Bolus-tracking MRI with a simultaneous T1- and T2*-measurement

Magn Reson Med. 2009 Sep;62(3):672-81. doi: 10.1002/mrm.22042.

Abstract

The aim of this study was to propose and evaluate a methodology to analyze simultaneously acquired T2*-weighted dynamic susceptibility contrast (DSC) MRI and T(1)-weighted dynamic contrast enhanced (DCE) MRI data. Two generalized models of T2*-relaxation are proposed to account for tracer leakage, and a two-compartment exchange model is used to separate tracer in intra- and extravascular spaces. The methods are evaluated using data extracted from ROIs in three mice with subcutaneously implanted human colorectal tumors. Comparing plasma flow values obtained from DCE-MRI and DSC-MRI data defines a practical experimental paradigm to measure T2*-relaxivities, and reveals a factor of 15 between values in tissue and blood. Comparing mean transit time values obtained from DCE-MRI and DSC-MRI without leakage correction, indicates a significant reduction of susceptibility weighting in DSC-MRI during tracer leakage. A one-parameter gradient correction model provides a good approximation for this susceptibility loss, but redundancy of the parameter limits the practical potential of this model for DSC-MRI. Susceptibility loss is modeled more accurately with a variable T2*-relaxivity, which allows to extract new parameters that cannot be derived from DSC-MRI or DCE-MRI alone. They reflect the cellular and vessel geometry, and thus may lead to a more complete characterization of tissue structure.

Publication types

  • Evaluation Study

MeSH terms

  • Algorithms
  • Animals
  • Cell Line, Tumor
  • Colorectal Neoplasms / diagnosis*
  • Colorectal Neoplasms / metabolism*
  • Computer Simulation
  • Contrast Media / pharmacokinetics*
  • Diffusion Magnetic Resonance Imaging / methods*
  • Humans
  • Image Enhancement / methods
  • Image Interpretation, Computer-Assisted / methods*
  • Meglumine / pharmacokinetics*
  • Mice
  • Mice, Nude
  • Models, Biological
  • Organometallic Compounds / pharmacokinetics*
  • Reproducibility of Results
  • Sensitivity and Specificity

Substances

  • Contrast Media
  • Organometallic Compounds
  • Meglumine
  • gadoterate meglumine