PT  - JOURNAL ARTICLE
AU  - Sheryl Roberts
AU  - Eshita Khera
AU  - Crystal Choi
AU  - Tejas Navaratna
AU  - Jan Grimm
AU  - Greg M. Thurber
AU  - Thomas Reiner
TI  - Optoacoustic Imaging of Glucagon-like Peptide-1 Receptor with a Near-Infrared Exendin-4 Analog
AID  - 10.2967/jnumed.120.252262
DP  - 2021 Jun 01
TA  - Journal of Nuclear Medicine
PG  - 839--848
VI  - 62
IP  - 6
4099  - http://jnm.snmjournals.org/content/62/6/839.short
4100  - http://jnm.snmjournals.org/content/62/6/839.full
SO  - J Nucl Med2021 Jun 01; 62
AB  - Limitations in current imaging tools have long challenged the imaging of small pancreatic islets in animal models. Here, we report the first development and in vivo validation testing of a broad-spectrum and high-absorbance near-infrared optoacoustic contrast agent, E4x12-Cy7. Our near-infrared tracer is based on the amino acid sequence of exendin-4 and targets the glucagon-like peptide-1 receptor (GLP-1R). Cell assays confirmed that E4x12-Cy7 has a high-binding affinity (dissociation constant, Kd, 4.6 ± 0.8 nM). Using the multispectral optoacoustic tomography, we imaged E4x12-Cy7 and optoacoustically visualized β-cell insulinoma xenografts in vivo for the first time. In the future, similar optoacoustic tracers that are specific for β-cells and combines optoacoustic and fluorescence imaging modalities could prove to be important tools for monitoring the pancreas for the progression of diabetes.