The following year I developed the combined A and B-scan technique, which is illustrated in the next slide. This technique demanded that the midline echo was demonstrated on B-scan before the A-scan measurements were taken. With hindsight, nowadays, I think I should have just taken the measurements on the Polaroid, but in general, the A-scan measurements were more precise.
Because the Diasonograph had a strong gantry also rather heavy! The following slide shows the sort of pictures that were being obtained from Denver in those days. You can see that there are no midline structures in the Denver picture and there is a very thick outline to the head, so I had a tremendous advantage in having a machine that could do the business.
This was a case of anencephaly in the third trimester, associated with polyhydramnios. Sunden produced some excellent papers, both on obstetric scanning and in assessing gynaecological tumours. He was the first person to recognize, for instance, an ovarian follicle transvaginally.
I will now show a few more slides from my own collection. On the left you will see a picture of the first early diagnosis of anencephaly at 18 weeks , which I described in and the other slide shows a picture of the early diagnosis of a spina bifida which I diagnosed in So the early diagnosis of fetal abnormalities was now a reality.
After I left Glasgow, Hugh Robinson, who is shown in the next slide, took my place and concentrated his efforts on first trimester diagnosis. Hugh was the first to chart the growth of the crown-rump length in the first trimester and did some seminal work on the early fetal heart rate. George had visited Howry in the old days and still believed that water delay scanning was the way to do it, and he built this huge tank on top of which the patient lay.
Here he is with David Robinson and Bill Garrett, who was the obstetrician who worked with him, and they built this tank, which held 50 gallons of water. I understand that one day the water leaked out and spilled on the floor and they thought at first that the patient had ruptured her membranes.
I guess a 50 gallon leak would suggest polyhydramnios. This was because Kossoff had invented the scan converter, which allowed the demonstration of small back-scattered echoes to give the appearance of tissue texture.
In other words, grey scale. To show you the impact of this, the next slide shows a typical abdomen circumference, which I was measuring at this time, and the one on the right is their picture of an abdominal circumference.
So the scan converter was the breakthrough in showing subtle small-reflected echoes. Eventually, of course, the scan converter was incorporated into all our contact scanning machines, and the water delay scanner fell out of existence. Real-time scanning began in with the development of the Vidoson by Siemens, and the great practitioner of this equipment was Dr.
Manfred Hansmann in Bonn. Manfred Hansmann used this machine to do intraperitoneal transfusions under direct ultrasound control and I think he was the first person to do that. You can see it had a large water bag in which the transducer was placed, so it was a very large probe that you placed on the abdomen and angling this to get fetal planes was difficult.
Furthermore, because the beam was swept mechanically with a parabolic mirror, it was a very flickery picture, and I was personally unimpressed with the quality of the images. When I arrived there, I found I had to use the Vidoson and was a bit shattered because I found it difficult to obtain planes of the biparietal diameter and abdominal circumference, which I was used to getting.
However, Manfred Hansmann did brilliant work with this machine. As I said, he pioneered invasive needling procedures under real-time control with this equipment, but when the ADR came into existence in , then everyone was able to get beautiful real-time images with a small manoeuvrable probe, so ultrasound guided invasive procedures quickly became the norm. This is a typical ADR picture in You can see that the image looks a bit stripey, because at this time they had not learnt to interpolate scanning lines, but really the quality was actually quite good.
How about routine ultrasound scanning in pregnancy? I would like to claim that I was the first person who drew the attention of people that routine ultrasound was a desirable thing. It is strange to think that it could take up to 10 minutes to measure a biparietal diameter in those days, when now we would expect to do all fetal biometry in the same period of time.
Anyway, this is one prediction which has come to pass, because it has been demonstrated that routine second trimester biometry will reduce the number of unnecessary inductions of labour, as is demonstrated in the meta-analysis of 8 trials of routine versus selective ultrasound in pregnancy, where one of the significant advantages of routine ultrasound is reduction in the numbers of inductions for post-term pregnancies.
