Kretz Museum Tour - The History of Ultrasound


Radiological Society of North America (RSNA) Chicago, Illinois - November, 2000

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Kretz – Foundation - founded in 1991

Accompanying photos can be viewed here - images will open in new windows.

A-mode machines

B-mode machines

Early Combison Models

Combison 100 Series

Combison 200 Series

Combison 300 Series

Combison 400 Series



Roberta Speyer: “I’m here in Zipf, Austria with Franz Wiesauer. Franz is one of the original engineers that have worked for many years in the ultrasound industry, and he is now Vice-President of Kretz Technik. Franz, tell us a little bit about your early career; how long you’ve been with Kretz and then of course what we all want to hear is the wonderful story of the development of ultrasound.”

Franz Wiesauer: “I was working for Kretz for twenty-five years and I started to compute the sound field of ultrasound transducers for the so-called compound units. This was one single transducer, which was moved manually over the body. Then I also worked on the first real-time sector scanner worldwide which was developed by Kretz Technik, it’s the famous COMBISON 100. As you may know, now we’ve developed the 3-D and 4-D technology, which at the moment is the leading edge of ultrasound.” 

Roberta Speyer: “We’re talking twenty-five years ago, about 1975, what had you been doing up until that time and how did you transition into ultrasound as a medical application?”

Franz Wiesauer: “I started my career in ultrasound, I made styles of engineering over electronic engineering and by chance I met Mr. Carl Kretz who was owner of the Kretz Technik Company, which came from his name. He was the Technical Director of the company, and I visited this company and I was very happy at what I had seen because it was a company in a pioneer state of the technology and this is when engineering, of course, was very interesting.”

Roberta Speyer: “Yes, what were the applications that were being used at that time for the technology?”

Franz Wiesauer: “At that time, the main application was for the eyes and also the first steps in gynecology, abdomen scanning, and so on.”

Roberta Speyer: Franz, I’m looking at a very interesting piece of equipment; it certainly doesn’t look like it relates at all to any ultrasound equipment that I’ve seen before but I hear this is actually the beginning of where ultrasound technology started. Could you tell me a little bit about what we’re looking at?” 

Franz Wiesauer: “Yes, this is the very beginning of the ultrasound technology. At this time, ultrasound technology was not used for medical diagnosis; it was used for non-destructive testing of materials. If there was an air bubble inside a metal, for example, here you could check and see if there was a crack inside, and all these units are the so-called A-Mode units. That means that the result was not an image, there was only one ultrasound scene and you could see with an oscilloscope on a screen if a crack was hidden. By the ultrasound you could find a little blip in this and you could measure it and say this wheel has a crack of 1 cm perhaps or so.”

Roberta Speyer: “What year is this that we’re doing this type of scanning?”

Franz Wiesauer: “This is in the mid-fifties.” 

Roberta Speyer: “With the application for ultrasound in medicine, who originally thought of the idea of taking this technology that was used for analyzing metals and apply it to the medical industry?”

Franz Wiesauer: “That was worldwide; one pioneer was Professor Kratochwil from the Vienna University. He tried with one of our industrial units, a unit for non-destructive testing and applied it to a pregnant woman, and he interpreted for the first time what all these blips mean and how they related to the anatomy.”

Roberta Speyer: “What were they seeing at that point in time, it wasn’t what we understand to be ultrasound images of today so what were they looking for? Was it the distance between points?”

Franz Wiesauer: “Yes, for distances, for example, measuring the diameter of the head of the baby is a very strong indicator for the growth status of the baby. They could measure, for example, this diameter but they had no image at this time.”

Roberta Speyer: “Did he work with the people at Kretz to develop some new equipment?”

Franz Wiesauer: “Yes, there was a very close relationship to develop these units, and from the mid-sixties they modified the units for medical use. The first units were really made for non-destructive testing and simple use, for example, to examine a pregnant woman. Then we modified the units so that they would better treat for the application in the medical field.”

Roberta Speyer: “Which one is the first machine that was actually modified and made especially for medical use?”

