Ultrasound

What is ultrasound?

Is a technology that uses ultrasound in medical imaging and uses sound waves with frequencies greater than 20 kHz, which is greater than the frequencies heard by the human ear.

How the ultrasound works?

The idea of ​​the sonar is based on ultrasonic waves falling on the body and reflected by the sonar probe to the device which calculates the distance between the sensor and the skin layer or organ reflected by the ultrasonic waves using the speed of those waves in the human body, which is 1540 meters / second and using the time required to return Ultrasound of the sensor.

The ultrasound then shows the relationship between the distance and the intensity of the signal reflected from the human body in the form of the image we see on the screen.

Mechanism of ultrasound waves reflection

Hazards of ultrasound

No cases were reported in either humans or animals that underwent ultrasound tests

Ultrasound is a non-radiological diagnostic method which do not use radiation or surgery or the use of radioactive material injected into the patient

Disadvantages of sonar

1-The sonar causes a local temperature rise in the areas exposed to ultrasound as a result of exposure to sound energy resulting from ultrasound, which is easily absorbed in the water in living tissue.

Therefore, Doppler ultrasound should be avoided to hear the fetal pulse in the first three months of pregnancy to avoid exposing the embryo at the stage of development to the risk of this heat.

2-An important disadvantage of the sonar is that it depends on the accuracy of the device used and the purity of the image in addition to that it depends on the skill of the doctor or technician performing the ultrasound scan, and therefore the result may vary from place to place and from person to person depending on the type of device used and the experience of the sonar.

3-Another important disadvantage is that if the doctor doing the sonar finishes the examination and does not examine an area during the imaging, we cannot conclude the information except if we repeated the scan again to examine that area, unlike the radiation films that we can return to it at any time after the completion of the radiation and re-analyze the image and infer the information from any other doctor.

Probe types

The probe used in ultrasound devices is the main part of the device. It produces sound waves and monitors the echo feedback.

These sensors are manufactured to take different shapes and sizes to be used depending on the area to be scanned and each probe emits a different frequency of ultrasound to determine the depth required to penetrate inside the human body to obtain the desired image with high accuracy.

The relation ship between the frequency and wave length

Types of Sonar Examination by Probe Type

Trans-abdominal ultrasound scans:

Trans- abdominal sonar is commonly used in obstetrics and gynecology to detect pregnancy in the second and third trimesters where the fetus has grown to a size that allows us to see the details we want by the abdominal probe.

The abdominal probe penetrates the layers of skin and fat under the skin and then the muscle layer until it reaches the organs to take a picture of the uterus, ovaries and fetus in case of pregnancy.

Trans-abdominal ultrasound scan

Therefore, the abdominal sonar probe uses low-frequency waves so that it can penetrate these layers and therefore as a result of penetration of many layers and low frequency of the waves, it gives a picture with low accuracy than the vaginal probe and so it is better in scanning big things like the fetus more the scanning small organs such as ovaries and uterus in a non-pregnant women

Trans- abdominal ultrasound examination needs a full urinary bladder to enhance the scanning

Trans-vaginal ultrasound scans:

Trans- vaginal sonar is used in the field of gynecology and obstetrics usually to detect pregnancy in the first trimester of pregnancy in addition to the examination of the uterus and ovaries in the non-pregnant woman to identify the causes of pelvic pain or to follow ovulation or to detect any other pelvic pathology.

Trans-vaginal ultrasound scan

Sonar vaginal probe was made to enter the vagina and settle before the cervix ​​closer to the organs to be seen, namely the uterus and ovaries giving a more accurate picture and details.

Due to the proximity of the distance between the probe and the organs to be seen and therefore the few layers required to be penetrated to reach these organs, the vaginal probe uses high-frequency waves, which gives a clearer picture and more accurate details.

Trans-vaginal ultrasound examination needs an empty urinary bladder for the scanning

2D Ultrasound

Two-dimensional sonar devices rely on capturing the image in only two dimensions, the horizontal dimension and the vertical dimension and give the image in black and white, which is the most common devices and it has the ability to diagnose the vast majority of problems and if more accurate details are required 3D sonar can be requested.

2D ultrasound image

If the pregnancy hormone is 6000-6500 mIU / ml and we are not able to see the pregnancy with abdominal sonar or 2000-1500 mIU / ml and we cannot see it with a vaginal sonar, then an ectopic pregnancy should be considered.

When the pregnancy appears in the sonar:

We can see the gestational sac with a abdominal probe  starting from the fifth week of pregnancy when the quantitative hCG has reached 6000-6500 mIU / ml in the blood while we can see the gestational sac with vaginal probe early in pregnancy from the fourth week of pregnancy when the quantitative hCG has reached 2000-1500 mIU / ml in the blood.

Early detection of gestational scan at 5 weeks GA

3D Ultrasound

The idea of this device is to obtain three-dimensional stereoscopic images of the internal organs in the human body or the fetus by passing the sensor over the body to scan for this area and take several images and the computer to create stereoscopic images of them.

3D ultrasound image of the fetal face

This image is fixed and is stored for later analysis by looking at it from more than one angle or plane and changing the axis of vision of the image to reach the desired image in stereoscopic form.

4D Ultrasound

4-D device is only three-dimensional but with real time viewing or the scanned area

4D ultrasound scan

5D Ultrasound

 Is the same devices as 3D and 4D, but with automated analysis of the image taken, so that the machine is sharing with the doctor in the analysis of the image and extract the results from the sonar, where the device to retain the image and then divided into several parts from more than one direction and on more than one axis to give us the image of all directions of detection and then analyzed automatically and extract the required measurements and results as in the examination of the heart of the fetus.

5D ultrasound scan

Doppler Ultrasound

Doppler is actually an ultrasound scan, but different in that it feels the movement of objects and can measure the speed and direction of moving objects.

These devices use Doppler phenomenon and rely on the frequency change between the fallen ultrasonic waves and feedback from moving objects. It is this difference in frequency that can calculate the speed of blood flow to and from the heart and blood vessels throughout the body

The image is colored, and blood appears either red or blue depending on the direction of flow toward or away from the probe. The device provides excellent information in assessing the velocity of blood flow in blood vessels, so it can explain any deficiency in blood supply organs as a result of narrowing vessels or excessive expansion.

Doppler ultrasound

Doppler is used to measure the blood flow of the fetus in the umbilical cord artery, brain arteries (main cerebral artery) and others that reflect the health status of the fetus

Doppler is performed for many reasons, including delayed delivery after the end of the ninth month and in cases of gestational diabetes and in cases of lack of fetal movement.

Outside the medical field, the most common use of Doppler phenomenon is the radar used by the police to detect vehicles exceeding the speed limit.

Doppler examination requires skill and patience from the radiologist, and may take a relatively long time depending on the part to be examined.

Saline Infusion Sonohysterosalpingoraphy

This method is similar in concept to hysterosalpingography (HSG), it depends on doing ultrasound during the injection of normal saline solution into the uterus through the vagina and cervix to be able to see the uterine cavity and whether it has a congenital change such as the uterus with two horns or uterine barrier or contains fibroids or endometrial polyp, as we can also see the fallopian tubes when the saline moves inside it, but not as accurately as the (HSG).

Image of Saline Infusion Sonohysterosalpingoraphy