Artifacts of 3-D Sonography

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Terry DuBose: "This is Terry DuBose at the last day of the 9th Congress for Ultrasound in Obstetrics and Gynecology in Buenos Aires, Argentina. I just heard a remarkable talk by Andrew Hull, who's from San Diego, on artifacts dealing with 3-D, and there's been quite a bit of 3-D here. He's really the first one to come out with a good lecture on cautions about artifacts that can be generated. He can't give us the complete understanding of this because it takes a bit of graphics and physics, but I think he can give us a good idea of some of the things we need to start looking for in the future."

Dr. Andrew Hull: "Thank you. Clearly, at recent meetings over the last couple of years, three-dimensional ultrasound has become the flavor-of-the-month, and one sees the most beautiful pictures in almost any obstetric meeting or venue. I think one has to be aware that with the introduction of any new technology there are potential pitfalls, and three-dimensional ultrasound has potential for misdiagnosis and for errors in assessment of the fetus, and in assessment of almost any way that it is used.

These potential errors are not unique to three-dimensional ultrasound. Those of us that scan using conventional ultrasound are well aware of artifact generation and well aware of the potential for errors in diagnosis because of artifacts. However, with three-dimensional ultrasound that potential is there just as much and, in fact, there are some artifacts which are unique to three-dimensional ultrasound which can cause potential errors in diagnosis.

To give you one or two examples, the attenuation or drop out artifacts that one sees in two-dimensional ultrasound are very well known because they are acquired in real-time. You can often change transducer orientation and convince yourself on the fly that what you're seeing is not real, that it's an artifact. With three-dimensional ultrasound, attenuation artifacts may not become apparent until after the patient has left and you're looking at the volumes. There may appear to be missing bones and limbs or, for instance, a cleft lip that was generated by the presence of an umbilical cord across the face. One needs to be aware that these errors can occur and that we need to be very careful in assessing any potential abnormality by using multiple planar views, by assessing multiple volumes of image structures."

Terry DuBose: "Thank you Andrew. We'll look forward from more from you. People have thought that 3-D was going to give us quick answers to a lot of questions, but obviously it's going to introduce a lot more physics understanding of what we're doing. Thank you very much."

Dr. Andrew Hull: "I would like to say that I'm part of the University of California in San Diego's three-dimensional ultrasound imaging group and my colleagues in the group-Dolores Pretorius, Tom Nelson-have been working in this field for many years. I'm a relative newcomer to the group."

Terry DuBose: "Thank you, Andrew."