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MR angiography: noninvasive vascular imaging of the abdomen
J P Laissy1, H Trillaud, P Douek
1Department of Radiology Hôpital Bichat, 46 rue Henri Huchard, 75877 Paris Cedex 18, France.
Abstract:
Magnetic resonance angiography (MRA) has been used to image abdominal vessels less frequently than renal arteries. Until the use of fast contrast-enhanced (CE) techniques, an important limitation was the acquisition time of phase-contrast or time-of-flight imaging and, consequently, the creation of motion artifacts. Recent advances in MRA technology have shortened acquisition times, so it is now possible to obtain successive images in the arterial and then the portal phase. MRA can be used as an adjunct to any MR examination to assess, e.g., the arterial feeding of hepatocellular carcinoma, the encasement of arteries, and segmental portal thrombosis in pancreatic carcinoma. However, MRA has been used mainly to study chronic mesenteric ischemia, portal vein diseases, and complications from liver transplantation. The portal venous system is exquisitely portrayed with this method; MRA is as accurate as digital subtraction angiography (DSA) in the diagnosis of portal vein diseases. Acute mesenteric ischemia is an emergency in which computed tomography is the most appropriate imaging modality. Conversely, chronic mesenteric ischemia is best examined with CE-MRA, which is almost as accurate as DSA. CE-MRA is superior to DSA for the simultaneous exploration of the aorta, renal arteries, and iliac arteries, thereby providing a panoramic view of abdominal vascular involvement. MRA can be coupled with measurements of flow. With this functional approach, MRA is the only modality that can completely assess vascular diseases of the abdomen.
Insights
Magnetic resonance angiography (MRA) now offers fast imaging of abdominal vessels, excelling in diagnosing chronic mesenteric ischemia and portal vein diseases. This advanced technique provides a comprehensive assessment of abdominal vascular conditions.
Area of Science:
- Radiology
- Vascular Imaging
- Medical Technology
Background:
- Magnetic resonance angiography (MRA) was historically underutilized for abdominal vessels compared to renal arteries due to long acquisition times and motion artifacts.
- Advancements in fast contrast-enhanced (CE) techniques have significantly reduced MRA acquisition times, enabling dynamic imaging of arterial and portal phases.
Purpose of the Study:
- To evaluate the efficacy and applications of modern Magnetic Resonance Angiography (MRA) in visualizing abdominal vasculature.
- To compare the diagnostic accuracy of MRA with other imaging modalities for specific vascular conditions.
Main Methods:
- Utilized fast contrast-enhanced Magnetic Resonance Angiography (CE-MRA) techniques.
- Acquired successive images during arterial and portal venous phases.
- Integrated flow measurements for functional vascular assessment.
Main Results:
- CE-MRA is highly accurate for diagnosing portal vein diseases, comparable to digital subtraction angiography (DSA).
- CE-MRA is the preferred modality for examining chronic mesenteric ischemia, nearly as accurate as DSA.
- CE-MRA provides a superior panoramic view of abdominal arteries (aorta, renal, iliac) compared to DSA.
Conclusions:
- Modern CE-MRA is a powerful tool for assessing a wide range of abdominal vascular diseases, including portal vein issues and chronic mesenteric ischemia.
- MRA, especially with functional flow assessment, offers a unique and complete non-invasive evaluation of abdominal vascular health.
- While CT remains crucial for acute mesenteric ischemia, CE-MRA is the optimal choice for chronic conditions and comprehensive abdominal vascular imaging.