Figure 3 from VCAM-1–targeted MRI Improves Detection of the Tumor-brain Interface

<p>Anti-VCAM-1–targeted MRI reveals tumor margins in MDA231Br-GFP brain metastases. Pre-/post-gadolinium <i>T</i>₁-weighted images from rat brains either with intrastriatal MDA231Br-GFP tumors (<b>A</b> and <b>B</b>) or injected intrastriatally with PBS (<b>C</b>). Matched pre-/post-MPIO <i>T</i>₂*-weighted images from the same anatomic locations and same animals as for <b>A</b> and <b>B</b>, injected intravenously with either VCAM-MPIO contrast (<b>D</b>), or IgG-MPIO (<b>E</b>). <b>F,</b> Pre-/post-MPIO <i>T</i>₂*-weighted images from a rat injected intrastriatally with PBS and VCAM-MPIO intravenously. Dashed red line encircles visible hypointense regions. <b>G,</b><i>T</i>₂-weighted images showing areas of tumor-associated hyperintensity (white arrowhead). <b>H,</b> Representative MR images of MDA231Br-GFP tumor-bearing rat brain with hypointensities (green pixels) from <i>T</i>₂*-weighted imaging overlaid on contrast-enhanced <i>T</i>₁-weighted imaging. Note the green pixels extend into regions of the striatum with no associated <i>T</i>₂ hyperintensity (red arrowheads). Scale bar = 2 mm. <b>I,</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> < 0.01; ***, <i>P</i> < 0.001; <i>post hoc</i> Tukey test (<i>n</i> = 8 MDA231Br-GFP groups and <i>n</i> = 3 PBS group). <b>J,</b> Representative <i>T</i>₂*-weighted MR image slice of a MDA231Br-GFP tumor, with white box highlighting the invasive tumor margin confirmed histologically (<b>K</b>); scale bar = 500 μm. <b>L,</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>