Identification and Quantitative Assessment of Different Components of Intracranial Atherosclerotic Plaque by Ex Vivo 3T High-Resolution Multicontrast MRI.

BACKGROUND AND PURPOSE: High-resolution 3T MR imaging can visualize intracranial atherosclerotic plaque. However, histologic validation is still lacking. This study aimed to evaluate the ability of 3T MR imaging to identify and quantitatively assess intracranial atherosclerotic plaque components ex vivo with histologic validation. MATERIALS AND METHODS: Fifty-three intracranial arterial specimens with atherosclerotic plaques from 20 cadavers were imaged by 3T MR imaging with T1, T2, and proton-density-weighted FSE and STIR sequences. The signal characteristics and areas of fibrous cap, lipid core, calcification, fibrous tissue, and healthy vessel wall were recorded on MR images and compared with histology. Fibrous cap thickness and maximum wall thickness were also quantified. The percentage of areas of the main plaque components, the ratio of fibrous cap thickness to maximum wall thickness, and plaque burden were calculated and compared. RESULTS: The signal intensity of the lipid core was significantly lower than that of the fibrous cap on T2-weighted, proton-density, and STIR sequences (P < .01) and was comparable on T1-weighted sequences (P = 1.00). Optimal contrast between the lipid core and fibrous cap was found on T2-weighted images. Plaque component mean percentages were comparable between MR imaging and histology: fibrous component (81.86% ± 10.59% versus 81.87% ± 11.59%, P = .999), lipid core (19.51% ± 10.76% versus 19.86% ± 11.56%, P = .863), and fibrous cap (31.10% ± 11.28% versus 30.83% ± 8.51%, P = .463). However, MR imaging overestimated mean calcification (9.68% ± 5.21% versus 8.83% ± 5.67%, P = .030) and plaque burden (65.18% ± 9.01% versus 52.71% ± 14.58%, P < .001). CONCLUSIONS: Ex vivo 3T MR imaging can accurately identify and quantitatively assess intracranial atherosclerotic plaque components, providing a direct reference for in vivo intracranial plaque imaging.

Epidemiological study of influenza B in Shanghai during the 2009-2014 seasons: implications for influenza vaccination strategy.

A new quadrivalent influenza vaccine has been available for influenza B, which can pose a significant global health burden. Shanghai has the highest GDP and largest metropolitan population in China. To understand the impact of influenza B in Shanghai in terms of age-related incidence and relative prevalence compared with other subtypes, we conducted this retrospective epidemiological study of influenza B in the 2009-2014 seasons. A total of 71 354 outpatients with influenza-like illness were included, and both lineages of influenza B and subtypes of influenza A were identified using real-time RT-PCR. The antigenic characteristics of influenza B isolates were analysed by sequencing and reciprocal haemagglutinin inhibition assay. On average, 33.45% of influenza strains were influenza B, and 40.20% of strains isolated from children were influenza B. The incidence of influenza B was highest (12.52 per 100 people with influenza-like illness) in children ages 6-17 years and usually peaked in this age group at the early stage of an influenza B epidemic. Overall, both matched and mismatched influenza B strains co-circulated in Shanghai annually, and 44.57% of the circulating influenza B belonged to the opposite lineage of the vaccine strains. We concluded that influenza B has caused a substantial impact in Shanghai and that school-aged children play a key role in the transmission of influenza B. Hence, it may be beneficial to prioritize influenza vaccination for school-aged children to mitigate the outbreaks of influenza B.