Figure 4 from VCAM-1–targeted MRI Improves Detection of the Tumor-brain Interface

<p>Anti-VCAM-1–targeted MRI reveals tumor margins in U87MG brain tumors. <b>A</b> and <b>B,</b> Pre-/post-gadolinium <i>T</i>₁-weighted images from rat brains with intrastriatal U87MG tumors. Matched pre-/post-MPIO <i>T</i>₂*-weighted images from rat brains with intrastriatal U87MG tumors, injected intravenously with VCAM-MPIO (<b>C</b>) or IgG-MPIO (<b>D</b>); dashed red line encircles visible hypointense regions. Scale bar = 2 mm. <b>E,</b> Representative images from U87MG tumor-bearing rat brain with hypointensities (green pixels) from <i>T</i>₂*-weighted images overlaid on contrast-enhanced <i>T</i>₁-weighted images. Scale bar = 2 mm. <b>F,</b> Graph showing volumes of hypointensities post-<i>T</i>₂*-weighted MRI; data shown as mean ± SD, blue = ipsilateral striatum, yellow = contralateral striatum. *, <i>P</i> < 0.05; **, <i>P</i> < 0.01; <i>post hoc</i> Tukey test (<i>n</i> = 5 per group). <b>G,</b> Graph showing volume of MPIO-induced hypointensities beyond the border of gadolinium enhancement for rats injected with either VCAM-MPIO or IgG-MPIO. *, <i>P</i> < 0.05; Student <i>t</i> test. <b>H,</b> Pseudocolored three-dimensional reconstruction of imaged animal brain, with coregistration of post-VCAM-MPIO <i>T</i>₂*-weighted and contrast-enhanced <i>T</i>₁-weighted images; blue = gadolinium enhanced region and yellow = <i>T</i>₂* hypointensities. <b>I,</b> Representative <i>T</i>₂*-weighted MR image slice of an U87MG tumor, with white box highlighting the invasive tumor margin confirmed histologically (<b>J</b>); scale bar = 500 μm. <b>K,</b> Corresponding high-power magnification of highlighted regions of interest (black and red boxes) from stained adjacent sections, demonstrating bound VCAM-MPIO beads (black arrowhead/brown spheres) in a VCAM-1–positive vessel lumen (brown); scale bar = 10 μm.</p>