Basic Obstetric POCUS

Chapter 4. Image Capture and Enhancement with Knobology

This chapter will focus on the basic techniques used to capture the best ultrasound image. Although it seems obvious, any assessment made by ultrasound depends on the quality of the image. Approach and orientation to the body and its structures, as well as how to maneuver the transducer, are integral to finding the best image. In addition, basic machine ‘knobology’ (adjustments) used to refine an image will be presented. All of these help you to achieve the best image for making an appropriate clinical decision.

Objectives:

By the end of this section you will be able to:

Apply the concept of tomography to ultrasound in how it obtains a slice of a structure for an image

Describe what is meant by scanning planes, or orientation to the body and its internal structures

Learn the terms of sagittal, longitudinal (or long), transverse, coronal, and how these are obtained

Demonstrate classic movements of a transducer: sliding, tilting, rocking, and rotating

Describe the relationship between the probe indicator (notch) and the color indicator or “dot” on the screen; recognize the clinical importance of this relationship

Utilize the adjustment features of the machine to improve the image quality.

There are two basic steps we will review in this chapter.

Step 1. Locating the structure

As discussed in the last chapter, the first major step in ultrasound is being able to locate a structure, then to adjust the transducer for optimal view.

Step 2. Adjusting the machine controls to enlarge or improve the image. A clear image makes it easier to determine normalcy versus abnormality. It is also a way to communicate what we see to another provider who may be looking at that image for consultation.

The ultrasound machine is essentially a computer attached to a specialized “camera”, in a sense. As we have learned, a typical camera captures reflections of light waves. But the ultrasound machine, instead, captures reflections of sound waves. Preceding chapters explain the properties of sound involved in this process. The ultrasound computer will capture the image and adjust it, but it must be directed by the operator in that process.

Tomography

Ultrasound is an imaging modality that uses the technique of tomography. Tomography is the technical term for how imaging acquires a single “slice” of the body to examine it. A CT or CAT (computerized tomography) scan produces multiple slices of the body taken by a sequence of x-ray images, and slices are reviewed separately and in sequence, looking for abnormalities.

Figure 1. Tomography illustration

In ultrasound, the same thing is done, except it is done in real-time. Each movement of the transducer over the body changes the angle, direction, and depth of that slice. Once the ideal view is seen, the image is “frozen” for capture and measurement.

How the “cut” or slice is made, and where it is angled, determines what is seen. Imagine the transducer as a beam of light but instead slicing through a single plane as a thin vertical ‘cut-out’ instead of a round cylindrical beam.

But when looking at this single image slice, it is difficult to discern the location or general position of the structure without using certain guidelines on how we approach or capture the image. In other words, is the structure right or left? Is it cephalic (toward the woman’s head) or caudal (toward the woman’s feet)? Or is it anterior (toward the front of her body) or posterior (toward the back)?

This is why correct orientation is critical to accurate interpretation.

Orientation

This section describes principles needed to learn how to find what we are trying to image.

This section describes how to orient the transducer to find structures, their location, and characteristics. This process is like using a compass to help find location. With ultrasound, it is critical to identify where you are in the body, and from which angle you are imaging. Locating a key body region as a frame of reference (such as the spine or other easily identified organ) helps to know where a particular part lies. Correct orientation to the woman’s anatomy is criticIn defining orientation, the body is sectioned into planes or lines that divide the body into equal parts.

Figure 2. Orientation

Orientation in ultrasound has to do with the placement and relationship of the transducer to the anatomy.

The common planes used to obtain an accurate representation of the body or structures are:

Sagittal (longitudinal)

Transverse

Coronal – used more with 3D and 4D scanning

‘Median plane’ has to do with midline of the body

Note: Orientation helps to identify the scanning region and helps to display the image correctly in relationship to other organs. It helps you know where in the body you would expect to find a structure so you can image it better. It also helps describe where you found the structure you were looking for, and at what angle or position the image was taken.

Understanding how planes are defined is critical for ultrasound or any imaging modality, as it gives the frame of reference for describing the location of the body part being captured by the image.

