PET-Derived Biodistribution and Dosimetry of the Benzodiazepine Receptor-Binding Radioligand 11C-(R)-PK11195 in Children and Adults

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FIGURE 1.
Interleaved PET protocol used for acquisition of dynamic PET scan. Short 1-min interval was used to reposition patient between 2 bed positions. Subset of patients was scanned at level of urinary bladder instead of liver.
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FIGURE 2.
Three sequential whole-body ¹¹C-(R)-PK11195 PET/CT scans showing time-dependent biodistribution of PK at 20 min after injection (A), 40 min after injection (B), and 60 min after injection (C). PK uptake was highest in gallbladder and urinary bladder, followed by liver, kidney, bone marrow, salivary gland, and heart wall, with minimal localization in all other organs including normal brain and lungs.
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FIGURE 3.
Decay-corrected (A) and non–decay-corrected (B) time–activity curves for kidneys, liver, brain, urinary bladder, and gallbladder in 5-y-old subject. Tracer activity in brain reached maximum within first 2 min and then decreased exponentially (inset of A). Non–decay-corrected time–activity curves were extrapolated to 240 min (12 half-lives), applying only physical decay of tracer (inset of B).

TABLE 1

Mean Residence Times (Hours) Obtained from PET

Organ	Children 4–7 y	Children 8–12 y	Children 13–17 y	Adults
Gallbladder	0.002 (47)	0.003 (52)	0.002 (44)	0.002 (59)
Urinary bladder	0.005 (68)	0.007 (61)	0.010 (55)	0.014 (71)
Liver	0.025 (21)	0.025 (36)	0.024 (27)	0.031 (20)
Kidneys	0.007 (55)	0.007 (43)	0.003 (12)	0.011 (18)
Marrow	0.012 (31)	0.013 (11)	0.016 (16)	0.022 (33)
Brain	0.016 (22)	0.011 (23)	0.006 (34)	0.005 (14)
Lungs	0.003 (21)	0.002 (30)	0.002 (27)	0.003 (33)
Heart	0.002 (27)	0.002 (38)	0.003 (42)	0.006 (41)

TABLE 2

Radiation Doses for ¹¹C-(R)-PK11195 in Children and Adults

TABLE 3

¹¹C-(R)-PK11195 Radiation Doses

↵* For injected activity of 17 MBq/kg (0.45 mCi/kg). Total EDE was calculated as EDE multiplied with age-appropriate injected activity (340 MBq for children 4–7 y, 560 MBq for children 8–12 y, and 970 MBq for children 13–17 y).
Data in parentheses are rem/mCi in EDE column and rem in Total EDE column.