California
    Search for more papers by this author
    • The first two authors contributed equally to this work.

  • Thomas N. Butler,

    1. Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California
    Search for more papers by this author
    • The first two authors contributed equally to this work.

  • Iman Rahwa,

    1. Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California
    Search for more papers by this author
  • Nguyen Bao,

    1. Varian, Inc, Palo Alto, California
    Search for more papers by this author
  • Kayvan R. Keshari,

    1. Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California
    Search for more papers by this author
  • Mark G. Swanson,

    1. Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California
    Search for more papers by this author
  • John Kurhanewicz

    Corresponding author
    1. Department of Bioengineering, University of California Berkeley and University of California San Francisco, San Francisco, California
    2. Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California
    • Urology and Pharmaceutical Chemistry, University of California, San Francisco, Byers Hall, Room 203E, 1700 4th Street, Box 2520, San Francisco, CA 94158
    Search for more papers by this author

Abstract

The Electronic REference To access In vivo Concentrations (ERETIC) method was applied to 1H 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-d4 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 ≤2.9% and an accuracy error ≤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. Magn Reson Med 61:525–532, 2009. © 2009 Wiley-Liss, Inc.

Ancillary