How It Works: Vascular Ultrasound Probes and Transducers
Our “How it Works” ultrasound series has been an outstanding hit after the first few articles – leading us to continue our breakdown of ultrasound transducers and how they work. After discussing sector array cardiac probes and curved array abdominal probes, we now move on to discussing vascular transducers.
Vascular ultrasound imaging is a very generic term, as vascular means “veins” “vessels” or any means that permits blood to travel through the body. Because blood flows through our entire body at all times, vascular ultrasounds can be applied to nearly every part of the body. We’ll discuss the transducers that are employed to capture vascular images, how they work, various applications of vascular ultrasounds, and more
Just like most abdominal and cardiac probes generally have certain lenses that are shaped very specifically (curved and square shaped, respectively), most vascular probes have their tell-tale shape as well. Vascular transducers have a long, thin rectangular shape, and subsequently are known as “linear array” probes.
We’ve also discussed in prior articles the importance of the sound frequency that the probe emits, but this is such an important part of ultrasounds to understand that we’ll review again:
Transducers work by emitting a very high pitched sound that harmlessly penetrates the body. Depending on where the probe is pressed against (the chest, the arm, the throat), and the frequency pitch that the probe sends out, the sound echoes off of an internal structure and is translated into an image by the ultrasound system.
The general rule for frequency is that the higher the pitch, the more shallow the penetration. Conversely, the lower the frequency, the deeper the penetration. Most vascular ultrasound applications, and most veins and vessels are closer to the surface than other internal structures (like the heart for example) – and therefore require an ultrasound probe to emit a higher frequency pitch than a curved array or phased array transducer.
Although vascular ultrasound exams are usually conducted on surface veins and vessels, sometimes the vascular exam may require deeper penetration – to conduct a cardio-vascular exam for example. Because of this, most vascular probes have a very wide frequency range – spanning sometimes between 6 – 13 MHz. This ability to generate frequency pitches that range from extremely high to relatively low allows the probe to capture images of veins very close to the surface, as well as vessels that are deeper in the body.
Vascular Ultrasound Imaging
Vascular ultrasound applications, as mentioned earlier, can be applied to nearly anywhere on the body. There are two styles of vascular ultrasound tests: Doppler and conventional ultrasounds.
Doppler ultrasound, as discussed in our article “How it Works: Doppler Ultrasound Imaging”, shows blood flow, any blockages or obstacles, and using color coding, identifies which direction the blood is flowing. Vascular ultrasound, rather than simply showing blood flow and pulses, creates actual images of the veins and vessels and captures images of the circulation.
Vascular ultrasounds are employed in order to diagnose various ailments including: blood clots, strokes, seizures, heart attacks, and any affliction that can occur as a result of obstructions in the veins, vessels and arteries.
Cardiac Vascular: Also known as Cardiovascular studies, this test is conducted in order to examine the vessels and veins coming to and from the heart, along with the blood that runs through it. This particular exam, due to the location of the heart in the body, requires a lower frequency range then other vascular studies. These exams are usually performed using either linear probes on a low frequency setting, or the occasional advanced cardiac transducer.
Abdominal Vascular: Another popular location to conduct a vascular ultrasound is in the abdominal region of the body. The primary malady that an abdominal vascular test is used to diagnose an aortic aneurysm.
Anesthesia / Surgical Vascular: This application of vascular ultrasound exams during surgery greatly reduces risks of blood clots, strokes, seizures and other afflictions that may occur in surface veins during surgical procedures. This test is almost exclusively done with linear array transducers on a very high frequency – considering how shallow the veins and vessels that are being examined are in the body.
HFL50x Linear Array Probe Transducer
Vascular Ultrasound Machines:
The leading manufacturer of vascular ultrasound machines in the world is Philips. With the HD15, IE33, IU22, and Epiq ultrasound systems, Philips has remained the authoritative experts on vascular ultrasounds.
GE, originally specializing in general imaging and radiology, began to develop ultrasound series’ that each specialize in specific applications. The GE Vivid series, including the Vivid E9, Vivid E and the Vivid S5 are all popular and advanced vascular systems.
There is always the concern, particularly when it comes to medical equipment, regarding the safety of the devices and the potential side effects that occur as a result of employing these machines.
It is important to know that ultrasound machines are known to be completely harmless. They function through the utilization of sound waves emitting from the probe or transducer. These sound waves are then translated into images by the ultrasound machine or system. There is no need to fear when using ultrasound machines – it is a quick, easy and efficient way to diagnose and help determine a patient’s ails.
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