However, Persson and Grennert from the Malmo group were the first researchers to publish a study on routine ultrasound in pregnancy. You can see that they started in and published in The first national programme for routine ultrasound scanning was in the Federal Republic of Germany and I think there is no doubt they were influenced by the persuasive powers of Manfred Hansmann; they recommended two routine scans for all women.
They did produce a list of seventeen indications for an antenatal scan, which could allow for liberal interpretation, but still basically in the United States you do not believe in routine scanning, which I have to say with current knowledge on the benefits of routine scanning is difficult to understand.
I am putting this in very diplomatic language. All of these researchers and centres made singular contributions to the development of the ultrasound scanning techniques and the various applications to which ultrasound is put today. In the following slides I will go through some of the seminal papers on the various applications of ultrasound in obstetrics and gynaecology, which have shaped the way in which ultrasound is practiced today.
Fetal Biometry:. I had earlier in produced the first BPD growth curve, but the paper, I think, had a seminal influence on the construction of growth charts. In , the Campbell and Wilkin paper on measurement of abdominal circumference was an important milestone because this remains the most important parameter in the assessment of fetal weight and nutrition.
Fetal Anomalies :. Again I begin with one of my papers in , which was the early diagnosis of anencephaly followed by termination of pregnancy. This was in effect the beginning of early prenatal diagnosis by ultrasound and I followed this up a few years later with the early diagnosis of spina bifida. The seminal paper on echocardiography was produced by Lindsey Allan in Many other centers in the United States, Europe and the United Kingdom, also run well-attended and effective courses in the prenatal ultrasound diagnosis of congenital anomalies.
Guidelines formulated by accreditation bodies also have a positive effect on ensuring quality of the examinations. It was a development that has culminated from developments in skill, training, practice, attitudes, machinery and administration.
Screening basing on multiple biochemical parameters in the low-risk population had started around in some centers and because of its relative convenience had soon caught on and become standard antenatal care in many parts of the world.
Screening basing on ultrasonic parameters had not become popular until the mids. Measurement of the nuchal translucency , which was first described by Beryl Benacerraf and her group at the Harvard Medical School in formed the basis of such screening.
Working with fetuses between 15 and 20 weeks of gestation her group discovered good correlation between a thickened nuchal skin fold that was above 5mm and the presence of Down syndrome in the fetus.
Endocardial cushion defect, atrial and ventricular septal defects, omphaloceole, pyelectasis, choroid plexus cyst, echogenic cardiac foci, echogenic bowels, hypoplasia of the middle phalanx of the fifth digit and simian creases were considered as other 'indirect' or 'soft' signs of fetuses with Down syndrome.
Benacerraf had on top of other things brought to the attention of researchers and clinicians the necessity and feasibility of visualising ' small ' abnomalites in the fetus and had in so doing pushed scanning skills, machine resolution and operator patience to the limit. Anomalies such as club foot, early hydrocephalus, phalangeal abnormalities, facial clefts Although many fetal anomalies -- such as anencephaly, hydrocephalus, and anterior abdominal wall abnormalities -- can now be diagnosed sonographically even in the second trimester, more refined diagnosis involve examination of the face and extremities.
It is not sufficient, however, to diagnose isolated cleft lip and palate or a clubfoot. Rather, the presence of these lesions should stimulate the ultrasonographer to seek a pattern and fit the pieces of the puzzles together in order to recognize the syndromes associated with chromosomal anomalies Measurement of the nuchal fold at this latter gestation is demanding on operator skill and machine resolution and is also error prone. With improved resolution of ultrasound scanners, better understanding of fetal patho-physiology and more emerging data, ultrasonic screening for nuchal fold thickness has moved from between 16 and 19 weeks using a cutoff level of around 6mm to between 11 and 14 weeks using a cutoff of around 3mm in the first trimester.
Kypros Nicolaides and his group at King's published the landmark paper in in the British Medical Journal , where the measurement of nuchal translucency between 11 and 14 weeks was used to screen for Down syndrome.
He demonstrated the importance of likelihood ratios in the detection. The group later on turned out some of the most important data regarding the appication of nuchal translucency measurements including risk estimates and the quantitization of the measurement into gestational-age related multiples of the median MoM.
