Optimize Screening of the Fetal Heart

Posted on November 1, 2022 by aium1952

The keys to optimizing screening of the fetal heart are to understand how the ultrasound machine’s functions and controls can affect your image, utilize the entire maternal abdomen, adjust your image presets, and optimize your angle of insonation. So how do you do all that?

You start with the transducer. Be sure to select a transducer that allows for adequate penetration and optimal resolution. All transducers have different operating frequencies and capabilities; high frequencies produce better detail resolution but, of course, with limited sound penetration. These frequencies can be applied in all trimesters, particularly since the advent of high-resolution transducers, which are helpful when imaging delicate heart structures, such as the valves and vessel walls. If, however, the imaging is subpar with a high-frequency transducer, switch to a low-frequency transducer, which is more useful in your patients with a high body mass, in the late second trimester, in the third trimester, and in the event that there is also polyhydramnios syndrome, even when there is rib shadowing. Keep in mind too, that transvaginal imaging is helpful for evaluating the fetal heart in the first or early second trimester, in the event that there is suspected fetal cardiac abnormality, and even when maternal body habitus causes imaging to be difficult.

For your next step, adjust your image presets to optimize your temporal resolution so that you maintain a high frame rate of greater than 25 frames per second. A few of the technical settings that affect temporal resolution are the frame rate (in Hz), frequency selection, depth & focus, sector angle width, and zoom magnification. The better the temporal resolution, the improved detail resolution. To optimize your image, avoid unnecessary depth and make sure your focus is on the region of interest. A multiple focal zone may be applied to structures that don’t move, such as the placenta, but when looking at the 4-chamber heart, you will need a single focal zone. In addition, adjust your sector angle width. Reducing it increases lateral line density, which improves the image quality. Finally, make small adjustments to your settings, such as applying speckle-reduction imaging, adjusting the dynamic range (more or less gray), and scanning in different tones.

When incorporating color Doppler, the color box, color gain, wall motion filter, velocity scale/pulse repetition frequency (PRF), balance, and angle of insolation can each affect the image. The color box slows the frame rate by a significant degree so the smaller the color box, the higher the frame rate. Set color gain initially on low (ie, less color) and gradually increase it until you have optimized the amount of color. The wall motion filter eliminates signals caused by wall motion and low velocities. The velocity scale is the range of mean velocities or PRF in the region of interest. If it is too low, it can produce aliasing, which could lead to a misdiagnosis; too high and the low-velocity flow will not be displayed. Here is a sample of potential ideal velocity flows:

High-velocity flow (>60–80 cm/sec)	Low-velocity flow (<30 cm/sec)
Atrioventricular valves	Pulmonary veins
Semilunar valves	Bicaval (IVC/SVC)
The great vessels (3VV)	Evaluating atrial and ventricular septum

The scale is dependent on factors such as body mass index and fetal positioning within the uterus.

The balance allows you to display how much grayscale and color Doppler information you would like to see. Reducing the balance will show grayscale elements within the color box. And, finally, the angle of insonation is very important to keep in mind as the signal from the transducer should be parallel to the direction of blood flow.

*J of Ultrasound Medicine*, Volume: 35, Issue: 1, Pages: 183-188, First published: 01 January 2016, DOI: (10.7863/ultra.15.02036)

One of the major challenges in ultrasound imaging is scanning a morbidly obese patient. This is a result of the increased distance between the transducer and fetal anatomy, causing degraded resolution. Some techniques for optimizing your imaging in these cases include scanning above the tissue, when the patient’s bladder is full, through the umbilicus, or when the patient is in the Sim’s position (with the patient on their left side), which allows the extra tissue to fall to the left side. Also, keep in mind that when scanning an obese patient, the color doesn’t always fill in. Lowering the color attenuation can help clarify the image.

So, remember, the key to optimizing your fetal heart imaging is in understanding your machines’ functions and controls and how they can affect your image, utilizing the entire maternal abdomen, adjusting your image presets, and optimizing your angle of insonation!

To learn more and see case scenarios, see the American Institute of Ultrasound in Medicine’s (AIUM’s) on-demand webinar with speaker Mishella Perez, MS, RDMS, RDCS, “Fetal Heart Image Optimization: The Key to Screening”, from which this post was adapted. AIUM members can access the webinar for free.

Interested in learning more about fetal imaging? Check out the following resources from the American Institute of Ultrasound in Medicine (AIUM):

On-demand lecture: How to Perform a Detailed Anatomic Ultrasound Examination in the First Trimester
JUM article: Trouble With the Curve: Pearls and Pitfalls in the Evaluation of Fetal Growth
On-demand course: Fundamentals of OB-GYN Ultrasound
on-demand webinar: Utilizing Ultrasound Technology to Maximize Information in the Age of COVID-19

Do More With Less: Ultrasound

Posted on August 24, 2021 by aium1952

Life is not always easy, sometimes you just have to manage with what you have. To work with limited resources is one of the skills you acquire once you are a primary care physician and particularly in Africa.

