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3D and 4D Ultrasound

4d ultrasoundWe have seen some very appealing ads from GE, aimed at the public, the patients. So now ultrasound machine manufacturers are doing what the drug companies have been doing for several years: advertising to the public, with the intent of getting patients to influence what doctors prescribe, and now, which ultrasound machines they will buy and use.

There is no question that 3D and 4D (I will explain the difference in a moment) ultrasound is the wave of the future, and some day, in a few years, all serious ultrasound departments will have machines capable of 3D and 4D ultrasound.

3D and 4D machines have advantages in evaluating abnormalities of the uterus, ovaries, and the fetus. 3D and 4D does provide outstanding images for the parents and family and provides outstanding “bonding” of the mother and father to the unborn child. Many feel this is important. We are beginning to see reports in the ob/gyn ultrasound literature that the routine prenatal scan can be accomplished more quickly using 3D.

3D gives us a 3 dimensional image of whatever we are scanning. With a machine that can give 3D imaging, the transducer takes a series of images, thin slices, of the subject, and the computer processes these images and presents them as a 3 dimensional image. Using computer controls, the operator can manipulate the image and obtain views that might not be available using ordinary 2 dimensional sonography (2D).

In the 3D machine, the series of images is called a volume. After the volumes are obtained, the computer has to have time to work on these volumes, like a huge math project. A 4D machine has sufficient computer power that the images are almost real time, just like with 2D.

There are different kinds of 3D. For example, some machines require that the operator move the transducer over the area of interest by hand to capture the volume. This is not ideal because it takes a good deal of skill and practice to move the transducer perfectly steadily at the proper rate, angle, etc.

Other (probably more expensive) machines have a motor built into the transducer so all the operator has to do is hold the transducer steady and still, and the internal workings of the transducer will move at just the correct speed to capture a volume. This is better than doing it by hand.

Patients, of course, are anxious to see cute pictures and video of the baby. As we go through the next few years, I am sure patients will apply more and more pressure for 3D and 4D ultrasounds. The practice of medicine is quite competitive in Fairbanks, and when the first department gets a 3D or 4D machine, the others probably will follow as quickly as possible. (Remember, top of the line ultrasound machines are about $250,000. Many times they are leased, and there may be reasons why we cannot immediately dump our present machine to get the new one).

Although I have never used a 3D machine, I suspect that if I had one, most of my scanning (I do ob/gyn ultrasound only) would be done with the machine set to 2D. Lets describe a usual prenatal ultrasound. Exactly what we do will depends on when in the pregnancy the scan is done, and what, if any, the clinical problem is. But lets assume this is a “routine” second trimester prenatal ultrasound.

There are very specific standards that describe what the 2nd trimester prenatal ultrasound should consist of. We are required to meet those standards if we expect to be paid. We have to look at the uterus, often look at the cervix, look at the placenta, count the vessels in the umbilical cord, look at both ends of the umbilical cord, and note the relationship of the placenta to the cervix.

Then we note the presentation of the baby, look for hands and feet, try to see if the feet are clubbed, try to see if any fingers are missing. We look for the stomach, bladder, diaphragm, genitalia, nose and mouth (cleft lip?), kidneys, eyes. We measure the distance between the eyes, measure the pelvis of each kidney if we can see the pelvis, measure the femur length, abdominal circumference, biparietal diameter, and head circumference. We may measure each of these 2 or 3 times, depending on how clearly these areas are imaged. We look at the tongue, look at the skull, look at the long bones, carefully examine the spine for neural tube defects, and look at the heart. Not only do we count the heart rate, but we look at the four chamber view, interventricular septum, atrioventrticular valves, the atrium, the foramen ovale, and do color flow imaging of the heart looking for valvular regurgitation, and the direction of blood flow in the aorta and pulmonary artery. We examine the brain and make a number of important measurements of the brain.

All of this is done with the understanding that we should keep the exposure of the fetus to ultrasound As Low As Reasonably Achievable (we call that the ALARA principle). At the end of the scan I have to prepare the formal report of the scan, using software in my computer.

Note that there are no requirements that we take cute pictures of the baby for the family, and note that if you have a third party payer (insurance, Denali Kid Care, Medicaid, etc) they are not going to pay for a scan done for cute pictures of the baby.

So what is the 4D machine going to do here? Well, if I think I see a spina bifida, for example, I certainly will want to obtain 3D images of that. If I think there is a club foot or a cleft lip, I certainly will want to get 3D of that for future study. One of the nice things about 3D: the volumes obtained while the patient is there can be studied and restudied long after the patient is gone.

Were do the cute pictures of the baby’s face come in? That has to be extra time and extra exposure. Will sonography departments do it? That depends on how busy they are and how anxious they are to please the patients in that area. I suspect that in the next few years many 3D/4D machines will be purchased because of their marketing potential, marketing the doctors’ practice. Obviously those practices will be motivated to use the cute picture potential to increase their referrals and business (to help pay for the machine and maybe make some profit with the machine).

But what about the busy university medical center department, more patients scheduled each day than they can really do a proper job with, sonographers booked to the max, no shortage of patients here. They might be a little less anxious to take some cute 4D images at the end of a scan. In fact, it is likely that at least in the next few years most of their machines will be 2D only, and their 3D/4D machine will be reserved to study anomalies. Eventually, as the years go by, all the machines in the department probably will be 3D/4D.

A word about entertainment prenatal ultrasound

Perhaps this is a good place to mention entertainment ultrasound. There are many businesses being established that offer prenatal ultrasound, with no connection with a medical practice or hospital. These businesses offer videos, photos, narration. They make it clear that they are not there to take the place of a medically indicated ultrasound, they do not look for abnormalities, and they are strictly for entertainment purposes.

The use of an ultrasound machine in this manner is probably illegal or against the rules of the Federal agencies that control medical devices, but there has been little or no enforcement. The medical ultrasound establishment is for the most part against these businesses for a variety of reasons. These businesses flourish because they provide a service that people are willing to pay for.

These businesses take trained sonographers away from the medical field, and there is a big shortage of trained sonographers at the present time. Why would a sonographer go into this type of business? No night work, and probably because they can earn more money than they earn in the medical field. These businesses get cash on the barrelhead, do not have to try and collect money from insurance companies, welfare agencies, and other third party payers. And I would presume they collect pretty close to 100%. I do not know how other medical ultrasound practices do, but I collect about 60 % of what I charge.

I have not heard of any entertainment ultrasound businesses in Alaska, and I am pretty sure there are none in Fairbanks, but they will be coming.