Number 41, May 4, 1999. The newspaper. Caracas Venezuela.
By Leandro Fernandez, MD.
ULTRASOUND: Advanced Technology at the Service of Health
Ultrasound is a type of sound inaudible to the human ear that has been used in medicine for about 40 years, for the exploration of various organs of the body. In all that time it has not been shown that there is any negative effect on the organs or on the fetuses examined by ultrasound.
The ultrasound emitted by a special piece that connects to a computer crosses all the organs and tissues and from them, a part of that sound echoes in the form of echoes. These echoes are collected by the special piece, which is called transducer, which carries the information that is then processed to build an image of the area of the body that the doctor is examining. Since ultrasounds and echoes are used, it is the same to call the ultrasound or echo-sonogram or simply “echo”, as many people call it.
The development of powerful computers that perform millions of operations per second, in turn, allowed the development of what is called ULTRASONOGRAPHY OR ADVANCED ECOGRAPHY. This technology has allowed the detection of images that cannot be visualized with conventional ultrasound equipment, providing new knowledge of the structures and allowing earlier diagnosis, for which the doctor can initiate an earlier treatment.
The leap from analog technology to digital formats allows the execution of special studies in a shorter time and with more precision. To better understand this concept we can compare the purity of the digital image with the coarse sound of vinyl records and the clear sound of compact discs, which use digital technology. With digital systems, the resolution of the sonograms has been further improved and resolution is the ability to detect the minimum distance between two points. Well, with this sophisticated equipment you can see lesions on organs that measure 0.1 mm. , that is, one-tenth of a millimetre. With such resolution, the diagnoses are of a great precision.
SEEING THE ARTERIES
The application of a concept of astronomy pronounced in 1842 by an Austrian scientist named Christian Andreas Doppler, originated the creation of a type of ultrasound that bears his name, the Doppler echo, which allows the visualization of the arteries and veins of the whole organism, even those of the fetus.
Previously, the observation of blood vessels was only possible with cumbersome methods that use iodine contrasts and X-rays. However, with this Doppler echo-sonography technique, alterations, obstructions, thrombosis, etc. can be diagnosed, without reaching the vast majority of patients. cases, to use the so-called invasive methods. Only a small group of patients will have to undergo the tests, depending on the type of disease and the results of Doppler.
The observation of blood vessels often helps to detect alterations that are not seen with conventional echosonograms and that also do not produce abnormalities in laboratory tests. Such is the case of the kidney. In patients with diseases that can potentially affect this organ, such as diabetes, arterial hypertension and some rheumatic diseases, the Doppler echocardiogram of the renal arteries allows the diagnosis of nephropathy, that is, kidney disease, before the exams are modified, allowing the installation of a treatment and thus prevent the progression of the disease.
With this met, od all the arteries of the body can be studied, in the search of atherosclerosis or arteriosclerosis, as it is called by the public. This technique has great value especially in the arteries that are directed towards the brain or towards the legs. In the case of the heart, the Doppler echosonogram does not have the capacity to correctly evaluate the coronary arteries.
It is possible to examine the arteries of the abdomen, ovaries, testes, etc. All organs are susceptible to be evaluated with this wonderful technology.
It is of great importance the observation of the arteries in the cases that suspect the presence of tumors, because the malignant masses tend to have a greater number of blood vessels and their presence can alert the doctor and indicate that his patient may have a tumor of origin malignant, so it will request the prompt realization of a biopsy of the tissue in question.
In men with erection disorders, a special study of the arteries of the penis is performed by injection with a very fine needle, a drug capable of producing a strong erection if the circulation is normal. The measurement of the speed of the passage of blood in these arteries provides an accurate diagnosis if the impotence is of vascular origin or if it is a psychological or hormonal problem.
The study of the arteries of the legs is very important, especially in smokers or diabetics, because these conditions cause frequent obstructions of these vessels. The Doppler echosonogram allows to see the obstruction, locate it, quantify it and thus decide the treatment required by the patient.
VEINS AND VARICOSE VEINS
Not only arteries are studied, but veins can also be analyzed, with the great advantage that in addition to seeing their walls, the passage of blood through them and detecting the presence of clots, we can evaluate their functioning. The veins have small valves inside that prevent the blood that is slowly rising towards the heart, to return to lower levels.
When these valves, which are like small gates, are damaged, they let the blood come back, producing the dilation of the veins below the problem site, thus forming what we know by the name of varicose veins.
Varicose veins can occur in many parts of the body. In the rectum, they are known as hemorrhoids, in the testicles as a varicocele and in the esophagus and legs, simply as varicose veins. All are dilations of the veins and depending on where they are located, they will produce different types of symptoms, but regardless of their location, they can be diagnosed by Doppler ultrasound.
If a patient presents varicose veins problems in the legs, it is essential to carry out an echo-sonographic study with color Doppler technique, because that way you can know if there is a malfunction of the internal valves: if they are normal, you will be It can indicate any type of treatment at the discretion of your doctor, but if your valves are incompetent, the treatments are more limited.
In the case of men with infertility problems, performing a color Doppler scan allows the diagnosis of varicocele and, when operated on, these dilations of the veins restore the correct production of semen.
Patients carrying liver cirrhosis should be evaluated with these novel techniques since the Doppler echosonogram allows the visualization of the circulation of the liver and of a very important vessel called portal vein. In this way, decisions are made for the special treatment of this disease.
TYPES OF ECOSONOGRAMS DOPPLER
Doppler studies are performed as any echosonogram, by applying a gel on the surface of the body that you want to evaluate and then without any pain, you pass the transducer that emits and captures the ultrasound.
