Postnatal myocardium remodelling generates inhomogeneity in the architecture of the ventricular mass

Figures

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  Fig. 1. Illustration of the different maps obtained by PLI. a Short-axis section (thickness, 500 µm) made after resin embedding and viewed in transmitted light. b Same section, orientation map in streamline representation, LIC texture. c False colour elevation map with superimposition of LIC texture (false colour scale from − 90° to + 90°). d False colour azimuth map of the section with superimposition of LIC texture (false colour scale from 0° to 180°)

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  Fig. 2. Representation of regional index (RI). a Part of the lateral wall of the left ventricle of a 12-weeks post-natal heart, LIC texture. The two white centred dashed circles represent the intersection of a 1 mm radius sphere with the section plane. The ellipsoid of the orientation tensor is calculated on the set of voxels intersecting the surface of this 1 mm radius sphere. From this tensor is calculated the RI index that is allocated to the voxel center of the sphere (white point). b The result of RI map of the same 2 centred spheres: on the left, the central pixel has a low RI index: 0.2 (neighbourhood pixels have nearly similar orientation as the centre pixel) and on the right the central pixel has a high RI index: 0.6 (almost every orientation of neighbourhood voxels are represented)

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  Fig. 3. Linear regression analysis of the median of RI value distribution according to ventricular weight of 20 stillbirth and postnatal hearts. The distribution of RI has been calculated for each heart in three equatorial sections and is shown as “box and whisker” plots (lower whisker, box lower edge, box centre, box upper edge, upper whisker corresponding to 5th, 25th, 50th, 75th and 95th percentiles, respectively; perinatal hearts in grey; post-neonatal hearts in white). Regression analysis shows a statistically significant negative link between the RI median and ventricular weight

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  Fig. 4. Regional isotropy maps superimposed with LIC texture of two hearts: stillbirth (a) and 12 weeks of age (b). i Basal section, ii mid-section, iii apical section, iv reconstructed long horizontal long-axis RI map, red dotted lines of the i, ii and iii section levels. The combined examination of the short-axis section levels and the horizontal long-axis section shows that the RI areas extend through the ventricular mass. The comparison of the two columns (a, b) confirms a general thinning tendency of the high RI layers and conversely broadening of the low-RI layers

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  Fig. 5. Comparative histograms of mean RI values in the IVS (a) and the left ventricular wall (b), in the 2 groups: perinatal (grey) and post-neonatal (empty boxes). i RI map of an equatorial section of one of the studied heart (12 weeks of age), the yellow rectangles indicate the region of interest (ROI) in the IVS and left ventricular wall for determination of the RI plot profiles, ii plot profile with “W” pattern in the IVS (A) and left ventricular wall (b), iii histograms of mean RI values and standard deviation in the IVS (a) the left ventricular wall (b) and in 2 groups (10 perinatal hearts in grey and 10 post-neonatal hearts empty boxes). From right side to left side of IVS, the averaged RI minima RV tier is higher in the perinatal group than in the postnatal group (p < 0.05). From endocardium to epicardium at the left LVW level, the RI-Minima endocardial tier and the RI-Peak midwall is lower in the post-neonatal group than in the perinatal group (p < 0.01; p < 001 respectively). *Statistically significant differences (p value < 0.05)

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  Fig. 6. 3D views of the low-RI layers in a 12-week postnatal heart and artist drawing summarizing the organization pattern. a Ventricular areas with an RI index < 0.3 were segmented and reconstructed with the 3D viewer. False colour scale (red to deep blue) is used to encode the axial level from base to apex. b The artistic view emphasizes the representation of the inhomogeneous pattern sustained by the study of RI distribution in post-neonatal life. The same false colour coding than in A is used for baso-apical representation. The high RI areas are not directly viewed but inferred from the vacuum between low-RI areas, for representation they are shadowed in grey. The high RI area of the IVS is not visible in A because it is hidden by superficial subepicardial basal low RI areas but is still represented in B for summarizing (refers to Fig. 4iv)