Intravoxel Incoherent Motion (IVIM)

This lecture covers Intravoxel Incoherent Motion (IVIM), a quantitative MRI technique that captures both tissue diffusion and microvascular perfusion without the need for external contrast agents. The lecture explains the physical principles of IVIM, which models the signal decay as a bi-exponential function consisting of slow water diffusion and fast "pseudo-diffusion" caused by blood flow in randomly oriented capillaries. By comparing IVIM with other perfusion methods, such as DCE-MRI and Arterial Spin Labeling (ASL), the video highlights IVIM's advantages, including its non-invasive nature, independence from arterial input functions, and high resolution. Advanced topics, including the correction for T2 relaxation differences and the transition to tri-exponential models to account for larger vessel flow, are also discussed.

Learning objectives:
By the end of this lecture, students will be able to:

• Understand how Intravoxel Incoherent Motion combines diffusion and perfusion measurements into a single quantitative model
• Describe the mathematical separation of the signal into diffusion and pseudo-diffusion components 
• Evaluate the pros and cons of IVIM versus Gadolinium-based DCE-MRI and non-invasive ASL 
• Recognize how non-blood motions, such as cardiac and respiratory movement, can impact IVIM signal decay