The development of echoencephalography in Sweden

Although neurosurgery has a long history it was thanks to brave pioneering neurosurgeons such as Harvey Cushing in the United States — and in Sweden Herbert Olivecrona — that the speciality made huge progress during the first half of the 20th century. However, around 1950, the possibility to reveal pathological processes taking place inside the closed skull, was still very restricted. The only available rapid procedure was the neurological examination of the patient. X-ray of the skull is of restricted value, pneumo-encephalography was much too complicated and time-consuming for acute situations, and angiography was still in its infancy. Thus the neurosurgeon, receiving an acute patient with a suspected intracranial haematoma, had to make a qualified guess about where to start placing his trephine on the skull in order to save the life of the patient — often within minutes in the case of a bleeding between the skull bone and the dura. The mortality in those days was 40 % , often because the diagnosis was made too late. Thanks to an ingenious Swedish neurosurgeon, Lars Leksell, working at Lund University Hospital, a new approach to reveal the secrets inside the skull was introduced in clinical praxis — echoencephalography. Lars Leksell graduated from the Karolinska Institute (KI) and received his neurosurgical training in Herbert Olivecrona’s department from 1935. He volunteered as a neurosurgeon in the Finnish winter war in 1940 in Karelia. His team could operate on 24 head injuries per 24 hours and already by this point, Leksell showed his creative mind in constructing the double-action rongeur for more efficient removal of shell-splinters from the vicinity of the spinal cord. In 1941 he joined Professor Ragnar Granit (1967 Nobel laureate in Medicine) at the Institute of Neurophysiology where he presented his thesis on gamma nerve fibres in 1945. In 1946 he became the chief of the new neurosurgical unit in Lund and in 1958 he was appointed the first Professor of Neurosurgery at Lund University. In 1960 he succeeded Olivecrona as Professor and Chairman of the Neurosurgical Department at the Karolinska Institute/Hospital.

Ultrasound in paediatric cardiology — state of the art

The development of ultrasound technology to visualize cardiac structures, based on the pioneering work by Edler and Hertz at the University of Lund in Sweden, has literally created a revolution in the field of paediatric cardiology. Before the era of cardiac catheterization and echocardiography the diagnosis of congenital heart disease was mainly based on combining physical findings, cardiac auscultation, electrocardiogram (ECG), and chest X-ray. This was largely based on the work by Helen B. Taussig at John Hopkins in the 1930s who established the field of clinical paediatric cardiology by integrating pathology knowledge with clinical findings. Diagnosis at that time was based on clinical skills and was more an art than science. The introduction of paediatric cardiac surgery in the 1950s was made possible due to the simultaneous development of cardiac catheterization and angiography which allowed an accurate description of the different cardiac lesions and the associated haemodynamics prior to surgery. For a long period catheterization was the diagnostic gold standard and all surgical patients underwent an invasive cardiac evaluation. In the 1970s, echocardiography was developed as a clinical tool and due to its non-invasive nature, was introduced quickly in paediatric cardiology. As anatomical diagnosis is challenging by M-mode echocardiography, it was really the development of two-dimensional (2-D) echocardiography in the late 1970s and early 1980s that deeply influenced the field. For the first time the congenital defects could be imaged noninvasively and the 2-D images were extensively validated by comparing them with pathological and surgical findings. Adding pulsed, continuous, and colour Doppler data to the 2-D images resulted in a complete detailed description of congenital cardiac defects and their haemodynamic consequences. Further optimization of ultrasound technology specifically for paediatric imaging, such as the development of higher-frequency probes and increasing the standard grey-scale frame rates, further improved spatial and temporal resolution and overall image quality. Based on its excellent diagnostic accuracy and its non-invasive nature, echocardiography quickly became the primary non-invasive diagnostic technique for all children with heart disease. Currently every paediatric patient with suspected heart disease will undergo an echocardiographic examination as the first (and often only) diagnostic test.

