Two-dimensional (2D) ultrasound is a straightforward and relatively cheap form of medical imaging. In skilled and experienced hands, it can be a powerful tool for visualising organs and what may be wrong with them. However, it is often regulated to use in emergency medical situations in hospital settings. Its other main use is to generate foetal imaging for obstetrics and related practices.
On the other hand, 2D ultrasound can only offer a slice through a particular area at a specific angle. Volumetric, or 3D, ultrasound may provide even more detailed information on the region of interest. While 3D ultrasound machines are available, they are expensive and require specialised equipment.
A team of researchers from two universities in the United States have investigated the possibilities of combining microchips that offer orientational information with conventional ultrasound devices. They claim that this has resulted in reliable volumetric imaging. The team believe that this will increase the clinical profile of ultrasound imaging, as well as confer added benefits for doctors who care for pregnant women.
Combining data chips and ultrasound
Most modern smartphones contain chips, or specific subsections of their SOCs, that are responsible for ‘sensing’ the device’s orientation, or which way it’s facing and the angle at which it’s being held. It may also give rough data on the direction in which the device is travelling and at what speed. This information can be used for purposes such as waking the screen when the device is picked up, step-counting and silencing the device when it is flipped onto its screen in some cases.
In other words, these circuits give a phone a sense of three-dimensional space and how it should behave as it moves through it. Dr Joshua Broder, who works as a researcher at the Duke School of Medicine and as an emergency medical doctor, decided to find out if the integration of orientation-data chips could also bring 3D capabilities to standard ultrasound imaging. He formed a team with Matthew Morgan from Duke and Jeremy Dahl and Carl Herickhoff, both from Stanford, to complete a proof-of-concept study on this concept, which is described in a 2017 research article in the journal Ultrasound Imaging.
Broder asserts that the addition of volumetric data to conventional ultrasound will generate high-quality images. This, he argues, is not necessarily a feature of expensive, purpose-built 3D ultrasound machines, as image quality is still largely determined by the skill of the operator in question. Broder also claims that 3D ultrasound makes imaging quicker rather than more effective in diagnostic power.
On the other hand, the new ‘upgraded’ 2D ultrasound device may make images generated with it more consistent, regardless of who is wielding the device or what is being imaged. His team used a conventional research-grade scanner with an ultrasound probe - the wand-like attachment that is applied to the skin over the organ of interest, and usually coated in ultrasound-conducive gel, augmented with an orientational chip. This arrangement generated complementary data on ultrasonically-delineated tissue shape and depth, according to the July paper. The data is ultimately converted into usable 3D images using offline software.
The system has a number of advantages besides its update to include volumetric capabilities. The chip mounted on the ultrasonic probe costs about $10, thus representing a cost-effective upgrade for existing ultrasound equipment. Broder got the idea for this upgrade by watching his children play with their Nintendo Wii consoles. This device translates the movements of the user to corresponding movements of characters and objects on-screen, using similar sensor chips in the console’s handheld controllers.
Broder then sourced the relevant equipment on his own, and set out to test the potential of their combination. After solo tests, he subsequently linked up with Morgan, who was studying at the Pratt engineering school (also affiliated with Duke) at the time. Dahl and Herikhoff, who also worked at Duke at this point, also became involved, and continued to develop their eventual prototype while moving to Stanford.
Easy addition to standard ultrasound equipment
The prototype as described consists of a 3D-printed plastic probe attachment containing the orientational circuits. Therefore, an operator can fit this attachment to a conventional probe when 3D imaging is required, or leave it off for normal 2D imaging. Both the probe and attachment need to be connected to the same laptop, which runs the volumetric image-generation software, for 3D imaging in real time.
As with normal ultrasound imaging, the operator sometimes needs to hold the probe to the patient’s skin for some time before finding the region of interest and getting a clear enough image of the issue in question. The team has also developed a plastic stand for the upgraded probe in order to facilitate this. Broder has also claimed that the 3D-augmented probe has been used to image hydrocephaly in a newborn baby without discomfort for the patient.
Ultrasound has many advantages in terms of diagnostic imaging. It does not emit radiation or involve any other potentially harmful substances such contrast material, as with computed tomography (CT). Therefore, it is most often approved for in utero imaging or imaging in newborns. Modern ultrasound devices may also be streamlined, portable and easy to use; this is why they are often brought into situations such as medical care during natural disasters or armed conflict.
On the other hand, the addition of 3D imaging to new machines has not improved on these features, sometimes requires additional equipment and is not necessarily linked to better imaging. However, a new, cheap and innovative adaptation to existing ultrasound technology may stand to change all that. The team behind it claim that it can offer high-quality volumetric images regardless of other factors such as the skill level of the operator. This proof-of-concept may translate into a new accessory offering an upgrade to 3D for many clinical professionals who use ultrasound.
Top image: YouTube Screenshot
Herickhoff CD, Morgan MR, Broder JS, Dahl JJ. Low-cost Volumetric Ultrasound by Augmentation of 2D Systems: Design and Prototype. Ultrasonic Imaging. 0:(0). pp.0161734617718528.
Khanna S. How a $10 Microchip Turns 2-D Ultrasound Machines to 3-D Imaging Devices. DukeHealth News & Media. 2017. Available at: https://corporate.dukehealth.org/news-listing/how-10-microchip-turns-2-d-ultrasound-machines-3-d-imaging-devices?h=nl