Imaging Characteristics of DHOG, a Hepatobiliary Contrast Agent for Preclinical MicroCT in Mice

Abstract

This study was performed to assess the imaging characteristics and pharmacokinetics of 1,3-Bis-[7-(3-amino-2,4,6-triiodophenyl)-heptanoyl]-2-oleoyl glycerol (DHOG, Fenestra LC), a hepatobiliary contrast agent for microCT. We investigated the abdomen of 18 female C3H mice in a MicroCAT II microCT scanner before contrast agent injection and at multiple time points up to 48 hours after intravenous injection of DHOG (1 g I/kg body weight). The contrast agent effect was determined quantitatively and dynamically by measuring pre- and postcontrast Hounsfield units (HU) of the liver, aorta, spleen, and kidneys. Based on additional phantom measurements, the reproducibility of lesion detection was estimated for different lesion sizes. DHOG caused a marked early postcontrast enhancement of blood in the aorta and a very high enhancement of the spleen, both slowly declined after 90 minutes. The liver parenchyma showed a slow contrast agent accumulation and clearly increased HU data between 3 and 7 hours after injection. No significant renal parenchymal enhancement or excretion was noticed. At early time points after administration, DHOG exhibits characteristics of a macromolecular contrast agent by demonstrating a blood pool effect. At later time points, DHOG provides a prolonged, marked liver enhancement on microCT images due to its specific liver uptake. For a lesion size of 1 mm diameter, the variability in between two scans was 27.7 HU (P < .05) and the variability for different planes of one scan was 19.8 HU (P < .05). DHOG yields a very good visualization of the liver and delineation of the surrounding structures with a long plateau. It is a very suitable contrast agent for liver imaging in mice for microCT imaging. The presented protocol provides a high reproducibility for lesion detection with a relatively low radiation dose.