Figure 3\ Body planes illustration

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Sagittal means:

—Dividing the body into two longitudinal halves (right and left

Transverse means:

—Dividing the body into two sections – upper and lower halves

Coronal means:

—Dividing the body into two sections – front and back (ventral and dorsal)

When referring to a structure or organ (instead of the body as a whole), the orientation concepts remain the same, but some use the term “long” instead of “sagittal” when referring to a body structure as opposed to the use of

Figure 4. Planes through the uterus

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Longitudinal (or “long”) means:

Dividing the organ or structure into two longitudinal halves (right and left)

Transverse means:

Dividing the organ or structure into two sections – upper and lower halves

Coronal means:

Dividing the organ or structure into two sections – front and back (ventral and dorsal)

Note: Coronal imaging is not typically used in 2D or POCUS exams

Figure 5. Sagittal versus transverse slicing

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Think of the body part you are imaging as a familiar object, as in the above illustration of a loaf of bread. Slicing the object lengthwise gives you what is called the sagittal view. Slicing the object crossways gives you slices that are known as transverse.

TRANSDUCERS

Transducer selection

For those using a handheld, such as the Lumify, there is only one transducer (probe) type – the curvilinear probe. There may be other probes developed for this machine in the future, but for now this is the only probe you need to know about.

For your general information, each type of transducer has a slightly different frequency and view, affecting depth of penetration and field of view. If you were to choose a transducer, you would select one with the appropriate frequency range for what is to be scanned. In other words, if you were tryijng to visualize a superficital sructure, you would us a tranducer that uses high frequency. If you want to look deeper into the body, you would select one that has a lower frequency.

Positioning the transducer

It is important to hold the transducer correctly to prevent stress on wrists and hands. Hold the transabdominal transducer like holding a pencil or a paintbrush (see Figure 5). If while scanning, the probe needs to be rotated in an awkward position, re-position the hand to avoid twisting the arm and wrist. But in general, holding the probe consistently as shown will cause less fatigue. When first learning to scan, many tend to hold the probe too tightly, which can cause muscle fatigue. Keeping the hand relaxed helps avoid this. Remember to loosen your grip so you don’t cause muscle fatigue while scanning.

Handedness can sometimes be a factor in how one scans. Those who are right-hand dominant may need to use the right hand to hold the transducer, since this hand has better fine motor control. And vice versa for the left-handed person. However, some find that even if left-handed, they accommodate by holding the transducer in the non-dominant hand. The room constraints, and limitations of whether the machine is on the right or left of the woman, can also affect which hand the practitioner uses to scan.

Figure 6. Correct hold on the transducer.

Figure 7. Interpreting orientation depth

When placing the transabdominal transducer on the abdomen, the part of the screen image that is at the top is what is closest to the transducer. So “up” on the screen is not up toward the maternal head, it is “up” toward the transducer.

Orienting the transducer with use of the notch.

A curvilinear abdominal transducer is an arced probe. Each probe has a notch or marker on the side to designate that this is the side you should be pointing either to the woman’s head or toward her right side.

Figure 8. Notch on curvilinear transducer.

The area toward the notch is called the “toe”, and the opposite end is called the “heel”. The notch is not always clearly marked, but you will be able to find it once you begin to scan.

The transducer’s “notch” should always be pointing to the patient’s head in sagittal, and always to the patient’s right in transverse. This will be repeated throughout this course to emphasize its importance.,

Figure 9. Notch demonstration

Matching the notch to the screen

Figure 10. The transducer ‘footprint’ is the shape of the curve at the top of the image (yellow line) and it should be the same shape as the end of the transducer you are using

There is usually a “dot” or an indicator on the upper left corner of the screen that represents where the transducer notch is in relationship to the body. It will indicate direction toward the woman’s head in sagittal, or her right (in transverse). Sometimes, instead of a green or blue dot there will be some sort of symbol, which can be an icon of the machine brand.

Figure 11. General principles of orienting the probe.