This is also true concerning point-of-care ultrasound (POCUS); it is possible to do more with less. If you really understand how it works, you can find new ways to use your tools to get the correct diagnosis.

Now, I want to share with you the case of a 53-year-old male patient whose major complaint was joint pains, particularly in the left wrist and knee. Upon physical examination, the joints were warm, swollen, and painful. I hypothesized that the diagnosis was a primary gout episode but in my health facility I don’t have a uric acid test that I would ordinarily use for confirmation of the diagnosis. I then performed a POCUS examination to confirm the diagnosis by looking for the double contour cartilage line, which is a sign of gout in joints due to uric acid deposit at the surface of bone cartilage. I didn’t have a linear high-frequency probe, so I used an endocavitary probe just as you can see in the pictures.

Ultrasound images of the knee showing the double contour sign indicative of gout.

POCUS can greatly increase healthcare in low-income countries. Usually, the healthcare gap between upper-income and low-income countries is huge but, with POCUS, the same technics can be applied to both, with the same results, if ultrasound devices are available.

However, the problem remains that there is a lack of healthcare professionals who are skilled enough to use it and teach others. The problem is no longer an absence of devices but is now due to an absence of knowledge of how to use them.

Fortunately, due to COVID-19 lockdowns, we know almost everything that can be taught online. Therefore, it is time for us to think about establishing a new way to teach, learn, and practice ultrasound. Many ultrasound societies, such as the AIUM, ISUOG, and EDE, have started to share free POCUS education on their websites. Free online courses should be encouraged since they will lead us to the democratization of ultrasound, particularly in low-resource settings.

Yannick Ndefo, MD, is a general practitioner at St Thomas hospital in Douala, Cameroon.

Interested in learning more? Check out the following posts from the Scan:

Pioneering Ultrasound Units

Posted on October 8, 2019 by aium1952

If you think your ultrasound machine is out-dated, imagine if you still had to use these from as long ago as the 1940s.

1940s

Ultrasonic Locator
Dr G. D. Ludwig, a pioneer in medical ultrasound, concentrated on the use of ultrasound to detect gallstones and other foreign bodies embedded in tissues. During his service at the Naval Medical Medical Research Institute in Bethesda, Maryland, Dr Ludwig developed this approach that is similar to the detection of flaws in metal. This is A-mode in its operation and was Dr Ludwig’s first ultrasonic scanning equipment.

Locator

1950s

Ultrasonic Cardioscope
Designed and built by the University of Colorado Experimental Unit, the Cardioscope was intended for cardiac work.

1960s

Sperry Reflectoscope Pulser / Receive Unit 10N
This is an example of the first instrument to use an electronic interval counter to make axial length measurements of the eye. Individual gates for the anterior segment, lens, and vitreous compartment provided accurate measurement at 10 and 15 MHz of the axial length of the eye. This concept was the forerunner of all optical axis measurements of the eye, which are required for calculation of the appropriate intraocular lens implant power after cataract extraction. This instrument, which includes A-mode and M-mode, was developed by Dr D. Jackson Coleman and Dr Benson Carlin at the Department of Ophthalmology, Columbia Presbyterian Medical Center.

Sonoray Model No. 12 Ultrasonic Animal Tester (Branson Instruments, Inc.)
This is an intensity-modulated B-mode unit designed exclusively for animal evaluations. The instrument is housed in a rugged aluminum case with a detachable cover that contains the cables and transducer during transportation. The movable transducer holder on a fixed-curve guide was a forerunner of mechanical B-scan ultrasonic equipment.

Smith-Kline Fetal Doptone
In 1966, pharmaceutical manufacturer Smith Kline and French Laboratories of Philadelphia built and marketed a Doppler instrument called the Doptone, which was used to detect and monitor fetal blood flow and the heart rate. This instrument used the continuous wave Doppler prototype that was developed at the University of Washington.

Smith-Kline Ekoline 20
Working in collaboration with Branson Instruments of Stamford, Connecticut, Smith-Kline introduced the Ekoline 20, an A-mode and B-mode instrument for echoencephalography, in 1963. When B-mode was converted to M-mode in 1965, the Ekoline 20 became the dominant instrument for echocardiography as well as was the first instrument available for many start-up clinical diagnostic ultrasound laboratories. The A-mode was used in ophthalmology and neurology to determine brain midlines.

University of Colorado Experimental System
Developed by Douglas Howry and his team at the University of Colorado Medical Center, this compound immersion scanner included a large water-filled tank. The transducer moved back and forth along a 4-inch path while the carriage on which the transducer was mounted moved in a circle around the tank, producing secondary motion necessary for compound scanning.

1970s

Cromemco Z-2 Computer System (Bioengineering at the University of Washington)
This color-Doppler prototype, introduced in 1977, was the computer used for early color Doppler experiments. Z2 “microcomputers” were used for a variety of data acquisition and analysis applications, including planning combat missions for the United States Air Force and modeling braking profiles for the San Francisco Bay Area Rapid Transit (BART) system during actual operation.