In Gynecology , ultrasound has started as a diagnostic tool in the differentiation and assessment of solid, cystic or mixed masses in the pelvis. Even in the late s still very much a static-B era , it has already become a well-established and indispensibe tool in the evaluation of a variety of pelvic pathologies. A 'very-full' bladder was a pre-requisite for good visualization of the ovaries. Other morphological parameters were also described. Ultrasound monitoring was 'formally' introduced into ovulation induction programs in By about there were a number of important reports attesting to the usefulness of abdominal ultrasound in the assessment of follicular development and ovulation.
In , the Colm O'Herlihy , Lachlan de Crespigny and Hugh Robinson group at the Royal Women's Hospital in Melbourne, Australia, published on important follicular size criterion and protocols for ovulation inductions. Other important early work had also come from the Joupilla group in Finland, the Lopata group in Melbourne, the Queenan and O'Brien group in England and the Fleischer group in Tennessee. Transvaginal scanners replaced the abdominal counterparts after they became available in the mid 's.
The addition of endometrial evaluation using transvaginal scanning enhanced diagnostic accuracies in the mangement of ovulation induction cycles. Follicular and edometrial sonography, although tremendously useful when used in combination with estrogen assays was unable to ro predict ovulation and avoid multiple pregnancies.
Vaginal sonography had also become indispensible in the evaluation of non-palpable masses , ascites , uterine and cervical leisions , early pregnancies and the localization of IUCDs. It's value as a tool in the diagnosis of ectopic pregnancies and ovarian and edometrial cancers was extensively re-evaluated in the late 's and later on in the early 90's with addition of transvaginal color flow imaging see below.
As mentioned the greatest development of transvaginal imaging in the late s has been in assisted reproduction , where all aspects of diagnosis and management are incomplete without a vaginal scan.
The diagnosis of ectopic pregnancies continued to be a challenge, despite better machines and the transvaginal approach. A number of authors such as Roberto Romero at Yale devised diagnostic criterion for making a diagnosis, combining the use of sonography, HCG levels and color doppler assessment, which allowed a vast majority of the diagnosis to be made. Interventional sonography in gynecology dated back to the early s when Hans Henrik Holm described percutaneous puncture of ovarian tumours in They performed over procedures with very few serious complications.
It was not until that David Graham and Roger C Sanders at the Johns Hopkins Hospital, Baltimore, revisited the idea of transvaginal aspiration of pelvic masses under transabdominal ultrasound guidance. There was a necessity to develop similar techniques for the retrieval of follicles in IVF programmes which has hitherto been achieved only through laparoscopy.
Susan Lenz and JG Lauritsen at the University Hospital Rigshospitalet in Copenhagen described percutaneous transabdominal - transvesical aspiration of ovarian follicles in and which showed for the first time that ovum retrieval can be performed as an ultrasound-guided and out-patient procedure.
Transvaginal ovum retrieval under abdominal ultrasound guidance was further described by Norbert Gleicher in Chicago in in a letter to the Lancet and several months later by the P Dellenbach group in Shiltigheim, France in They reported for the first time successful pregnancies 5 out of 30 patients using this technique. They further reported on favorable results in in more than cases of oozyte retreival using this ' transabdominal scan - transvaginal puncture ' method.
The advantage of this technique is that the ovaries are more accessible and the procedure is safer and relatively pain free. More importantly, the procedure is repeatable on an out-patient basis, and dramatically cuts down the cost of the IVF procedure.
The true impact on ovum pickup came with the appearance of the mechanical transvaginal sector scanner from Kretztechnik in when Wilfried Feichtinger and Peter Kemeter in Austria described its use in transvaginal aspiration of ovarian follicles for IVF.
Since then, ovum retrieval had steadfastly become an outpatient routine compared to just a few years ago when it was done as a laparoscopic procedure under general anaesthesia. The technique has also found its way into many ultrasound-guided interventional procedures in gynaecology refer to Part 2.
