Abstract |
The SPECT radiopharmaceuticals labeled with I-123 for
dopamine transporter imaging have been used to measure
dopamine transporters in patients with movement
disorders. However, a cyclotron produced I-123 limits
its availiability and ease of use as a radioisotope to
be labeled with pharmaceuticals in routine clinical
diagnostic procedures. Recently, new
radiopharmaceuticals for Tc-99m which has optimal
characteristic for SPECT imaging have been developed to
overcome the limits of using I-123. The purpose of this
study was to compare the quality of [Tc-99m]TRODAT-1
with [I-123]IPT SPECT data and then to evaluate the
usefulness of [Tc-99m]TRODAT-I SPECT by using three
noninvasive simplified quantitative methods. TRODAT-1
labeled with Tc-99m(15.93¡¾0.82 mCi) and IPT labeled
with I-123(6.60¡¾0.11 mCi) were injected into five
normal controls. Dynamic [Tc-99m] TRODAT-I SPECT scans
of brain were performed for 10 minutes each over 180
minnutes, and for 20 minutes at 4 hrs and 5 hrs. [I-
123IPT SPECT scans were performed for 5 minutes each
over 120 minutes. Time activity curves were generated
for the left basal ganglia(LBG), right basal
ganglia(RBG), and occipital cortex(OCC). Dopamine
transporter parameters were obtained using (BG-
OCC)/OCC, graphical method(Rv), and area ratio
method(RA). TRODAT-1 and IPT SPECT imaging showed high
uptake at the level of the basal ganglia. (BG-OCC)/OCC
ratios for TRODAT-1 and IPT were 0.80¡¾0.14, and
3.22¡¾0.81, Rvs were 0.62¡¾0.12, and 2.30¡¾0.35,
and RAs were 0.37¡¾0.08 and 1.73¡¾0.31,
respectively. In conclusion, further improvement of
[Tc-99m]TRODAT-I imaging characteris- tics may be
required to estimate the dopamine transporter
concentrations in human brains although it shows clear
BG localization. |