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Figure 12. Sagittal view of a uterus, demonstrating that the notch on the transducer is pointed to the woman’s head

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Figure 13. Transverse view of a uterus, demonstrating that the notch on the transducer is pointed to the woman’s right

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Below are additional illustrations showing what the transducer looks like when oriented in sagittal and transverse planes.

Figure 14. What the transducer looks like in the sagittal plane, and what you will see on the screen

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When the transducer is held transverse to the body (or the structure), the notch should always be directed to the patient’s right.

Figure 15. shows that when the transducer is rotated with the notch toward the maternal right, the image you see on the screen will be a transverse view of the pelvis

Figure 15. Orientation - transverse.

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Figure 16. Image of bladder seen in the transverse plane, meaning that the green dot is toward the patient’s right side

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Figure 17. Image of uterus obtained in a transverse plane, with the dot on the patient’s right and what the transducer position would look lik

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When looking at an internal structure as the primary focus, such as a fetus, the terms sagittal or “long” are used to describe the orientation to the fetus, and not the mother.

This is because the fetus could be lying in a different plane than the vertical axis of the mother.

Figure 18. Sagittal to the FETUS, and sagittal to the abdomen. Notice the spine of the fetus is toward the top, indicating that it is closest to the probe.

Figure 19 (below) demonstrates scanning a fetus in a transverse plane. In this case we are also scanning the mother in transverse, but this is not always the case. Once again, the object of interest, and what is described as transverse, is the fetus.

Figure 20.(below) 78/+-Sagittal to the FETUS. Notice we are ‘slicing’ the fetus in a transverse way, so that we are seeing a cross-section of the fetus’s abdomen. We are also scanning the mother in transverse.

The following illustrations demonstrate that you may see a transverse (cross-section) of the baby’s abdomen while scanning the woman’s torso in the sagittal plane.

Figure 19. Illustration of woman being scanned in the sagittal plane but the baby is lying in a transverse position, so we will see a cross-section of the baby.

Figure 20. Illustration of same woman with baby in transverse lie. When scanning the woman transversely, you will be viewing a sagittal view of the baby.

Transducer adjustments to improve images

Ultrasound positioning is not always either true sagittal or true transverse, just like body organs are not aligned either as exactly vertical or horizontal. When describing the above orientation concepts, this does NOT mean that those are the only angles that can be used. If there is a structure that lies in a different angle than perpendicular or parallel to the body planes, it may be necessary to turn the transducer slightly one way or the other to get a correct view.

If it is difficult to see a structure, additional movements may be needed to help bring it into better alignment. Changing angles can also affect artifacts.

The following slides illustrate movements of the transducer to better locate and image the structure.. The cardinal movements that can be used include sliding, tilting, rocking, rotating, and compressing.

Figure 21. Overview of transducer adjustments to improve an image

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Sliding is the movement of the transducer in one plane – either up and down, or side to side in the transverse plane, as shown in Figure 22. Sliding over the entire pelvic area in both sagittal and transverse directions at the start of an exam enables the practitioner to get a view of the entire pelvis or gravid uterus before focusing on a single area.

Figure 22. Illustration of transducer sliding; up and down in sagittal, and side to side in transverse

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Tilting (or angling) involves leaving the transducer in the same place on the body, while angling it one direction or another. This allows changing the direction of the scanning plane without moving the probe (Figure 23).

Figure 23. Illustration of tilting or angling the probe

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Rocking is a technique where the transducer is tilted forward or backward to view different angles (Figure 24). Angling the transducer heel to toe is most helpful in bringing an object of interest into the center of the screen. It is very helpful when you are only seeing part of the structure you want to see. Rocking the transducer toward the direction of the organ will bring it into a more central view, allowing you to see the entire structure. This does not require the probe to be moved - it only changes the direction of the view.

Figure 24. Rocking the prob

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Rotating the transducer from sagittal to transverse or vice versa allows us to see the structure in those respective planes (Figure 25).

Figure 25. Rotating the transducer from sagittal to transverse, or from transverse to sagittal.