In Campbell's department was the first to publish on a large scale screening project for ovarian cancer using abdominal ultrasound over a span of 5 years. Their results showed a low positive predictive value. Subsequent to this Paul DePriest's group in Kentucky published in results in ovarian cancer screening using the vaginal approach which arrived at similarily low postitive predictive values. Morphological scoring systems to improve the diagnosis of ovarian cancer in ultrasound-detected pelvic masses were described by several workers, notably Ilan E.
Timor-Tritsch and AM Sassone in Results of studies appeared to indicate that many women would undergo surgical procedures to diagnose relatively few cancers. It has so far not been convincingly demonstrated that screening will reduce morbidity or mortality from ovarian cancer or for that matter improve the health status of women. Bengt Karlsson and Seth Granberg in Helsinki, Finland reported in the use of endometrial thickness measurement over 5mm to predict endometrial cancer.
The application of doppler ultrasound in gynecology did not appear until the mid 's when Kenneth Taylor at Yale described blood flow in the ovarian and uterine arteries in and Asim Kurjak in Croatia pioneered the use of transvaginal color doppler in the assessment of the pelvic circulation in Kurjak was the founder of the Ian Donald Inter-University School of Medical Ultrasound in Dubronik, one of the largest and most important Ultrasound schools in the world.
The Coatian group continued to contribute heavily to the applications of trans-vaginal color doppler in Obstetrics and Gynecology. It should be mentioned here that the use of transvaginal 2-D, doppler and color doppler ultrasound almost started around the same time in the late s, and one finds the introduction of vaginal doppler studies almost coincided with the first reports on vaginal sonography. Work also came out from the United States from the Arthur Fleischer group in Nashville, Tennessee in the early s on ovarian tumour vascularity using transvaginal color doppler.
The group had around the same time published other important work on transvaginal ultrasound in gynecology. Color flow imaging of Intra-follicular blood flow and impedance in the uterine arteries during assisted reproductive cycles further added to the diagnostic capabilities of vaginal doppler ultrasound. The work of Tom Bourne and the group at Kings also confirmed the usefulness of color doppler in refining the prediction of ovarian cancer in ovarian masses, and in a screening setting.
Their group had also made exhaustive investigations into the use of transvaginal color doppler in the diagnosis of a variety of gynecological conditions. They have also documented the usefullness of periovulatory blood flow in ovarian and uterine arteries in the management of assisted reproductive cycles.
In Color power imaging Power doppler , red or blue luminosity is used to indicate the power or amplitude of the blood flow signal. The process is more sensitive than color velocity imaging. The display of color from image areas with low amplitude echoes can by adjustment be inhibited and only high amplitude echoes are displayed and color coded according to their power or velocity.
This was expounded in by K Miyatake and M Yamagishi in Japan in the evaluation of left ventricular wall motion. The development had come about with the availability of more powerful electronics.
Further developments had also led to the degree of tumor vascularization being quantitatively estimated. The approach has received much attention from the gynecology sector in the investigation of pelvic malignancies.
With improvements in ultrasonic and computer technology, work on three-dimensional visualization began to appear in the early 's. Other work came from the domain of cardiologists where initial efforts were directed to acertaining the volume of cardiac chambers. Real-time scanner probes mounted on articulated arms were often employed where positions of the probe can be accurately determined. The principle has always been to stack successive parallel image sections together with their positional information into a computer.
Kazunori Baba at the Institute of Medical Electronics, University of Tokyo, Japan, first reported on a 3-D ultrasound system in and succeeded in obtaining 3-D fetal images by processing the raw 2-D images on a mini-computer in Their setup was reported in the Acta Obstetrica et Gynaecologica Japonica.
Baba , with Kazuo Satoh and Shoichi Sakamoto at the Saitama Medical Center described the improved equipments in in which they used a traditional real-time convex array probe from an Aloka SSD scanner mounted on the position-sensing arm of a static compound scanner Aloka M8UC. The images obtained were processed on elaborate computer systems see picture with description below. This approach successfully produced 3-D images of the fetus which were nevertheless inferior to that produced on convenional 2-D scanners.
At the same time, to generate each 3-D image it took on an average some 10 minutes for data input and reconstruction making the setup impractical for routine clinical use. Baba published in in the Japanese language the first book on ultrasonography in Obstetrics and Gynecology which contained chapters on 3-D ultrasound. Kazunori Baba's 3-D setup in the mid s.
