ABDOMINAL ULTRASOUND IMAGE OPTIMIZATION

abdominal ultrasound image optimization :
Misinterpretation of ultrasound images is a significant risk in ultrasound diagnosis. Because ultrasound
scanning is operator-dependent, it is imperative that the sonographer has proper training in order to
achieve the expected diagnostic capabilities of the technique. The skill of effective scanning lies in the
operators ability to maximize the diagnostic information available and in being able to interpret the
appearances properly.

This is dependent upon:
● Clinical knowledge : knowing what to look for and why, knowing how to interpret the appearances on the image and an understanding of physiological and pathological processes.

● Technical skill : knowing how to obtain the most useful and relevant images, knowledge of artifacts and avoiding the pitfalls of scanning.

● Knowledge of the equipment being used : i.e. making the most of your machine. The operator must use the controls to their best effect. There are numerous ways in which different manufacturers allow us to make compromises during the scanning process in order to improve image quality and enhance diagnostic information.


The quality of the image can be improved by:
● Increasing the frequency : at the expense of poorer penetration.

● Increasing the line density : this may be achieved by reducing the frame rate and/or reducing the
sector angle and/or depth of field.

● Using the focal zones correctly : focus at the level under investigation, or use multiple focal zones at the expense of a decreased frame rate.

● Utilizing different pre- and post-processing options, which may highlight particular areas.

● Using tissue harmonics to reduce artefact. This technique utilizes the second harmonic rather than the fundamental frequency using either filtration or pulse inversion. This results in a higher signal-to-noise ratio which demonstrates particular benefits in many difficult scanning situations, including obese or gassy abdomens. It is far better to have a scan performed properly on a low-tech piece of equipment by a knowledgeable and well-trained operator than to have a poorly performed scan on the latest high-tech machine. A good operator will get the best out of even the lowliest scanning device and produce a result that will promote the correct patient management. A misleading result from a top-of-the-range scanner can be highly damaging and at best delay the correct treatment or at worst promote incorrect management. The operator should know the limitations of the scan in terms of equipment capabilities, operator skills, clinical problems and patient limitations, take those limitations into account and communicate them where necessary.


Making the most of your equipment
● Use the highest frequency possible : try increasing the frequency when examining the pancreas or anterior gallbladder.

● Use the lowest frame rate and highest line density possible. Restless or breathless patients will require a higher frame rate.

● Use the smallest field practicable sections through the liver require a relatively wide sector angle and a large depth of view, but when examining an anterior gallbladder, for example, the field can be greatly reduced, thereby improving the resolution with no loss of frame rate.

● Use the focal zone at relevant correct depth.

● Use tissue harmonic imaging to increase the sgnal to noise ratio and reduce artefact.

● Try different processing curves to highlight subtle abnormalities and increase contrast resolution.