Franz Wiesauer: “I cannot really identify it precisely, but one of the first machines modified for medical use were these units for ophthalmology. This is for the eyes, and you have very special small transducers. For example, you could measure the distance between the lens and the background of the eyes.” 

Roberta Speyer: “What was the purpose of that?”

Franz Wiesauer: “The purpose was to detect, for example, tumors in the bottom of the eyes or the background of the eyes.”

Roberta Speyer: “Then after that application, was there any interest at this point in time in obstetrics and gynecology?”

Franz Wiesauer: “Not really, just scientific work was done with this. For example, Professor Kratochwil would use such machines but this was more for scientific work. The next step in the application for gynecology and obstetrics was the invention of the compound scanners. These are the units that we started with in the interview.”

Roberta Speyer: “It was not very well accepted at that point in time in obstetrics and gynecology, is that correct?”

Franz Wiesauer: “That’s correct, yes.”

Roberta Speyer: “What types of changes did you see in the technology and how did that change the acceptance rate clinically?”

Franz Wiesauer: “The most important step was from the manually moved transducers to the so-called real-time scanner where the images were renewed automatically. This was the step with the compound scanning that only specialists in ultrasound could really get results for diagnosis but with the real-time scanner, the not so experienced doctors could get a chance to get excellent results to make the diagnosis. This was a big step in ultrasound.”

Roberta Speyer: “It was really ease of use that made ultrasound more adaptable to clinical practices rather than just something like, let’s say, a research toy for the specialists.”

Franz Wiesauer: “That’s right, yes.”

Roberta Speyer: “How did Kretz’s development of the early machines impact that? What were the types of features that you needed to add and what were the issues - the size or portability? At that time, those probably weren’t even issues, were they? How big were the machines back then?”

Franz Wiesauer: “The compound machines were really huge machines with a bed and with a huge housing of the machine, and you can see in the museum such a machine. This machine could only be used in a fixed place and the elder machines were much smaller. It’s not practical but they could easily be moved from one room to another, and the most important step was the ease of use to find the right cut through the body where the diagnosis could be done. The next very important step was also made by Kretz Technik on a leading position was to computerize ultrasound. Because the image alone is not the final result of a diagnosis, you had to measure, for example, the diameter of the head of a fetus and so on.”

Roberta Speyer: “That’s how you could age it or manipulate the data to make it have clinical significance.”

Franz Wiesauer: “Yes, that’s right.”

Roberta Speyer: “This machine that we’re looking at over here is the COMBISON 200, is that one of the first stationary machines that you’re talking about?” 

Franz Wiesauer: “Yes, this was the compound machine and you can see this huge mechanic and this small wide thing is the transducer.”

Roberta Speyer: “So this is all part of this machine so it actually came with a bed. It certainly is a lot larger than the MySono, the new portable handheld we have today. Now with the images that you got with this piece of equipment, how were they different than the ones you get today?”

Franz Wiesauer: “These images had a lot of artifacts because the body is moving during the examination and you have a very slow and only one time image acquisition so it was one time. If the patient moved in between, you had artifacts and the other thing is the result with these machines for image quality was very, very dependent on the skills of the doctors. So a very experienced doctor could make nice images with this machine and with a real-time machine the image quality was more or less independent from the skill of the doctor.”

Roberta Speyer: “Do you know roughly how much a machine like this would have cost in its day? Was it a very expensive piece of equipment and only a large institution could afford to buy one?”

Franz Wiesauer: “Yes, this was more or less for clinics and universities so it was really an expensive machine.”

Roberta Speyer: So that period of time was around 1975?”

Franz Wiesauer: “This was around the late sixties and until the mid-seventies. Around 1975, the first real-time machines replaced these huge units.”

Roberta Speyer: “Can you show us some real-time machines now? What are the names here – the COMBISON 100?” 

Franz Wiesauer: “The COMBISON 100 and with this real-time machine this special unit is a prototype number 4. Worldwide, this is really the first sector based real-time machine.”

Roberta Speyer: “It’s entirely different, it’s on a rack, it’s portable, and it has wheels. Actually, it’s not any larger than a lot of the systems that you have today. What type of changes do you now have in the technology besides the portability? Has the cost come down, has the ease of use increased, and has the ability to get rid of the artifacts then enhanced?”

