Ultrasonography

It is the BEST eye and ear of the BEST Radiologist and Interventional Radiologist. Because; “The doctor who diagnoses with the least damage, in the MOST economical way, in the shortest time is the best physician”

What is ultrasonography and how does it work?

It uses sound waves. Ultrasonic sounds, which are so high that the human ear cannot hear, are used. These sounds are in the 2 – 20 Megahertz (MHz) band. Sound is produced by the vibration of objects. In order to obtain such high vibration, the PIEZO-ELECTRIC phenomenon is used. This phenomenon is that some crystals such as Quartz expand and contract when electrical energy is supplied, vibrating and thus creating sound, and converting the sound that comes to them into electrical energy with the same method.

In this way, energy converting materials are called TRANSDUCERS. Ceramic discs are used as transducers in ultrasonography devices. The head carrying the transducer is called PROBE. As sound passes through the material, its intensity (ie density) decreases due to absorption and reflection. The absorption coefficient of water is very low, while bone is high. Therefore, sound passes through liquids without attenuation. The greater the difference between the tissues in the direction of propagation of the sound, the greater the reflection will be.

Due to the physical rules in ultrasonography, the following are important:

Structures inside or behind liquids are better studied. So liquids transmit sound very well. For this reason, it is desirable to have a full bladder in the examination of the uterus and ovaries in women. The full bladder acts as a very good acoustic window (sound transmission window) for the organs behind it.

Intestinal gases prevent the structures behind them from being seen. Because no sound can pass behind the air. Therefore, imaging of intra-abdominal organs is difficult in patients with excess intestinal gases.

Not enough sound passes behind the bone and calcification (eg stones). Therefore, it is not possible to examine organs covered with bone.

HOW IS ULTRASONOGRAPHIC EXAMINATION DONE?

The patient is placed on the table. Gel is applied to the area to be examined. If the uterus and ovaries or adjacent organs are to be examined, the bladder should be full. A probe with a frequency and shape suitable for the depth of the organ and tissue to be examined is selected. Superficial structures are examined with high frequency probes (8-14 MHz). Deep structures are examined with low frequency probes (3.5 MHz). LINEAR (flat-ended) and high-frequency transducer-bearing probes are selected for surface examinations. Convex shaped and lower frequency transfers are preferred when examining deep structures such as intra-abdominal organs. The probe should be thought of as a blade that cuts across the length and width of its surface.

If there is no obstacle at the entrance door (such as gas or bone), it can be cross-sectioned from any desired angle. Anatomy must be known very well. Sections are formed according to the plane of the probe’s mouth and the inclination of the probe. Therefore, US images can only be interpreted if the position, position, plane and tilt of the probe during examination are known. Ultrasonography is an imaging method that is very dependent on the experience of the user. That’s why experience is so important.

The ultrasound image is live (real-time). The sectioned area is monitored live on the monitor and the sonographic diagnosis is made during the examination. For example, in the examination of the upper abdomen, the lowering of the liver with respiration or the pulsation of the great vessels can be observed. When desired, the image can be frozen and the picture can be taken.

WHAT ARE ULTRASONOGRAPHIC EXAMINATION METHODS?

There are two basic methods.

GRAY SCALE ULTRASONOGRAPHY (US)

COLOR DOPPLER ULTRASONOGRAPHY (RDUS)

In gray scale ultrasonography; Images are composed of shades of gray between black and white. In order to obtain a good image, it is necessary to get as close as possible to the tissue to be examined. Based on this idea, endosonography and intraoperative applications were developed. In endosonography, a transducer is placed on the endoscope tip.

The structures adjacent to the stomach and duodenum (pancreas, biliary tract, etc.) are examined with the transducer at the end of the endoscopy. With transvaginal probes, the uterus and ovaries are displayed in detail. The prostate gland is examined with transrectal probes and a biopsy can be performed if necessary. With intraoperative US, the borders of tumors can be determined very well during surgery.

Color Doppler Ultrasonography; It is based on determining the direction and speed of blood flow in the vessels. Vascular stenosis is examined. The blood flow velocity in the vein can be measured. Although high-frequency sound is used in Doppler US, the frequency change in the rotating sound is within the limits of what the ear can hear. The ear is the most sensitive sound separator. An experienced radiologist can have enough information about the quality and quantity of the flow by listening to this sound.