A linear array probe was mounted on an articulated arm for position sensing. On the right is the computer setup for making the calculations. The Combison which appeared in , was the first commercial 3-D scanner in the market.
The Taiwanese group were also the first to describe 3-D visualisation of the fetal heart in the same year although at that time they were only able to image static parts in 3-D. In , the Center for Emerging Cardiovascular Technologies at Duke University started a project to develop a real-time volumetric scanner for imaging the heart.
In they produced a matrix array scanner that could image cardiac structures in real-time and 3-D. In , Olaf von Ramm , Stephen Smith and their team produced an improved scanner that could provide good resolution down to 20 centimeters.
The team developed state-of-the-art "Medical Ultrasound imaging" integrated circuits MUsIC which were capable of processing signals from multiple real-time phased-array images. The microprocessors were developed in collaboration with the Volumetric Medical Imaging Inc.
The MUsIC 3. This became available commercially from Volumetric Medical Imaging, Inc. The matrix-array transducer, which steered the ultrasound beam in three dimensions, contained 2, elements in which were used for image formation. The beam-former produced 4, lines running at 30 frames per second. This required as much ultrasound signal processing power as eight top-end 2-D systems, running on microprocessors that execute instructions 30 times the speed of a typical 2 GHz Pentium tm.
Due to the relatively small size of the 2-D matrix array probe, it is more suited to cardiac examination rather than for the abdomen. The apparatus is also costly to produce and poses problem in manufacturing and in image quality due to the large amount of crystals and interconnections. They were able to demonstrate early gestational age fetuses with their apparatus. Wilfried Feichtinger at the University of Vienna, Austria reported images of 10 weeks embryos imaged with 3-D transvaginal transducers in Kretztechnik had in this year marketed their 2nd generation 3-D scanner the Voluson D.
Alfred Kratochwil had continued his support in the development of 3-D technology at Kretztechnic and was active in the teaching of 3-D sonography after his retirement. The Ulrike Hamper group at Johns Hopkins reported images of various congenital malformations with a prototype 3-D scanner. Thomas Nelson and Dolores Pretorius at the University of California, San Diego , approached the carotid arteries with their prototype 3-D system in and produced very successful images.
The signal chain consisted of a transducer-array moving along the patient's neck producing sequentially sampled images which were digitised, acquired and surface-rendered on the connecting workstation.
Read an important Treastise on 3D ultrasound by Thomas Nelson here. Their group continued to make refinements to the instrumentation and started to publish on fetal visualization in the following years and continuing on to become one of the most important research teams in the field of 3-D ultrasound in Obstetrics and Gynecology.
In , Nelson's group and the Medical Imaging group at the university College Hospital in London published independent researches on 4-D motion 3-D fetal echocardiography , using sonographic cardiac gating methods to remove motion artefacts, which are present with conventional static 3-D methods.
A useful feature of 3-D display is the cine loop , in which the rendered 3-D volumes are viewed as they rotate. This capability enhances depth perception and gives a true 3-D perspective of both normal and abnormal structures. In , Eberhard Merz at the Center for Diagnostic Ultrasound and Prenatal Therapy, University of Mainz, Germany, demonstrated the usefulness of multiplanar orthogonal imaging as well as as surface views and transparent views in the diagnosis and confirmation of fetal surface and skeletal anomalies such as cleft lips and complex multiple malformations.
He and his co-workers reported a large series of over cases of fetal diagnosis using 3-D ultrasound. In , his team reported on the diagnosis of facial anomalies using trans-vaginal 3-D scans. In Obstetrical and Gynecological 3-D imaging , mechanical designs appeared to be the only popular choice. Two-dimensional arrays are mechanically moved to provide the third dimension by sweeping or rotating, using either constrained free-hand adapters or an existing probe alongside with an external motion-sensing system.
