Comparison of iodine-123-epidepride and iodine-123-IBZM for dopamine D2 receptor imaging.
Although 123I-IBZM is widely used as a D2 receptor imaging agent, image quality is compromised by a relatively low target-to-nontarget ratio. Animal studies suggest that 123I-epidepride (Kd 0.024 nM) may be superior to 123I-IBZM, but this agent has not been systematically studied in humans.


METHODS
We directly compared 123I-epidepride and 123I-IBZM in five normal volunteers (age range 30-58 yr, mean 43 yr). Brain SPECT imaging was performed 2 hr after the 123I-IBZM injection (average dose 153 MBq). Iodine-123-epidepride scans were performed 1 hr (n = 3), 2 hr (n = 5) and 3 hr (n = 3) postinjection (average dose 149 MBq).


RESULTS
Both radiopharmaceuticals were well tolerated. Iodine-123-epidepride provided excellent visualization of the striatum. Percent specific striatum uptake at 2 hr (71.7 +/- 4.9%) was much greater than with 123I-IBZM (32.6 +/- 5.3%, p < 0.01).


CONCLUSIONS
Iodine-123-epidepride is a new D2 receptor agent that exhibits excellent neuroimaging properties and has a much higher affinity for striatal uptake than 123I-IBZM.
Leslie
W D
WD
Department of Nuclear Medicine, University of Manitoba, Winnipeg, Canada.
Abrams
D N
DN
Greenberg
C R
CR
Hobson
D
D
D000328:Adult; D001549:Benzamides; D001921:Brain / Q000000981:diagnostic imaging*; D001923:Brain Chemistry; D003287:Contrast Media; D018492:Dopamine Antagonists; D006801:Humans; D006816:Huntington Disease / Q000000981:diagnostic imaging / Q000235:genetics / Q000378:metabolism; D007457:Iodine Radioisotopes; D008875:Middle Aged; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2 / Q000032:analysis*; D012307:Risk Factors; D015899:Tomography, Emission-Computed, Single-Photon
D001549:Benzamides; D003287:Contrast Media; D018492:Dopamine Antagonists; D007457:Iodine Radioisotopes; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2; C063525:epidepride; C055743:3-iodo-2-hydroxy-6-methoxy-N-((1-ethyl-2-pyrrolidinyl)methyl)benzamide