Franz Wiesauer: “The most important progress in the ultrasound technology was first in the image quality so the resolution, axial resolution, lateral resolution is much poorer with this type of unit if you compare it with state of the art technology today in ultrasound. The second thing was it was easy to use and was supported by using computers. In this unit, there was no computer, everything is solved and done by special hardware. With the 320 unit, beginning in the eighties, these units were computerized so a lot of user interaction was supported by computer programs.”

Roberta Speyer: “Now you’re talking about the COMBISON 320?” 

Franz Wiesauer: “Yes, the 320.”

Roberta Speyer: “Now this has an entirely different look to it. You’re going from a piece of equipment that looks, shall we say, like it’s from another time to a piece of equipment that if you saw it today in a doctor’s office, I don’t think you would be surprised unless you’re an ultrasound specialist but it looks very current in its styling. What types of things were going on within the Research and Development Department when you were changing from this type of equipment to this other? Are there any interesting stories you can share with us about how you really started to accelerate the development?”

Franz Wiesauer: “Yes, the first thing with this unit is the hardware was very flexible and the software running on this hardware could then determine the final functions of these units. So at former times the hardware could only do one dedicated thing and here it was really the first time that software could aid some value for the customer and aid some functionality. At this time the time-to-market was determined not by hardware development but with software development. If a software group finished, the unit was finished. With the former units, when the hardware was finished, then it was finished.”

Roberta Speyer: “I noticed the 320 unit has speakers on it.”

Franz Wiesauer: “Yes, that’s right.”

Roberta Speyer: “Why speakers? I don’t see speakers on the other equipment.”

Franz Wiesauer: “These were the first units of Kretz Technik acquisition Doppler, modality inside. Everybody knows the Doppler effect, and that means that sound waves coming from a moving target are reflected on a different frequency, that’s the Doppler frequency. By these loud speakers, you can hear the flow of the blood inside the body.”

Roberta Speyer: “Really, I went by Doppler’s house, he was from Salzburg, yes?”

Franz Wiesauer: “Yes, that’s right.”

Roberta Speyer: “Therefore, you were obliged to include the Doppler effect. As we move along looking at the equipment, there are many different types of machines. What time frame are we at now and what were the types of technologies that were leading edge and that you were trying to perfect now? We’re up to around 1980 or is it the beginning or the middle of the eighties?”

Franz Wiesauer: “We are here with these two units at the beginning of the nineties so let’s say this unit was launched to the market precisely in 1989. By the software features, we could really make units which were dedicated to certain applications and, therefore, we offered this unit - the 310, for the private office market.” 

Roberta Speyer: “It’s smaller.”

Franz Wiesauer: “It’s a smaller unit and the basic technology inside is from the 320 but it’s smaller and dedicated for private office practice.”

Roberta Speyer: “Was this the time frame when having a piece of equipment in your private office started to catch on?”

Franz Wiesauer: “Yes.”

Roberta Speyer: “Was it the end of the eighties?”

Franz Wiesauer: “Yes, that’s right. Other companies came from the low-end units or from the smaller units so for Kretz Technik, our focus was always on the leading edge of technology. This was the first unit of Kretz Technik dedicated for the private office market and on the other side of the market segment, on the high end market, we launched at the end of the eighties the COMBISON 330 which was the first unit worldwide with 3-D capabilities. This is the basis of our leading technology position in 3-D and now in 4-D.”

Roberta Speyer: “So the 3-D actually was developed and released in what year?”

Franz Wiesauer: “This was launched in1989.”

Roberta Speyer: “How did the technology at that time differ from what’s available now?”

Franz Wiesauer: “There’s a lot of differences; first, with this unit, we could not reconstruct nice surfaces of the face of an embryo, for example. This unit could only reconstruct three or two planes and the flexibility of how you can move the planes through the object of interest was very, very limited compared to the technology we have now.”

Roberta Speyer: “And was it, again, a case where the skill level required was fairly steep?”

