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Large vessel vasculitides (LVV) comprise a group of inflammatory disorders that involve the large arteries, such as the aorta and its primary branches. The cause of LVV is often rheumatologic and includes giant cell arteritis and Takayasu arteritis. Giant cell arteritis is the most common form of LVV affecting people >50 years of age with a slight female predominance. Takayasu arteritis is more frequently seen in younger populations and is significantly more common in women. Prompt identification of LVV is crucial as it can lead to debilitating complications if left untreated, including blindness in the case of giant cell arteritis and large artery stenosis and aneurysms in the case of all forms of LVV. Noninvasive imaging methods have greatly changed the approach to managing LVV. Today, imaging (with ultrasound, magnetic resonance imaging, computed tomography, and positron emission tomography) is routinely used in the diagnosis of LVV. In patients with giant cell arteritis, imaging often spares the use of invasive procedures such as temporal artery biopsy. In addition, vascular imaging is also crucial for longitudinal surveillance of arterial damage. Finally, imaging is currently being studied for its role in assessing treatment response and ongoing disease activity and its potential value in determining the presence of vascular wall remodeling (eg, scarring). This review explores the current uses of noninvasive vascular imaging in LVV., Competing Interests: Dr Tawakol receives research support (to his institution) from Lung Biotechnologies and consulting fees from Cunningham Bounds LLC for unrelated work and is supported by National Institutes of Health (NIH) R01HL152957, R33HL141047, R01HL1495, P01HL131478, R01AR077187, and R01HL16433, and the International Atomic Energy Agency (IAEA) for unrelated work. Dr Weber receives consulting fees from Novo Nordisk, Kiniksa, and Horizon Therapeutics (now Amgen) for unrelated work, and is supported by NIH/NHLBI K23HL159276 and American Heart Association 21CDA851511. Dr Osborne receives consulting fees from WCG Clinical for unrelated work, and is supported by the NIH K23HL151909 and the American Heart Association 23SCISA1143491. Dr Bucerius receives institutional funding from the IAEA in the context of the PIAF (Prognostic Value of Arterial 18F-FDG PET Imaging in Patients with History of Myocardial Infarction) trial (core laboratory). Dr Unizony reports Research support from Genentech, NIH 1UM1AI144295-01 for unrelated work, and consulting fees from Novartis, Sanofi, and Harvard Pilgrim Health Care. The other authors report no conflicts.

Background: 18 F-Fluorodeoxyglucose (FDG) positron-emission tomography/computed tomography (PET/CT) was recently introduced as a new tool for the diagnosis of prosthetic heart valve endocarditis (PVE). Previous studies reporting a modest diagnostic accuracy may have been hampered by unstandardized image acquisition and assessment, and several confounders, as well. The aim of this study was to improve the diagnostic performance of FDG PET/CT in patients in whom PVE was suspected by identifying and excluding possible confounders, using both visual and standardized quantitative assessments., Methods: In this multicenter study, 160 patients with a prosthetic heart valve (median age, 62 years [43-73]; 68% male; 82 mechanical valves; 62 biological; 9 transcatheter aortic valve replacements; 7 other) who underwent FDG PET/CT for suspicion of PVE, and 77 patients with a PV (median age, 73 years [65-77]; 71% male; 26 mechanical valves; 45 biological; 6 transcatheter aortic valve replacements) who underwent FDG PET/CT for other indications (negative control group), were retrospectively included. Their scans were reassessed by 2 independent observers blinded to all clinical data, both visually and quantitatively on available European Association of Nuclear Medicine Research Ltd-standardized reconstructions. Confounders were identified by use of a logistic regression model and subsequently excluded., Results: Visual assessment of FDG PET/CT had a sensitivity/specificity/positive predictive value/negative predictive value for PVE of 74%/91%/89%/78%, respectively. Low inflammatory activity (C-reactive protein <40 mg/L) at the time of imaging and use of surgical adhesives during prosthetic heart valve implantation were significant confounders, whereas recent valve implantation was not. After the exclusion of patients with significant confounders, diagnostic performance values of the visual assessment increased to 91%/95%/95%/91%. As a semiquantitative measure of FDG uptake, a European Association of Nuclear Medicine Research Ltd-standardized uptake value ratio of ≥2.0 was a 100% sensitive and 91% specific predictor of PVE., Conclusions: Both visual and quantitative assessments of FDG PET/CT have a high diagnostic accuracy in patients in whom PVE is suspected. FDG PET/CT should be implemented early in the diagnostic workup to prevent the negative confounding effects of low inflammatory activity (eg, attributable to prolonged antibiotic therapy). Recent valve implantation was not a significant predictor of false-positive interpretations, but surgical adhesives used during implantation were.

In this study, we unravel a molecular imaging marker correlated with the known reduction of cardiovascular events (most commonly related to vulnerable plaques) in morbidly obese patients after bariatric surgery (BaS).We prospectively imaged 10 morbidly obese subjects with F-fluorodeoxyglucose (F-FDG) positron emission tomography/computed tomography before and 1 year after BaS. F-FDG uptake-which is enhanced in inflamed, atherosclerotic vessels and in metabolically active adipose tissues-was quantified in the carotids, pericardial adipose tissue (PAT), visceral adipose tissue (VAT), as well as brown adipose tissue (BAT). The degree of carotid inflammation was compared to lean and overweight controls.Carotid inflammation significantly declined leading to an F-FDG uptake comparable to the 2 control groups. Metabolic activity significantly decreased in PAT and VAT and increased in BAT.BaS leads to a normalization of carotid artery inflammation and a beneficial impact on the metabolic activity in PAT, VAT, and BAT that is related to the metabolic syndrome observed in this patient group.

Background and Purpose: Hallmarks of vulnerable atherosclerotic plaques are inflammation that can be assessed with 18fluorine-fluorodeoxyglucose positron emission tomography/computed tomography, and increased neovascularization that can be evaluated by dynamic contrast-enhanced-MRI. It remains unclear whether these parameters are correlated or represent independent imaging parameters. This study determines whether there is a correlation between inflammation and neovascularization in atherosclerotic carotid plaques., Methods: A total of 58 patients with transient ischemic attack or minor stroke in the carotid territory and ipsilateral carotid artery stenosis of 30% to 69% were included. All patients underwent positron emission tomography/computed tomography and dynamic contrast-enhanced-MRI of the carotid plaque. 18Fluorine-fluorodeoxyglucose standard uptake values with target/background ratio were determined. Neovascularization was quantified by the mean (leakage) volume transfer constant Ktrans. Spearman rank correlation coefficients between target/background ratio and Ktrans were calculated., Results: Images suitable for further analysis were obtained in 49 patients. A weak but significant positive correlation between target/background ratio and mean Ktrans (Spearman ρ=0.30 [P=0.035]) and 75th percentile Ktrans (Spearman ρ=0.29 [P=0.041]) was found., Conclusions: There is a weak but significant positive correlation between inflammation on positron emission tomography/computed tomography and neovascularization as assessed with dynamic contrast-enhanced-MRI. Future studies should investigate which imaging modality has the highest predictive value for recurrent stroke, as these are not interchangeable., Clinical Trial Registration Url: http://www.clinicaltrials.gov. Unique identifier: NCT00451529.