Ultrasound of the liver …. CFD
Figure 3
22.11.2011 18:21
8
Gallbladder level as the most caudate scanning plane [video]. GB, gallbladder; LTH, ligamentum teres hepatis; S4, segment IV of the liver (quadrate lobe).
Using these levels as, more or less, parallel scanning sections allows the examiner to visualise a real-time three-dimensional (“4D”) image of the patient’s individual anatomy and pathology. Standardised scanning in a systematic sequence of probe- and patient–positions, and of scanning planes is mandatory to cover all segments and the complete liver surface [see videos]. The patient should be examined from the sub- to the intercostals in the decubitus position as well in the modified, slightly oblique, positions with the right arm above the head and the right leg stretched during all respiration cycles to identify the best approach and to avoid artefacts caused by the thorax. Examination in the standing position is also helpful owing the liver moving caudally with gravity. Scanning from the sub- or intercostal probe positions (depending on the individual anatomy) avoids interposed lung, which can occur in the right posterolateral (superficial) parts of the liver when using the intercostal approach. There are other examination techniques that can also be used, but these will not be mentioned here in detail. There are a number of variations from the norm that will be encountered (e.g. with respect to accessory lobules, vascular branching, shape and configuration). The anatomy and examination technique are explained in the videos available online [www.efsumb.org].