Sample positioning and preliminary imaging of PVA contrast agent.

<p>(a) Mouse carcass fixated on the animal bed of a preclinical phase-contrast and dark-field CT scanner. A plastic tube was surgically inserted underneath the peritoneum and some spare volume of the tube for flushing the contrast agent downwards was attached to the right side of the mouse. (b) Transmission image of plastic vials containing water (left) and PVA microbubbles (right). Grey values ranging from 0 to 0.35. (c) Dark-field image of plastic vials containing water (left) and PVA microbubbles (right). Grey values ranging from 0 to 0.75. (d) Visible-light brightfield microscopy image of PVA microbubbles.</p

Measurement of pure PVA bubbles contrast agent.

<p>Grey value scaling is given in brackets. The first column shows the same image with the tube filled with water for three different contrast modalities: (a) transmission [0, 0.9], (d) differential phase [</p><p></p><p></p><p><mo>−</mo></p><p><mi>π</mi><mn>2</mn></p><p></p><p></p><p></p>, <p></p><p></p><p></p><p><mi>π</mi><mn>2</mn></p><p></p><p></p><p></p>], (g) dark field [0, 1.0]. The second column shows the same image with the tube filled with pure PVA-microbubbles suspension in three different modalities: (b) transmission [0, 0.9], (e) differential phase [<p></p><p></p><p><mo>−</mo></p><p><mi>π</mi><mn>2</mn></p><p></p><p></p><p></p>, <p></p><p></p><p></p><p><mi>π</mi><mn>2</mn></p><p></p><p></p><p></p>], (h) dark field [0, 1.0]. The third column shows the subtraction of the image with contrast agent (second column) from the image with water (first column) for three different contrast modalities: (c) transmission [0, 0.04], (f) differential phase [<p></p><p></p><p><mo>−</mo></p><p><mi>π</mi><mn>2</mn></p><p></p><p></p><p></p>, <p></p><p></p><p></p><p><mi>π</mi><mn>2</mn></p><p></p><p></p><p></p>], (i) dark field [0, 0.3].<p></p

Transmission electron microscopy image of a PVA microbubble.

<p>The bubble is coated with iron-oxide nanoparticles, manufactured by Surflay nanotec GmbH, Berlin, Germany. Image courtesy Johan Härmark, School of Technology and Health, KTH Royal Institute of Technology, Sweden.</p

Transmission signal subtraction images.

<p>Left column: transmission signal subtraction images. Right column: threshold-limited, filtered superimposition of the transmission subtraction image (in color) on the respective original transmission image (grey values range: [0, 0.9]). (a)-(b) 100% Solutrast, (c)-(d) 10% Solutrast.</p

Measurement of pure Solutrast contrast agent.

<p>Grey value scaling is given in brackets. The first column shows the same image with the tube filled with water for three different contrast modalities: (a) transmission [0, 0.9], (d) differential phase [</p><p></p><p></p><p><mo>−</mo></p><p><mi>π</mi><mn>2</mn></p><p></p><p></p><p></p>, <p></p><p></p><p></p><p><mi>π</mi><mn>2</mn></p><p></p><p></p><p></p>], (g) dark field [0, 1.0]. The second columns shows the same image with the tube filled with pure Solutrast in three different modalities: (b) transmission [0, 0.9], (e) differential phase [<p></p><p></p><p><mo>−</mo></p><p><mi>π</mi><mn>2</mn></p><p></p><p></p><p></p>, <p></p><p></p><p></p><p><mi>π</mi><mn>2</mn></p><p></p><p></p><p></p>], (h) dark field [0, 1.0]. The third column shows the subtraction of the image with contrast agent (second column) from the image with water (first column) for three different contrast modalities: (c) transmission [0, 0.2], (f) differential phase [<p></p><p></p><p><mo>−</mo></p><p><mi>π</mi><mn>2</mn></p><p></p><p></p><p></p>, <p></p><p></p><p></p><p><mi>π</mi><mn>2</mn></p><p></p><p></p><p></p>], (i) dark field [0, 0.13].<p></p

Dark-field signal subtraction and multimodal images.

<p>Left column: dark-field signal subtraction images. Right column: threshold-limited, filtered superimposition of the dark-field subtraction image (in color) on the respective original transmission image (grey values range: [0, 0.9]). (a)-(b) 100% PVA microbubbles suspension, (c)-(d) 10% PVA microbubbles suspension, (e)-(f) 1.3% PVA microbubbles suspension.</p