Franz Wiesauer: “That’s right, the result was very dependent on the skill of the doctor and how to place the three-dimensional transducer on the body, and with the new developments, the reconstruction of the planes could be selected in a very free way. This means the result was independent if you scanned in this direction or in this direction, you could electronically adjust the plane of interest after that.”

Roberta Speyer: “What was happening at this point in time with ultrasound acceptance clinically? Now you have it in the office, you have applications in cardiology, obstetrics, gynecology, and in other fields. At this point in time which was around 1989-1990, was there an acceleration in the field of use of equipment?”

Franz Wiesauer: “I think the most accelerated time to use ultrasound was in the second half of the eighties with the computerized machines. At this time, ultrasound entered not only gynecology and obstetrics but also radiology and internal medicine. In the early nineties we also had color Doppler which is a new mobility to show the blood flow.”

Roberta Speyer: “Do you have one of the machines that does the color Doppler?”

Franz Wiesauer: “Yes, from here on all the Kretz machines have the color Doppler.”

Roberta Speyer: “So that would be the 4 series, the 410?”

Franz Wiesauer: “This was the 410.” 

Roberta Speyer: “What was the advantage of the color Doppler?”

Franz Wiesauer: “As I told you, the Doppler mobility can show you the blood flow inside the body, and with the standard Doppler, you could only detect the flow in one special volume of interest. With the color Doppler, you could have the information in the complete image about the flow. So the traditional B-mode image is superimposed by color information which is corresponding to the flow information of the blood which is much easier to use in color flow then to use it with a standard Doppler.”

Roberta Speyer: “When Dr. Kretz started the company and when you first joined, this was really a pioneering effort to develop this type of equipment and make it a universal standard of care, is that correct?’’

Franz Wiesauer: “That’s correct, this was really a pioneer phase of the ultrasound technology.”

Roberta Speyer: “Did he spend a great deal of time speaking and traveling at that time to kind of educate physicians around the world, and did you have physicians come here to your facility? Tell me a little bit about what it was like socially in developing this whole new field. What did you have to do to convince people that this was something they needed to pay attention to?”

Franz Wiesauer: “The most important success factor was to cooperate with some luminary doctors, for example, Professor Kratochwil who is also famous now. He retired already but he visits congresses, etc. and to cooperate with these luminary doctors. These luminary doctors made education in their clinics so this was the way the use of ultrasound was growing. First, would be a seed on the luminary side and then from the luminary side growing by education.”

Roberta Speyer: “Would you personally as the head of Research and Development talk to these doctors about the types of enhancements?”

Franz Wiesauer: “Yes, of course, this was the most important feedback to give us direction for the new developments.”

Roberta Speyer: “Can you give us any little stories of any of the luminaries you’ve worked with that gave you some specific insights that you would say helped accelerate the development?”

Franz Wiesauer: “Yes, for example, to develop the 3-D the idea was born because we talked with some doctors and they told us it’s easy to scan from the skin perpendicular to the skin so you can make such cuts with the body but you cannot make a cut parallel to the surface. They told us they know that’s not possible but this would be a very interesting point.”

Roberta Speyer: “Who were these doctors?”

Franz Wiesauer: “These were doctors like Dr. Kratochwil.”

Roberta Speyer: “And some of his assistants?”

Franz Wiesauer: “Some other doctors, luminaries, for example, in France, Dr. Weill who’s also very famous at this time and they had a lot of new ideas. At this time they had more ideas than we could realize really.”

Roberta Speyer: “They told you this was not possible but it would be ideal, and so you decided maybe it is possible.”

Franz Wiesauer: “Yes, we made the 3-D and they were absolutely correct, it’s not possible. You cannot scan in another way and more or less perpendicular to the skin but we scan through the 3-D movement and we can reconstruct after that the coronal plane so the plane parallel to the surface, this was the solution.”

Roberta Speyer: “How did you come up with that solution - many late evenings and many discussions and did you work together as teams? How would you in your Research and Development Department attack a problem like that and find the solution?”

Franz Wiesauer: “The Research and Development was organized and also at this time project oriented so we had no hierarchy. We were project oriented so we had maybe two software engineers, three hardware engineers, and application people. These people discussed together how to solve the problem and this is how they decided.”

