Scanning Planes

Scanning Planes in Liver Ultrasound

In liver ultrasound imaging, different scanning planes are used to comprehensively evaluate the liver's anatomy, vasculature, and any pathological changes. Here’s a concise overview of the scanning planes in liver ultrasound:
1. Transverse (Axial) Plane

• Orientation: The transducer is placed horizontally across the upper abdomen.
• View:Cross-sectional view of the liver.
• Structures Visualized:
• Right and left lobes of the liver.
• Portal vein in its transverse section ("Mickey Mouse sign").
• Gallbladder (if included).
• Inferior vena cava (IVC).

2. Sagittal (Longitudinal) Plane

• Orientation:The transducer is oriented vertically along the midline or right upper quadrant.
• View: Longitudinal view of the liver.
• Structures Visualized:
• Liver span (craniocaudal length).
• Relationship to the kidney (e.g., "liver-kidney interface").
• IVC in longitudinal section.

3. Subcostal Plane

• Orientation:Transducer is angled upward under the costal margin.
• Use:Often used in deep inspiration to improve liver visualization by moving the liver below the rib cage.
• Structures Visualized:
• Anterior liver segments.
• Hepatic veins and diaphragm.

4. Intercostal Plane

• Orientation:Transducer is placed between the ribs in the right upper quadrant.
• Use:Helps avoid rib shadows.
• Structures Visualized:
• Superior liver segments.
• Diaphragmatic surface.
• Right hepatic lobe.

5. Coronal Plane

• Orientation: Transducer placed in the mid or anterior axillary line, scanning vertically.
• View: Vertical slice from side to side.
• Structures Visualized:
• Lateral and medial segments.
• Hepatic veins draining into the IVC.

6. Oblique Planes

• Orientation:Angled transducer positioning tailored to follow vascular pathways or segmental anatomy.
• Use:For targeted views of:
• Portal vein bifurcation.
• Hepatic veins.
• Lesions.

Key Tips for Liver Ultrasound Scanning

• Patient Position:Supine, left lateral decubitus, or upright to optimize visualization.
• Breathing Technique: Deep inspiration enhances liver window by displacing the liver downward.
• Acoustic Window:Use the right kidney or full bladder (if scanning caudally) as acoustic windows.

Technical Assessment: Liver Ultrasound

Technical Assessment: Liver Ultrasound

A technical assessment for liver ultrasound involves evaluating the image quality, anatomical coverage, and sonographic technique to ensure accurate diagnosis and documentation. This is typically done by the sonographer or radiologist and is often included in structured reporting.

1. Study Type

• Complete abdominal ultrasound
• Focused liver ultrasound
• Follow-up / Targeted liver exam
• Doppler liver ultrasound

2. Image Quality

• Adequate / Good / Suboptimal
• Acoustic window: Clear / Limited (due to bowel gas, body habitus, or motion artifact)
• Liver parenchyma: Well visualized / Poorly visualized

3. Structures Evaluated

• Liver size and contour
• Liver echotexture (homogeneous/heterogeneous, fatty infiltration, cirrhotic changes)
• Intrahepatic bile ducts (normal/dilated)
• Hepatic vessels (portal veins, hepatic veins, IVC)
• Gallbladder and biliary tree
• Focal liver lesions (if any)
• Right kidney and Morrison’s pouch (for reference)

4. Doppler Assessment (if performed)

• Hepatic artery and portal vein flow direction and velocity
• Hepatic venous waveform
• Portal hypertension signs (e.g., collaterals, reversed flow)

Transducer Selection

1. Transducer Types

• Curved Array Transducer (2–5 MHz): Primary probe for abdominal imaging; deep penetration with wide field of view.
• Linear Array Transducer (5–12 MHz): For superficial lesions or guiding interventional procedures.
• Phased Array Transducer: Used in intercostal views or in critically ill patients.

2. Imaging Modes Utilized

• 2D Grayscale Imaging: Standard for liver anatomy and pathology.
• Color Doppler Imaging: For portal vein, hepatic veins, hepatic artery.
• Spectral Doppler: Waveform analysis of hepatic vessels.
• Elastography: Liver stiffness in fibrosis (kPa or m/s values).
• Contrast-Enhanced Ultrasound (CEUS): Lesion characterization using microbubbles and low MI settings.

3. Machine Settings and Optimization

• Depth and Gain: Full liver visualization with proper contrast; TGC for uniform brightness.
• Focal Zones: Placed at/just below region of interest.
• Dynamic Range: Tuned for contrast resolution.
• Harmonic Imaging: Enhances detection, reduces artifacts.

Doppler Settings

• Minimized color box size and correct angle.
• PRF set for flow velocities.
• Low wall filters for slow flow.
• Angle correction < 60°.

Elastography Calibration

• Right lobe, intercostal view, during breath-hold avoiding vessels.

CEUS Optimization

• Low MI (0.08–0.2), real-time dual view, high frame rate.

Ultrasound Transducer Types

Type	Frequency (MHz)	Use
Curvilinear (Convex)	2–5 MHz	Standard abdominal imaging
Linear Array	5–12 MHz	Superficial structures, pediatrics, thin patients
Phased Array	2–4 MHz	Intercostal/limited windows

Ultrasound Imaging Modes

Mode	Purpose
B-mode	Liver parenchyma, contour, lesion visualization
Color Doppler	Hepatic vessel blood flow assessment
Spectral Doppler	Flow direction and velocity measurement
Power Doppler	Detect low-velocity flow (e.g., portal HTN)
Elastography	Liver stiffness assessment
CEUS	Lesion characterization (requires contrast)

Machine Settings and Optimization Summary

• Depth: Full posterior segment visibility.
• Gain: Balanced brightness.
• TGC: Uniform field brightness.
• Focus: Just below the area of interest.
• Dynamic Range: Medium setting preferred.
• Frame Rate: High for motion and Doppler analysis.

Additional Tips

• Fasting 6–8 hours improves view.
• Use ample gel.
• Reposition patient for better acoustic windows.