Analysis of small abdominal aortic aneurysms with the radiotracer technetium-99m- 6-hydrazinylnicotinoyl-C-C-chemokine receptor-2 ligand (99mTc-HYNIC-CCR2-L) with single-photon emission computed tomography.

Abstract

Purpose: Monocyte chemoattractant protein-1 (MCP-1/CCL2) plays a key role for infiltration of monocytes/macrophages and studies have demonstrated that the MCP-1/C-C chemokine receptor 2 (CCR2) axis might be involved in the pathogenesis and progression of abdominal aortic aneurysms (AAA). Molecular imaging has shown potential for human clinical research studies. We evaluated the expression of CCR2 in patients with small AAA using single-photon emission computed tomography (SPECT) with the technetium-99m-6-hydrazinylnicotinoyl-C-C-chemokine receptor-2 ligand (^99mTc-HYNIC-CCR2-L).

Material and methods: A pilot study was performed to evaluate patients with small asymptomatic AAA. The equipment used was a Symbia T2 (Siemens, Germany), with radiolabeled ^99mTc-HYNIC-CCR2-L. The SPECT uptake and activity were assessed and counted based on the region of interest (ROI), with nonparametric statistics being employed to compare the aneurysms site, left ventricle (Control 1) and regions with a nondiseased aorta (Control 2).

Results: The three patients were male (100%) (mean age 81 years, and mean AAA maximum diameter of 40 mm, SD 3 mm). All patients tolerated the studies well. Images were obtained at one, two and four hours. The ROI mean value of the aneurysm site was 37,783 (SD 11,890), compared to the left ventricle (Control 1) 16,779 (SD 4397) (p-value = 0.0001); ROI for the nondiseased aortic region (Control 2) was significantly lower, 12,520 (SD 2141) (p-value = 0.0001).

Conclusions: Significant differences of CCR2 expression SPECT were found in the AAA site compared to the left ventricle and nondiseased aortic segments. The introduction of well-designed longitudinal studies with nuclear imaging modalities may assist in the molecular characterization of aneurysmal and rupture prediction.