Identification of culprit lesions after transient ischemic attack by combined 18F fluorodeoxyglucose positron-emission tomography and high-resolution magnetic resonance imaging.
OBJECTIVE
Carotid endarterectomy is currently guided by angiographic appearance on the assumption that the most stenotic lesion visible at angiography is likely to be the lesion from which future embolic events will arise. However, risk of plaque rupture, the most common cause of atherosclerosis-related thromboembolism, is dictated by the composition of the plaque, in particular the degree of inflammation. Angiography may, therefore, be an unreliable method of identifying vulnerable plaques. In this study, plaque inflammation was quantified before endarterectomy using the combination of 18F fluorodeoxyglucose positron (FDG)-emission tomography (PET) and high-resolution MRI (HRMRI).


METHODS
Twelve patients, all of whom had suffered a recent transient ischemic attack, had a severe stenosis in the ipsilateral carotid artery, and were awaiting carotid endarterectomy underwent FDG-PET and HRMRI scanning. A semiquantitative estimate of plaque inflammation was calculated for all of the lesions identified on HRMRI.


RESULTS
In 7 of 12 patients (58%), high FDG uptake was seen in the lesion targeted for endarterectomy. In the remaining 5 patients, FDG uptake in the targeted lesion was low. In these 5 patients, 3 had nonstenotic lesions identified on HRMRI that exhibited a high level of FDG uptake. All 3 of the highly inflamed nonstenotic lesions were located in a vascular territory compatible with the patients' presenting symptoms.


CONCLUSIONS
Our data suggest that angiography may not always identify the culprit lesion. Combined FDG-PET and HRMRI can assess the degree of inflammation in stenotic and nonstenotic plaques and could potentially be used to identify lesions responsible for embolic events.
Davies
John R
JR
Division of Cardiovascular Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom. jrd36@mole.bio.cam.ac.uk
Rudd
James H F
JH
Fryer
Tim D
TD
Graves
Martin J
MJ
Clark
John C
JC
Kirkpatrick
Peter J
PJ
Gillard
Jonathan H
JH
Warburton
Elizabeth A
EA
Weissberg
Peter L
PL
D000368:Aged; D000369:Aged, 80 and over; D016893:Carotid Stenosis / Q000150:complications / Q000175:diagnosis*; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D007089:Image Enhancement; D002546:Ischemic Attack, Transient / Q000150:complications / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D058225:Plaque, Amyloid / Q000378:metabolism*; D049268:Positron-Emission Tomography
D019788:Fluorodeoxyglucose F18