Detection of acute heart transplant rejection using ultrasound imaging of ICAM1 in rats with abdominal heterotopic heart transplantation. A. Each animal was separately administered microbubbles with anti-ICAM1 antibody (MBICAM, left panels) or isotope control non-specific IgG (MBCTL, right panels) on their surface. In the rejecting allografts (upper panels), MBICAM caused persistent contrast enhancement not seen after injection of MBCTL. In the non-rejecting isograft hearts (lower panels), there was no significant persistence of myocardial contrast enhancement after injection of either microbubble species. B. Histology of myocardium showing inflammatory infiltrate and ICAM1 (brown) on hematoxylin and eosin and immunohistochemical staining, respectively, in rejecting allograft (upper panels); this was not seen in control isograft myocardium (lower panels). Reprinted with permission from Ref 43.