Yi Wang1,2, Allison Payne3,
Seong-Eun Kim3, Edward DiBella3, Dennis L. Parker3
1Bioengineering, University of Utah,
Salt Lake City, UT, United States; 2Utah Center for Advanced
Imaging Research , University of Utah, Salt Lake City, UT, United States; 3Utah
Center for Advanced Imaging Research, University of Utah, Salt Lake City, UT,
United States
The
Pennes bioheat transfer equation (BHTE) is the most widely used equation to
model the effects of heat deposition and dissipation in tissues. The
formulation includes terms for thermal conductivity and an effective
perfusion, which represents the rate at which blood flow removes heat from a
local tissue region. MR thermometry
has allowed accurate estimations of these subject-specific thermal
properties. Using these estimated
parameters enables more accurate treatment planning. However, tissue properties, particularly
perfusion, are known to change over the course of a thermal therapy treatment. Detecting perfusion changes during a
thermal therapy treatment would allow for the adjustment of treatment
parameters to achieve a more efficacious therapy. In this work, we present a method to use
arterial spin labeling to determine the rate at which flow passes through a
point. The pulse sequence combines the
turbo-FLASH imaging and Look-Locker-like readout at multiple inversion times
in a single scan. The data obtained from
this newly developed sequence approximates the average velocity of blood (fluid)
passing through a thin slice, providing a surrogate for the Pennes perfusion
term. This method is independent of MR thermometry, decoupling the blood flow
measurement from the MR temperature maps, allowing the perfusion changes to
be monitored throughout the thermal therapy session.