Rotating the transducer means that you leave the probe in place while turning it like turning a dial. Starting from the sagittal plane, the probe is turned so that the notch angles toward the maternal right. If already in a transverse plane and rotating back to sagittal, then rotation would typically be in a clockwise fashion.

When rotating, a key thing to remember is to avoid any movement of the probe other than rotating. The purpose of rotating is to keep the object of interest still in view, but to provide a transverse look at that object. Slight movement of the probe one way or another can make the object of interest no longer visible, requiring repositioning the probe to find it again.

Compression

Compressing the transducer against the patient’s skin can improve contact or bring us nearer a structure. In general, the closer the transducer is to the structure, the better the image will be. However, care must be taken not to compress the imaged structure too hard, resulting in a distorted image or measurements. For example, when measuring pockets of amniotic fluid, too much compression can make the pocket look smaller, altering the measurements. This is also true of compressing the fetal abdomen.

Figure 26. Remember: direction of the notch correlating with cephalic and caudal

IMAGE ADJUSTMENTS (KNOBOLOGY)

Now that we understand orientation and how to approach the body or structures to find them, we are ready to learn how to further adjust our image by adjustments made on the machine. This section reviews what was learned in Chapter 2, enabling you to apply knowledge about sound properties to select the right adjustment features of the machine. let’s move on to learning how to find what we are trying to image. Then we will discuss techniques to improve both.

These are the machine functions we will cover in this next section.

a. Patient identification

b. Application selection

c. Mode selection

d. Keyboard

e. Depth

f. Zoom

g. Freeze

h. Measurements and caliper selection

i. Set

j. Cine loop

k. Image saving and storage

l. Gain

Simply stated, the ultrasound computer needs to be told what type of scan to do and how it is to be done. It also needs to be directed to change certain settings to make the image clearer. This is the purpose of all the functions and adjustments.

Figure 27. Reasons for improving an image.

In your setting a handheld ultrasound machine (the Lumify), will be used. Some handheld machines have their own screen attached, but most (including the Lumify) consist of a probe that attaches to an Android-based cell phone or tablet.

Machine manufacturers are required to provide default settings for certain functions having to do with power or energy emitted, for safety precautions. The terms power output, TI (thermal index) and MI (mechanical index) are described in more detail in the next chapter Chapter 5 in the section on ultrasound safety. The machine automatically alters these settings depending on the type of scan that is selected. For example, it reduces output power for obstetric scans since it aims to keep the power at a minimum for safety’s sake.

However, the operator (person scanning) needs to be aware of these indicators to practice ultrasound safely.

Figure 28. Machine functions versus functions controlled by the operator

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For example, selecting “application” tells the machine whether the intent is to do an abdominal, ob, gyn scan, etc. The reason this is important is that when a certain application is selected (such as first-trimester ob), the machine will auto-regulate the amount of power it transmits and allow access to a menu of measurement options (called calculations or “calcs”) specific to first-trimester ob ultrasound.

This section will describe the functions of the machine that are within the control of the operator. Below are the initial selections when starting an exam:

1. Patient demographics

2. Application (telling the machine what type of ultrasound you intend to do

3. Output or intensity (power) (safety monitors)

4. Mode choice allows you to select B-mode ( 2-d, or regular grey scale scanning), M-mode (which will help you measure heart rate), Color, or other Doppler)

5. Machine adjustments

NOTE: Every machine manufacturer will provide a user manual describing all the functions specific to that machine. Locations of knobs and adjustment features can vary widely in location on the console or touchscreen, and even in the terminology used for that function. Although this chapter highlights the general purpose of the primary functions, each clinician will need to master the functions of the machine being used. Chapter 10 in this series provides instructions specific to the Lumify machine.

Since multiple options need to be selected at the start of an exam, a suggestion is to have a list of the most common functions of your machine (and where to find the corresponding buttons) posted nearby as a quick reference. It is especially helpful if using the ultrasound is not done regularly, or if there is a specific function not used often. It is also good to have the machine’s operating manual in a central location for reference.

Why are machine adjustments needed?

