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Intravascular hematocrit effect in cross-sectional CT imaging
M C Lin1, J V Forrest, R F Mattrey
1Department of Radiology, University of California Medical Center, San Diego.
Journal of Computer Assisted Tomography
|May 1, 1991
Summary
Venous fluid-fluid levels on CT or MR scans can indicate slowly flowing blood, not thrombosis. This finding, confirmed by in vitro studies, helps differentiate between actual clots and normal blood flow patterns.
Area of Science:
- Radiology
- Vascular Imaging
- Medical Diagnostics
Background:
- Venous fluid-fluid levels on computed tomography (CT) and magnetic resonance (MR) imaging can be mistaken for thrombosis.
- Accurate differentiation is crucial for appropriate patient management and treatment.
Observation:
- Three patients presented with venous fluid-fluid levels during evaluation for possible thrombosis.
- Further investigations including ultrasonography, venography, and surgery ruled out thrombosis in all cases.
- CT imaging with intravenous contrast revealed a denser nondependent half compared to the dependent half of the vessel.
Findings:
- An in vitro study using blood with diatrizoate sodium confirmed that non-clotted, settling blood creates a fluid-fluid level visible on CT.
- This level mimics the appearance seen in patients, with a denser upper layer due to contrast medium.
- The observed fluid-fluid level on cross-sectional imaging represents slowly flowing blood, not a thrombus.
Implications:
- Revises the interpretation of venous fluid-fluid levels in diagnostic imaging.
- Reduces the likelihood of misdiagnosis and unnecessary invasive procedures for thrombosis.
- Enhances the diagnostic accuracy of CT and MR imaging in vascular assessments.