Cardiac ultrasound is a challenge for most ultrasound machines, but with two echocardiographers on team, it’s our favourite way to put our systems to the test.

Today’s challenge, though, was a tough one – even for our machines. We put the Vinno D6 through its paces, scanning rats and mice. The higher spec Vinno D10 might have been marginally easier, but our goal was to achieve the highest possible performance at the minimal viable cost.

When it comes to scanning rodents, companies charging around £200,000 for an ultrasound machine have traditionally dominated the market. As if £200k wasn’t quite enough to charge for an ultrasound machine, many often levy an additional charge per scan performed. Not every research lab has this type of grant money available for an ultrasound scanner, and we have supplied a number of laboratories across the UK for both rodent reproductive and cardiac ultrasound.

Scanning Rats’ Hearts

The parasternal long-axis view was quick and easy to obtain in rats, with visualisation of the aortic root and ascending aorta particularly impressive. Small though they are, they weren’t a whole lot smaller than some kittens I’ve performed congenital screening echocardiograms on in the past. The short-axis was more of a challenge with the linear probe due to the large footprint of the probe over the ribs, but the phased array performed well. The colour Doppler performance on the phased array was also extremely impressive – it did not struggle at all with the challenge of such a fast heart rate. It coded flow just as accurately as it would for a dog or cat.

For the apical 4 chamber, the phased array was essential – it was practically impossible with the linear. Getting the correct angulation was a challenge, and I know that in full ‘lab rat’ setups, the animals are often reclined in order to get the best angle. We found that obtaining the parasternal short axis and sliding down toward the tail from this position was the easiest approach to finding an on-axis 4 chamber view.

I had the opportunity to speak with an expert in rodent echocardiography, who came down from his lab to try out the Vinno, and it was reassuring to hear that he deems clear apical images with good endocardial definition an unrealistic goal in rodents; for him, as long as he can get his Dopplers (as one invariably can, even when 2D imaging is poor), that is all that matters as this is the only real purpose of the apical views for him. We had hoped to try out the Vinno’s impressive Global Longitudinal Strain (GLS) software, but it had become apparent that this was not going to deliver meaningful results.

One of the things we really wanted to test was the D6’s ability to obtain various parameters needed for the assessment of diastolic function. Unfortunately for us, the rat we chose to take a mitral pulse wave Doppler trace from had E/A fusion, but with a bit of patience we did manage to capture one or two beats with enough separation between E and A waves. We were also able to obtain tissue Doppler traces, in order to calculate an E/E’ ratio, proving the theory that good Doppler sensitivity easily overcomes challenging 2D imaging.

Mouse Echocardiography

Mice presented us with a whole new challenge. A rat’s heart is in the first 2cm away from the transducer face; a mouse’s heart, within the first 0.5cm. With the phased array probe, the lowest we could reduce our depth to was 3cm, meaning that our area of interest was still quite small at the top of the screen. Interestingly, the probe did not particularly struggle with the heart being so close in the near field, as most phased arrays would. This is something we have noticed before when scanning small cats (on many echo machines often the right ventricle, being completely in the near field, is obscured by artefact), and one of the reasons why we absolutely love the new Vinno systems for small animal echocardiography in general.

The linear probe solved this problem, but then struggled to obtain an adequate frame rate for a heart rate of over 400bpm. Nevertheless, it performed very well for Doppler studies, which was the most important factor for us as we were assessing diastolic function.

As a reminder, our aim today was to test the Vinno D6 in the laboratory animal setting, without exceeding a budget of £20,000. Vinno actually excels in laboratory ultrasound equipment, and comparing the images on the regular D6 linear probe that we used, versus the dedicated (but more expensive) research D6 machine and linear probe, there definitely is a step up in quality. The decision to be made is whether this level of image quality is necessary (if your measurements are primarily performed on M-mode and PW Doppler, it probably is not).

Take a look at the two videos below. The first one shows images we obtained on the day with the standard Vinno D6 and linear probe. The second one shows the more impressive lab version of the D6, with X10-23L research probe.

Regular D6 linear probe on a mouse:

Research D6 linear probe (X10-23L) on a mouse:

Summary

The Vinno D6 performed exceptionally well for echocardiography on rats, and we have previously demonstrated its success in pregnancy scanning in rats and mice also.

Mouse echocardiography presented more of a challenge due to the even faster heart rates and much tinier heart. A stand-off would be unlikely to have helped, and was indeed unnecessary, as the D6’s near field performance was exceptional.

Whether the Vinno D6 with a phased array and/or linear probe does the job for you will therefore depend on your research questions. If you are scanning mainly rats, it will definitely achieve all of the 2D, M-mode and Doppler that you require. For mice, if you are looking to quantify using M-mode and Doppler, its high Doppler sensitivity means that it can still do the job. If, however, you require the ability to perform measurements from 2D images (for example, wall thickness or ejection fraction), it seems prudent to consider investing in one of Vinno’s dedicated lab systems – just contact us and let us know your requirements.

Finally, it is worth nothing that one of the many reasons people choose to work with us is our trade-in plans, whereby companies and institutions can upgrade their equipment later down the line, trading in their existing machine to receive the majority of their original investment off the cost of the next machine up. This is a great way for research projects to get going and generate exciting results. As these results come in, it becomes easier to expand the scope of the project and justify upgrading to the higher spec offering.