Position paper of the Cardiovascular Committee of the European Association of Nuclear Medicine (EANM) on PET imaging of atherosclerosis

Abstract

Cardiovascular diseases are the leading cause of death not only in Europe but also in the rest of the World. Preventive measures, however, often fail and cardiovascular disease may manifest as an acute coronary syndrome, stroke or even sudden death after years of silent progression. Thus, there is a considerable need for innovative diagnostic and therapeutic approaches to improve the quality of care and limit the burden of cardiovascular diseases. During the past 10 years, several retrospective and prospective clinical studies have been published using 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) to quantify inflammation in atherosclerotic plaques. However, the current variety of imaging protocols used for vascular (arterial) imaging with FDG PET considerably limits the ability to compare results between studies and to build large multicentre imaging registries. Based on the existing literature and the experience of the Members of the European Association of Nuclear Medicine (EANM) Cardiovascular Committee, the objective of this position paper was to propose optimized and standardized protocols for imaging and interpretation of PET scans in atherosclerosis. These recommendations do not, however, replace the individual responsibility of healthcare professionals to make appropriate decisions in the circumstances of the individual study protocols used and the individual patient, in consultation with the patient and, where appropriate and necessary, the patient’s guardian or carer. These recommendations suffer from the absence of conclusive evidence on many of the recommendations. Therefore, they are not intended and should not be used as "strict guidelines" but should, as already mentioned, provide a basis for standardized clinical atherosclerosis PET imaging protocols, which are subject to further and continuing evaluation and improvement. However, this EANM position paper might indeed be a first step towards "official" guidelines on atherosclerosis imaging with PET.

18F-FDG PET/CT for the quantification of inflammation in large carotid artery plaques

“…4 In contrast to oncology, 5 there is no consensus on methodological guidelines for 18 F-FDG PET/CT in atherosclerosis imaging. A recent position paper from the Cardiovascular Committee of the European Association of Nuclear Medicine 6 proposed optimized and standardized protocols for the imaging and interpretation of 18 F-FDG PET scans in atherosclerosis. However, they admitted that many of the recommendations suffer from the absence of conclusive evidence.…”

Technical considerations for quantification of 18F-FDG uptake in carotid atherosclerosis

“…[24][25][26]29 Striking technical variability is another limitation of 18 F-FDG PET of atherosclerosis. 30,31 This is of particular concern as the small size of plaques and their close proximity to blood pool make them prone to partialvolume effects, which influence the accuracy of 18 F-FDG uptake quantification. 31 Therefore, any meta-analysis or comparison between the results of different studies need to be performed with extreme caution to account for these technical variabilities.…”

“…32 High levels of glucose reduce 18 F-FDG uptake in cultured cells and vessel wall, presumably through competition for glucose transporters, while it increases the blood pool activity. 30,32,33 It is recommended that a blood glucose level \ 130 mg/dl is optimal for 18 F-FDG PET of vessel wall. 30 But, glucose levels of up to 200 mg/dl have been used in multiple investigations.…”

“…30,32,33 It is recommended that a blood glucose level \ 130 mg/dl is optimal for 18 F-FDG PET of vessel wall. 30 But, glucose levels of up to 200 mg/dl have been used in multiple investigations. 32 The injected dose of 18 F-FDG is another potential confounding factor, which varies between studies from 185 to 925 MBq.…”

Can FDG-PET imaging play a role in guiding indications to endovascular treatments in patients presenting acute aortic syndromes?

“…In this study, PET acquisitions were acquired after injection of high activities of FDG to patients (7 MBq/kg), at early time points after injection (1 hour) and with relatively short acquisition times (2 mn/ bed position) in contrast to the current recommendations for vascular imaging. 16 In fact, these choices might significantly affect the validity of the quantitative measurements that have been performed in this work. Measurements performed in the vascular wall are very sensitive to parameters selected for image acquisition and reconstruction as well as to partial-volume effects, in particular in relation to the residual blood signal.…”