ADR-Model 2130
ADR of Tempe, Arizona, began delivering ultrasound components to major equipment manufacturers in 1973. Linear array real-time scanners, which began to be manufactured in the mid-1970s, provided greater resolution and more applications. Grayscale, with at least 10 shades of gray, allowed closely related soft tissues to be better differentiated. This 2-dimensional (2D) imaging machine was widely used in obstetrics and other internal medicine applications. It was marketed as an electronic linear array, which was faster and more repeatable without the need for a water bath as the transducer was placed right on the skin.

Sonometrics Systems Inc, NY BR-400V
The first commercially available ophthalmic B-scanner, this system provided both linear and sector B-scans of the eye. The patient was examined in a water bath created around the eye by use of a sterile plastic ophthalmic drape with a central opening. Both A-scan and B-scan evaluations were possible with manual alignment of the transducer in the water bath. The instrument was developed at the Department of Ophthalmology, Columbia Presbyterian Medical Center by Dr D. Jackson Coleman, working with Frederic L. Lizzi and Louis Katz at the Riverside Research Institute.

Unirad GZD Model 849
Unirad’s static B-scanner, allowing black-and-white anatomic imaging, was used with a scan arm and had similar controls as those used today, including processing, attenuation compensation, and gain.

1980s

American Flight Echocardiograph
This American Flight Echocardiograph (AFE) is a 43-pound off-the-shelf version of an ATL 400 medical ultrasonic imaging system, which was then modified for space shuttle compatibility by engineers at the Johnson Space Center to study the adaptations of the cardiovascular system in weightlessness. Its first journey to space was on the space shuttle Discovery in 1985 and its last on the Endeavour in 1992. The AFE generated a 2D cross-sectional image of the heart and other soft tissues and displayed it in video format at 30 frames per second. Below, Dr Fred Kremkau explains more about it.

To check out even more old ultrasound machines, visit the American Institute of Ultrasound in Medicine’s (AIUM’s) An Exhibit of Historical Ultrasound Equipment.

How old is the ultrasound machine you use now? What older ultrasound equipment have you used? Did it spark your desire to work with ultrasound? Comment below, or, AIUM members, continue the conversation on Connect, the AIUM’s online community.

The AIUM is a multi-disciplinary network of nearly 10,000 professionals who are committed to advancing the safe and effective use of ultrasound in medicine.

Are You Sonogenic?

Posted on September 24, 2019 by aium1952

Most of us who do ultrasound commonly use the disclaimer that “the study is suboptimal because of the patient’s body habitus” (we stay away from the word “limited” because this word has specific billing implications). This phrase conveys to the referring physician that we are not getting the pictures we hope to get because of something we can’t control, namely the patient’s size. No matter how we tweak the transducer frequency, adjust the time-gain compensation curve, or simply press harder we cannot achieve optimal image quality. Lev

Sometimes, however, we are either pleasantly or unpleasantly surprised. A thin individual may have soft tissues that are difficult to penetrate, leading to an image of suboptimal quality.

Conversely, a patient with high body mass index may turn out to be a breeze to scan. Clearly, there is something more than simply patient size that is at work here. After all, echoes on ultrasound are created at interfaces between tissues that differ in acoustic impedance. A larger patient with relatively homogenous subcutaneous tissues (fewer interfaces) may reflect and scatter the beam less than a patient whose tissues are composed of a more varied mixture of fat, fibrosis, and/or edema (more interfaces).

When people consistently look great in photographs, we call them “photogenic”. The implication of this word is that somehow the camera loves the subject so much that their still image “overachieves” compared to the expected output. When you think about it, that may be a subtle insult, but it is usually used as a compliment. Conversely, a person we find attractive may, for reasons that are unclear, not be at their best in photographs.

In light of the above, I would like to coin a new word, “sonogenic”. A sonogenic person is one who transmits sound so well that their ultrasound images consistently exceed expectations. A patient that frustrates us because their images are of lower quality than expected would be characterized as “non-sonogenic”.

Using this word can potentially facilitate communication. The sonographer could say to the reading physician: “Sorry for these images; the patient wasn’t sonogenic”. The physician’s reports can become shorter: “The study is suboptimal because of patient’s body habitus” becomes “the patient is not sonogenic”. The noun form would be “sonogenicity” (yes, “photogenicity is a word”). A simple grading system may even become part of the ultrasound report, i.e., sonogenicity is above average, average, or below average.

In conclusion, I hereby propose that the word “sonogenic” be added to the formal ultrasound lexicon. What do you think?

Would you use the term sonogenic? Do you have any other suggested new terms that could better describe an aspect of an ultrasound examination? Comment below, or, AIUM members, continue the conversation on Connect, the AIUM’s online community.

Levon N. Nazarian, MD, FAIUM, FACR, is Professor and Vice Chairman for Education in the Department of Radiology at Thomas Jefferson University Hospital in Philadelphia, Pennsylvania.

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