There are several types of Doppler echo sounders and they depend on the sophistication of the ultrasound equipment. The most elementary is one called “blind” that is like a pencil that moves in the skin over the veins and allows to hear the passage of circulation, there is another similar one that is used in obstetrics and allows to hear the heartbeat of the fetus.
There is another type called Duplex or White / Black, in which you can see the blood vessel but not the passage of the blood, but it allows you to hear its sound and represent it in graphic form, in order to measure it. The next type is Color Doppler, which allows us to see the blood flows when circulating through the veins or arteries, in addition to performing Doppler Doppler measurements.
Subsequently, a technique called Amplitude Doppler was introduced, through which extremely detailed studies of the vessels and the areas they irrigate are carried out. Our center was the first in Venezuela to practice this type of study in January 1995.
The most recent Doppler is the three-dimensional reconstruction of the images obtained with the Amplitude mode, which we also call Digital Ultrasonic Angiography with three-dimensional reconstruction.
All these exams require a sophisticated computer system within the ultrasound equipment and, of course, a deep training of the medical specialists who perform the study.
THE THIRD DIMENSION IN ULTRASOUND
The conventional ecosonograms are presented in two planes, the doctor is making “cuts” of the organs and with the turn of the hand, the team can make presentations of the image in axes along or across. The current technological breakthrough is the possibility that with a single cut the three planes can be visualized simultaneously: long, wide and deep. This allows the doctor to observe in a truly spatial way, the shape of an organ or a fetus and the alterations that may exist.
Three-dimensional ultrasonography is very useful in locating tumors in different organs, which makes it easier for the surgeon to work, providing accurate information about the injuries before operating the patient. The monitoring of the effectiveness of an oncological treatment is much more precise if ultrasound in the third dimension is used.
In this ultrasound service, research protocols are carried out in cooperation with important international laboratories, research is carried out jointly with our hospitals and an Advanced Ultrasound School was implemented to update ultrasound physicians in these new technologies.
THREE-DIMENSIONAL ULTRASOUND IN OBSTETRICS
The three-dimensional ultrasound is images where the distribution of sound information, obtained by an ultrasonic beam, is done in three spaces.
The method was first described in 1992 and illustrated by sonograms from the hand of an adult immersed in water. It is a product of the research of man in the search for more information and to be able to evaluate, in the case of obstetrics, the fetus from different angles. When we work in two dimensions there are angles, fetal structures, that we can not evaluate or that to study depends on whether the baby moves or changes position to visualize them, or we had to rotate the mother many times to obtain better fields of vision, all this is overcome by three-dimensional ultrasound.
3D ultrasound becomes a new resource, a complement to everything we had already, to more fully evaluate the anatomical structures and in our case the pregnant woman. The most recent development is real-time three-dimensional ultrasound, better known as 4D or live ultrasound, which not only allows us to evaluate the surface and fetal organs but also the baby’s breathing and body movements. This technique is currently only available in the “Vista Alegre” Clinical Ultrasound Unit, which is the pioneer.
When we use 3D ultrasound we can do it transabdominally and also transvaginally or complement the study using one way and then the other. The transvaginal route is ideal to evaluate pregnancies of 14 weeks or less since the transducer makes direct contact with the uterus and does not require urination, this allows us to obtain very clear and larger images, both in 2D and in 3 D and also in 4D.
We can do three dimensions in a pregnancy in three ways:
- We also perform indirect volume visualization, when based and once selected, a frontal plane, coronal or profile of the anatomy, we make tomographic cuts of it, allowing us to evaluate section by section of the structure, and thus determine size and depth of the lesion, if any.
- Reconstruction of surface: When based on the capture of an image in two dimensions, its visualization in three planes, we can process the image, and see it as a reconstructed three-dimensional image, rotate it in different directions and assign color, if we want it.
- Volume reconstruction: It is a three-dimensional image obtained thanks to the software of the computer incorporated into the equipment, which does not require medical processing or very little, and in real time.
In the first trimester, both abdominally and transvaginally, we can observe the embryo, the gestational sac, the activity of the fetus and rule out malformations.
Later in the second trimester and towards the third one, we can appreciate fontanelles and cranial sutures in the fetal head. When evaluating the face, we see the lips, the upper gum, the nose, the eyes, the ears. We must remember that facial defects can be signs of chromosomal defects. The fetal column can be observed in all its extension by reconstruction of surface and volume, discarding anomalies such as scoliosis, kyphosis, lordosis and spina bifida. The fetal thorax, ribs, vertebrae, clavicles, and sternum can be seen. As well as abnormalities of the abdominal wall, omphalocele and gastroschisis, confirm the suspicion of the multicystic kidney or the absence of a kidney. The defects in the area of the extremities are more clearly identified, foot equinovarus, foot in seesaw, the absence of a limb or segment of the same multiple fingers or absence thereof. Also, alterations in the formation of the genitals can be observed.
LIMITATIONS OF THREE-DIMENSIONAL ULTRASOUND
- Distorted images are obtained if the fetus or the mother moves during the acquisition of the data. Maternal hyperventilation, very common in pregnant women, is a limiting factor.
- The presence of the hands, legs or umbilical cord on the face or genitals, prevents its visualization.
- The quality of the reconstructed image depends on the volume of amniotic fluid at the time of the study.
- Maternal obesity is also a limiting factor, both for 2D and 3D ultrasound.
PSYCHOLOGICAL IMPACT OF THE THREE-DIMENSIONAL FETAL IMAGE
3D ultrasound provides a more realistic picture of the fetus in utero, this may offer the opportunity for a different conception of the fetus and subsequently a closer mother and child relationship. Decreases levels of anxiety and in particular maternal or family anguish.