Practical Application of 3D Ultrasound

September 14, 2006

OBGYN.net Conference CoverageFrom 45th Annual Conference of the AIUM - Orlando, FL 2001

Audio/Video Link *requires RealPlayer - free download

Dr. Don Shuwarger: "I'm Dr. Don Shuwarger from Forest, Virginia and I'm sitting here today with Dr. Dolores Pretorius. You're from San Diego, right?"

Dr. Dolores Pretorius: "Yes."

Dr. Don Shuwarger: "Tell me about your practice."

Dr. Dolores Pretorius: "I'm an academic radiologist. I do a lot of work in fetal ultrasound and have really spent the vast majority of my career doing that working on fetal anomaly detection."

Dr. Don Shuwarger: "But you do some gynecology too."

Dr. Dolores Pretorius: "Absolutely, we do a little of everything. We do some gynecology, I do some livers, carotids, etc. but mostly I spend my time doing OB and a little bit of GYN."

Dr. Don Shuwarger: "So all your patients come to you by way of referral?"

Dr. Dolores Pretorius: "Yes, all of our patients do come by way of referral."

Dr. Don Shuwarger: "Do they come to you because anomalies have been diagnosed already at the primary care or the gynecologist's office or are they coming to you just for routine scanning?"

Dr. Dolores Pretorius: "We have both, we have patients who have anomalies detected elsewhere that are coming for a second opinion but we have a lot of high-risk patients who have either an elevated AFP, low AFP, a previous anomaly, family history, or diabetes. So we have a fair number of people who walk in hoping their baby is normal as well as those who are worried that there's an abnormality and they don't know it."

Dr. Don Shuwarger: "If an amniocentesis is needed at the time of the ultrasound, who performs that?"

Dr. Dolores Pretorius: "We work in conjunction with perinatologists so there's two of us there together, and if there's an amnio that's needed then the perinatologist comes in and does that. I ask them to look on the monitor while I show them the anomalies that we're looking at and they may come in and scan or not, it just depends how busy we are."

Dr. Don Shuwarger: "When you do your fetal echos, is it your department or the perinatologists or have you sorted that out?"

Dr. Dolores Pretorius: "We have a pediatric cardiologist who comes in and works with us for the fetal hearts. We've done a few ourselves as well but we finally worked into this arrangement where he comes in and does our fetal hearts for us."

Dr. Don Shuwarger: "That's great, you have a mediator then."

Dr. Dolores Pretorius: "Right and we work together, it's basically a team approach."

Dr. Don Shuwarger: "That's very nice, now what type of equipment do you use in your center?"

Dr. Dolores Pretorius: "We have all different types of equipment as you might expect but our number one machine that we use for fetal ultrasound is the Elegra-Siemens unit. We have more of those than anything else; we think it's an excellent piece of equipment. For our 3D ultrasound, we mainly use the Medison unit."

Dr. Don Shuwarger: "How long have you been doing 3D ultrasound?"

Dr. Dolores Pretorius: "That's a great question - twelve years."

Dr. Don Shuwarger: "Really, so you're a true pioneer in that area."

Dr. Dolores Pretorius: "Absolutely. We started it out in this country and it's been really an exciting road."

Dr. Don Shuwarger: "What are some of the changes that you've seen in 3D ultrasound over the last twelve years that impressed you?"

Dr. Dolores Pretorius: "Mainly, we started from a very developmental stage of trying to prove the concept in doing it in water baths and then gradually patients that took a long time to do in a laboratory setting. Then in about 1994 we started doing clinical studies with a clinical machine in a clinical office, and that has just gotten faster and faster, better image resolution, faster image rendering, and more editing tools have come in to allow us to take away parts of the placenta or the arms out of the front of the face or whatever. Color has come in so now we have color 3D so I think right now is a very exciting time because all of the companies are now jumping onboard in trying to put 3D on the machines. Before it was only a couple of companies that were really pushing 3D so now everyone seems to want it and my colleagues and good friends are calling me now on the phone and saying - hey, I want to buy 3D, what am I going to use it for, Dolores?"

Dr. Don Shuwarger: "What are they going to use it for?"

Dr. Dolores Pretorius: "I have a talk at this AIUM about the referral patterns of our last 200 patients over the last 2 years of who's been coming to us in OB-GYN. What we've found is that about 75 patients out of that group have come because of a specific 3D referral for a cleft lip and palate, for a uterine anomaly, for a sono-hysterogram to be done under 3D, for a neural tube defect to find the level better, or we couldn't find the neural tube defect and we're highly suspicious because of a biochemical screening. Clearly, facial anomalies are the top of that list for us. The second reason we'd use 3D is because of troubleshooting 2D problems, and there's about 75 patients in that category. Patients that we find a brain abnormality on 2D and we can't quite figure it out, we put it on a 3D machine, we make it totally symmetrical, and we rotate that head so we get a perfect coronal, sagittal, and axial view. Then we can decide where that hemorrhage is - it's definitely in the choroid, it's not in the perikyma, or that this is a symmetrical lesion developmental anomaly versus an asymmetrical lesion so things like that, things you would never put on your list of I'm going to use 3D for, like a cystic structure pushing on the stomach. Is this real or is it not real? You put it on 3D, you find it's just the bowel sitting right next to the stomach, and you're not worried about it at all."

