Now there are a few other knobs/buttons among the many that the scanner can use to help with image optimization and garnering information from the ultrasound image. As you know, the amazing Diagnostic tool that you have is also used by the human medicine world and there will be settings that we will never utilize. Once we identify those settings, we can know how best to use or not use them. So let us jump right into the deep end of the pool!
B mode – You may have heard it called “Real Time” or 2D. This is the two-dimensional ultrasound image display that we see when we scan. It is composed of bright dots representing the ultrasound echoes. The brightness of each dot is determined by the amplitude of the returned echo signal. This allows for visualization and quantification of anatomical structures.
Gray maps – a series of shades of gray (from white to black) settings that determine how dark or light you prefer to show each level of white/gray/black based upon the strength of the ultrasound signal. These are set up with their individual unique image manipulations and this becomes personal preference. However, choosing a good B-map for starting the overall image quality is essential.
Color Maps- along with gray maps there are color maps as well. Why use a color map? Sometimes you may suspect a subtle lesion within an organ. When you apply a color map on the image it can make the lesion “pop” out.
Advanced image manipulation and diagnostic capabilities (harmonics and image compounding for example)
1. Harmonics – allows high resolution identification of tissues in the near field and reduces artifacts. The disadvantage is that it decreases visibility of far field tissues. The best way to see what harmonics does is to turn it on and off in different situations to see what helps. You’ll find many presets on your machine that have harmonics enabled and disabled. Be sure to try them all.
2. Image Compounding – this combines three or more images from different steering angles into a single image. Traditionally, transducers send ultrasound signals in a single “line of sight.” This means it sends a sound signal perpendicular to the probe head, then listens for the echo. With compound imaging, the ultrasound sends signals at multiple angles, allowing it to “see” tissue from multiple angles increasing image resolution by using the multiple lines of sight to eliminate artifacts, shadows, and increase edge detail.
Example of traditional single and compounded signal:
Persistence – multiple image frames are combined, or “averaged” into a single image making it appear smoother and noise is reduced in the image.
Auto Optimization (Auto Optimize, Auto Tuning, Tissue Equalization) – most systems offer, what I like to call, a “cheat button.” Once you place the transducer/probe onto the patient and press this button it automatically optimizes the gain and overall contrast of the image. This feature analyzes the tissue in the image and attempts to provide you with the most optimized image. This is a great feature but, don’t be too disappointed if it doesn’t work every time. Every machine calls this function something different so you will have to find out what it is for your machine. For the Samsung machines it is the “Q Scan” button.
Doppler settings:
1. PW Doppler – Pulsed Wave Doppler; the transducer sends out short and quick pulses of sound so it becomes possible to accurately measure the blood flow in real time at a single point, or within a small window of space (gate).
2. Gate -the sample site from which the signal is obtained with pulsed Doppler. The gate size can be shortened and widened to match vessel size. Also the Doppler angle can be manipulated with the ultrasound beam to get the most accurate velocity when the beam is parallel to flow.
Color Doppler (Flow) – Color Doppler provides a method to visualize blood flow direction and speed so it can be differentiated from surrounding tissues. The color image that is produced from pulse-echo Doppler flow principle is superimposed on the 2D grayscale image. The red and blue colors provide an indication of the flow velocity and direction. You have probably heard the mnemonic BART. That is the “Blue Away” and Red Towards” indicating the direction of the color in relation to the flow. Just remember that color doppler is a QUALITATIVE analysis of data and does not provide velocity information.
Power Doppler – Traditional Power Doppler is more sensitive than color Doppler for the detection and demonstration of blood flow, but provides no information about the direction of flow. Power doppler provides greater detail of blood flow, especially in vessels that are located inside organs. The Samsung machines now have S-Flow, which gives bi-directional power doppler!
Wow, with going over all this information I am reminded of a song lyric from Elton John’s Rocket Man… “and all the science I don’t understand. It’s just my job five days a week.”
Image optimization is not complicated but it seems very intimidating at the start due to the unfamiliarity with the controls and terminology. It begs the question where should you begin? Begin by opening your systems user manual! Each user manual has a section in the front which outlines the location of different controls. Find that page and leave it open. Don’t have a hard copy? You can search for one online to download to your computer. Have your computer near your ultrasound with the guide open to the page that outlines the different controls. You can’t find one online? Most manufacturers store a PDF version on the system. Press the F1, “?”, or help key on the keyboard to open it. You may want to take a picture of the console/control page with your smart device to use as a reference.
Bottom line is this: your best bet at tackling these knobs/buttons is to get a dog volunteer, place the transducer on the abdomen and start turning those knobs!! See what they do and take them to their extremes! You can always reset the image and start again if it gets too crazy. PRACTICE, PRACTICE, PRACTICE!!