Can An Ultrasound Detect Cancer
In many ways, ultrasound is like X-ray photography — you shine a beam of sound waves onto a person’s skin, which reflects back into the machine where the echoes get recorded on film. But unlike an X-ray image, which is basically just a picture, ultrasound has a lot more information than that. For example, if there was something wrong with your heart muscle, ultrasound would let you know by showing thickening or even holes in the lining of your chambers.
You might think that this kind of imaging technology would have been developed long ago, but ultrasound actually dates back only about 100 years. The first human studies were conducted in 1924 by German physicist Fritz Haber, who wanted to measure blood flow in arteries. Today, we still rely heavily on ultrasound for prenatal tests and other kinds of diagnostic testing. One common type is called “transvaginal” ultrasound, meaning that doctors can insert a transducer — essentially a handheld wand — directly inside a woman’s vagina to take pictures of her uterus. And another kind of ultrasound uses high-energy sound waves, such as those produced by a piezoelectric crystal, to send out beams that bounce off bones rather than skin. This technique, known as sonography, is used to examine internal organs, muscles, tendons, ligaments, nerves and blood vessels.
So how does it work? Sound waves, when they’re focused, cause particles within any medium — including liquids, gases and tissues — to vibrate rapidly. When these waves hit an object, they reflect back, creating their own wave pattern. By measuring the time between the original sound wave striking the surface and the reflected one returning, scientists can calculate the speed of the sound waves. They can also determine the size of objects based on how long it takes the sound waves to pass through them. That’s why ultrasounds can sometimes look like blurry black-and-white photos instead of crisp color ones.
With all of this power comes responsibility. Ultrasound machines emit radiofrequency energy, so they must comply with safety guidelines set forth by the U.S. Food and Drug Administration. As of 2012, there were no reported cases of anyone dying during an examination, but it’s important to note that you should never lie down for an ultrasound test. If you do, the technician may need to put you on a stretcher or wheeled platform while he or she conducts the exam. You could receive a burn from the ultrasound probe, too, since it gets very hot.
Another thing to keep in mind is that the FDA recommends against having an abortion right before an ultrasound test, since the procedure puts pressure on the unborn baby, causing it to move around. Afterward, however, women are free to resume normal activities.
But what exactly happens during a typical ultrasound test? Next, we’ll learn how an ultrasound works.
How Do Sonograms Work?
An ultrasound isn’t just sound; it’s sound coupled with light. A small hand-held device called an ultrasound probe emits high-pitched tone bursts that travel through the patient’s body until they reach the outer layer of the skin, which then converts them into low-energy sound waves. These waves eventually return to the probe, which picks up the signal generated by the sound waves hitting the inner layers of skin. In order to create an image, technicians will adjust the gain controls on the ultrasound equipment. Gain refers to the amount of amplification needed for the signals picked up by the probe. High gain allows for better detail, whereas lower gains improve resolution without sacrificing quality. Then, the operator can choose to display either gray scale or color images. Gray scale displays the intensity levels of each pixel individually. Color displays combine red, green and blue pixels into specific colors, allowing for greater contrast and color differentiation. Technicians can also add special effects, such as blurring, sharpness and brightness adjustments.
Sonographers typically perform two types of examinations: B-mode and Doppler. With B-mode exams, they can produce cross-sectional views of various structures, such as the liver, kidneys and gallbladder. They can also monitor fetal development by viewing the movements of amniotic fluid within the fetus’ sac. Doppler exams allow them to study bloodflow within both living organisms and surrounding areas. Bloodflow can help diagnose certain conditions, such as stroke, blockages in blood vessels, infections and tumors. Doctors can see how fast blood flows by comparing the rate at which the blood moves toward the ultrasound probe versus its ability to do so naturally. Another method is to compare the velocity of blood moving within a vessel to the velocity of blood flowing past a fixed point outside the area being examined [source NIH].
