Abstract 11245: Simultaneous PET/MRI With [64Cu]-DOTATATE Image Activated Macrophages in-vivo in Patients With Atherosclerosis
Introduction: Molecular imaging can potentially identify vulnerable plaques. Macrophages are essential in plaque development and can be imaged using our novel [64Cu]-DOTATATE tracer.
Hypothesis: Specific and sensitive assessment of the somatostatin receptor by [64Cu]-DOTATATE-PET combined with superior soft tissue resolution of MRI allow in-vivo evaluation of activated macrophages in human carotid plaques.
Methods: Patients with clinical indication for carotid endarterectomy were prospectively included for simultaneous PET/MRI (Siemens Biograph mMR) after injection of [64Cu]-DOTATATE. PET/MRI of the carotid plaque was performed a median of 77 min after injection and included four MRI sequences. Regions of interest were drawn to include the carotid plaque and tracer uptake (SUVmean) was calculated. Carotid endarterectomy was performed the next day. Plaque specimens were sliced and aligned to the PET/MRI slices. Activated macrophages (CD163) and all macrophages (CD68) were assessed by gene expression analysis using real-time PCR.
Results: Ten patients (5 men) with median age 63 years (range 53 to 73) were included. PET/MRI of the carotid artery was feasible in all patients. Activated macrophages (CD163) in the plaque were significantly correlated with the biomarker of all macrophages (CD68; r=0.8; p<0.001). In-vivo tracer uptake correlated with markers of activated macrophages in the plaque (p=0.04) whereas tracer uptake did not correlate with the molecular marker of all macrophages (p=0.7). However, a model including both activated and all macrophages was highly associated with tracer uptake in the plaque (r=0.5; p<0.001). This remained significant when adjusting for age and gender.
Conclusion: Hybrid PET/MR imaging using a novel PET tracer is feasible and allows non-invasive assessment of activated macrophages within human atherosclerotic plaques. This could potentially improve the non-invasive identification of vulnerable plaques.
Author Disclosures: S.F. Pedersen: None. B.V. Sandholt: None. A.E. Hansen: None. S.H. Keller: None. H. Sillesen: None. R.S. Ripa: None. L. Højgaard: None. A. Kjær: None.
- © 2014 by American Heart Association, Inc.