The principal reason that adjustments are necessary after the structure is “seen” by the transducer has to do with the concept of attenuation, defined in an earlier chapter. To review, attenuation is how sound is slowed down as it travels through tissue. The amplitude strength or power of the sound wave diminishes as it travels from the transducer, and the reflection returning to the machine is reduced even more due to attenuation.

Adjustments with the knobs can assist in overcoming attenuation by boosting signals and changing image properties to eliminate artifacts and other properties that can impact image clarity.

GETTING STARTED – locating the knobs

This section gives an overview of using the Lumify machine; however, you will have more training and videos to familarize yourself with the machine before the actual training.

The first button to locate is the “on-off” switch. With using the Lumify, the transducer will be attached to a tablet which will serve as the controls and the screen. So the Lumify is turned on when the tablet is turned on.

With the Lumify there is no need to select a transducer since you there is only one curvilinear transducer you will use at this time. It will display connectivity on the tablet or other display device.

The transducer will continue to be operative as long as the tablet attached to it has power.

It is important to pay attention to the power display on the screen to avoid machine shut-off during an exam. If that happens, you will not be able to scan while the tablet is charging.

When not using the Lumify, recharge the tablet to have it ready to use with an adequate amount of power

Figure 29. Midwife using a Lumify in a rural setting.

Opening Page

Once you have logged into the Lumify app it will show an opening page.

Figure 30. Opening page of Lumify

Patient identification (demographics)

Patient identification is essential to create a file to archive the images. Most ultrasound machines will not allow images to be saved or archived without a designated patient. If you don’ t identify a patient the machine will ‘create’ a folder for the person you are scanning and give that patient a temporary ID number. Figures 31 and 32 show examples of how to locate knobs/buttons to access the patient data entry page.

Figure 31. Select the menu by pressing the 3 lines in the upper left corner of the screen, and press ‘add patient’

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Figure 32. Page to enter patient data (left).

When the data entry screen is displayed, there are a number of entries to complete. At the very least, the patient’s name and ID number (it might be a medical record number) are required. A date of birth is important, since many patients have a common name, and the machine will need a way to separately identify the patient apart from the name. Also, to retrieve a previous scan of a patient from the machine archives, the date of birth will help distinguish which is the correct patient. Some machines, like the one above, allow for additional information such as gravida and para. For any woman it is important to put in the LMP or last menstrual period if it is known. This way the machine will make a note of gestational age if a pregnancy is discovered. The machine will compare her actual measurement with her last menstrual period to look for consistency or discrepancy. If it is known that she has twins, that information is entered, so that when measurements are done, the computer will divide the measurement calculations into sections of Baby A and Baby B, etc. It can also be helpful to write in why the exam is being performed, for example “routine ob” or “pelvic pain”, or IUD check, as examples. Some machines will have a pre-populated dropdown with those options to select.

Another important demographic is the name of the person performing the ultrasound, as well as any other practitioner who may have ordered the exam.

Application or Preset Selection

Once the patient information is entered, an application must be selected. The application selector allows selection of the type of scan desired. Application has to do with the general type of exam – whether it is an abdomen exam, a cardiac exam, a vascular exam, or obstetric. When selecting an application, the machine then automatically sets the safety parameters, depth, and gain settings that are most appropriate for that type of exam. For ob exams, for example, the machine will create the best output energy settings within the parameters of what is safest for a pregnancy.

On the Lumify, the presets are selected on the opening page (the dial with all the various applications such as abdomen, lung, fetus etc.

On the Lumify, the applications or presets are already selected when you go to the opening page. You select the type of imaging you want to do from the green and blue dial (Figure 30)

Safety indicators (Output)

Before using a transducer you need to know if your settings are safe. All ultasound screens will display what is called ‘TI’ and ‘MI’, usually in the right upper corner of the screen. These are known as output indicators, indicating the level of power being created by the transducer.

Figure 33. Location of output (safety) indicators on the screen.

