Imaging intraplaque inflammation in carotid atherosclerosis with 11C-PK11195 positron emission tomography/computed tomography
European Heart Journal. 2011-09-19; 33(15): 1902-1910
DOI: 10.1093/eurheartj/ehr367
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1. Eur Heart J. 2012 Aug;33(15):1902-10. doi: 10.1093/eurheartj/ehr367. Epub 2011
Sep 19.
Imaging intraplaque inflammation in carotid atherosclerosis with 11C-PK11195
positron emission tomography/computed tomography.
Gaemperli O(1), Shalhoub J, Owen DR, Lamare F, Johansson S, Fouladi N, Davies AH,
Rimoldi OE, Camici PG.
Author information:
(1)Medical Research Council Clinical Sciences Centre and National Heart and Lung
Institute, Hammersmith Hospital, Imperial College, London, UK.
Comment in
Eur Heart J. 2012 Aug;33(15):1857-60.
AIMS: We sought to determine whether intraplaque inflammation could be measured
with positron emission tomography/computed tomography angiography (PET/CTA) using
(11)C-PK11195, a selective ligand of the translocator protein (18 kDa) (TSPO)
which is highly expressed by activated macrophages.
METHODS AND RESULTS: Patients (n = 32; mean age 70 ± 9 years) with carotid
stenoses (n = 36; 9 symptomatic and 27 asymptomatic) underwent (11)C-PK11195
PET/CTA imaging. (11)C-PK11195 uptake into carotid plaques was measured using
target-to-background ratios (TBR). On CTA images, plaque composition was assessed
by measuring CT attenuation of the carotid plaque. Eight patients underwent
carotid endarterectomy and ultrathin contiguous sections were processed for TSPO
and CD68 (using immunohistochemical staining, (3)H-PK11195 autoradiography, and
confocal fluorescence microscopy). Carotid plaques associated with ipsilateral
symptoms (stroke or transient ischaemic attack) had higher TBR (1.06 ± 0.20 vs.
0.86 ± 0.11, P = 0.001) and lower CT attenuation [(median, inter-quartile range)
37, 24-40 vs. 71, 56-125 HU, P = 0.01] than those without. On
immunohistochemistry and confocal fluorescence microscopy, CD68 and PBR
co-localized with (3)H-PK11195 uptake at autoradiography. There was a significant
correlation between (11)C-PK11195 TBR and autoradiographic percentage-specific
binding (r = 0.77, P = 0.025). Both TBR and CT plaque attenuation had high
negative predictive values (91 and 92%, respectively) for detecting symptomatic
patients. However, the best positive predictive value (100%) was achieved when
TBR and CT attenuation were combined.
CONCLUSION: Imaging intraplaque inflammation in vivo with (11)C-PK11195 PET/CTA
is feasible and can distinguish between recently symptomatic and asymptomatic
plaques. Patients with a recent ischaemic event had ipsilateral plaques with
lower CT attenuation and increased (11)C-PK11195 uptake.
DOI: 10.1093/eurheartj/ehr367
PMID: 21933781 [Indexed for MEDLINE]