Tracer kinetic modelling in MRI: estimating perfusion and capillary permeability

Area of Science:

• Medical Imaging
• Biophysics
• Pharmacokinetics

Background:

• Early dynamic contrast-enhanced MRI (DCE-MRI) tracer-kinetic models (1990s) are standard but limited by hardware advancements.
• Increased MRI image quality and temporal resolution highlight the need for next-generation models.

Purpose of the Study:

• To review and clarify second-generation tracer-kinetic models for DCE-MRI.
• To provide a physically intuitive and mathematically rigorous overview of these advanced models.
• To encourage wider adoption of these tools by improving understanding of their assumptions and requirements.

Main Methods:

• Derivation of models from common first principles using tracer-kinetic theory.
• Classification of models to reveal links between them and with first-generation models.
• Inclusion of detailed formulae for model solutions to aid implementation.

Main Results:

• Second-generation models enable separate estimation of perfusion and capillary permeability, unlike the combined K(trans) parameter of older models.
• A unified framework is presented, clarifying terminology, notations, and physiological assumptions.
• Historical origins are linked to facilitate knowledge transfer from related fields like PET, SPECT, and CT.

Conclusions:

• This review offers a clear, unified perspective on advanced DCE-MRI modeling.
• Researchers gain a better understanding of model assumptions and requirements for accurate tissue status assessment.
• The work aims to promote the application of sophisticated tracer-kinetic models in DCE-MRI research.