Video Transcript

JG: Jon Garrin, MJ, Communications Coordinator

DF: David Fetzer, MD, Medical Director of Ultrasound for Parkland Health and Hospital System and University Hospitals and Clinics.

JG: Hello everyone. I'm John Garrin the Communications Coordinator for the Department of Radiology at UT Southwestern Medical Center, and I'm here with Dr. David Fetzer. He is the Medical Director of Ultrasound for Parkland Health and Hospital System—a role that he also plays at University Hospitals and Clinics. So, we're happy to welcome him today because October is medical ultrasound awareness month and so what better time for us to discuss medical ultrasound and in particular its application in cancer imaging. I just want to remind you that we appreciate your sharing this live chat with your friends, helping them become aware of the importance of medical ultrasound in cancer imaging, and we will be broadcasting this chat later on, so please check back if you haven't had an opportunity to get your questions answered. A reminder that Dr. Fetzer is unable to answer individual patient questions due to patient privacy laws, but we will be happy to take any questions that you have regarding medical ultrasound as long as they don't pertain to any particular case. So, having said that, let me say welcome to you, Dr. Fetzer.

DF: Thank you very much. It's good to be here.

JG: Thank you for being with us. Let’s begin with the basics. What exactly is ultrasound, and how does it work?

DF: Sure. So, a lot like how whales communicate underwater by sending these very low frequency sound waves through the water to communicate, we use similar sound pulses, but instead of being very low like whales talk to each other, we use sound pulses that are very, very high, so very high tone, high frequency, so above the level where we can hear them, but allows us to send those sound waves into the body. And, a lot like how a submarine tries to detect where a rock is or a landmine is listening for an echo of that sound bouncing off of the landmine, we are looking at detecting the echoes from inside the body. And so, our well-trained sonographers will take our ultrasound machine and take a transducer (a little handheld device), put it up against your body, and that same device sends sound pulses into the body and then listens for the echoes coming back.

JG: I see. Are there are particular tissues or organs within the body that are more receptive to ultrasound waves than others? How effective is ultrasound in certain parts of the body?

DF: Sure. Each system in medical imaging has its benefits and drawbacks. One of the benefits of ultrasound is that it is very safe and it can see many parts of the body that a physician may want to look into. So, we use ultrasound very commonly for soft tissues, so soft parts: hands, feet, neck (like the thyroid and lymph nodes). We also look deep into the abdomen to look at the liver, and kidneys, and pancreas, and spleen for anyone who may have had children. Obviously, ultrasound is used to monitor the growth of the little baby, the fetus. Really, anywhere that we have tissue or fluid between the transducer and the target we can we can look at. Ultrasound is not good for things that may be surrounded by or associated with bowel gas. [Ultrasound is not good for], for instance, the inside of the stomach/inside of the colon because sound doesn't travel well through air and in areas like the brain because it's encased by bone, and bone is also very difficult for sound waves to travel through. So, unless you're a little baby and your skull hasn't completely formed, all of it’s bone in an adult. We can't look usually in the brain with ultrasound, but we use it very commonly for head, neck, and organs in the abdomen.

JG: Well, I think most new parents, of course, are aware of, you know, the grainy images that they see when they look at their fetal ultrasound. Is that typically what you deal with--a kind of a grainy image or can you get more clarity in an image than we typically see in fetal ultrasound?

DF: Sure. There's a wide range of quality of ultrasound machines out there, and we rely on the industry standard highest quality ultrasound machines possible to produce the clearest image as possible for any particular patient. And, we have a lot of new techniques that many parents may not be aware of that we can use an ultrasound to, not just take pictures, but also interrogate tissues and organs and tumors in different ways. We can measure their stiffness, we can measure their blood flow, and we can measure their contrast enhancement now—all newer techniques that may not have been used for, just say, an evaluation of a mother's new baby

JG: Well, of course our conversation is going to focus on ultrasound and cancer imaging, and I'm glad that you mentioned ultrasounds ability to determine the stiffness of an organ because I know that that pertains particularly to diseases of the liver. So, can you tell us a little bit about how ultrasound can be used to distinguish between a cirrhotic liver and a liver that has cancer?

