Inflammation is a determinant of atherosclerotic plaque rupture, the event leading to most myocardial infarctions and strokes. Although conventional imaging techniques identify the site and severity of luminal stenosis, the inflammatory status of the plaque is not addressed. Positron emission tomography imaging of atherosclerosis using the metabolic marker fluorodeoxyglucose allows quantification of arterial inflammation across multiple vessels. This review sets out the background and current and potential future applications of this emerging biomarker of cardiovascular risk, along with its limitations.

ObjectivesWe investigated factors for carotid artery inflammation by [ 18 F]-fluorodeoxyglucose (FDG) positron emission tomography (PET).

It is difficult to say that there is more evidence for cardiac amyloidosis (CA) than for ischemic heart disease. On the other hand, 99 m technetium pyrophosphate ( 99 m Tc-PYP) scintigraphy has been reported to be useful with high sensitivity and specificity, especially in transthyretin (TTR) amyloidosis (ATTR) 1,2 Due to the spread of diagnosis using this method, CA, especially wild-type ATTR (ATTRwt) amyloidosis, which has traditionally been considered a rare disease, is more prevalent than previously assumed, and encountered relatively frequently in daily clinical practice. Furthermore, treatment for not only amyloid light-chain (AL) amyloidosis, but also ATTR, has also progressed rapidly. Tafamidis, a drug that stabilizes the TTR tetramer and suppresses amyloid fibril formation and tissue deposition, was listed and used in Japan in November 2013 for the treatment of peripheral neuropathy in patients with hereditary (variant) ATTR (ATTRv) amyloidosis. In addition, following the results of the 2018 Transthyretin Amyloidosis Cardiomyopathy Clinical Trial (ATTR-ACT), which showed the efficacy of tafamidis for CA, 3 the use of TTR to treat CA was approved in March 2019 in Japan.Needless to say, amyloidosis is a systemic disease, and in Japan, numerous studies have been conducted and medical treatments devised by the Ministry of Health, Labour and Welfare (MHLW)'s "Research Group on Amyloidosis", a research project on intractable disease policy. The present guidelines have been developed in coordination between the MHLW's "Research Group on Amyloidosis", the Japanese Circulation Society (JCS) and cardiology-related societies, the Japanese Society of Amyloidosis, and the Japanese Society of Hematology. Systemic amyloidosis specified by the MHLW as being an incurable disease is classified into the following four types.

18F-fluorodeoxyglucose PET visualized plaque inflammation and simvastatin attenuated it. The LDL-C-independent effects of simvastatin may participate in the beneficial effect. 18F-fluorodeoxyglucose PET has a potential for visually monitoring plaque inflammation and the therapeutic effectiveness of statins.

Progressive inflammation in atherosclerotic plaques is associated with increasing risk of plaque rupture. Molecular imaging of activated macrophages with 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG) has been proposed for identification of patients at higher risk for acute vascular events. Because mannose is an isomer of glucose that is taken up by macrophages through glucose transporters and because mannose receptors are expressed on a subset of the macrophage population in high-risk plaques, we applied (18)F-labeled mannose (2-deoxy-2-[(18)F]fluoro-D-mannose, [(18)F]FDM) for targeting of plaque inflammation. Here, we describe comparable uptake of [(18)F]FDM and [(18)F]FDG in atherosclerotic lesions in a rabbit model; [(18)F]FDM uptake was proportional to the plaque macrophage population. Our FDM competition studies in cultured cells with 2-deoxy-2-[(14)C]carbon-D-glucose ([(14)C]2DG) support at least 35% higher [(18)F]FDM uptake by macrophages in cell experiments. We also demonstrate that FDM restricts binding of anti-mannose receptor antibody to macrophages by approximately 35% and that mannose receptor targeting may provide an additional avenue for imaging of plaque inflammation.

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Abstract-Angiotensin II (Ang II) is implicated in the proinflammatory process in various disease situations. Thus, we sought to determine the role of Ang II in early inflammation-induced fibrosis of pressure-overloaded (PO) hearts. PO was induced by suprarenal aortic constriction (AC) at day 0 in male Wistar rats, and they were orally administered 0.1 mg/kg per day candesartan every day from day Ϫ7. This was the maximum dose of candesartan that did not change arterial pressure in hypertensive rats with AC (AC rats). In AC rats, cardiac angiotensin-converting enzyme (ACE) activity was transiently enhanced after day 1 and peaked at day 3, declining to lower levels by day 14, whereas serum ACE activity was not changed. In AC rats, PO induced early fibroinflammatory changes (monocyte chemoattractant factor [MCP]-1 and transforming growth factor [TGF]-␤ expression, perivascular macrophage accumulation, and fibroblast proliferation), and thereafter, left ventricular hypertrophy developed, featuring myocyte hypertrophy, intramyocardial arterial wall thickening, and perivascular and interstitial fibroses. Candesartan suppressed the induction of MCP-1 and TGF-␤ and reduced macrophage accumulation and fibroblast proliferation in PO hearts. Candesartan significantly prevented perivascular and interstitial fibrosis. However, candesartan did not affect myocyte hypertrophy and arterial wall thickening. In conclusion, a subdepressor dose of candesartan prevented the MCP-1-mediated inflammatory process and reactive myocardial fibrosis in PO hearts. Ang II might play a key role in reactive fibrosis in hypertensive hearts, independent of arterial pressure changes.

OBJECTIVEAdvanced glycation end products (AGEs) evoke inflammatory reactions, contributing to the development and progression of atherosclerosis. We investigated the relationship between serum AGE level and vascular inflammation.RESEARCH DESIGN AND METHODSThe study involved 275 outpatients at Kurume University, Japan (189 males and 86 females; mean age 61.2 ± 8.8 years) who underwent complete history and physical examinations and determinations of blood chemistry and anthropometric variables, including AGEs. Serum AGE level was examined by enzyme-linked immunosorbent assay. Vascular [18F]fluorodeoxyglucose (FDG) uptake, an index of vascular inflammation, was measured as blood-normalized standardized uptake value, known as the target-to-background ratio (TBR), by FDG–positron emission tomography (FDG-PET). Furthermore, we examined whether the changes in serum AGE level after treatment with oral hypoglycemia agents (OHAs) were correlated with those of TBR in another 18 subjects whose AGE value was >14.2 units/mL (mean ± 2 SD).RESULTSMean serum AGE level and carotid TBR values were 9.15 ± 2.53 and 1.43 ± 0.22 units/mL, respectively. Multiple stepwise regression analysis revealed that TBR was independently correlated with AGEs (P < 0.001), carotid intima-media thickness (P < 0.01), and BMI (P < 0.02). When age- and sex-adjusted AGE values stratified by TBR tertiles were compared using ANCOVA, a significant trend was observed (P < 0.01). In addition, the changes in AGEs after OHA treatment were positively (r = 0.50, P < 0.05) correlated with those in TBR value.CONCLUSIONSThe current study reveals that serum AGE level is independently associated with vascular inflammation evaluated by FDG-PET, suggesting that circulating AGE value may be a biomarker that could reflect vascular inflammation within an area of atherosclerosis.