Detection of macrophages in aortic aneurysms by nanoparticle positron emission tomography-computed tomography

Arterioscler Thromb Vasc Biol. 2011 Apr;31(4):750-7. doi: 10.1161/ATVBAHA.110.221499. Epub 2011 Jan 20.


Objective: Current management of aortic aneurysms (AAs) relies primarily on size criteria to determine whether invasive repair is indicated to preempt rupture. We hypothesized that emerging molecular imaging tools could be used to more sensitively gauge local inflammation. Because macrophages are key effector cells that destabilize the extracellular matrix in the arterial wall, it seemed likely that they would represent suitable imaging targets. We here aimed to develop and validate macrophage-targeted nanoparticles labeled with fluorine-18 ((18)F) for positron emission tomography-computed tomography (PET-CT) detection of inflammation in AAs.

Methods and results: Aneurysms were induced in apolipoprotein E-/- mice via systemic administration of angiotensin II. Mice were imaged using PET-CT and a monocyte/macrophage-targeted nanoparticle. AAs were detected by contrast-enhanced micro-CT and had a mean diameter of 1.85 ± 0.08 mm, whereas normal aortas measured 1.07 ± 0.03 (P < 0.05). The in vivo PET signal was significantly higher in aneurysms (standard uptake value, 2.46 ± 0.48) compared with wild-type aorta (0.82 ± 0.05, P < 0.05). Validation with scintillation counting, autoradiography, fluorescence, and immunoreactive histology and flow cytometry demonstrated that nanoparticles localized predominantly to monocytes and macrophages within the aneurysmatic wall.

Conclusions: PET-CT imaging with (18)F-labeled nanoparticles allows quantitation of macrophage content in a mouse model of AA.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Validation Study

MeSH terms

  • Angiotensin II
  • Animals
  • Aortic Aneurysm, Abdominal / diagnosis*
  • Aortic Aneurysm, Abdominal / diagnostic imaging
  • Aortic Aneurysm, Abdominal / etiology
  • Aortic Aneurysm, Abdominal / immunology
  • Apolipoproteins E / deficiency
  • Apolipoproteins E / genetics
  • Autoradiography
  • Contrast Media*
  • Disease Models, Animal
  • Female
  • Flow Cytometry
  • Fluorodeoxyglucose F18*
  • Macrophages / diagnostic imaging*
  • Macrophages / immunology
  • Metal Nanoparticles*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Monocytes / diagnostic imaging
  • Positron-Emission Tomography*
  • Predictive Value of Tests
  • Radiopharmaceuticals*
  • Reproducibility of Results
  • Splenectomy
  • Time Factors
  • X-Ray Microtomography*


  • Apolipoproteins E
  • Contrast Media
  • Radiopharmaceuticals
  • Fluorodeoxyglucose F18
  • Angiotensin II