DF: Sure. So, we use ultrasound evaluate the liver very commonly. It's an inexpensive, low-risk examination, very reproducible in many patients, and allows us to not only look for liver disease, but when there is liver disease, look for cancer of the liver. One new test that you alluded to is called elastography. It's a way that ultrasound can measure the stiffness of a tissue and it's approved currently for measuring the stiffness of the liver. Why is that important? Well, in liver disease, the liver builds up fibrosis or scar and as the liver builds up more and more scar, it becomes stiffer and stiffer and stiffer. So, using ultrasound, we can basically do a virtual or non-invasive biopsy and measure the stiffness of the liver and then estimate the amount of scar or fibrosis in that liver. Once you develop a certain amount of fibrosis, then you're considered to be a cirrhosis patient or have cirrhotic liver or end stage liver disease, and those patients have a very high risk for liver cancer—[the] most common being hepatocellular carcinoma or HCC. So patients who may have cirrhosis…they should be getting screened every six months or so, and that screening is usually done by ultrasound.

JG: And one of the benefits of screening with ultrasound is that you're not exposed, of course, to radiation [like] the typical tests that we associate with imaging. You're not exposed to all those hazards.

DF: Sure. There are several imaging tests we can use to evaluate the liver and look for liver cancer—CAT scan, MRI, and ultrasound—but when you're looking at trying to take care of a large population of patients, ultrasound has many benefits on a population basis, meaning that it's as you alluded to: it's safe, there's really no contraindications, there's no radiation risk as there is with CT or CAT scan, there's no risk with the magnetic field that you may get with MRIs. Some patients can't get an MRI because of pacemakers or other metal in their body, and it's relatively low cost compared to those modalities, so ultrasound fits in an area we called as a screening tool to screen large numbers of patients at risk—in this case liver disease at risk for liver cancer—and screen them for a tumor.

JG: So, we've talked about ultrasound’s role in liver cancer. What other types of cancer can ultrasound help us in terms of imaging?

DF: Sure. It's commonly used to look at the kidneys for various reasons. [For] patients who have chronic kidney problems, we can look to see how much kidney loss there is, if there's a blockage of the urine in the kidney, if there are kidney stones, and also for kidney masses such as kidney tumors. And, patients with chronic kidney disease are also increased risk of developing kidney cancer. And so we can look at the kidneys and screen them for that in pelvic ultrasound. And [for] women we can use ultrasound to look at the uterus and the ovaries [also] for cancer.

JG: That requires the use of a more invasive probes.

DF: Yes, So, there is a probe that will be inserted into the vagina to get a very close, high detailed resolution image of the uterus and ovaries, and we don't typically do that for screening unless a patient has a genetic predisposition, or a strong family history, or personal history. So, for instance, there's a lot in the media right now about the BRCA gene which conveys a risk of breast cancer, but that also increases the risk of cancers in the pelvis, so sometimes we screen those patients looking at their uterus and ovaries for cancer in those organs as well.

JG: Likewise, in men there's also a probe that can be inserted into the anus—correct?—so that you can take an ultrasound view of the prostate. Is that correct?

DF: Correct. That's generally done for biopsy guidance. The primary imaging tool for the prostate at our institution is going to be MRI. So, we use MRI very frequently to screen patients at risk for prostate cancer—either they've had a low, low-risk lesion identified in the past, or they have an elevated PSA blood test, or the urologist may have felt something on a manual exam—and then we can screen those patients to see if we see a tumor and how big and how bad it is. Ultrasound is then used after the fact that a tumor is identified or suspected for biopsy guidance.

JG: So, you said that ultrasound is used primarily as a screening tool, but I suspect it's also used to monitor cancer spread. Is that correct?

