Ultrasound Image Optimisation and Helpful Tips
This month our Account Manager Q&A session is with Laura Oldroyd. Our Account Manager for the North West who is discussing Ultrasound Image Optimisation Q&A
One of the most common requests when providing ultrasound support is ‘how do I make this picture better?. To understand how to get the most of any ultrasound system. You have to be able to determine what it is that you are trying to achieve. And then identify which aspects of image optimisation will help you achieve this. It can sometimes be overwhelming when working with a new ultrasound system. However if you work through it systematically and identify the main control buttons it should be relatively straight forward.
Preparing the patient
Regardless of the structure and animal you are trying to ultrasound. You can follow the same basic principles in terms of setting up your ultrasound system. Before approaching the more technical aspects, there are a few practical things to consider. Properly preparing the patient and ensuring you clip a large enough area of hair is vital. As trying to correct this mid-scan can be challenging. Then, if you can allow around 15 minutes for the ultrasound gel to sit on the skin before starting the examination. It will dramatically increase your image quality. In addition to patient prep, making sure you can keep the exam room relatively dark and quiet will also contribute to a better experience.
Presets
Once you are ready to start scanning it is important to work out if your ultrasound system has presets on it. As this will make your life a little easier. These are pre-selected settings that are optimised for the structure and possibly animal that you are examining. Even after using a preset, due to the variety in size of veterinary patients. You will still need to further optimise your image. There are five main settings to consider and generally. The first thing to look at is the depth that the ultrasound image is set to. As a basic rule the structure you want to examine should fit 2/3-3/4 of your window. If you don’t do this as the initial step. You may optimise the rest of your settings and then have to adjust them again when you set up the depth correctly.
Frequency
The next step would be to select the most suitable frequency for the structure you are viewing. To work what this is, it is important to remember that a higher frequency will provide greater resolution. But poorer penetration whereas a lower frequency will compromise on resolution although allowing for greater penetration. As you can already see, when performing an abdominal examination for example. It would be necessary to adjust these settings as you move between the different organs as they will have varying depth and frequency requirements.
Focal Point
From experience the next aspect is probably the most neglected. In terms of optimising the image quality of an ultrasound system. The focal point, often indicated by a small triangle on the right-hand side of the image. Refers to creating a narrow point in the cross-sectional area of the ultrasound beam. This provides the area of greatest lateral resolution. So therefore should be adjusted so that it is located just under or at the base of the structure you are examining. It is often possible to set multiple focal zones on an ultrasound system to increase these areas of greater resolution. However this will negatively impact the frame rate of the ultrasound system. So can cause the picture to appear to blur or lag. So unless necessary, one focal point is normally sufficient in most cases.
Gain and Time Gain
Finally the last two settings to consider before you can start examining your patient are the gain and time gain compensation. The gain is just the overall amplitude of the ultrasound signals being displayed by the ultrasound system. It is important to remember. This will also increase the visibility of the echoes you wouldn’t normally see. Therefore creating artefacts that might inhibit diagnosis.Iit is recommended to find a balance with the gain that provides a bright enough image without causing any interference.
As a general rule it is easy to set the gain correctly by using a fluid filled structure and adjusting the gain to make it as high as possible whilst the fluid remains black on the screen. Time gain compensation or TGC are controlled by the small group of sliders and are simply able to adjust the gain along different zones of the ultrasound image. It is often recommended that the gain in the far field will have to be increased compared to the gain in the near field, however a lot of the modern ultrasounds systems allow for this and compensate accordingly. This is a bit dependent on each individual system so just make a note of your own scanner and set it up with this in mind.
Practice makes perfect
There are many more imaging controls on an ultrasound than mentioned already in this article, such as dynamic range, harmonics and crossbeam to name a few. It might be that these are some things to consider if still struggling to get an optimal image on your ultrasound scanner, however from experience a lot of issues seen in practice can be resolved by focusing on these five main parameters. Don’t be scared of changing settings on your ultrasound system and seeing how it affects your image, even if takes a bit more time initially it will improve your ability to perform a through examination dramatically. In addition if you do end up adjusting a lot of the settings and then can’t remember what they were initially, you can use your presets to return to your starting point.
Hopefully these tips on image optimisation will help with your next ultrasound exam and if you need any further advice, please feel free to contact your local account manager to discuss.