Their technique was described in the paper " 3D ultrasound - the Kretztechnik Voluson approach " in the European Journal of Ultrasound in The process of acquisition is microprocessor-controlled and automatic. In the display of the acquired data, the degree of transparency is first chosen which involves applying a mixture of ray-traced, volume-rendered illumination and maximum intensity or summed voxel projection.
Perception in 3-D surface is acheived by a combination of depth shading, color-mapping, texture mapping and ray-traced volume rendering. The introduction of Multiplanar reformatting has allowed the generation of any arbituary slice within the data aquired. In obstetrics this is valuable for measurement, and for obtaining re-constructed critical views such as the 4-chamber view or scans orthogonal to the face and soft palate.
All these are heavily dependent of the software algorithms and processing power of the computers within the machines. Volume rendering in medical imaging has in fact much of its roots in computer graphics engineering. Volume rendering developed as a separate body of techniques, mainly within the computer graphics literature, before and independent of its application to medical data.
One of the earliest pioneers in volume rendering is Marc Levoy. Levoy began his work in volume rendering at the University of North Carolina, where he published many of the major papers in the field. He continued to advance the field by developing new algorithmic approaches, finding ways to improve efficiency, and demonstrating practical applications for the technique. Following his initial paper in : " Display of Surfaces from Volume Data " where he described the classic volume ray tracing algorithm and has been the basis directly or indirectly for most commercial 3D ultrasound systems, Dr.
Levoy has published a number of important papers that have continued to break new ground. He has also developed several algorithms for increasing the efficiency of volume rendering, including taking advantage of spatial coherence, adaptively refining the image. Volume rendering has made a major impact on the many scientific, engineering and medical disciplines that create and display large multi-dimensional datasets.
Many of the volume rendering agorithms and technology had actually originated from computer scientists at the filmmaking company Pixar Animation Studios , famous for its 3D computer animated films!
Initial volume rendering techniques and agorithms were "invented" by company founders Robert Drebin , Loren Carpenter , and Pat Hanrahan. The algorithm embodied three key ideas: Directional shading based on the gradient in a volume, digital compositing to combine the slices of a volume, and Image warping, also applied to a volume.
Gradient shading of volumes first appeared in a paper by Karl-Heinz Hoehne , hamburg, who called it graylevel gradient shading. Image warping is a special case of texture mapping, which dates back to Edwin Catmull's PhD thesis at the University of Utah. Volume rendering approximates the passage of light through a participating media. In this respect, James Blinn 's paper on clouds and dusty surfaces, Jim Kajiya 's paper on volume densities, and Holly Rushmeier 's paper with Ken Torrance on zonal radiosity must also be regarded as formative.
This relationship between volume rendering and light transport was pointed out to the volume rendering community by Wolfgang Krueger. It will give you a clear notion about the functionality of this system. The ultrasonic sound waves are the types of sound waves, which our ears are not capable of hearing.
Their frequency is more than Hz. When the ultrasonic sound wave reflects after touching the body surface and tissues, it provides images. One of the perks that you will witness after using the ultrasound is that it is non-invasive. Well, millions of women go through this process during their pregnancy.
And it provided accurate and useful results. However, the high-power ultrasound is capable of damaging the tissues of a human. So, make sure that you are doing ultrasound treatment for clinically acceptable reasons. Now, this is one of the exciting aspects. Well, most of the time, pregnant women delivered positive reception about the ultrasounds.
In addition to revealing the baby's health, the images themselves provide a keepsake. In fact, Nicolson said, some women report not feeling pregnant until they've seen the ultrasound image. Seeing a developing fetus has a humanizing effect, too. Donald, the physician who helped develop the technology, was a devout High Anglican, and knew the images carried moral significance for women contemplating having an abortion.
Ultrasound images sometimes play a role in decisions to maintain or terminate a pregnancy. Anti-abortion proponents take ultrasound images as proof that a fetus is fully alive and therefore should not be aborted.
On the other hand, ultrasound can be used to diagnose potentially fatal or debilitating abnormalities in the fetus, which can encourage termination of the pregnancy. In some East Asian countries, ultrasound is used to detect the sex of the baby expressly so that a fetus of less desirable sex usually female can be aborted, Nicolson said. He called the practice "unfortunate and worrying.
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