Vascular and perfusion imaging using encapsulated laser-polarized helium

Area of Science:

• Medical Imaging
• Biophysics
• Nanotechnology

Background:

• Hyperpolarized (HP) helium-3 (3He) offers unique imaging properties but suffers from low solubility in blood.
• Developing effective delivery agents is crucial for in vivo applications of HP 3He.

Purpose of the Study:

• To report the use of HP 3He for in vivo intravascular imaging in animal models.
• To present a novel approach for enhancing helium solubility using lipid-based microbubbles.
• To evaluate the potential of this technique for lung perfusion imaging and ventilation-perfusion assessment.

Main Methods:

• Encapsulation of HP 3He in lipid-based carrier agents to form microbubbles (mean diameter 3.0±0.2 µm).
• In vitro characterization of microbubbles, including longitudinal relaxation time T(1) (90 s) and apparent transverse relaxation time T(2)(*) (4.5 ms).
• In vivo imaging in rats via intravenous injection, including angiographic and lung perfusion imaging, and assessment in an embolism model.

Main Results:

• Successful in vivo intravascular imaging, including venous and cardiac cavity visualization, and lung perfusion imaging in rats.
• Achieved suitable signal and spatial resolution for diagnostic imaging.
• Demonstrated visualization of lung perfusion defects and recovery in an experimental embolism model.
• Validated a new ventilation-perfusion lung exploration method using HP 3He.

Conclusions:

• HP 3He encapsulated in microbubbles is a viable method for in vivo intravascular imaging.
• The technique shows significant potential for non-invasive lung perfusion assessment and ventilation-perfusion studies.
• This approach overcomes helium solubility limitations, opening new avenues for advanced medical imaging.