The development of ultrasound in otorhinolaryngology

The use of ultrasound in the field of otorhinolaryngology goes back almost 40 years. Ultrasonography with simple A-mode has proved to be successful for identifying diseased maxillary and frontal sinuses. It is generally accepted that ultrasonography is of value in diagnosing acute rhinosinusitis; in cases of chronic rhinosinusitis both A- and B-mode ultrasound have limited value. B-mode ultrasound is mainly used for soft tissue examination of the neck and has not developed to the extent that was expected for the paranasal sinuses. Computed tomography (CT) is still the gold standard for investigation in chronic rhinosinusitis when grading the severity of the disease and when the patient will be subject to surgical intervention. Ultrasound-guided fine-needle biopsy of the neck and Doppler ultrasound for evaluation of the blood vessels of the neck will also be of great value in the future. Doppler ultrasound of the paranasal sinus shows promising results in identifying the characteristics of sinus secretion, and there is ongoing research on this application. The first clinical evaluation in patients with sinusitis, examined with ultrasound Doppler, will be performed in 2011. Ultrasound examination of the neck and ultrasound-guided fine-needle biopsy are well established methods in the field of otorhinolaryngology. The ultrasound technique is of great value when identifying lymph nodes, cysts, and abscesses of the neck. Furthermore, ultrasound can be used to differentiate diffuse changes in the thyroid and salivary glands from solitary lumps and cysts. Ultrasound is also of importance when examining the parathyroid glands. Additionally, Doppler ultrasound is a very successful method to diagnose stenosis of the arteries of the neck. However, these examinations are mainly executed by physicians skilled in ultrasound outside the departments of otorhinolaryngology. Another field of application is the development of user-friendly ultrasound equipment, which can be used by physicians in primary care or by otolaryngologists in order to improve the diagnostics of rhinosinusitis. This is an important diagnostic tool, since it has been known for more than 40 years that diagnoses of acute rhinosinusitis (ARS) based on clinical examination alone, is correct in only 50 % of cases.

The development of ultrasound in ophthalmology

The clinical applications of diagnostic ultrasound in ophthalmology were initiated by G.H. Mundt and w.F. Hughes ( 1 ) (1956) as well as A. Oksala and A. Lehtinen ( 2 ) (1957) introducing A-scan, and by G. Baum ( 3 ) (1958) introducing and pioneering B-scan. The first medical society for diagnostic ultrasound was founded in 1964 (Societas Internationalis de Diagnostica Ultrasonica in Ophthalmologia) with subsequent biennial congresses. Ophthalmic diagnostic ultrasound is the only ultrasonographic method heavily relying on A-scans besides the B-scans. Today, four distinct echographic methods (utilizing different types of instrumentation) are being used in ophthalmology: 1) Biometric A-scans for measuring the axial eye length. 2) Low-frequency B-scans for the examination of the posterior eye segment and the anterior orbit utilizing 10–20MHz. 3) High-frequency B-scans for the evaluation of the anterior eye segment applying 25–50MHz. 4) Standardized Echography , a combination of diagnostic as well as biometric A-scan (8MHz) and B-scan echography (10–50MHz) for a comprehensive ultrasonographic examination of the eye (anterior and posterior segments) and of the entire orbit and periorbital region. A-scan (8–12MHz) is used for measurements of the axial eye length, today an important contribution to the calculation of intraocular lens power in cataract surgery. F. Jansson ( 4 ) (1963) proposed biometric A-scan as an immersion (non-touch) technique and also measured the involved sound velocities of the anterior chamber, the lens, and the vitreous cavity which since then have been the accepted standard values. At first, axial eye length measurements were mostly used in studies regarding glaucoma and myopia. when, in the early 1970s, the implantation of artificial lenses during cataract surgery spread quickly, the much more precise but more time-consuming and demanding immersion method temporarily gave way to an easier and quicker contact method. Lately, however, advances in cataract surgery, especially the use of multifocal lenses as well as the competition from laser technology, resulted in a return of Jansson’s immersion method.

