Self‐gated, dynamic contrast‐enhanced magnetic resonance imaging with compressed‐sensing reconstruction for evaluating endothelial permeability in the aortic root of atherosclerotic mice

Figures

• 

  FIGURE 1. Study design. The study comprised a total of 32 mice, divided into five groups. The first group of eight mice (group 1 at the top), underwent four longitudinal dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) sessions, at 4, 8, 12, and 16 weeks, after initiation of a high‐fat diet. Groups 2–5 were instead used for comparison between DCE‐MRI and histology. Each group consisted of six mice, which underwent imaging and euthanasia respectively at 4, 8, 12, and 16 weeks after high‐fat diet initiation. Green circles indicate DCE‐MRI–only sessions for group 1. Green and yellow circles indicate DCE‐MRI and euthanasia sessions for groups 2–5. The gray dashed arrows indicate maintenance of a high‐fat diet

• 

  FIGURE 2. (A) Representative raw, cardiac, and respiratory navigator signal (top, middle, and bottom, respectively). In the middle panel, the red line indicates the cardiac signal extracted from the raw navigator. In the bottom panel, the red line indicates the extracted respiratory signal, while the red shaded areas indicate the detected respiratory motion. (B) Apparent long axis (left) and four‐chamber view (right) used for localizing the aorta root. Blue dashed line, aortic root plane. White rectangle, position of navigator slice. AA, ascending aorta; LV, left ventricle; nav, navigator; RV, right ventricle. (C) Representative images of the aortic root (AR; blue arrow) during the dynamic acquisition, including a representative tracing of the inner (green) and outer (orange) vessel wall counters for frame 19. The number in the top left corner of each panel indicates the corresponding dynamic frame

• 

  FIGURE 3. (A) Average curves and fitted curves of mice on 4 (red), 8 (black), 12 (gray), and 16 (green) weeks of a high‐fat diet; from the graph it can be noted that the washout slope b 2 becomes less negative as the mice are kept on a high‐fat diet for longer periods of time. (B) Boxplot (left) and linear regression plot (right) of macrophage density in mice 4, 8, 12, and 16 weeks on a high‐fat diet. Midlines in boxplots represent the median, while whiskers represent the minimum and maximum datapoints

• 

  FIGURE 4. (A) Representative CD68 staining of aortic root of mice at 4 (top left), 8 (top right), 12 (bottom left), and 16 (bottom right) weeks on a high‐fat diet. (B) Quantification of the macrophage percentage area: the inner and outer contours of the aortic root are delineated (left panel); macrophage‐rich areas are then selected using a semiautomated threshold (right panel); macrophage density is calculated as the ratio between macrophage‐rich areas and the whole vessel wall area and is expressed as a percentage (%). (C) Boxplot (left) and linear regression plot (middle) of macrophage density in mice 4, 8, 12, and 16 weeks on a high‐fat diet; the right panel shows a linear regression plot of macrophage density for each animal against the parameter b 2 from dynamic contrast‐enhanced magnetic resonance imaging. Midlines in boxplots represent the median, while whiskers represent the minimum and maximum datapoints