Machine manufacturers are required to provide default settings for certain functions having to do with power or energy emitted, for safety precautions. The terms power output, TI (thermal index) and MI (mechanical index) are described in more detail in the next chapter Chapter 5 in the section on ultrasound safety. The machine automatically alters these settings depending on the type of scan that is selected. For example, it reduces output power for obstetric scans since it aims to keep the power at a minimum for safety’s sake.

However, the operator (person scanning) needs to be aware of these indicators to practice ultrasound safely. In some cases, the person scanning can change the application in order to enhance the power settings – this is done only if necessary so as to keep the power output as low as possible in obstetric scans.

Mode

Once the patient ID and application/preset is complete, the next step is to choose the Mode selector. As described in earlier chapters, there are 3 basic modes used in ob/gyn ultrasound: 2-D or B-mode (grey scale), M mode, and Color Mode.

2-D or B-mode

The default scan mode is 2D or B-mode (unless programmed otherwise). When selecting this mode, it will continue in this mode until changed. When scanning in another mode and the need is to change back to 2D, simply push this button again and it will revert back to B-mode.

M-Mode

When you are ready to record a heartbeat (usually a fetal heartbeat), M-mode (or motion mode) is the desired selection.

Selecting M-mode will bring up a split screen –one above the other. The top screen shows in 2D real-time the heart beating. A moveable vertical line is present that can be moved with the trackball (or touchscreen) so that it intersects with the part of the heart with the most visible motion. Placing the line so it intersects with a moving structure (such as a heart valve) is best. This will be discussed in more detail in the First Trimester OB Course. Once the vertical line is placed over the area of the heart that is moving the most, then push the M mode button again to activate the bottom screen. The bottom screen will be a scrolling, moving series of lines that should have “blips” reflecting the movement that is transected by the line on the top screen. Once a series of “blips” (usually at least 4-5) is seen, then freeze to stop the scrolling. To calculate the actual rate, calipers are placed on one blip, set, and then another caliper is dragged over 1 to 2 blips over and set again. This is how the machine calculates the heart rate and displays it.

Figure 34. M-mode on the Lumify

Color mode C-mode

The third mode we will describe is color mode or C-mode. It may also be called Color Flow or Color flow wave. When this is selected, the image continues to be in grey-scale, but blood vessels will be seen with shades of red or blue within them, indicating the direction of flow. More detail is covered in later parts of the course, but it is important to know that the red does NOT indicate artery, and the blue does NOT indicate vein. The colors have to do with flow direction. In general, the way to interpret color in doppler is use of the acronym “BART” (Blue Away, Red Toward the transducer).

Figure 35. Color flow selection on the Lumify. When selected it pulls up a box (right) that will activate color flow to any structure seen within that box.

Figure 36. Image of color flow used on a Lumify

SCANNING

With the Lumify, to begin your exam, activate the scanning function by simply pressing the freeze button to unfreeze the screen. This will bring you to the active window to begin your scan.

OTHER MACHINE CONTROLS

Keyboard

The keyboard is primarily used to annotate on the image on the Lumify. You can type, or backspace, or do page-up, enter, etc. It will display a digital keyboard on the tablet you use with the Lumify. The keyboard will allow you to label structures on the image. Annotation is an essential part of describing what you see on the image. Annotation is described near the end of this chapter in more detail.

Depth

Depth is a function used often to adjust the size of the object being viewed. While scanning, there may be a structure that is out of range and below the area (deeper in the body) seen on the screen. Instead of changing the probe or increasing power, the depth function can be used to view deeper structures. The disadvantage of using this is that although it penetrates deeper, everything in the image is reduced in size, reducing the resolution. However, if general measurement is what is important, rather than details, depth is very helpful to use.

Figure 37. Depth adjustments on the Lumify. The green arrow points to a scrolling icon that you can move with your finger to increase or decrease the depth.

This function assists in increasing or decreasing how deep into the body you want to look. (depth of penetration). This can be helpful in many ways if there is a structure that seems to be below your view on the screen. It allows you to see further into the body, but the compromise is that when depth is increased, all the structures appear smaller.