Ultrasound in radiology —state of the art

The practice of ultrasound in radiology has continued to develop and shows no signs of slowing down. The changes affect the systems themselves, with important technical developments, as well as the ways they are used, and to some extent these are interlinked. The earliest static scanners were so difficult to use that only dedicated personnel could find the time and make the effort required to use them. This led to a small cohort of enthusiasts offering a limited and expensive service. Strangely, they were a mixture of doctors (many of whom were not radiologists) and physicists, perhaps reflecting the complexity of the scanners. with the development of real-time systems and increasingly as they have become easier to operate, ultrasound found its place within radiology departments and, in parallel, in cardiology and obstetric units as well as in vascular labs. Here the role of physicists faded and most of the people performing the scans were medical, a situation that still obtains in many parts of the world, notably in the Far East (in China, the doctors are ultrasound specialists) and in many European countries. In others, especially in the United States, technologists or radiographers took over the actual scanning, leaving radiologists or their equivalent (cardiologists, obstetricians) to read and report the studies by analogy with other scanning modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). The driver for this major change has mainly been financial: medics are expensive and sharing the workload with technologists is cost-effective. However, this shift comes with a penalty: as ultrasound is a real-time method and the techniques required to make the studies are very interactive, simply reading a set of images on a PACS (picture archiving and communication system) workstation deprives the radiologist of dynamic information that can be critical to making the diagnosis. In some places the response to this has been to train the technicians or radiographers to interpret and report their own cases. Though often disapproved of by the regulatory authorities and exposing practitioners to risks of litigation, this approach has been popular amongst radiographers only partly because their extended role is rewarded by additional pay.

The early development of diagnostic ultrasound in Denmark

The development of diagnostic ultrasound in medicine began in Denmark in November 1965 at the Surgical Department H at Gentofte County Hospital in Copenhagen, and a prosperous time for diagnostic ultrasound began. It was the young surgeon Hans Henrik Holm who took the initiative, strongly supported by the head of the department Professor P.A. Gammelgaard. Hans Henrik Holm had for years studied ultrasound and earlier in 1965 he had visited Helmuth Hertz in Lund in Sweden to discuss the prospects of ultrasound. A grant from a national scientific foundation of 60 000 Danish kroner (approximately $10 000) made it possible to buy the American Physionic A-mode ultrasound machine. It was installed in a spare room at the Surgical Department H at Gentofte County Hospital in Copenhagen. An ultrasound laboratory was hereby established, and it was increasingly involved in a variety of clinical ultrasound studies and in the development and testing of new ultrasound equipment. The expenses were met by both the hospital and the University of Copenhagen, and a great deal of the research was financed by foundations. Hans Henrik Holm became the day-to-day head of the laboratory and he kept this position for many years. The Surgical Department and the ultrasound laboratory, designated the Ultrasound Department, were relocated to the new Herlev County Hospital in 1976 where Hans Henrik Holm became consultant at the Urology Department and Professor in Ultrasound and Interventional Ultrasound affiliated with the Surgical Department. The Ultrasound Department at Herlev had an increasing number of rooms and staff members. A senior registrar (Jø rgen Kvist Kristensen) was associated to the department in 1975 and Søren Torp-Pedersen was appointed consultant at the department in 1989. In 1966, 250 patients were examined annually. Thirty years later the Ultrasound Department at Herlev Hospital examined 17 000 patients annually, and ultrasound departments had been established at other hospitals in the Copenhagen area. By 1966 two papers in Danish were published and two papers in English were published in 1967 and 1968 . The number of staff rapidly increased, and a group of enthusiastic doctors and technicians was formed, working with patients and on scientific projects.

