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[MRI of the normal portal system: the artefacts. Apropos of 45 cases]
C Davy-Miallou1, C Guinet, M F Bellin
1C.H.U. Pitié, Service de Radiologie Centrale, Paris.
Abstract:
The protal system of 45 normal patients have been retrospectively studied on spin echo MRI sequences (interleaved cuts): multiple artifacts have been evaluated and 24% of them were visualized at the portal system level. Thus, partial volume effect responsible for almost 25% of the artifacts is not always easily seen on a single sequence. Respiratory and aortic artifacts can deteriorate the visualization of the vascular lumen but cannot be confused with a thrombosis. Well-known artifacts, as slice entry phenomenon and even echo rephasing, represent more than 60% of the artifacts: they are readily recognized when they are typical and indicate flowing blood. On the contrary, an other artifact, representing less than 5% of the total and seen at the level of the left portal vein, simulates a thrombus, on T2 weighed images. We conclude that the frequency and polymorphism of the artifacts are limiting factors of MRI value in the diagnosis of portal vein thrombosis.
Insights
Magnetic Resonance Imaging (MRI) artifacts frequently appear in the portal system, potentially mimicking portal vein thrombosis. Understanding these common MRI artifacts is crucial for accurate diagnosis.
Area of Science:
- Radiology
- Medical Imaging
- Vascular Imaging
Context:
- Retrospective study of 45 normal patients' portal systems using spin echo MRI sequences.
- Evaluation of artifact frequency and types within the portal venous system.
- Focus on artifacts that can impact the diagnosis of portal vein thrombosis.
Purpose:
- To assess the prevalence and characteristics of artifacts in the portal venous system on MRI.
- To determine the impact of these artifacts on the diagnostic accuracy of portal vein thrombosis.
- To differentiate artifacts from actual thrombi in portal vein imaging.
Summary:
- Multiple artifacts were identified in 24% of portal system MRI scans.
- Partial volume effect accounted for nearly 25% of artifacts, often subtle on single sequences.
- Common artifacts like slice entry and echo rephasing (over 60%) are recognizable, while a rare artifact (<5%) can mimic portal vein thrombosis on T2-weighted images.
Impact:
- Artifacts are significant limiting factors in diagnosing portal vein thrombosis using MRI.
- Awareness of artifact polymorphism is essential for radiologists interpreting portal venous studies.
- Improved artifact recognition can enhance the reliability of MRI in vascular diagnoses.