Cardiovascular disease is one of the leading causes of death worldwide, with approximately 20 million deaths attributed to it each year. The most common cause of cardiovascular disease is the rupture of vulnerable atherosclerotic plaques followed by thrombosis. Vulnerable plaques are typically characterized by a thin fibrous cap and a large necrotic core. Therefore, the accurate assessment of vulnerable plaques requires intravascular imaging technologies to have high resolution and large penetration depth, so as to provide information such as the thickness of the fibrous cap and the proportion of the necrotic core. However, current intravascular imaging technologies (such as IVUS and OCT) are still unable to provide high-resolution and comprehensive morphological information of the vascular inner wall.

Intravascular ultrasound (IVUS) imaging equipment plays an active role in the assessment of cardiovascular diseases and has been an important tool in interventional catheterization laboratories for more than 30 years. Nevertheless, IVUS imaging equipment is limited by the bandwidth of traditional piezoelectric transducers. Moreover, considering the high attenuation of high-frequency ultrasound in tissues, IVUS imaging must make a trade-off between resolution and penetration depth.

This study reports an all-optical intravascular ultrasound (AO-IVUS) imaging method that abandons piezoelectric transducers and uses optical methods instead of electrical methods for ultrasound imaging. The method utilizes picosecond laser pulses to excite carbon nanocomposites for generating wide-bandwidth ultrasound, and employs a performance-optimized π-phase-shifted fiber Bragg grating for ultrasound detection. It achieves ultra-wide bandwidth (147%) and high-resolution intravascular ultrasound imaging that is difficult to achieve with traditional technologies, solving the incompatibility between high resolution and large penetration depth. The all-optical intravascular imaging system achieves an axial resolution of 18 μm, a lateral resolution of 124 μm, and an imaging depth of 7 mm, realizing high-resolution imaging while ensuring a large penetration depth. In 2D and 3D imaging of porcine coronary arteries, rabbit iliac arteries, and blood vessels implanted with drug-eluting metal stents, the AO-IVUS system exhibits imaging range and vascular morphology images comparable to those of commercial IVUS systems. However, it depicts richer details of vascular structures by virtue of its high resolution, demonstrating great potential for clinical application.