When using Doppler techniques, sonographers can find the pulse waveform of a pulsating structure, such as the carotid artery. From here, they can deduce the average velocity of blood passing through the vessel over a given period. They can also estimate the resistance index and pulsatility index, which are related to the elasticity of blood. Resistance indexes represent the ratio of systolic peak velocity divided by diastolic peak velocity. Pulsatility indices indicate the width of the arterial peaks and valleys relative to total duration. Finally, a Doppler scan can reveal the direction of blood flow as it leaves the heart and enters smaller arteries.
Although ultrasound is helpful in diagnosing medical problems, it can’t always detect abnormalities. We’ll talk about what makes an abnormal result next.
What Are Abnormal Results On An Ultrasound Scan?
Sometimes ultrasound produces inconclusive results, especially when looking at fetuses. There are several reasons why this may happen. Ultrasound creates an outline of the fetus based on the measurements made when it sends out sound waves. If the fetus’ shape changes after that, the software adjusts accordingly. However, sometimes a change occurs within the fetus itself, such as when it stops growing. Or perhaps the mother gained weight after giving birth, making the fetus appear bigger. In addition, the distance between the ultrasound probe and the fetus affects the accuracy of the measurement. To compensate for these factors, technicians must use multiple measurements to create a three-dimensional model. Sometimes they can’t account for every factor, leading to inaccurate estimates of gestational age.
There are also times when ultrasound fails to pick up anything at all. In these instances, a biophysical profile can provide additional data. A biophysical profile measures fetal movement and responses to stimuli, along with blood volume and pH levels. While the ultrasound won’t identify a problem, it can give clues to a condition. For instance, it can indicate fetal distress caused by placental insufficiency or uterine contractions.
The next step is figuring out how to proceed with whatever condition you’ve detected. How are you going to treat it? What treatments exist, and which ones should you try first? Read on to learn about treatment options available through ultrasound technologies.
Treatment Options Through Ultrasound Technologies
Ultrasound can play an integral role in providing patients with alternative methods of care. For example, in 1996, researchers discovered evidence of malignant brain tumors in a fetus via ultrasound. Subsequent investigations revealed that the child had a genetic abnormality that led to leukemia. This discovery allowed doctors to administer chemotherapy drugs specifically tailored to the child’s needs. The child lived for 11 months after his diagnosis.
Other examples of alternative forms of therapy include hyperthermia, which involves raising temperatures above normal limits, and cryotherapy, which freezes cells to destroy them. Both techniques employ heat and cold elements respectively, which are created by magnetic fields. Magnetic resonance thermal therapy relies on strong magnets to generate heat, while magnetic particle therapy utilizes iron oxide nanoparticles to kill cancerous cells. Although promising, these therapies haven’t yet become widely accepted due to the difficulty involved in finding proper subjects and ensuring consistent treatment regimens.
Most importantly, ultrasonic frequencies aren’t harmful to humans. Because of this, patients undergoing therapy often feel little discomfort. Some practitioners believe that ultrasound therapy may benefit patients suffering from arthritis and rheumatism. The key word here is carefully. Too much exposure to ultrasound can lead to burns, so patients shouldn’t lay on their backs for extended periods of time. Also, be sure to consult your doctor before trying to self-medicate with ultrasound therapy.
Despite the many benefits associated with ultrasound, it certainly has limitations. Find out what they are on the next page.
Limitations Of Diagnostic Imaging Technology
While ultrasound offers great advantages over other imaging technologies, it has its shortcomings. First, ultrasound can only penetrate through softer materials, such as fleshy tissue or water. Bone, however, is opaque and therefore impossible to view with ultrasound. This means that doctors can’t conduct a full physical examination of a patient’s skeleton. Second, ultrasound waves are unable to travel through space. Therefore, patients who live far away from hospitals or clinics are likely to miss out on necessary diagnoses and treatments. Third, ultrasound has difficulty penetrating hard surfaces, such as cartilage, bony plates, metal implants and plastics.
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