Roberta Speyer: “Did it help that you had the brewery nearby?”

Franz Wiesauer: “Of course, at the end of the day a good glass of beer here is helpful the next day.”

Roberta Speyer: “Yes, it’s always helpful in the design process. So now we’ve come up to current day technology like 3-D and 4-D ultrasound. Tell us a little bit about that, and what you think of the technology now and what you see for the future.”

Franz Wiesauer: “We introduced to the market this year the so-called 4-D technology, and this means a 3-D object is scanned several times per second. For example, a moving baby can be observed in 3-D during the movement and the condition that makes this possible is new transducer technology, it’s a new process of technology and new memory technology. So you need a lot of different steps to be solved so that you can really make 4-D data acquisition and reconstruction.”

Roberta Speyer: “What’s the application that this is best suited to?”

Franz Wiesauer: “The application is in obstetrics and gynecology. For example, in obstetrics it accelerates the examination time because if you make a 3-D acquisition it’s low 3-D acquisition and the fetus is moving during this acquisition time, you have artifacts, and you have to find the fetus again and this is time consuming. With the 4-D, you have the immediate result on the screen and the doctor can follow a moving fetus in 3-D so that means the length of time it takes to find the right volume of interest can be shortened by this.”

Roberta Speyer: “With the going forward of ultrasound into the next century, it seems that we’re finding more and more applications for diagnostic use of ultrasound in that it is such an incredibly non-invasive way to diagnose. How do you see that developing in the future? Do you see that trend going even further?”

Franz Wiesauer: “Yes, I think in the future there’s a special plane to combine several people’s features and the diagnosis procedure in the same action. For example, if you look at a breast biopsy, you have to hit with a fine needle a small nodule, and with 4-D you can observe the biopsy procedure online.”

Roberta Speyer: “While you’re doing it.”

Franz Wiesauer: “We are doing this and we are developing combinations with therapy, for example, external beam radiation and to localize the object of interest during the beam radiation procedure.”

Roberta Speyer: “I know that’s certainly an application for fibroids where if you’re going to do an office based hysteroscopy, you can identify the problem and go in and solve it all in the same visit for the patient. Franz, tell us about the technology for the probes. While the actual equipment was developing and being computerized, what was happening - was the ability to make better probes an enhancement in the output that the physicians could get?”

Franz Wiesauer: “Until the real-time scanners, the probes used on compound scanners were only one single probe with a piezo electric element inside but it was a very simple mechanical design. With the real-time probes, we had movement of transducers inside. You can see, for example, this was the first probe on the COMBISON 100, the real-time scanner.”

Roberta Speyer: “Is that the orange probe?” 

Franz Wiesauer: “That’s the orange probe with a moving wheel with five transducers inside. This wheel was rotating and the transducers scanned this area several times per second, up to twenty times per second. You can see with the size of this probe, it can only be used for abdominal scanning.”

Roberta Speyer: “Absolutely, it was quite large.”

Franz Wiesauer: “It was quite large and also heavy. Then there were some modifications for small part scanning and that means to make images near the surface of the skin with the stand off. After that, I would say in the early eighties, we developed a lot of special transducers for special applications - transvaginal transducers and transrectal transducers. Here, you can see some of these types; this is for example, a transvaginal transducer, transrectal transducer, and we also developed a lot of accessories like biopsy sets.” 

Roberta Speyer: “With the ability to place the needle.”

Franz Wiesauer: “Yes, here you can see, for example, for a seed implantation this is a special process in the treatment of prostate tumors.”

Roberta Speyer: “Now there are many, many different types of probes and that will allow you to do different types of scanning with the same equipment.”

Franz Wiesauer: “That’s right, you could say we have probes for any application, which can really optimize the performance in this application, and we don’t have only one probe and doing everything with it.”

Roberta Speyer: This has certainly been a fascinating interview, and we appreciate you taking the time to show us your wonderful museum. I wish all our viewers and listeners could see it; it’s here in a beautiful forest in the middle of Austria on a beautiful sunny day. It’s been a delight to talk to you, thank you so much.”

Franz Wiesauer: “Thank you very much for the interview.”

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