Immunoglobulin G4 (IgG4)-related disease can affect the cardiovascular system, including the coronary arteries and pericardium and especially the walls of large and medium-sized vessels. The presence of coronary involvement is critical, as this condition can cause myocardial ischemia or sudden cardiac death. Although histopathologic examination remains the reference standard for detecting organ involvement and diagnosing IgG4-related disease, obtaining biopsy or surgical specimens from the vessel wall is still challenging. Because patients may be only mildly symptomatic, noninvasive imaging evaluation of IgG4-related cardiovascular disease (CVD) has an essential role in not only the diagnosis but also the management of this condition. Multidetector CT is a useful noninvasive examination for establishing the primary diagnosis and defining anatomic landmarks and their relationships. The spectrum of vessel involvement is vast, with varied manifestations. Radiologists should be familiar with inflammatory vasculitis, aneurysmal change, and pseudotumor formation in all vessels and the distribution of these conditions throughout the body. Electrocardiographically gated CT enables accurate, fast, and noninvasive characterization of coronary pathologic conditions and thus has an important advantage over catheter angiography. Combined PET/CT can depict inflammatory processes and help distinguish IgG4-related CVD from atherosclerosis. Familiarity with the PET/CT and CT findings of inflammatory processes involved in IgG4-related CVD is important for accurate diagnosis and evaluation of therapeutic response during follow-up. The multidetector CT and PET/CT characteristics of IgG4-related CVD, such as aortitis, periaortitis, arteritis, and periarteritis and including coronary artery involvement and pericarditis, are reviewed. In addition, the inflammatory process, quantification of active inflammation, and therapeutic response during follow-up associated with IgG4-related CVD are described.Abbreviations: CVD = cardiovascular disease, ECG = electrocardiography, FDG = fluorine 18 fluorodeoxyglucose, IgG4 = immunoglobulin G4, RCA = right coronary artery, SUV max = maximum standardized uptake value, TBR = target-to-background ratio
BackgroundWe aimed to assess the positivity, distribution, quantitative degree of vessel inflammation, and clinical characteristics of IgG4-related aortitis/periarteritis and periarteritis (IgG4-aortitis), and to examine the difference in these characteristics between cases with and without IgG4-aortitis, using fluorodeoxyglucose positron-emission tomography/computed tomography (FDG-PET/CT) co-registered with contrast-enhanced CT (CECT).We retrospectively evaluated 37 patients with IgG4-related disease (IgG4-RD) who underwent both FDG-PET/CT and CECT. The arterial SUVmax and its value normalized to the background venous blood pool (BP)—the target-to-background ratio (TBR) in the entire aorta and the major first branches—were measured. Active vascular inflammation was considered in cases with a higher FDG uptake than BP and a thickened arterial wall (>2 mm).ResultsFifteen (41%) patients exhibited IgG4-aortitis. Most patients (80%) showed multiple region involvement. The entire aorta, including the major first branches, were involved, typically showing a thickened wall and high FDG uptakes. The most common site was the iliac arteries (35%), followed by the infrarenal abdominal aorta (33%), thoracic aorta (8%), first branches of the thoracic aorta (8%), suprarenal abdominal aorta (6%), and the first branches of the abdominal aorta (5%). The IgG4-aortitis-positive vessel regions were thickened, with an average maximal wall thickness of 6.3 ± 2.9 mm. The SUVmax and TBR values were significantly higher in the IgG4-aortitis-positive regions (median 3.7 [1.6–5.5] and 2.1 [1.4–3.7], respectively) than in the IgG4-aortitis-negative regions (median 2.1 [1.2–3.7] and 1.3 [0.9–2.3], respectively; p < 0.0001). The IgG4-aortitis-positive group patients were older (69.5 ± 6.0 vs. 63.3 ± 12.6 years, respectively) and had a higher male predominance (80 vs. 55%, respectively) than the negative group, although the differences were not significant (p = 0.17 and p = 0.06, respectively).ConclusionsWe investigated the image characteristics of IgG4-aortitis. The entire aorta and major branches can be involved with more than 2-fold higher FDG uptake than the venous background pool, and with wall thickening. The most common involved site is the iliac arteries, followed by the infrarenal abdominal aorta.
The presence of an intratumoral artery in the arterial phase on contrast-enhanced dynamic CT was a predictable finding for ICC, and the presence of a washout pattern was a predictable finding for p-HCC, differentiating between ICC and p-HCC.
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