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Contrast-enhanced MR angiography of intracranial giant aneurysms
H R Jäger1, H Ellamushi, E A Moore
1Lysholm Radiological Department, The National Hospital for Neurology and Neurosurgery, The Institute of Neurology Queen Square, London.
Background And Purpose:
Intravoxel phase dispersion and flow saturation often prevent adequate depiction of intracranial giant aneurysms on 3D time-of-flight (3D-TOF) MR angiography (MRA). Additional diagnostic difficulties may arise from T1 contamination artifact of an associated blood clot. Our aim was to assess whether contrast-enhanced MRA could improve the evaluation of giant aneurysms and to compare two different types of contrast-enhanced MRA.
Methods:
We studied 11 aneurysms in 10 patients (age range, 31-77 years) with giant aneurysms of the anterior (n = 9) and posterior (n = 2) cerebral circulation by comparing 3D-TOF, first-pass dynamic contrast-enhanced MRA, and steady-state contrast-enhanced 3D-TOF sequences. Additional comparison with digital subtraction angiography (DSA) was performed in eight aneurysms.
Results:
In nine of 11 aneurysms, 3D-TOF did not adequately show the lumen and exiting vessels. Contrast-enhanced 3D-TOF and dynamic contrast-enhanced MRA showed the aneurysm sac and exiting vessels in all of these cases. Dynamic contrast-enhanced MRA showed a better intravascular contrast than did contrast-enhanced 3D-TOF, which led to better delineation of the aneurysms. T1 contamination artifact from intra- or extraluminal blood clot was evident on the 3D-TOF images in four cases. The artifact was less marked on the contrast-enhanced 3D-TOF image and was completely eliminated on the dynamic contrast-enhanced MRA image by subtraction of precontrast images. The diagnostic information provided by dynamic contrast-enhanced MRA was comparable to that provided by DSA.
Conclusion:
Precontrast 3D-TOF is inadequate for the assessment of giant cerebral aneurysms. Both contrast-enhanced 3D-TOF and dynamic contrast-enhanced MRA reliably show the aneurysm sac and connected vessels. Dynamic MRA provides a superior contrast between flow and background and eliminates T1 contamination artifact. It should therefore be considered as the MRA sequence of choice.
Insights
Dynamic contrast-enhanced MRA offers superior imaging of giant cerebral aneurysms compared to 3D-TOF MRA. This advanced technique improves visualization of the aneurysm sac and vessels, overcoming limitations of traditional methods.
Area of Science:
- Neuroradiology
- Medical Imaging
- Vascular Imaging
Background:
- 3D time-of-flight (3D-TOF) MR angiography (MRA) is often limited in depicting intracranial giant aneurysms due to intravoxel phase dispersion and flow saturation.
- Associated blood clots can cause T1 contamination artifact, further complicating diagnosis with 3D-TOF MRA.
Purpose of the Study:
- To evaluate the effectiveness of contrast-enhanced MRA in improving the assessment of giant cerebral aneurysms.
- To compare the performance of two distinct contrast-enhanced MRA techniques against conventional 3D-TOF MRA and digital subtraction angiography (DSA).
Main Methods:
- A study involving 10 patients with 11 giant cerebral aneurysms compared 3D-TOF MRA, first-pass dynamic contrast-enhanced MRA, and steady-state contrast-enhanced 3D-TOF MRA.
- Digital subtraction angiography (DSA) served as a reference standard for eight of the aneurysms.
Main Results:
- 3D-TOF MRA inadequately visualized the lumen and exiting vessels in 9 out of 11 aneurysms.
- Both contrast-enhanced 3D-TOF MRA and dynamic contrast-enhanced MRA successfully depicted the aneurysm sac and vessels in all cases.
- Dynamic contrast-enhanced MRA provided superior intravascular contrast and eliminated T1 contamination artifacts, offering diagnostic information comparable to DSA.
Conclusions:
- Precontrast 3D-TOF MRA is insufficient for evaluating giant cerebral aneurysms.
- Contrast-enhanced MRA techniques reliably visualize aneurysm sacs and connected vessels.
- Dynamic contrast-enhanced MRA is recommended as the preferred MRA sequence due to its enhanced contrast and artifact elimination capabilities.