Ultrasound in vascular disease —state of the art

The current use of ultrasound in vascular disease extends from diagnosis of several disorders to guidance of operative intervention. Duplex ultrasound (DU) is the main diagnostic modality used in patients with carotid disease, deep venous thrombosis (DVT), peripheral arterial disease, monitoring patients with subarachnoid haemorrhage for vasospasm transcranially, and many other routine examinations. The introduction of new technology is permitting the expansion of these applications. New interventions such as carotid stenting and endovascular aneurysm repair have necessitated the use of DU for detecting in-stent restenosis or endoleaks. In preparation for lower extremity bypass, arterial mapping of the lower extremity by DU is used as the sole imaging modality for lower extremity bypass procedures. DU is also used intraoperatively in evaluating carotid endarterectomy, endovenous procedures such as laser and radiofrequency ablation, and the patency of in situ vein bypasses. Most recently, the breakthroughs in bioengineering have resulted in a plethora of applications for vascular ultrasound. Three-dimensional ultrasound has been used in the assessment of carotid plaque volume together with the monitoring of its evolution with time and its response to various treatments. The use of microbubbles as contrast agents during ultrasound imaging allows the assessment of microcirculation and can be used for ultrasound-guided delivery of drugs and genetic therapies. In addition the assessment of brachial flow mediated dilatation and carotid intima–media thickness by DU has provided a non-invasive way of assessing the arterial wall behavior and to evaluate these patients’ risks of adverse cardiovascular events. Finally, the development of intravascular ultrasound has given birth to the field of virtual histology and has opened new frontiers in the measuring intimal thickness and assessing vulnerable plaques. In recent years, the ‘gold standard’ of angiography for arterial mapping of the lower extremities has been challenged by DU. It has been supported as the sole method for evaluating patients undergoing lower extremity interventions by a number of authors. However, scanning the whole arterial tree is time-consuming, and might be obscured in obese patients or patients with tortuous or heavily calcified vessels.

Eugene Strandness and the development of Doppler ultrasound in vascular disease

This is the story of how a young surgeon, Donald Eugene Strandness Jr (Gene) was instrumental in the development of the Doppler ultrasonic flow meter, which evolved into the duplex scanner — perhaps the most versatile instrument in the modern vascular lab. He was born in Bowman, North Dakota, in 1928, and attended high school in Olympia, washington, where he was a football player and a star gymnast. He graduated from Pacific Lutheran University in 1946, studied medicine at the University of washington (Uw), and in 1950 entered the general surgical residency programme. At the time of the Korean war, Gene was drafted out of his residency; met his 2-year service obligation to the United States Air Force; and in 1959 returned to Seattle, where he hoped to join in the extensive research underway on the gastrointestinal system under the direction of Professor Henry Harkins. Instead, Dr Harkins urged him to change directions and join a small group at the Seattle VA Hospital who were investigating arterial disease. This group included John Bell, Hub Radke, and J.E. Jesseph. Strandness, swallowing his initial disappointment at having to give up gastrointestinal research, quickly embraced the vascular challenge. The 1950s were a particularly exciting time in the history of vascular surgery. Improved sutures, grafts, and anaesthesia made it possible for the first time to perform major arterial surgery, such as resection of abdominal aortic aneurysms, endarterectomy of the carotid bifurcation, and bypass of iliac, femoral, and popliteal arteries. In preparation for major arterial surgery, the need for imaging was keenly felt. Physiological studies to select patients for surgery took a backseat to arteriograms and physical examination — in part because pulse palpation and patient testimony were the only methods readily available for measuring preoperative functional impairment or postoperative success. Invasive methods for studying blood flow were limited to electromagnetic flowmetry, which was performed in the operating room with the patient anaesthetized. No effort was made to duplicate normal physiological conditions. Prior to the 1960s, a few surgeons and internists maintained rudimentary vascular labs where systolic blood pressure and blood flow were measured plethysmographically.