DF: It can be in some parts of the body. For instance, [for] patients who've had thyroid cancer, we monitor them regularly for recurrence in the neck. So, most thyroid cancers are going to show back up in the neck, either where the thyroid used to be before it was taken out by the surgeons, or in the lymph nodes of the neck. And so, those patients will come back, usually annually, and we will do a full ultrasound of the neck looking for any evidence of recurrence. What's nice about ultrasound is that not only can we try to identify cancer recurrence in the neck, but we can also use ultrasound to guide a small needle and take a biopsy of it to confirm or refute cancer recurrence.

JG: Well, we've received a couple of questions. Glenn wants to know, “how do you determine blood flow with ultrasound?”

DF: Sure. There's a technique called Doppler. So, if anyone has ever been in traffic and an ambulance has gone by, you noticed that as the ambulance is coming toward you it's a higher pitch than when it's driving away from you. That's called the Doppler Effect. That means that the motion of the object creating the sound changes in pitch whether it's coming toward you or away from you. So we use that technique to find out if blood cells in blood vessels (red blood cells) are moving away from you or toward you and how fast. So we can use that technique to then [usually] paint the red or blue toward or away from you over our ultrasound image, and then we can tell if a tissue has blood flow, and then we can do a finer analysis and actually tell the velocity of those blood cells in those blood vessels and give us some information. For instance, we use it for the carotid arteries to look for plaque buildup and how bad a blockage may be, and we use those velocities, those speeds of blood flow in the vessel, to determine how bad the blockage is.

JG: Now, specifically in terms of cancer imaging, it's my understanding that blood flow through the tumor…if you can measure the velocity of blood flow through a tumor, it helps you in assessing a cancerous tumor. Is that correct?

DF: Well, there's some research to support that maybe the degree or type of blood flow and a tumor may correlate with how aggressive the tumor may be, but primarily what we do is determine if there's blood flow or not. So, there are some lesions in the body, such as cysts, that don't have any blood flow in them, so if we can by ultrasound and Doppler determine something is a simple cyst, then we know it's not a tumor and it doesn't need to follow up. So we can use it to show that there's no blood flow in a tissue and let us suggest that it's not a cancer, or if we find a lesion, say in the liver or the kidney ,and we show that it has blood flow by Doppler ultrasound, then we could be suspicious that it's a cancer and then suggest further workup.

JG: Bridgette asks, “Are there any instances where 3D ultrasound should be used versus traditional ultrasound?” Before you tackle that question, can you tell us what 3D ultrasound is?

DF: Sure 3D ultrasound is not [necessarily] a separate machine. In most cases, often, it can be used on our contemporary machines that we already have here on campus, and certain probes or certain software is used. [So] instead of taking one picture, like a single bread slice picture, of the human body, we take a series of pictures and basically can get the whole loaf of bread. That whole image is that whole loaf in our ultrasound machine. Then we can go back and try to cut up the bread in different ways—one way or the other way—and try to look at an organ or a tumor or other tissue from various vantage points. It's commonly used in the pelvis. People who are familiar with looking at pictures of babies online may have seen some of those 3D pictures of the baby's face while still in the uterus, so that's a well-known used for 3D ultrasound. There are probably some other good uses (looking at blood vessels or organs such as the kidneys or thyroid), but we really rely mostly in diagnostic ultrasound on the 2D ultrasound. I would venture to say that in most cases a 3D ultrasound is typically not specifically needed.

JG: Compared to other imaging tests, what's the cost of a traditional ultrasound test, and is ultrasound covered by insurance?

DF: Sure. In in most cases, ultrasound is going to be covered by insurance. It's considered an introductory imaging test [for] someone coming in with a certain malady, a blood test problem, or a complaint like abdominal pain. Usually, the ultrasounds going to be approved by insurance and covered as far as cost. That's a typical question because who really knows what the cost medicine is these days, but on a relative scale, I would say that ultrasound is less expensive both to [an] insurance company, to a patient, and to a healthcare system, than, say, an examination like a CAT scan or an MRI. Those machines are much more expensive to purchase, much more expensive to run, and they take a lot of management beforehand to prepare a patient. All those factors are not as significant to an ultrasound. The cost of the machine is not as great, the maintenance of the machine is not as expensive, and there's really very little preparation involved. So, if we're talking about both an individual as well as a healthcare system, ultrasound is a very cost effective imaging test.

