Sonoelastography and Nuchal Translucency

September 15, 2006
Martin Necas, RDMS, RVT
Martin Necas, RDMS, RVT

,
James S. Smeltzer, MD
James S. Smeltzer, MD

OBGYN.net Conference CoverageFrom AIUM 44th Conference held in San Francisco, California - April, 2000

Martin Necas, RDMS, RVT: "Hi, I’m Martin Necas the Coordinator of the Ultrasound section of OBGYN.net and I’m here at the 44th Annual Convention of AIUM with Dr. Smeltzer from Atlanta, Georgia. James is one of our Editorial Advisory Board Members and he’s also very active on the Ultrasound Forum. James has been here having a great time in San Francisco and seeing some of the presentations as well, and today we’re going to just briefly touch on two topics - one is sonoelastography and then we’ll talk a little bit about nuchal translucency. So let’s turn to the first topic, James, could you tell us a little bit about what has been done in sonoelastography and how we can implement it in our practice?"

Dr. James Smeltzer: "Sonoelastography is a new issue with me but it’s very exciting. As you know, one of the difficulties with ultrasound is figuring out whether a particular mass is a cancer or malignancy or not. Based on the sonoelastographic properties, it is possible to distinguish between malignant and benign lesions especially of the breast and with a fair degree of reliability. I just learned that in a nice, beautiful course that was here this morning and will be continued in the afternoon. In addition, I know a student of mine who collaborated on several research projects with me, V . Dogra, who’s now a radiologist, was here presenting on sonoelastography in the liver in oral presentation which I missed because I didn’t know he was going to be talking. But we spent a delightful evening yesterday talking about this exciting topic, and I believe it will be very helpful to us in the future clinically."

Martin Necas, RDMS, RVT: "Do you think that the technique can also be implemented in other organ systems, for example, in superficial structures or the kidney?"

Dr. James Smeltzer: "Superficial structures - yes, definitely and it can be used for that purpose in the breast as well. In the liver they demonstrated a benefit, and in the kidney I think it may also demonstrate a benefit but it’s a little early for that."

Martin Necas, RDMS, RVT: "Are there certain technical difficulties with demonstrating sonoelastography properties in deeper tissues?"

Dr. James Smeltzer: "There was very interesting data presented today about the difference of the frequency response of varies benign tumors in the breast. Some people have reported excellent discrimination by so called fremitus having the patient hum, and others have reported very poor results. It may be that people in different parts of the world hum at different pitches because one group found a very definite frequency response of humming with benign tumors but it turns out that malignant tumors pretty much are like a rock, they don’t move at all, and that is the way that you discriminate between benign and malignant."

Martin Necas, RDMS, RVT: "Yes, this is certainly a hot and exciting new topic, and I’m sure more and more research will be done in this area. Perhaps next year in Orlando, Florida we’ll have the pleasure of seeing more of these presentations and learn what has been done during the year. If I may, I’d like to talk a little bit about our second topic, which is nuchal translucency. You do some work yourself in ultrasound, you’re a very key member of our forum, and I was wondering if you could give us a little bit of an overview of what nuchal translucency means to you and how you put it in your practice?"

Dr. James Smeltzer: "For the last several years, at least the last four or five, we’ve used it as a way of detecting women who have infants with aneuploidy. Personally, there’s only one with a heart defect but it can also be used for that and other major anomalies. Done between ten and fourteen weeks, Nicholides group in England in very large studies have shown a remarkable ability to predict and identify most babies with Down syndrome. We’ve used this information in our practice, and very few of our women now over 35 get amniocentesis and a high proportion of the ones that do, have positive amniocentesis for aneuploidy. I’ve always felt that was a much more satisfying thing; the nuchal translucency is a way for someone that’s adequately trained to identify about five out of six babies with a serious aneuploidy. Some of the American studies have shown that it does matter how much training you have because they were unable to reproduce Nicholides results. People really do need to be trained and certified in this technique to use it on a regular basis although all the misses and false-positive diagnoses that they’ve reported are not my personal experience. Several studies have indicated that attention to exactly how you do it, having the proper images, discriminating between the amnion and the nuchal lucency, and being sure that you’re measuring it in a neutral position and measuring it properly from edge to edge and not from edge to skin is very important."

Martin Necas, RDMS, RVT: "Yes, certainly ultrasound appears to be a very operator dependant technique. I think the Nicholides group has tried to bring in a certain level of absolute objectivity so that there’ll be very little space for error in intra-observer variability. Do you find that the nuchal translucency measurements are highly reproducible?"

Dr. James Smeltzer: "We have not done formal reproducibility studies in our laboratory, others have. Where ever you pay attention to how you do them, they are highly reproducible, and more important, they are very highly predictive of clinical outcome. In our practice in a fairly captive population, we’ve had no unidentified babies with Down syndrome born that were screened with nuchal lucency."

Martin Necas, RDMS, RVT: "Yes, and that’s a remarkable success rate. I remember you quoting this particular fact on the OBGYN.net forum. That is truly excellent."

Dr. James Smeltzer: "Either lucky or good, a good sonographer is the key, I think."

Martin Necas, RDMS, RVT: "I also believe it’s all in the quality. Thank you very much just for talking to us and we’ll be looking forward to seeing you on the forum again."

Dr. James Smeltzer: "Thank you, Martin."

Martin Necas, RDMS, RVT: "Thank you."