Application Cases

Experiment Name: High-Frequency Ultrasound Intravascular Imaging Experiment

Research Direction: Cardiovascular disease has become the leading cause of death and disability worldwide, with over 20 million people dying from it annually. Intravascular ultrasound imaging is an endoscopic imaging tool that can directly reflect the internal structure and pathological conditions of blood vessels. By combining ultrasound imaging technology with catheter intervention, it not only provides morphological information about the vascular lumen and plaques but also offers detailed characteristics of tissue structure, providing precise imaging guidance for the clinical diagnosis and treatment of intravascular diseases.

Experimental Objective: To test whether the performance of the transducer catheter meets the expected design parameters. Both the bandwidth and echo amplitude must be in an optimal state to satisfy the acquisition requirements for Doppler and B-mode signals, as well as meet the resolution and imaging depth requirements for detecting intravascular tissue information.

Testing Equipment: Radiofrequency power amplifier, preamplifier, digital oscilloscope, IVUS transducer, etc.

Experimental Procedure:
The control section of the main circuit board primarily involves an FPGA generating logical timing control signals, performing digital signal processing, and caching image data. Communication and data transmission with the host computer are carried out via a high-speed USB 3.0 module, while the host software interface is used to set experimental parameters and perform real-time imaging. Simultaneously, the digital signal is converted by a DAC and amplified by an ATA-8202 radiofrequency power amplifier. The ultrasound transducer, driven by the power amplifier, generates ultrasonic vibrations, enabling the piezoelectric crystal to resonate at the same center frequency as the external excitation signal. The experimental system flowchart is shown in Figure 1-1.

Figure 1-1: System Flowchart

Experimental Results:

Figure 1-2: Measured Echo Results of the Forward-Looking Probe

The intravascular dual-mode ultrasound transducer catheter has a total outer diameter of less than 1 mm, with two 0.4 mm coaxial cables extending from the tail end of the tube. The catheter includes both a forward-looking transducer and a side-looking transducer. The fabricated transducer is placed in a water tank, directly facing a solid medium suspended on a three-dimensional stand. This setup allows for three-dimensional adjustment of the reflector’s orientation during echo acquisition. A pulse generator provides excitation signals to the transducer, while echo signals are received synchronously via a preamplifier and displayed on an oscilloscope. Guided by the echo signals on the oscilloscope, the orientation and position of the solid medium are adjusted to maximize the echo amplitude. The oscilloscope’s signal processing function is then used to perform a Fast Fourier Transform on the acquired echo signal. The frequency range corresponding to the -6 dB points around the peak amplitude is selected to calculate the transducer’s center frequency and bandwidth.

Echo testing of the transducer reveals that the forward-looking transducer has a measured center frequency of 23.4 MHz, a bandwidth of 50.7%, and an echo amplitude of 0.654 V under a 50 Ω condition, as shown in Figure 1-2. The performance of this transducer catheter meets the expected design parameters, with both bandwidth and echo amplitude in an optimal state. It can satisfy the acquisition requirements for Doppler and B-mode signals while also meeting the resolution and imaging depth requirements for intravascular tissue information detection.

Recommended Radiofrequency Power Amplifier: ATA-8000 Series

Figure: ATA-8000 Series Radiofrequency Power Amplifier Specifications

The experimental materials in this article were compiled and published by Xi'an Aigtek Electronics.