Fig. 4.

T₂^* reveals severe cardiac iron deposition impacting on T₁ and T₂ measurements. Heart tissue damage was assessed by histology and MRI. (A) Global histopathological scores of RBC extravasation, iron and T₂^* values of Resiquimod-treated mice compared with control mice. The Mann–Whitney test was used for semiquantitative histopathology scores, n=3 (ctrl), n=10 (treated); unpaired two-tailed Student's t-test for MRI values, n=5 (ctrl), n=3 (treated); *P<0.05, **P<0.005. (B) Examples of T₁, T₂ and T₂^* maps of mid-section LV with corresponding Perls Prussian Blue-stained paraffin-embedded heart sections of Resiquimod-treated and control mice showing significant iron deposition. (C) High-magnification images of tissue areas with iron deposition (Perls Prussian Blue), immune cell infiltration (H&E) and mild fibrosis (Picrosirius Red). (D) Histograms of T₁, T₂ and T₂^* signal distribution in the anterior septum showing the impact of iron on the behavior of each relaxation time index. (E) Correlation between T₂^* values and individual histopathology scores. Pearson's correlation was used, pooling data from three independent experiments, n=3-5 (ctrl), n=3-10 (treated); *correlation significant at the 0.01 level, **correlation significant at the 0.05 level. Symbols represent individual animals; all data presented as mean±s.e.m.