Liver and Spleen Imaging Study Notes

Liver and Spleen Imaging Study Notes

• Liver Location: Located on the right side, beneath the ribs, and directly below the diaphragm.
• Liver Composition: Composed of Kupffer cells (RE cells) and hepatocytes.
• Liver Size: The largest solid organ in the body.
• RE Cell Function: Responsible for phagocytosis, ingesting particulate matter like bacteria.
• RE Cell Distribution: Primarily found in the liver (80%), with smaller amounts in the spleen, bone marrow, and lymph system.
• Liver Blood Supply: Receives oxygenated blood from the hepatic artery and nutrient-rich blood from the hepatic portal vein.

Clinical Indications

• Assessing liver and spleen size, shape, and position.
• Detecting tumors, hematomas, cysts, abscesses, and trauma.
• Evaluating liver diseases like cirrhosis and hepatitis.

Radiopharmaceutical

• Technetium-99m sulfur colloid: Used for liver/spleen imaging.
• Mechanism of Action (MOA): Engulfed by RE cells, distributed uniformly throughout the liver.
• Dose: 10 mCi.
• Route of Administration (ROA): Intravenous (IV).
• Mechanism of Localization (MOL): Phagocytosis

Patient Preparation

• No specific preparation needed.
• Important Patient History: Patient diagnosis, serum bilirubin level, liver enzyme levels (SGOT, SGPT), serum alkaline phosphatase, total serum protein levels (including globulin and albumin), urine bilirubin level, previous abdominal surgery.
• Imaging Priority: Liver/spleen imaging before GI tract studies using barium or contrast agents.
  • Reason: Contrast agents cause artifacts on nuclear medicine images.

Flow Imaging

• Positioning: Patient positioned under camera before tracer administration.
• Purpose: Demonstrates the vascularity of defects visible on static images.

Static Imaging

• Imaging Time: Static imaging begins after 10-15 minutes for tracer localization.
• Standard Views: Anterior, posterior, right lateral, left lateral, right anterior oblique, left anterior oblique, right posterior oblique, and left posterior oblique projections.
• Additional Image: Anterior image with a reference marker along the right costal margin for liver size and location assessment.

SPECT Imaging

• Purpose: To better assess the size, location, and depth of liver and/or spleen abnormalities.
• Benefits: Aids in assessing abnormalities, distinguishing between artifacts and true lesions, and detecting lesions not visible on planar images.

Imaging Findings

• Tc99m-Sulfur Colloid Distribution: Primarily localized in the liver (85%), followed by the spleen (10%), with minimal presence in the bone marrow.
• Liver Location/Variations: Typically situated above the right costal margin, exhibiting diverse shapes, including the enlarged Reidel’s lobe.
• Spleen Location/Visualization: Located in the left upper quadrant above the left costal margin, best visualized on the posterior view due to its posterior positioning.
• Artifact Sources: Heart, right kidney, porta hepatis, and gallbladder can distort the liver’s shape.
• Artifact Differentiation: SPECT imaging or additional planar views can help distinguish artifacts from true defects.
• Liver Displacement Causes: Emphysema, subphrenic abscess, or an enlarged left hepatic lobe can cause liver displacement.
• Tumor/Cyst/Abscess Appearance: Single or multiple areas of decreased or absent tracer uptake.
• Diffuse Liver Disease Appearance: Decreased or uneven tracer distribution throughout the liver.
• Severe Diffuse Liver Disease Appearance: Colloid shift, bone marrow visualization, and increased spleen tracer concentration.

Technical Considerations

• Timing: Imaging too soon after injection of Tc99m-sulfur colloid may result in cardiac blood-pool activity being seen.
• Attenuation Artifacts: Residual barium in the GI tract, particularly in the hepatic and splenic flexures, may appear as artifacts.
• Other Artifacts: Female breast tissue overlying the superior portion of the liver’s right lobe.
• Imaging Priority: Liver/spleen imaging should be performed before radiographic procedures using any contrast.
• Breast Shadow Artifacts: Can be eliminated by positioning the breast out of the way.
• Skin Fold Artifacts: Can be alleviated by imaging obese patients in an upright position.
• Respiration Artifacts: Can be decreased by imaging patients in an upright position.