Apparent Diffusion Coefficient (ADC) measurement in Diffusion-MRI
Diffusion MRI is used in a large fraction of clinical MRI exams, where quantitative “Apparent Diffusion Coefficient (ADC)” values are broadly used as biomarkers of therapy response and also reflect other tissue qualities such as cellular density, edema, and necrosis. However, current ADC measurement is in error due to inevitable imaging gradient non-linearity. Known methods that implement corrections and create proper ADC values usually need to acquire the “full diffusion tensor” (DTI), and thus require many DWI directions (at least 6, more commonly 16-32 directions), which renders these methods infeasible in practice.
Error Analysis and Correction of ADC measurements
A research group in the Radiology and Medical School of University of Michigan has reported a practical procedure that both builds on comprehensive physical system characteristics and achieves minimal algorithm complexity for quantitative control of ADC error. The key idea behind the technique is an efficient mathematical manipulation of the “system properties” based on known gradient properties. As a result, the disclosed procedure yields more quantitatively accurate ADC values from the fewest number of diffusion weighted images.
Applications and Advantages
- Accurate Diffusion-MRI ADC measurements
- Improved accuracy of ADC values
- Require the fewest number of DWI directions (i.e., only 3 directions)