Ian Donald and the Early Obstetric Scans

Obstetric and gynecologic sonograms, which Candace Cooley has both performed and read, in flat views as well as 3D and 4D, trace back to a set of experiments at an engineering works near Glasgow in the 1950s. The method those experiments tested is easiest to follow one step at a time. An industrial ultrasonic flaw detector sends a short pulse of high frequency sound into a piece of metal. Wherever the sound meets a boundary, such as a crack in a weld, part of it reflects back to the probe. The instrument displays each returning echo as a blip on a line, and the position of the blip shows how deep the boundary lies. A history of the Glasgow work by the patent firm Marks and Clerk describes how such detectors were essential to the city’s shipbuilding industry for finding cracks in welds.²

The same steps work in the body, because tissues reflect sound differently. The Naked Scientists explain that the time an echo takes to return gives the depth of whatever reflected it, and that solids and liquids echo in different ways.¹ Ian Donald put that difference to the test. Recalling the results, quoted in the Marks and Clerk account, he wrote that a cyst produced echoes only from its near and far walls, while a solid tumor weakened the echoes progressively as the sound went deeper. That contrast, read from the blips of the so called A mode, or amplitude mode, display, let him tell a fluid filled cyst from a myoma, the solid growth also called a fibroid.²

Figure

How the flaw detector told a cyst from a solid mass

1. 01
   PulseThe instrument sends a short burst of ultrasound into the specimen, as it would into a weld.
2. 02
   EchoEach boundary the sound meets reflects part of it back to the probe.
3. 03
   BlipsThe returning echoes appear as spikes along a line, their position marking depth.
4. 04
   CystFluid passes sound freely, so echoes appear only from the near and far walls, with a quiet gap between.
5. 05
   Solid massSolid tissue weakens the echoes progressively as the sound goes deeper.

From a shipyard instrument to a contact scanner

Donald came to the problem through war. Born in Cornwall in 1910 to a family of Scottish descent, he studied in Cape Town and then at St Thomas’s Hospital Medical School in London, qualifying in 1937. Hektoen International’s profile records that he served as a medical officer in the Royal Air Force during the Second World War, and that seeing radar and sonar in use led to his interest in technology for diagnosis. His research before Glasgow concerned the breathing of newborns, the subject of a named lecture he gave in 1954, the same year he was appointed to the Regius Chair of Midwifery in Glasgow. He also wrote a textbook of practical obstetric problems that ran to many editions.³

The link to industry came through a patient. According to the Marks and Clerk history, one of Donald’s patients at the Western Infirmary introduced him to a director of a boilermaking firm nearby, a member of her own household; the firm used ultrasound to inspect ship boilers. At a demonstration of the flaw detector, Donald noticed the technicians testing the machine by bouncing its beam off the bones of their own thumbs.² The Naked Scientists date his first visit to 1955 and describe what he brought on later ones: cysts and tumors removed from patients at his hospital, with a large piece of steak as a control for normal muscle. The results were limited but promising.¹

Turning blips into pictures took a team. The Radiopaedia biography records that in 1956 Donald formed a research group with Tom Brown, an engineer from a firm that made navigational instruments, and John MacVicar, a registrar on his unit at the Western Infirmary.⁴ Brown and MacVicar adapted the industrial detector into a contact scanner, its probe held against the body, that built two dimensional images in brightness mode, the ancestor of the pictures familiar today.² Radiopaedia’s survey of ultrasound history adds that in 1956 Donald was already using A mode to measure the diameter of the fetal head, and calls Brown’s compound scanner the turning point in the medical use of ultrasound.⁵

Figure

The 1958 paper

patients examined with the scanner

100

illustrations of gynecologic and obstetric findings

12

pregnancy at which a fetal skull was shown

34 weeks

The work became public in 1958. Donald, MacVicar and Brown published Investigation of abdominal masses by pulsed ultrasound in The Lancet on 7 June 1958.⁶ HistoryofInformation.com summarizes its contents: experience with the scanner in 100 patients and 12 illustrations, among them ovarian cysts, fibroids, a fetal skull at 34 weeks, excess amniotic fluid and twins lying in breech position. The grainy compound images were the first published obstetric or gynecologic sonograms.⁸ Despite the title, the Marks and Clerk account notes, the paper was really about obstetrics and gynecology, and one of its images, a uterus at 14 weeks, is reported to be the first published obstetric sonogram.² Hektoen notes that the paper was met at first with some skepticism, though the Academic Medicine and Surgery history reports that many came to regard it as the most important paper ever written on obstetric and gynecologic sonography.³⁷ The same year a patent application was filed for the contact scanner, and a prototype of that first machine is now displayed at the Hunterian museum in Glasgow. Its later commercial history was clouded by a dispute over earlier American patents on ultrasonic flaw detection, which were argued to cover any probe with something between it and the object being tested.² MacVicar went on to become the founding professor of obstetrics and gynecology at Leicester Medical School.³

What followed

After the paper, Donald saw that sonography could follow fetal growth by measuring the dimensions of the head in the uterus, and within a decade ultrasound had moved into the mainstream.¹ The first production machine was a giant. A history in Academic Medicine and Surgery describes it as eight feet tall, taking up nearly a third of the scanning room and producing static images slowly, with no real grayscale, yet still widely used in Europe for its image quality.⁷ Its American nickname compared it to a dinosaur, and Hektoen records that the first one sold went to Sweden.³

Figure

After Glasgow

1. 01
   1958The first two dimensional scanning machine is built, eight feet tall and filling much of its room.
2. 02
   1962A real time scanner produces fifteen images a second.
3. 03
   1960sTransvaginal scanners are developed, and the scan converter brings grayscale to images.
4. 04
   1984 to 1990Three dimensional imaging is studied, then returns in practical form.
5. 05
   2000Real time scanners with 3D and 4D options become affordable and widely available.

Donald’s own team used the scanner to study early pregnancy, and Radiopaedia credits the work with making pregnancy safer for women around the world.⁴ Others then pushed the technique further. The same history traces a real time scanner producing fifteen images a second in 1962, transvaginal probes from the mid 1960s, grayscale through the scan converter, and the use of ultrasound to locate the placenta, where Donald and a colleague later imaged the placenta in all its positions.⁷ Three dimensional imaging was studied from 1984 and returned in practical form in 1990, and by 2000 real time scanners with 3D and 4D options were affordable and widely available.⁷ The physics behind these advances is explained in how medical ultrasound works, the internal probe in transvaginal ultrasound, and the volume images in 3D and 4D imaging.

Recognition came in his lifetime. Radiopaedia lists the Eardley Holland Gold Medal of the Royal College of Obstetricians and Gynaecologists in 1970, appointment as a Commander of the British Empire in 1973, and honorary fellowships, including one from the British Medical Ultrasound Society in 1984.⁴ Donald died in 1987, and an international society devoted to obstetric and gynecologic ultrasound awards a gold medal in his name each year.³ His own test for a new method was whether it could prove clinically useful without harm, indignity or discomfort, and the lack of side effects is one reason the scan spread so quickly.¹ The scans now offered in pregnancy are shaped by that history, though the decision about any one woman’s scans rests with her and the clinician caring for her.

The habit Donald noticed on his first visit has a modern counterpart. Technicians checked their flaw detector by pressing the probe to their own hands and watching the echo from bone; today a sonographer spreads gel on an abdomen and watches echoes from a fetal skull, using the same pulse, the same echo and the same timing that once looked for cracks in the welds of Glasgow ships.²