Novel imaging technique used for DVT detection
MedWire News: US researchers have developed a novel peptide that targets fibrin and enables clots to be detected by near-infrared fluorescence (NIRF) imaging.
The team synthesized the fibrin-targeted peptide and conjugated it to Cy7, a NIR fluorochrome that can be viewed on fluorescence imaging using excitation and emission wavelengths of 743 and 767 nm, respectively.
To test the specificity of the peptide, the researchers conducted an in vitro clot binding analysis using human plasma clots. They observed a significantly higher NIRF clot target-to-background ratio (TBR) for the fibrin-targeted peptide than for free Cy7.
In addition, binding was significantly blocked with a 100-fold excess of competitor peptide, indicating that the engineered NIRF peptide is fibrin specific, said lead author Tetsuya Hara (Massachusetts General Hospital, Boston) at the Society of Nuclear Medicine's 58th Annual Meeting in San Antonio, Texas, USA.
Hara and team next tested the utility of the NIRF agent in a mouse model of deep vein thrombosis (DVT).
They performed intravital fluorescence microscopy of femoral vessels in mice with acute (at 2 hours post thrombus induction, n=5) and subacute (at 72 hours, n=3) thrombi, and observed a high TBR in both groups. The mean TBR was 2.9 in mice with acute thrombi and 3.9 in those with subacute thrombi.
"The synthesized NIRF fibrin-targeted peptide avidly binds human clots and enables sensitive, fast multimodal optical imaging detection of acute and subacute DVT in vivo," the researchers remarked.
Hara concluded: "The availability of a high-resolution fibrin sensor is important for two reasons: intravascular NIRF imaging of coronary-sized arteries is now possible, and coupling the fibrin peptide with this technique may allow researchers to study coronary artery plaques and stents, which could potentially help us identify patients at increased risk of heart attack."
MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011
By Laura Dean