Author: Ahmed Raza

Liver ultrasound, also called 'liver sonography', is one of the most frequently done exams in diagnostic medical imaging. Because of its non-invasive nature, nevertheless, it has the ability to take real-time images and is used as an initial imaging modality. What is a liver ultrasound? Additionally, liver ultrasound is one of the most frequently performed abdominal examinations and is often the first imaging modality that is employed to assess liver disease. However, to acquire diagnostic images, it is important to know the normal liver anatomy and the important sonographic landmarks. Therefore, here is an easy-to-follow guide to the structure of the liver. Surface anatomy of the liver: The liver is the largest solid organ, and the liver is located in the right upper quadrant (RUQ). However, part of the liver is extended into the epigastric region's left upper quadrant, particularly the left lobe. Moreover, it is located under the diaphragm and covered by ribs. consequently, Most of the liver is hidden behind the rib cage, so during liver ultrasound intercostal Scanning is often necessary. Patient preparation for liver ultrasound: So, patient preparation is essential for taking good-quality images and proper diagnosis. Ideally, to reduce interference from bowel gas, the patient should ideally fast for at least six hours before a liver ultrasound scan. Additionally, greyscale B-mode imaging is used for the evaluation, with Doppler studies added if needed. Patient position for liver ultrasound: Therefore, when performing routine liver ultrasound: The patient should be in the supine position Additionally, the arm raised above the head Alternative positions for liver ultrasound: However, if image quality is compromised, then the following positions may improve image quality: • Left lateral decubitus • Slight left posterior oblique Furthermore, these positions can shift the lever into a better acoustic position; additionally, it helps to reduce bowel gas. Probe Selection A general, Curvilinear Probe (2–5 MHz) is used Ideal for: • for General liver examination • and Deep structures • Most adult patients Alternatively, a phased array probe is used Useful for: • Intercostal windows • Bedside and POCUS examinations Meanwhile, the linear probe (7–12 MHz) can be Useful for: • Superficial lesions • Paediatric imaging • Detailed vascular evaluation Scanning technique: So, for liver ultrasound, follow this: Start with an extensive sweep of the liver to begin with. Next, ask the patient to take deep breaths to completely visualise the superior borders of the liver. Then, using a subcostal approach, look up and down the left lobe in the transverse direction. Afterward, examine the right lobe in the subcostal or intercostal approach. Additionally, carefully roll the patient onto their left side and assess the Rt lobe after checking for fluid. However, during a subcostal approach, the liver may be obscured by bowel gas, and it may be necessary to have the patient distend their abdomen in order to get a better picture. Alternatively, the intercostal approach may be used between the ribs and can also be a good way to ensure good visualisation. Scanning Approach The following guideline should be included in complete liver examinations: Together, they provide the comprehensive evaluation of the liver and surrounding vascular structure. I-Subcostal View: However, this is obtained through placing the probe just below the right ribcage and angling it upward beneath the diaphragm. Best for: Left lobe Portal vein Hepatic veins Porta hepatis ii - Intercostal View: nevertheless, this is obtaining when bowel gas or rib cage block the standard subcostal view; then it provides the best window for visualization of right lobe Additionally, ask the patient to hold their breath; this pushes the liver below the ribcage. As a result, it provides the best image. Therefore, best for: Hepatic dome next, right lobe Additionally, segments VII and VIII. iii – Sagittal Plane: shows the long axis of the liver. Moreover, it shows the relationship of the liver with vascular structures. Therefore, its shows: First, the long axis of the liver Then, inferior vena cava (IVC) Hepatorenal interface iv-Transverse Plane Demonstrates: • First, Portal bifurcation • however , right and left lobes • and Hepatic veins Normal Liver Echotexture If liver is slightly brighter then kidney then look for steatosis ( fatty liver) Therefore, a normal liver shows the following sonographic features: Homogenous parenchymal echogenicity Smooth borders Liver normal size less than 17 cm Liver lobes on ultrasound: The liver is divided into the right lobe, the left lobe and the caudate lobe. However, knowledge of these lobes is of great importance for the correct ultrasound examination and localization of lesions. Therefore, it includes the following: Right lobe: is the largest portion of the liver. however , its includes Segments V, VI, VII and VIII Moreover, we can access the right lobe with an intercostal approach. Left lobe: is located in the epigastric region. However, it contains Segments II, III and IV Moreover, we can access the left lobe with a subxiphoid approach. Caudate lobe In this we can access segment I. Therefore, found anterior to the IVC and posterior to the portal vein. Sonographic landmarks so , identifying sonographic landmarks are essential for accurate diagnosis Portal Vein in Liver Ultrasound: Therefore, the portal vein is the most important landmark Sono-appearances Thick echogenic walls Branches into right and left portal veins Remember: moreover, starry appearances on liver parenchyma Hepatic veins in liver ultrasound: However, hepatic veins consist of the following: Right hepatic vein Middle hepatic vein Left hepatic vein Sono appearances: Therefore, it appears on ultrasound: Thin walls Toward IVC Inferior vena cava: The portal vein and hepatic veins drain into the IVC. Sono appearances Thick walls Presented vertically and with respiration-change caliber Ligamentum Teres however ,it Is remnant of umbilical vein Sono appearance Echogenic band in left lobe It's a landmark for the identifying segment IV Couinaud segments simplified Therefore, the liver is divided into eight segments Segment I In this caudate lobe is present Segment -II and III Left lateral lobe ( left of hepatic vein and falciform ligament ) Segment IV Left medial lobe ( between left and middle hepatic veins ) 4a- superior (above) 4b-inferior (below) Segment V and VIII Right anterior section V is located below and VIII I located above the portal plane between middle and right hepatic veins Memory trick: Clockwise from left lobe II-III-IV-V-VI-VIII Segment VI and VII Right posterior section Normal Measurements StructureNormal SizeLiver length<15–16 cmPortal vein<13 mmCommon bile duct<6 mmIVCVariableHepatic artery<7 mm Frequently asked questions (FAQs) Is liver ultrasound performed for a variety of reasons? It is used to assess fatty liver, cirrhosis, liver enlargement, masses and other liver diseases. Is it necessary to have an ultrasound of the liver before fasting? Yes, it is usually recommended to fast for 6-8 hours to get better images. Is liver ultrasound painful? Not at all, liver ultrasound is safe, painless and non-invasive. Can liver ultrasound be used to detect fatty liver? Yes, fatty liver changes are often detected by ultrasound. On ultrasound, what is the normal size of the liver? The liver is normally about 15–16 cm long in adults. Does Doppler play a role in liver ultrasound? The Doppler can be used to evaluate blood flow in the vessels of the liver.

Author: Ahmed Raza

Liver ultrasound: complete guide from preparation to interpretation

HOW TO BECOME ULTRASOUND TECHNICIAN: COMPLETE GUIDE

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