How are images interpreted in ultrasonography?

The regions in the images where echoes are intense are defined as HYPERECOIC (white), the regions where they are low are HYPOECHOIC (dark gray-black), and the regions where they are absent are defined as ANECHOCIC (black). Those with equal echogenicity are called ISOECOIC lesions. Identification of ECOGEN for hyperechoic lesions can also be used.

Fluid-filled cystic structures are well-known. In addition, stones in the gallbladder, biliary tract, kidney and urinary tract can be visualized very well. In ultrasonography; Pathologies such as tumors, nodules and masses in all soft tissues except air, gas and bone structures can be visualized very well.

WHAT ARE THE STRENGTHS AND WEAKNESSES OF ULTRASONOGRAPHY?

Strengths:

No ionizing beam is used. It has no known harmful effects. Therefore, it is the first and basic diagnostic method in pregnant women and children.

Since ultrasonography devices are portable, bedside examination can be performed. With this feature, it is very valuable in intensive care units.

Ultrasonography devices are relatively inexpensive and examination is simple for experienced users. No discomfort is given to the patient during the examination.

Weaknesses:

Diagnosis is very dependent on the level of knowledge and skill of the examiner.

Normal lungs filled with air cannot be visualized. Intestinal gases also interfere with examination.

Intracranial structures cannot be visualized in adults because the sound cannot sufficiently pass through the thick skull bones.

WHAT IS THE PLACE OF ULTRASONOGRAPHY IN THE DIAGNOSIS OF DISEASES?

Ultrasonography is a soft tissue examination method.

Obstetrics and Gynecology: The fetus in a large water-filled sac is very suitable for ultrasound examination. The fact that it has no harmful effects has made US the main diagnostic method in pregnancy. Ultrasonography is the first and basic method in the examination of the uterus and ovaries.

Parenchymal organs: Liver, pancreas, spleen and kidney are well examined by US. Gallbladder and bladder, which are natural water-filled structures, are also very suitable structures for US examination.

Superficial structures: They are examined with a high-frequency, flat-tipped linear probe. Thyroid, parathyroid, salivary glands, eyeball, lymph nodes, breast, rotator cuff tears in the shoulder, congenital hip dislocations, soft tissue lesions, testis can be displayed in detail. The prostate is examined with a transrectal probe and a biopsy is performed if cancer is suspected.

Gaseous organs: The presence of gas limits the application of ultrasonography to the lung and digestive tract. However, formations that rest on the chest wall can be examined very well with US. Similarly, it is possible to detect the pleural fluid surrounding the lung.

Intestinal segments can be visualized with US. Enlarged bowel segments due to disease, cancer or inflammation (eg appendicitis) can be detected by US.

Baby brain: In babies with open fontanelle, the brain is perfectly visualized (transfontanel US). Since the bones are not calcified in babies up to one year old, the spinal cord can also be examined.

Color Doppler US: The presence, direction and velocity of the current in the vessels are determined. The degree of vascular stenosis can be determined by looking at the velocity and shape of the flow. In addition, vascularization of the masses can be evaluated.

WHAT ARE THE TYPES OF ULTRASONOGRAPHIC EXAMINATION?

GRAY SCALE US REVIEWS

Abdominopelvic (entire abdomen)

Transvaginal gynecological

obstetrics

superficial structures

Thyroid

Breast

scrotal

Musculoskeletal

muscle lesions

Neonatal DCT – Newborn hip dislocation screening

Achilles tendon

Shoulder

Wrist US in CTS – Carpal Tunnel Syndrome

Transfontanel Cranial US in Newborns

COLOR DOPPLER US REVIEWS (RDUS)

renal

Portal system

scrotal

Transvaginal gynecological

obstetrics

ophthalmic

Carotid-vertebral artery

Peripheral vascular studies

Lower Extremity Arterial

Lower Extremity Venous

Upper Extremity Arterial

Upper Extremity Venous

penile

Exception investigations

Evaluation of Hemodialysis Shunts

Evaluation of Arterial Pediculated Autografts

Femoral pseudoaneurysm treatment (with Color Doppler US)

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