By Allen 
From High-Intensity Focused Ultrasound and Shear Wave Research Systems to Ultrafast Doppler and Sonoporation, ultrasound techniques are undergoing several developments. This makes it important to know what each of these methods offers and how they work.
Medical and industrial technology that uses ultrasound imaging as its foundation is continuously evolving to increase imaging resolution and accuracy in non-invasive diagnostics and testing. And to deploy these new techniques effectively, engineers need to be aware of what these are, how they work, and the benefits they offer.
Here, we list the eight leading advanced ultrasound techniques that are making an impact on non-invasive testing, diagnosis, and imaging.
Top Advanced Ultrasound Techniques that Engineers Need to Know
From HIFU and Shear Wave Research System to CUES and UfD, 8 of the leading advanced ultrasound techniques that every engineer needs to know are listed as follows:
1. High-Intensity Focused Ultrasound (HIFU)
High-intensity focused ultrasound is a non-invasive material testing process used in both industrial and medical applications. However, it is more popular as a medical treatment procedure that uses highly focused, high-intensity sound waves to heat and ablate (destroy) targeted tissue non-invasively, without the need for any incisions.
The High-Intensity Focused Ultrasound Research Systems are built with a specialized, often curved, transducer. This focuses high-energy ultrasound beams onto a small target located deep within the patient’s body. The resulting localized thermal energy and mechanical effects (cavitation) induce tumor ablation, pain palliation in bone metastases, and treat uterine fibroids while the surrounding tissue remains largely unaffected.
2. Shear Wave Elastography
The Shear Wave Research System operates on the principle of Young’s modulus. Thus, it measures tissue stiffness by generating tiny shear waves with acoustic pulses, tracking their speed to calculate elasticity, helping differentiate hard, diseased tissue (like tumors or fibrotic liver) from softer normal tissue.
In Shear Wave Elastography (SWE), an ultrasound transducer is used to send a focused high-intensity ultrasound pulse into the targeted tissue, which creates shear waves. These are then tracked to determine the physical characteristics of the targeted tissue, which is then displayed as a color map overlaid on a standard ultrasound image.
3. Photoacoustic Imaging
Photoacoustic Imaging is a hybrid imaging modality that combines optical absorption contrast with ultrasonic detection, providing functional information not available from ultrasound alone. This is a highly effective technique for visualizing blood vessels and identifying malignant lesions from benign ones.
In this method, short pulses of light belonging to the near-infrared spectrum are directed towards the targeted tissue, which are absorbed. This causes the tissue to heat up slightly and expand rapidly, and the result is detected by ultrasound waves picked up using the transducer. The signals are then reconstructed into images that show the optical absorption properties of the targeted tissue.
4. 3D and 4D Ultrasound Imaging
Both 3D and 4D Ultrasound Imaging are methods that provide volumetric imaging of tissue structures. While 3D ultrasound produces static volume renderings, 4D adds the dimension of real-time motion to the 3D images.
A linear array probe or 2D matrix array transducer gathers multiple images, which are then processed into a comprehensive 3D image. For 4D imaging, this process is performed rapidly and continuously to display moving structures, such as a beating heart or fetal movements, in real-time video clips.
5. Ultrafast Doppler (UfD) / Plane Wave Imaging
An advanced Doppler imaging technique, Plane Wave Imaging is characterized by extremely high temporal resolution, often thousands of frames per second, which is much faster than conventional Doppler.
This technique transmits a plane wave to scan the entire field of view simultaneously instead of using a single focused beam. Further, the high frame rate tracks rapid movements and subtle changes, offering high spatiotemporal resolution.
6. Contrast-Enhanced Ultrasound (CEUS)
In the Contrast-Enhanced Ultrasound (CEUS) technique, microbubble contrast agents are injected intravenously. Microbubbles are typically filled with an inert gas like sulfur hexafluoride and stabilized by a shell. Being highly reflective to ultrasound waves, this significantly increases the backscattered signal for better imaging.
In the vascular system, this technique enhances the ultrasound signal from blood flow and tissue perfusion, resulting in better visualization and characterization. The method is popularly used for imaging blood flow in small vessels, tumor vascularization, and organ perfusion.
7. Molecular Ultrasound Imaging
Similar to CEUS, Molecular Ultrasound Imaging, too, uses targeted microbubbles for visualization. However, this functional imaging is used to look for specific molecular biomarkers, such as those related to inflammation or angiogenesis (new blood vessel formation), instead of simply improving the visualization of vascular tissue.
The microbubbles of Molecular Ultrasound Imaging contain ligands that bind to specific molecular targets (e.g., VEGFR2 receptors on tumor vessels). When these microbubbles accumulate at the site of interest, they produce a strong ultrasound signal. This allows researchers to image molecular processes at a high resolution greater than that offered by standard ultrasound.
8. Sonoporation and Ultrasound-Mediated Drug Delivery
Sonoporation involves the use of ultrasound, often with microbubbles, to temporarily increase the permeability of cell membranes or biological barriers (like the blood-brain barrier). This, in turn, enhances the delivery of drugs or genes to specific locations.
Oscillating or collapsing microbubbles under ultrasound exposure induce mechanical effects that temporarily create pores in cell membranes (sonoporation) or open endothelial junctions in blood vessels. This allows co-administered therapeutic agents to enter the targeted cells or tissues more effectively.
Wrapping Up
From High-Intensity Focused Ultrasound Research Systems to those that use Sonoporation for Ultrasound-Mediated Drug Delivery, the above advanced techniques are the next step towards targeted therapy, diagnostics, and patient care. Thus, these are expected to revolutionize safe, accurate, and precise non-invasive imaging, diagnostics, and treatment.
Achieving Accuracy in Medical Diagnostic and Treatment Through Advanced Ultrasound Techniques
Are you an engineer or medical professional interested in learning more about advanced ultrasound techniques? Do check out what each of the listed techniques offers and how they benefit your specific field of interest.