Test/retest reproducibility of iodine-123-betaCIT SPECT brain measurement of dopamine transporters in Parkinson's patients.
Iodine-123-beta-CIT has been used as a probe of dopamine transporters in Parkinson's disease patients using SPECT. We studied the test/retest reproducibility of SPECT measures in Parkinson's disease patients and healthy controls obtained after injection of [123I])beta-CIT in part to assess the utility of this tracer for longitudinal evaluation of striatal dopamine transporters as a marker of disease progression.


METHODS
Seven Parkinson's disease patients and seven healthy control subjects participated in two [123I]beta-CIT SPECT scans separated by 7-21 days. Subjects were imaged at 24 hr post injection of 360 MBq (9.7 mCi) of [123I]beta-CIT. Two outcome measures were evaluated; 1) the ratio of specific striatal (activity associated with DA transporter binding) to nondisplaceable uptake, also designated V3," and 2) the total specific striatal uptake (%SSU) expressed as a percentage of injected radiotracer dose. For both measures, test/retest variability was calculated as the absolute difference of test minus retest divided by the mean of test/retest and expressed as a percent. In addition, the reproducibility of left and right striatal asymmetry and putamen:caudate ratios were determined.


RESULTS
The two outcome measures demonstrated excellent test/retest reproducibility for both the Parkinson's disease and healthy subject groups with variability of striatal V3" = 16.8 +/- 13.3% and percent striatal uptake = 6.8 +/- 3.4% for Parkinson's disease patients and V3" = 12.8 +/- 8.9% and %SSU = 7.0 +/- 3.9% for control subjects. There were no statistically significant differences in test/retest variability between control subjects and Parkinson's disease patients for either outcome measure. The reproducibility of left/right asymmetry indices and putamen-to-caudate ratios showed no patient versus control subject differences. The asymmetry index had greater test/retest variability than the other outcome measures.


CONCLUSIONS
These data suggest that SPECT imaging performed at 24 hr postinjection of [123I]beta-CIT permits calculation of reliable and reproducible measures of dopamine transporters in both Parkinson's disease patients and control subjects and supports the feasibility of using [123I]beta-CIT in the evaluation of disease progression in Parkinson's disease.
Seibyl
J P
JP
Department of Diagnostic Radiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Marek
K
K
Sheff
K
K
Baldwin
R M
RM
Zoghbi
S
S
Zea-Ponce
Y
Y
Charney
D S
DS
van Dyck
C H
CH
Hoffer
P B
PB
Innis
R B
RB
D000328:Adult; D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D002352:Carrier Proteins / Q000032:analysis*; D003042:Cocaine / Q000031:analogs & derivatives*; D003342:Corpus Striatum / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D008875:Middle Aged; D009419:Nerve Tissue Proteins; D010300:Parkinson Disease / Q000000981:diagnostic imaging / Q000378:metabolism*; D011699:Putamen / Q000378:metabolism; D015203:Reproducibility of Results; D015899:Tomography, Emission-Computed, Single-Photon
D002352:Carrier Proteins; D050483:Dopamine Plasma Membrane Transport Proteins; D007457:Iodine Radioisotopes; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; C069723:2beta-carbomethoxy-3beta-(4-iodophenyl)tropane; D003042:Cocaine; D004298:Dopamine