Histological sections of the lateral LV wall.

<p>The sections were cut tangential to the epicardial surface. (A–C) At 10 weeks the myocardium is isotropic with no clear structural pattern. (D–F) At 14 weeks structural anisotropy begins to evolve and distinct patterns of fiber orientation can be seen at different transmural depths. (G–I) By 19 weeks clear differences in fiber orientation can be resolved in all layers of the myocardium, and the alignment of the myofibers resembles that seen in the adult heart. However, no sign of a dense sheet structure is seen.</p

Fiber architecture in the adult human heart.

<p>(A) Fiber tracts in the lateral LV wall. The tracts are color-coded by their inclination or helix angle (HA). Tracts in the subendocardium have a positive (right-handed) HA, tracts in the subepicardium have a negative (left-handed) HA, and those in the midmyocardium are circumferential. (B) The diffusion tensor in each voxel in the LV is represented by an ellipsoidal glyph. The color and orientation of the glyph is determined by its HA (inclination angle of primary eigenvector). The shape of the glyph is determined by the relative magnitudes of the diffusion eigenvalues. In isotropic tissues the eigenvalues are similar and the diffusion glyphs are thus spherical. In anisotropic tissues the primary eigenvalue is significantly larger, producing high FA values and elliptical glyphs. (B, C) The diffusion glyphs in the adult LV have a highly ordered arrangement, show a consistent gradient in their transmural orientation and are highly elliptical. (White box in panel B = magnified area shown in panel C).</p

Fluorochrome-Functionalized Nanoparticles for Imaging DNA in Biological Systems

Attaching DNA binding fluorochromes to nanoparticles (NPs) provides a way of obtaining NPs that bind to DNA through fluorochrome mediated interactions. To obtain a nanoparticle (NP) that bound to the DNA in biological systems, we attached the DNA binding fluorochrome, TO-PRO 1 (TO), to the surface of the Feraheme (FH) NP, to obtain a fluorochrome-functionalized NP denoted TO-FH. When reacted with DNA <i>in vitro</i>, TO-FH formed microaggregates that were characterized by fluorescence, light scattering, and T2 changes. The formation of DNA/TO-FH microaggregates was also characterized by AFM, with microaggregates exhibiting a median size of 200 nm, and consisting of DNA and multiple TO-FH NPs whose individual diameters were only 25–35 nm. TO-FH failed to bind normal cells in culture, but treatment with chemotherapeutic agents or detergents yielded necrotic cells that bound TO-FH and vital fluorochromes similarly. The uptake of TO-FH by HT-29 xenografts (treated with 5-FU and oxaliplatin) was evident by surface fluorescence and MRI. Attaching multiple DNA binding fluorochromes to magnetic nanoparticles provides a way of generating DNA binding NPs that can be used to detect DNA detection by microaggregate formation <i>in vitro</i>, for imaging the DNA of necrotic cells in culture, and for imaging the DNA of a tumor treated with a chemotherapeutic agent. Fluorochrome functionalized NPs are a multimodal (magnetic and fluorescent), highly multivalent (<i>n </i>≈ 10 fluorochromes/NP) nanomaterials useful for imaging the DNA of biological systems

Systolic and diastolic tensor maps with and without strain correction.

<p>Diffusion tensor fields acquired in systole (A,B) and diastole (C,D) are represented by superquadric glyphs and color-coded by the helix angle before and (A,C) after strain correction (B,D). The diffusion tensor fields before and after strain correction are merged (C,E) to visualize its impact. Insets demonstrate a major realignment of the tensor field into the typical helical pattern upon strain correction in systole (B). In diastole, strain correction effects are characterized mainly by small changes in the principal diffusivities (E).</p

Time course of the measured stretch tensor.

<p>The radial, circumferential and longitudinal components of the right stretch tensors are plotted as a function of time after the R-wave. The systolic (a) and diastolic (b) timing of the DTI sequence is indicated by the vertical solid line while the systolic sweet spot is marked by the vertical dashed line. The transmural course of the helix angles and the transverse and sheet angle histograms are presented for systole (c) and diastole (d) for a medial/basal level. Systolic and diastolic (black) as well as sweet-spot (gray) data are shown before (dotted line) and after (solid line) strain correction.</p

Systolic and diastolic transverse angles with and without strain correction.

<p>Transverse angle maps in systole (left column) and diastole (right column) without and with strain correction (a). Transverse angle histograms are given at the basal, medial and apical levels (b). The error bars indicate one standard deviation across the study population. Statistically significant differences between the uncorrected (blue) and the corrected case (red) are indicated by * and between systole and diastole by †.</p

Definition of fiber and sheet angles.

<p>A local orthonormal basis is defined (a) (radial: , circumferential: , longitudinal: ). Helix (α), transverse (β) and sheet angle (γ) definitions are given in (b). For angle calculation, projections of the first () and third () eigenvectors were used (grey planes). The sign indicates the polarity of the angle. For each tensor position a normalized transmural position is defined (c). An example of the transmural course of helix angles is shown in (d) with the angle range (grey) and linear fit (green) indicated. Histograms of sheet angles (e) were fitted using a quadratic function (green line).</p

Raw data of diffusion weighted and tagging acquisitions as well as strain maps for the sweet spot, the systolic and the diastolic heart phase.

<p>The “b = 0” image, the first three and the last diffusion encoding directions as well as the averaged diffusion weighted images are shown. Tagging data from the three orthogonally oriented line-tagged stacks are given alongside. The temporally averaged stretch tensors as calculated from the tagging data allow assessing radial, circumferential and longitudinal stretch components, which are presented as stretch maps, to be assessed.</p