Detection and quantification of large-vessel inflammation with 11C-(R)-PK11195 PET/CT

F. Lamare, R. Hinz, O. Gaemperli, F. Pugliese, J. C. Mason, T. Spinks, P. G. Camici, O. E. Rimoldi
Journal of Nuclear Medicine. 2010-12-13; 52(1): 33-39
DOI: 10.2967/jnumed.110.079038

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1. J Nucl Med. 2011 Jan;52(1):33-9. doi: 10.2967/jnumed.110.079038. Epub 2010 Dec

Detection and quantification of large-vessel inflammation with 11C-(R)-PK11195

Lamare F(1), Hinz R, Gaemperli O, Pugliese F, Mason JC, Spinks T, Camici PG,
Rimoldi OE.

Author information:
(1)MRC Clinical Sciences Centre and National Heart and Lung Institute, Imperial
College, Hammersmith Campus, and GE Imanet, Hammersmith Hospital, London, United

We investigated whether PET/CT angiography using 11C-(R)-PK11195, a selective
ligand for the translocator protein (18 kDa) expressed in activated macrophages,
could allow imaging and quantification of arterial wall inflammation in patients
with large-vessel vasculitis.METHODS: Seven patients with systemic inflammatory
disorders (3 symptomatic patients with clinical suspicion of active vasculitis
and 4 asymptomatic patients) underwent PET with 11C-(R)-PK11195 and CT
angiography to colocalize arterial wall uptake of 11C-(R)-PK11195. Tissue regions
of interest were defined in bone marrow, lung parenchyma, wall of the ascending
aorta, aortic arch, and descending aorta. Blood-derived and image-derived input
functions (IFs) were generated. A reversible 1-tissue compartment with 2 kinetic
rate constants and a fractional blood volume term were used to fit the
time-activity curves to calculate total volume of distribution (VT). The
correlation between VT and standardized uptake values was assessed.
RESULTS: VT was significantly higher in symptomatic than in asymptomatic patients
using both image-derived total plasma IF (0.55±0.15 vs. 0.27±0.12, P=0.009) and
image-derived parent plasma IF (1.40±0.50 vs. 0.58±0.25, P=0.018). A good
correlation was observed between VT and standardized uptake value (R=0.79;
CONCLUSION: 11C-(R)-PK11195 imaging allows visualization of macrophage
infiltration in inflamed arterial walls. Tracer uptake can be quantified with
image-derived IF without the need for metabolite corrections and evaluated
semiquantitatively with standardized uptake values.

DOI: 10.2967/jnumed.110.079038
PMID: 21149475 [Indexed for MEDLINE]

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