Reference Tissue-based Kinetic Modeling
The SRTM2 was used for the voxel-wise
[11C]CFT kinetic analysis21,
26, 27,
which generated two parametric images: R1 (the ratio
between the transport rate constants of target and reference tissues)
and DVR (distribution volume ratio between the target and reference
tissues). The R1 represents the relative transporter
rate constant of tracer from vascular space to the target organs or
brain regions, whereas DVR reflects the tracer specific binding to DAT.
The occipital lobe region lacking DAT distribution was selected as the
reference tissue. A linear regression with spatial constraint algorithm
was used to generate parametric images of R1 and DVR21,
28.
To the best of our knowledge, no clinical studies have yet conducted a
total-body dynamic [11C]CFT analysis utilizing the
voxel-wise SRTM2 method. Thus, we additionally performed the VOI-based
one-tissue compartmental modeling (1T2K) with the metabolite-corrected
TAC of descending aorta as the input function using PMOD to validate our
SRTM2 estimates 28. The
tracer transport rate constant (K1) and total
distribution volume (VT) as the estimates for early
blood perfusion and later tracer density were generated to validate the
use of R1 and DVR, respectively.