JG: I suspect that, just as there are differences between good photographers and bad photographers, there are probably differences between good sonographer and bad sonographers. How important is it that you have a well-trained sonographer who's performing the ultrasound test? How important is that to you as a radiologist who then must examine that test and then make a recommendation to a referring physician?

DF: It's a very good question, and it's critical. I think it's one of the most overlooked aspects of radiology—the relationship between the radiologist who's interpreting the images and the technologists and the sonographers who are taking those pictures for us. That's most critical in the world of ultrasound because we rely very heavily on well-trained sonographers to take very clear, precise pictures following our protocols. We have, you know, a specific set of instructions for, say, a liver ultrasound versus a kidney ultrasound versus the thyroid ultrasound, and [we] have to build a level of trust with our sonographers and build a relationship where we can rely on them to give us the pictures we need—making sure the whole organ is covered and that all the aspects of that organ are accounted for. I would say that going to a small imaging center where there's not that relationship between the radiologist and the sonographer, and there's not that focus on ultrasound sonographer training ultrasound quality, that patients may be missing out on how much ultrasound can provide them as an imaging tool.

JG: What do you suppose the future of ultrasound looks like? I read an article the other day that talked about how ultrasound is going to be available to physicians to look through an iPhone. Can you talk a little bit about where the technology is headed particularly how that might impact, you know, being able to provide ultrasound imaging in disaster areas, for example?

DF: It's a very exciting time that these devices are getting smaller and less and less expensive, and it's probably true that sooner or later there's going to be an ultrasound device in every physician’s pocket. In our hospitals, we already have physicians who use them in the ER, in the operating room, [and] in the intensive care units. It's usually for what we call “point-of-care ultrasound”. So, it's where a physician has a specific question—“Is there fluid?”, “Is the heart beating?”, “Is there blood flow?”—and so they can get those questions answered very fairly quickly with these simple devices, but I would say they're not a replacement for a full examination done in radiology—where the technology that we use is probably an order of magnitude more powerful, and it offers tests or components of ultrasound that you wouldn't find necessarily on a point-of-care device. So, I really see in the future this dichotomy of ultrasound and medicine where it's used like a stethoscope, kind of in the front line as a troubleshooting tool, as a point-of-care device to make quick assessments and diagnoses, but you still have a full diagnostic examination in the Department of Radiology. [For example], to do a full assessment of, say, the baby or the liver or the neck, we in ultrasound and radiology have additional tools in ultrasound they may not have access to the point-of-care device, say, in the ER, [like] elastography (we were talking about that with the ability to measure stiffness) and then contrast-enhanced ultrasound (which is now becoming more and more prevalent).

JG: Can you speak a little bit about what that is—contrast-enhanced ultrasound? So, my assumption is that there's the introduction of some kind of a contrast substance or agent into the body that helps you see better the ultrasound image. Is that correct?

DF: Yes. So, for those of you who may have not had a CAT scan or MRI with contrast, an intravenous catheter is placed, usually in the arm, and then contrast, or some people call it dye, is injected into the veins. In those two tests, CT and MRI, it helps us as Radiologists see organs, find tumors, [and map] blood flow. Well, we now have that ability to do that in ultrasound. Similarly, we start with an IV—an intravenous line—and we inject contrast, but we have a very unique contrast agent. They're called micro bubbles. And these tiny little bubbles are slightly smaller than the size of red blood cells. You can't see them with the naked eye, they're not like bubbles you'd blow out at the playground, but in the in the body they circulate around, and we can use a special ultrasound software to find them, to identify them, and it allows us to assess perfusion or blood flow within tissues much better than the Doppler. So, it allows us to not only identify cancers, say in the liver or the kidney, but to characterize them, so I could help them differentiate [them]. [For example] Is this a liver tumor or could this be a metastasis or a tumor that was, say, in the colon that has spread to the liver, or is it a benign tumor growth in the liver? So, whereas before we would see something in the liver, for instance on ultrasound, that patient would go on to CAT scan or MRI for further evaluation. Now in radiology, we have the ability to do that evaluation [with only] ultrasound. What's nice about the contrast we use (the micro bubbles we use) and ultrasound is they're incredibly safe. So, whereas patients may not be able to have contrast because of bad kidney function or allergy, our agents are very safe. They're not toxic to the kidneys, they're not cleared by the kidneys, and the allergy rate is very very low, so it's a very very safe, cost-effective alternative to those other tests.

