Visualisation of myocardial blood flow is crucial for studying the pathogenesis of coronary heart disease. In the quality control of surgeries, such as coronary artery bypass grafting, there is also an urgent need to constantly image myocardial blood flow perfusion.
Current techniques for monitoring myocardial blood flow are Transit Time Flow Measurement (TTFM) and Positron Emission Tomography-computed Tomography. Although both are widely used, the processes either fail in sufficient spatial sampling or cannot perform dynamic real-time imaging.
Laser Speckle Contrast Imaging (LSCI), a less-used technique, is a real-time wide-field technology that can offer a powerful means to assess tissue blood flow in both human and animal tissues throughout a wide dynamic range (WDR). The full-field vision and high spatiotemporal resolution of LSCI is drawing interest from the scientific and medical communities.
Scientists from China’s Capital Medical University, Technical Institute of Physics and Chemistry, and University of Chinese Academy of Sciences have shown (1) via animal experiments that the LSCI technique is capable of measuring velocities over a wide dynamic range in real-time. The imaging system documented the spatiotemporal evolution of myocardial perfusion in coronary artery bypass grafting, an advancement that could be of great benefit for future research in the life sciences and clinical medicine. All experiments were carried out in accordance with the guidelines for the humane care of animals.
HIGH-RESOLUTION, HIGH-SPEED IMAGES
The experimental setup consisted of a 785nm wavelength laser diode placed in a mount with a thermoelectric cooling stage. Before the samples were illuminated, a light pipe homogenized the laser beam. The imaging system itself was composed of a Mikrotron EoSens 4CXP CoaXPress CMOS camera set to acquire images at 2336×1728 resolution@563 frames per second (7×7μm pixel size), along with a bandpass filter, polarizer, tube lens ( f = 100 mm, AC508-100-B-ML), plus a Nikon CF Plan NA0.13 5× objective lens. The Mikrotron camera’s four CXP-6 channels were connected to a single CXP frame grabber via coaxial cables transmitting at a total of 25Gbit per second.
Using the Mikrotron CXP camera, the WDR-LSCI method was successfully demonstrated to measure a high blood flow rate with superior performance when compared to TTFM. The new system showed higher sensitivity and the ability to obtain a wide-field, high-precision blood flow rate map in the non-contact way while imaging in vivo.
