Comparison of intracranial 3D-ToF-MRA with and without parallel acquisition techniques at 1.5T and 3.0T

Purpose: To evaluate the performance of four 3D-ToF Magnetic Resonance Angiography (MRA) sequences with and without integrated parallel acquisition techniques (iPAT) at 1.5T and 3.0T in imaging of intracranial vessels.

Method and materials: 7 volunteers and 5 patients (4 aneurysms, 1 AVM) underwent 3D-ToF-MRA at 1.5T (Magnetom Sonata) and 3.0T (Magnetom Trio) with and without parallel acquisition techniques (iPAT) using similarly designed 8-channel phased-array head coils. Imaging time of the pulse sequences was set to 7.15 and 7.35 minutes, respectively. Images were analyzed quantitatively by calculating signal-to-noise (SNR) and contrast-to-noise (CNR) ratios of proximal M2 segments and qualitatively by using a five-point scale.

Results: SNR and CNR were significantly higher for both 3D-ToF sequences at 3.0T compared with pulse sequences at 1.5T. The highest SNR and CNR was obtained at 3.0T without iPAT. However, due to a higher spatial resolution (matrix 512×640) visualization of small vessel details was best at 3.0T with iPAT.

Conclusion: Intracranial 3D-ToF-MRA at 3.0T offers superior image quality compared with 1.5T particular in the delineation of smaller vessels. In contrast to 1.5T, implementation of iPAT at 3.0T is of additional benefit since the high SNR available at 3.0T allows for higher spatial resolution without prolongation of measurement time.