High-resolution intracranial and cervical MRA at 3.0T: technical considerations and initial experience

Area of Science:

• Radiology
• Medical Imaging
• Magnetic Resonance Imaging

Background:

• Magnetic Resonance Angiography (MRA) is crucial for visualizing blood vessels.
• Higher magnetic field strengths (3.0T) potentially offer improved signal-to-noise ratio (S/N) over standard 1.5T systems.
• Assessing the feasibility and efficacy of 3.0T MRA for intracranial and cervical vasculature is important.

Purpose of the Study:

• To evaluate the initial experience and performance of intracranial and cervical MRA at 3.0T.
• To compare 3.0T MRA techniques with existing 1.5T protocols.
• To assess the feasibility and image quality of contrast-enhanced MRA (CEMRA) at 3.0T.

Main Methods:

• Phantom measurements were conducted to quantify S/N differences between 1.5T and 3.0T.
• A 3.0T 3D Time-of-Flight (3DTOF) intracranial imaging protocol with advanced autoshimming was developed and compared to 1.5T in 12 patients.
• Cervical and intracranial CEMRA at 3.0T was examined in eight patients, with two having prior 1.5T studies for direct comparison.

Main Results:

• Phantom studies showed a significant S/N increase (2.14x) at 3.0T compared to 1.5T.
• Radiologist comparison revealed 3.0T 3DTOF MRA was significantly better (P < 0.001) for aneurysm visualization.
• 3.0T CEMRA achieved high spatial resolution (0.62-0.73 mm³) enabling visualization of aneurysms, dissections, and atherosclerotic disease; signal loss from T(*)(2) dephasing was comparable to 1.5T.

Conclusions:

• 3.0T MRA demonstrates superior performance for intracranial aneurysm visualization compared to 1.5T.
• 3.0T is a feasible and favorable field strength for cervical CEMRA, offering high-resolution imaging.
• While potential drawbacks like increased SAR exist, 3.0T MRA provides valuable diagnostic information with manageable technical challenges.