Quantification of Contrast in Clinical MR Brain Imaging at High Magnetic Field

Authors:
  • FWFelix W. Wehrli
    Felix W. Wehrli
  • RBRobert K. Breger
    Robert K. Breger
  • JMJAMES R. MacFALL
    JAMES R. MacFALL
  • DDDavid L. Daniels
    David L. Daniels
  • VHVictor M. Haughton
    Victor M. Haughton
  • HCH Cecil Charles
    H Cecil Charles
  • AWAlan L. Williams
    Alan L. Williams
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Abstract
The relative contrast between two tissues in a magnetic resonance (MR) image is shown to be quantifiable for any combination of pulse timing parameters, provided the intrinsic parameters are known. Based on multiple inversion-recovery and spin echo images, a region-of-interest T1, T2 and density analysis was conducted at 1.4T in selected patients with diagnosed neuropathology for various brain tissues. The resulting tissue parameters subsequently served to calculate the contrast-to-noise (C/N) ratio for typical tissue interfaces as a function of the operator-variable pulse timing parameters and the data were compared with the images. Although such calculations may be useful as a protocol selection aid, it is obvious that an optimized pulse protocol can only be established for a single tissue interface. The data also reveal that a T2-discriminating pulse sequence like Carr-Purcell-Meiboom-Gill with long repetition time, generally advocated as clinically most effective, may not always be ideal.