What is the best imaging modality to assess the spleen?

Best Imaging Modality for Splenic Assessment

Contrast-enhanced CT scan is the gold standard for assessment of the spleen in both adult and pediatric patients. 1

Primary Imaging Options

First-Line Imaging:

• Contrast-enhanced CT scan
  • Gold standard for splenic evaluation 1
  • Provides detailed visualization of splenic parenchyma, vascular structures, and surrounding anatomy
  • Can detect lesions, trauma, infarction, abscesses, and other pathologies with high sensitivity
  • Allows for accurate grading of splenic injuries in trauma cases
  • Total whole-body scanning time may be reduced to less than 30 seconds with modern multi-slice CT (MSCT) scanners 1

Alternative Imaging Options:

• Ultrasonography (US)

  • Less invasive initial screening tool 1
  • Considered first-line in Europe according to ATLS guidelines 1
  • Complete abdominal US may avoid the need for CT in stable patients 1
  • Limitations: operator-dependent, lower sensitivity (50-92%) compared to CT 1
  • Enhanced versions improve diagnostic capability:
    • Doppler US (DUS): Evaluates splenic blood flow
    • Contrast-enhanced US (CEUS): Increases sensitivity for splenic injuries 1

• Magnetic Resonance Imaging (MRI)

  • Useful for problem-solving when CT findings are equivocal 2
  • Advantages: no radiation, free choice of imaging plane, high contrast resolution
  • On T1-weighted images: normal spleen has less signal intensity than liver and slightly greater than muscle
  • On T2-weighted images: spleen shows higher signal intensity than liver 2
  • Particularly useful for characterizing lesions and differentiating between benign and malignant processes

Clinical Decision Algorithm

1. Hemodynamically stable patient with suspected splenic pathology:

   • Proceed directly to contrast-enhanced CT scan (gold standard) 1

2. Hemodynamically unstable patient:

   • Bedside FAST (Focused Assessment with Sonography for Trauma) examination
   • If positive and patient remains unstable: immediate surgical intervention
   • If positive and patient stabilizes: proceed to CT scan when stable 1

3. Low clinical suspicion for splenic trauma or in pediatric patients:

   • Consider starting with complete abdominal US
   • If findings are concerning or equivocal: proceed to CT scan 1

4. Follow-up imaging:

   • For mild injuries or post-treatment assessment: US may be sufficient
   • For complex cases or when complications are suspected: repeat CT scan

Special Considerations

• Pediatric patients: While CT remains the gold standard, consider radiation exposure risks; use low-dose protocols (3-6 mSv instead of 11-24 mSv) 1

• Splenic abscess evaluation: CT and MRI appear to be the best tests, with both sensitivities and specificities ranging from 90% to 95% 1

• Hypodense splenic lesions: CT offers morphological criteria to differentiate these lesions, including border appearance, attenuation, and presence of calcifications or solid components 3

• Splenic tuberculosis: Ultrasonography can be helpful for diagnosis and therapeutic response assessment, but CT may be necessary when extensive intra-abdominal involvement is suspected 4

Common Pitfalls

• Relying solely on FAST examination, which has limited sensitivity (around 66%) 1
• Failing to perform contrast-enhanced CT when indicated, which may miss vascular injuries or active bleeding
• Not considering radiation exposure in pediatric patients or those requiring multiple follow-up studies
• Overlooking the need for specialized imaging techniques (DUS, CEUS) when evaluating splenic vascularization

In conclusion, while ultrasonography serves as a useful initial screening tool, contrast-enhanced CT scan remains the definitive imaging modality for comprehensive splenic assessment due to its superior sensitivity, specificity, and ability to detect various splenic pathologies.