DMST 202: Ultrasound Scanning Fundamentals - Liver

Liver Anatomy and Location

• Location:

  • Occupies a major portion of the Right Hypochondrium Region.

  • Superiorly reaches the diaphragm.

  • Bulk of the liver lies under the right costal margin, protected by the ribs.

Patient Preparation

• Fasting:

  • Recommended to reduce abdominal gas for better imaging.

Normal Sonographic Appearance of the Liver

• Characteristics:

  • Appears homogeneous.

  • Typically, a mid-grey organ on ultrasound.

  • Echogenicity: The liver may have the same or slight increase in echogenicity compared to the Right Kidney Cortex.

  • Contouring:

  • Liver contours are smooth.

Detailed Sonographic Appearance

• Parenchyma:

  • Smooth parenchyma interrupted by vessels and ligaments:

  • Hepatic Veins:

    • Anechoic; traced into the Inferior Vena Cava (IVC); walls are less reflective.

  • Portal Veins:

    • Anechoic with hyperechoic fibrous walls.

  • Hepatic Artery:

    • Anechoic; pulsatile, often tortuous.

  • Bile Ducts:

    • Anechoic appearance.

  • Main Lobar Fissure, Ligamentum Teres, and Ligamentum Venosum:

    • Echogenic, with varying brightness (walls not very bright or bright).

Patient Positions for Imaging

• Positions Used for Scanning:

  • Supine.

  • Left Lateral Decubitus (LLD).

  • Left Posterior Oblique (LPO).

  • Right Posterior Oblique (RPO) when scanning the left lobe.

Scanning Windows and Breathing Techniques

• Scanning Windows:

  • Midline (xiphisternal) upper abdomen.

• Breathing Techniques:

  • Deep breath in and hold or normal breathing is preferred during imaging.

Indications for a Liver Sonogram

• Increased liver enzymes.

• Right upper quadrant pain.

• Hepatitis Screen.

• Cirrhosis of the liver.

• Fatty liver disease.

Required Sweeps of the Left Lobe Liver

• Transverse Plane Sweeps:

  1. Starting from the superior portion of the liver to inferiorly, possibly requiring a second sweep for lateral portions.

• Sagittal Plane Sweeps:

  1. Commencing from midline at IVC sweeping out to lateral left lobe, may need a second sweep for the inferior section.

Required Imaging for the Left Lobe of the Liver

• Images Required:

  • Transverse Plane:

  • TRX LIVER LT (at HVs).

  • TRX LIVER LT (at LPV).

  • Sagittal Plane:

  • SAG LIVER LT (at IVC).

  • SAG LIVER LT (at Aorta).

  • SAG LIVER LT (Lateral).

• Required Anatomy to Identify:

  • Left Hepatic Vein (LHV).

  • Middle Hepatic Vein (MHV).

  • Left Portal Vein (LPV).

  • Caudate Lobe.

  • Gastroesophageal (GE) Junction.

  • Ligamentum Teres.

  • Ligamentum Venosum.

Ultrasonography Techniques for Left Lobe Imaging

• Transverse Imaging (TRV):

  • TRX LIVER LT at HVs:

  • Focus on superior portion, demonstrating the right, middle, and left hepatic veins converging towards IVC.

  • Ensure even TGC (Time Gain Compensation) and gains throughout the image for appropriate echo levels.

  • SAG LIVER LT at IVC:

  • Adjust depth to show IVC at the image's posterior 1/3.

  • Image should show diaphragm and focus posteriorly.

  • SAG LIVER LT at Aorta:

  • Similar depth management as with IVC.

  • SAG LIVER LT (Lateral View):

  • Ensure clear view from left of Aorta and appropriate diaphragm display.

Identifying Liver Landmarks

• Key Anatomical Landmarks:

  • Ligamentum Teres: Divides medial and lateral lobes of left liver.

  • Ligamentum Venosum.

  • Caudate lobe.

  • Gastroesophageal junction (often seen in sagittal views).

Scanning Protocol for Liver Imaging

• Professionalism:

  • Introduce yourself as a SAIT student.

  • Confirm the patient’s identity (full name, date of birth).

  • Explain the examination process.

• Ultrasound Machine Setup:

  • Enter patient ID details (student’s ID, name, scanner’s initials).

  • Select the ABD SAIT Preset and use a 5 MHz curvilinear transducer.

• TGC Setup:

  • Apply gel below xiphoid process.

  • Place probe in a sagittal plane and instruct the patient to take a deep breath while holding it for optimal imaging.

  • Adjust angles to visualize IVC posterior to the liver and avoid cutting off organ images.

Sweeping Techniques for Left Lobe of Liver

• Methodology for Sweeping:

  • Sagittal Sweeping:

  • Start at IVC, angle towards lateral left lobe, ensuring images of the entire left lobe are obtained.

  • Conduct at least two interrogations for comprehensive capture.

  • Transverse Sweeping:

  • Begin with midline to visualize diaphragm and then sweep laterally.

  • Include two interrogations for broad imaging.