Zoom

Zoom is a function that allows one to “zoom in” on an area to enlarge it. Zooming in on an area does not increase the frequency, so there is not an increase in more detail; it simply makes the area of interest look larger. Just as with use of Zoom on a camera, the enlarged image may lose some resolution.

In performing ultrasound, you need to make the structure or area you are viewing occupy at least one-third of the screen.

Figure 38. Using touch to activate zoom.

On a handheld screen zoom is performed by using both fingers touching the screen. There may be a window at the top right highlight the part of the image being zoomed. This is very similar to using the zoom function on a digital or phone-based camera.

Freeze

The freeze button is one that is probably the most frequently-used. When a structure is viewed in the right plane to capture, pushing freeze will capture that image so the functions of labeling, annotating, and measuring can be done.

Freezing the image will allow you to annotate or save that image. When you freeze the machine, it stops the transmission of energy into the body from the transducer. This means that the transducer can stay in contact with the body without concern for extended exposure to sound waves. A hand can keep the transducer in the same location to enable rapid return to the same area just scanned, without having to “find” that structure all over again. Freezing also enables the Cine Loop (rewind) mode, which is described later.

Figure 39. Freeze button - blue icon with snowflake.

Handheld ultrasounds use various icons, but typically the icon representing ‘Freeze” is designated with a snowflake.

Measurements

Once the ideal image is captured, frozen, and optimized, measurement is the next step. There will be a place on the screen to select either a line or an elipse to use to make your measurement. Since you have already selected “OB” for your present, the measurement calculations for obstetrics will be automatically shown.

Figure 40. Measurement selection on the Lumify

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When entering the patient data (at the beginning of the scan) the LMP (last menstrual period) gives the ultrasound computer a gestational measure to compare the actual measurements obtained by the scan. I

Once the image is frozen, and the type of measurement or calc is selected, then the machine will give an option of how the measurement is to be obtained: either a straight line, ellipse, or a trace line. End-calipers are displayed either one at a time, or as in Figure 43 (handheld device) both are displayed at once. The clinician can select either of them to move around to adjust caliper placement. Once the measurement is made, the “set” button is selected, and the the machine will automatically display the measurement number. If it is a gestational measurement, then it may also display the gestational weeks correlating with that measurement.

Figure 41. Types of calipers. (linear, elipse)

Set

The set Button is what allows one to set or “stick” the cursor or measurement caliper to a certain place. For example, when measuring the distance between two areas, one must “set” the first caliper on one side of the structure. and then drag the line over to the other side; then “set” the second caliper. When selecting “set” on the second caliper, the machine then makes the calculation.

Cine Loop

When you are scanning, the machine is capturing a sequence of images (like a video clip) and saving them until you freeze. Once you freeze the image, you can go back in time (rewind) to see if there is a better image that you might have missed. This happens often while scanning babies. They can move last minute and leave you with an inadequate image. But using cine loop allows you to go back to a prior image without having to start over again to try to re-find that image. Once you have selected the ‘best’ image, you can then place your measurements.

Cine-loop is essentially a “re-wind” of the prior clip of image from a few minute before you freeze.

1. Machine captures a burst of images

2. Allows the operator to scroll back through the most recently achieved images during that scan time and select the best image

The Cine function on the handheld not only allows scrolling back in time, but it can display tiny views of each previous frame to allow selection of a particular view.

Image saving and storage (archiving)

The machine will have an icon that you push to capture and save what you are currently viewing on the screen. The icon appears like a small camera. There are several ways to view this image once it is saved for future reference. This will be explained in the last chapter of the course which is an overview of how to use the Lumify.

YOU MAY NOW TAKE THE QUIZ AND MOVE TO THE NEXT CHAPTER. YOU WILL NOT BE ABLE TO OPEN THE NEXT CHAPTER UNTIL YOU COMPLETE AND PASS THE QUIZ. YOU WILL HAVE AS MANY TRIES AS YOU NEED TO GET ALL THE ANSWERS CORRECT!

GULU Midwives Basic Obstetric POCUS

Chapter 4. Image Capture and Refining: Knobology