The development of ultrasound in obstetrics and gynaecology in Sweden

In the field of obstetrics, the advent of diagnostic ultrasound was most welcome because of the obvious lack of a non-invasive method providing information on the fetus in utero. The subsequent very fast and widespread use of ultrasound in clinical obstetrics was vindication that the method fulfilled the expectations and that it literally ‘opened a window into the uterus’. Ultrasound enabled direct examinations of fetal anatomy, measurements of fetal size and growth, and recording of intrauterine activities. Nowadays, 97 % of all pregnant women in Sweden undergo at least one ultrasound examination during their pregnancy. The early positive results reported from the application of ultrasound in cardiology and neurosurgery at Lund University elicited interest to test the method on pregnant women at the Department of Obstetrics and Gynecology in Lund. In 1957, Alf Sjövall, then professor in obstetrics and gynaecology, discussed over a lunch-table with neurosurgeon Lars Leksell his very first experience of diagnosing subdural hematoma using ultrasound. Professor Sjövall asked then Bertil Sundén, who worked at his department, to investigate early pregnancies with the Krautkrämer echoscope belonging to Leksell. The aim was to examine whether it would be possible to detect echoes from the fetus in early pregnancies and to differentiate it from myomatous enlargements of the uterus and from ovarian tumours. The Krautkrämer echoscope offered only an A-mode display of ultrasound signals so no tangible results were obtained as the origin of the echoes could not be identified. At that time, it was unknown whether or not ultrasound might have any harmful effects on embryonic tissue and therefore these first investigations in early pregnancies were done on patients admitted for interruption of pregnancy. After that Ian Donald published the first description of an echoscope generating a two dimensional display in 1958, Bertil Sundén went on a three-week visit to Professor Donald in Glasgow. There he met electronic engineer Tom G. Brown, employed by Smiths Industrial Division in Glasgow, who had built Donald’s machine. During his stay in Glasgow Sundén performed several investigations on obstetric and gynaecological patients using Brown’s equipment that was the only one of its type.

The industrial development of ultrasound —a Swedish perspective

My first contact with diagnostic ultrasound was in 1969, when I attended a demonstration of a Siemens Vidoson at Falun hospital, Sweden. A few Vidoson systems were installed in Sweden by the end of the 1960s. I was at that time sales engineer at the Medical Electronics Department at LIC, supplier of products to the public Swedish healthcare system. I joined Roche Bio-Electronics in 1971. There were some early ultrasound products — Fetasonde continuous wave (Cw) Doppler and Arteriosonde blood pressure units made in Cranbury, United States, and a French echoencephaloscope. I visited Lund several times in 1972 and became fascinated by the pioneering ultrasound work performed by Dr Inge Edler. Roche Bio-Electronics was transferred to Kontron, Zürich in 1973. I was entrusted to start up the Swedish subsidiary Kontron AB in February 1973. Bio-Electronics service engineer, Åke Larsén, also accepted the Kontron offer. I decided to focus on ultrasound in 1974, left Kontron, and joined a small trading company, wabloprodukter, as a third part-owner, starting an electromedical department, without salary but 10 % commission on sales. wablo became distributor for Parks Medical Electronics, Oregon, one of the early Doppler manufacturers. Doptone, the first fetal pulsedetector, was released in 1965 by Smith Kline Instruments (SKI), after a technology transfer agreement with Professor Rushmer’s team, headed by Don Baker, Bioengineering Department, University of washington, Seattle. Later, in 1965, Loren Parks released Parks first fetal and vascular Cw Doppler instruments. The two first wablo years became economically tough. I was close to giving up, but made a final week sales trip in southern Sweden in May 1975. On Friday of that week, visiting Allmänna Sjukhuset, Malmö (part of Lund University), Professor Lindell, of the Clinical Physiology Department said: ‘we have tried to find a Parks distributor, so far without success, we need to order two 806 Dopplers’. That became the turning point, and I decided to continue. During the coming years wablo delivered thousands of Parks Dopplers in the Nordic countries. Most of them are still today, 30 + years later, in daily clinical use! At the 2nd European Ultrasound Congress, Munich 1975, the Advanced Diagnostic Research (ADR) booth was crammed.