Dr. Don Shuwarger: "What about contents in omphaloceles?" 

Dr. Dolores Pretorius: "We've looked at omphaloceles and gastroschisis and I have to tell you honestly 3D hasn't helped me at all. It's just the parents like it to be able to see the omphalocele and see how it looks against the baby but from a diagnostic point of view, I wouldn't say it's added anything." 

Dr. Don Shuwarger: "What about for deeper screening like for esophageal atresia or TE fistulas or anything, have you looked at those issues?"

Dr. Dolores Pretorius: "I haven't found that I have been able to add anything yet to the data. The third category is reassurance; I think we've done a little over sixty patients or so for reassurance and these come from two categories. One, a physician calls us and wants his patient to be done for reassurance. She's on Tegretol, at risk for a cleft lip, she's had a previous cleft lip, she's got polydactyly in the family, and she wants to see if there are extra digits on 3D. That's the type of patient, so that's a reassurance. Most of those patients turn out to be normal but not all of them; I did a polydactyly that did have identified polydactyly on 2D and she just wanted to see it. Then you have patient initiated studies; they call or they write me on e-mail, they get on the Internet, and they want 3D. I do those under an IRB protocol and try to figure out who I'm helping and who I'm not so that data's also very interesting of who really seems to benefit versus it's just a nice picture."

Dr. Don Shuwarger: "The ones who contact you directly because they want 3D, what is it they think they want?"

Dr. Dolores Pretorius: "That's a good question. I think they mainly want to see their baby and it's hard to ferret out whether it's an anxiety issue, whether they just want a pretty picture, or whether they really are concerned about something and you being able to show it to them just makes them feel better. For example, I had a patient with a velamentous cord insertion that had a previous baby die at delivery of a cord insertion and she just wanted 3D to see her baby. It just meant everything in the world to her to see that baby. I had a patient who was carrying a baby with a fatal anomaly - osteogenesis imperfecta, and she knew the baby would die within the first twelve hours; it died within two hours of delivery. She just wanted to spend time with her baby and her quote is something like 'I felt such peace and such joy to see my baby alive and moving and knowing that I could share time with her while she's alive, and I won't have that time after birth except for a couple of hours.' At first glance it seems pretty sad, and it wasn't that easy for my team to actually do the studies with her but to see how she felt about it, I knew we had done the right thing. I knew we done it right when we agreed after I saw her and talked to her. Afterwards she sends us cards, she brings us presents, and her Christmas card had our 3D picture of her baby in it - for her this was very important."

Dr. Don Shuwarger: "Now when you give patients reporting, do you give it to them on a video cassette tape, do you give it to them on a floppy disk, do you e-mail it to them, or do you post it on your website? How do you communicate the information back to the patient?"

Dr. Dolores Pretorius: "For the patient, I tell them if they're coming for a 3D reassurance study and they bring their own videotape I will tape part of the 3D study for them."

Dr. Don Shuwarger: "So you're doing your 3D rendering online real-time?"

Dr. Dolores Pretorius: "Some of it is absolutely online real-time, it's called live 3D. The unit that we use currently is at four frames per second but the new machine we're suppose to get this week is at sixteen frames per second which really makes it live."

Dr. Don Shuwarger: "Which machine would that be?"

Dr. Dolores Pretorius: "That's the Medison unit and the pictures that we've seen you really see the baby open their mouth, close their mouth, and move their arms. I think it's been great diagnostically as well as for reassurance. I'm really looking forward to looking at clubfeet because we made a lot of mistakes with clubfeet on 2D and we're a great tertiary center but we've had about four patients with false-positives and negatives in the last two months. We're beginning to think - wow, we're just not so good at this, and I'm hoping 3D will allow me to see the flection of the feet and volume data rather than a slice which is kind of hard to see in 2D. So there'll be good reasons and not just reassurance for that really near real-time."

Dr. Don Shuwarger: "So when she leaves from her study and goes home, does she go home with her videotape at that moment or do you save her videotape and process all the pictures?"

Dr. Dolores Pretorius: "No we give it to her right then. She walks out with the videotape and we also give her a couple of regular little prints off the machine."

Dr. Don Shuwarger: "How much of this is marketing and how much is medicine?"

Dr. Dolores Pretorius: "I don't believe in giving false reassurance, I won't give reassurance to someone I haven't done a 2D exam on and know that their 2D ultrasound is as good as I can do to know that that's normal. I'm doing this under IRB; I'm not doing it for money right now. I charge them but I have to charge in order to pay for my sonographer to do the study and the time that we do and that's what we're charging just like any other 2D study of what the room time is to use that. I have no idea where it will go in the future, I certainly don't want to do it for entertainment. I do it because I believe this may help people and the human side of what we do is important as well as the diagnostic side of what we do."

Dr. Don Shuwarger: "Dr. Pretorius, thank you for visiting with us today. We look forward to hearing more interesting information about the advent of improved methods of 3D ultrasound. Thank you."

Dr. Dolores Pretorius: "Thank you."