What does an ultrasound show better than an x-ray?
X-ray shows bone, ultrasound shows soft tissue. It detects effusion in the joint cavity even in small quantities, thickening of the synovial membrane due to arthritis, bursitis, tendonitis and tendon ruptures, Baker's cyst under the knee. An important advantage is the study in motion: the doctor can ask you to bend or rotate the limb and see how the structures behave under load, which is not possible with MRI. The method is actively used in rheumatology to assess the activity of arthritis and as navigation during intra-articular injections and punctures. Limitation: the internal structures of large joints - menisci, cruciate ligaments - are poorly assessed by ultrasound, here MRI remains the method of choice.
Why ultrasound is the first line method
Ultrasound does not use ionizing radiation, is fast, inexpensive, and provides images in real time. Therefore, it begins with the diagnosis of most diseases of internal organs, thyroid and mammary glands, blood vessels, joints and soft tissues.
A separate advantage is the ability to evaluate not only structure, but also movement: blood flow in the vessels, heart contractions, peristalsis, and fetal movements. Neither CT nor MRI in standard mode show this.
Ultrasound modes
- B-mode - a conventional two-dimensional gray scale image of the organ structure
- Dopplerography - assessment of the speed and direction of blood flow in the vessels
- duplex scanning - a combination of vessel imaging and blood flow analysis
- 4D - volumetric image in real time
What influences the quality of research
Ultrasound does not pass through air and does not pass well through dense bone tissue. Therefore, gases in the intestines interfere with examination of the pancreas, and the lungs and brain of an adult are inaccessible for examination. This explains the preparation requirements: diet and fasting study significantly improve visualization.
The second important factor is the doctor: ultrasound diagnostics largely depends on the experience of the specialist, since the image is assessed at the time of the examination.