Leon Jonathan Menezes FRCR, Presenter: Nothing to Disclose

Carl Kotze, Abstract Co-Author: Nothing to Disclose

Vicky Joo-Lin Goh MBBCh, Abstract Co-Author: Nothing to Disclose

Justin Cross, Abstract Co-Author: Nothing to Disclose

James Stirling, Abstract Co-Author: Nothing to Disclose

Syed Waquar Yusuf, Abstract Co-Author: Nothing to Disclose

Peter Josef Ell MD, Abstract Co-Author: Nothing to Disclose

Ashley McAllister Groves MBBS, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

18F FDG PET/CT can be used to quantify inflammation within atherosclerotic plaques and predict vulnerability. The purpose of this prospective study was to determine the morphological characteristics of inflamed carotid plaques using MDCT angiography and 3T MRI, fused to PET images.

6 patients, (5 men, 1 woman, mean age 74, range 55-84 years) who had suffered a recent transient ischemic attack (mean 2.6 months since symptom onset, range 1-5 months), with severe ipsilateral stenosis awaiting carotid endarterectomy, were prospectively enrolled. 18F-FDG PET/CT, MDCT angiography, and 3T MRI scanning of the carotid arteries were performed the same day. Carotid FDG uptake was measured using maximum Standardized Uptake Values (SUV max). The corresponding CT and MRI images were fused to the PET images and analyzed for the presence of anatomical criteria of vulnerability.

9 focal sites of inflammation were identified in carotid plaques (SUV max >2.5) on PET. One patient scanned at 5 months since symptom onset showed no increased carotid uptake. 2/5 patients had inflamed carotid plaques on the contralateral, asymptomatic side. There were 7 inflamed plaques on the ipsilateral, symptomatic side. At these sites of raised FDG uptake, MDCT revealed 5 non-calcified plaques, 2 plaques with spotty calcification, and no sites of positive remodelling. At these sites of raised FDG uptake on PET, MRI demonstrated 4 lipid rich/ necrotic cores, and no fissured plaques, no intra-plaque hemorrhages and no stenoses >90%. Some of these MRI features were demonstrated at 6 other sites including 2 contralaterally, none of which took up 18F-FDG.

Inflammation in carotid atherosclerosis of symptomatic patients as identified by 18F-FDG, can be multi-focal and bilateral, and may vary according to the time elapsed since symptom onset. These initial data provide molecular imaging evidence that spotty calcification, or non-calcified or lipid rich/necrotic core plaques may represent vulnerability. Not all current morphological criteria for identifying vulnerable plaques co-localize with sites of focal inflammation on PET.

18F-FDG PET/CT provides information about the cellular processes in atherosclerotic plaque that cannot be addressed by anatomical imaging with CT or MRI alone. Multimodality imaging is complementary.

Menezes, L, Kotze, C, Goh, V, Cross, J, Stirling, J, Yusuf, S, Ell, P, Groves, A, et al, , Morphological Findings in Inflamed Carotid Atherosclerotic Plaques Identified by 18F-FDG PET/CT: A Comparison with 3T MRI and CT Angiography.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6009323.html