JG: So, you said that they were micro bubbles, but they're not the same as, like, a gadolinium agent. What are the bubbles composed of? Are they some kind of chemical?

DF: They're very small…

JG: Air bubbles?

DF: Well, the first generation was air. They just took air, agitated it (try to mix it in small little bubbles), and injected [it]. The problem with air is that those bubbles don't last very long in the body—just a few seconds. So, the second generation bubbles—what we use now—are a fluorinated gas (Fluorocarbon gas), which is breathed out by the lungs, so within 10 minutes it's cleared by the body. This gas is encased by proteins or sometimes lipids or fats to make them more stable so they can last in the body for several minutes—up to 10 or 15 minutes. Those lipids or proteins are broken up by the liver and the rest of the body just like parts of cells that are normally broken down in the body, and the gas is breathed out. So, again, no clearance from the kidney, and there's no heavy metals. You know, there's some worry about gadolinium, and some patients worry about iodine or have an iodine allergy which is used in CAT scan. So, there's really no heavy metals that are used in our contrast agents which gives them the added level of safety.

JG: I see. Well, we have a question here from Monica. She wants to know, “Are your sonographers well trained at UT Southwestern?” We've talked a little bit already about the importance of having well trained sonographers, but this strikes me as a question that's more aimed at the sonographers that we have here at UT Southwestern. What is it that distinguishes the training our sonographers receive at UT Southwestern from other, you know, perhaps what we call mom-and-pop operations?

DF: Sure. Well, I'm glad Monica has asked that question because, again, we take the training and dedication of our sonographers very seriously because, as I alluded to before, we rely on them to really make our jobs easy, to take very good pictures and reproducible pictures, and to give us the information we need to make a diagnosis for the patient and their doctor. So, as part of that reliance on a good sonographer, we do have pretty high expectations here at UT Southwestern and our hospitals as far as the training that those sonographers may have received in school [and] their experience that they have received before coming here. We require them to have certain number of certifications in certain areas of the body and then to maintain those certifications while they're here. We monitor our quality assurance of our sonographers through various programs, we give lectures on campus challenging case conferences, and then the radiologists are also providing continuous feedback to the sonographers to help them be better every single day. So in the mom-and-pop shops you were talking about, that process is often lacking, or the attention to what the sonographer has experience or training in may not be there, or there may not be that constant feedback from the radiologists to the sonographer to make them better each day.

JG: I see, I see. Well, we need to wrap up our chat. We've approached our half-hour mark, and I just want to thank everyone who has asked a question, and those of you who submitted questions, in advance as we wrap up our observance of Medical Ultrasound Month. Is there anything that you'd like to tell our listeners or our viewers with regard to ultrasound here at UT Southwestern?

DF: I would say that UT Southwestern excels in many areas of healthcare—many areas of imaging—and ultrasound is definitely one of those. So, I would say that I'm very proud of what we do here in Radiology and in Ultrasound, and for all of my sonographers and fellow radiologists who helped us in our ultrasound division, thank you very much. You make my job that much easier.

JG: Well, once again, I want to thank Dr. David Fetzer for being with us this afternoon. As I mentioned, Dr. Fetzer is the Medical Director of Ultrasound for Parkland Health and Hospital System--a role that he also plays here at UT Southwestern University Hospitals and Clinics. He is an Assistant Professor of Radiology and a member of our Abdominal Imaging Division. Thank you again, Dr. Fetzer, for being with us, and please share this video with your friends so that they can become aware of the safety and effectiveness of ultrasound in cancer imaging. Thank you.

DF: Thanks.