Influence of Spatial Resolution and Compressed SENSE Acceleration Factor on Flow Quantification with 4D Flow MRI at 3 Tesla

Tomography

Franziska Gaidzik¹  Philipp Berg¹  Olav Jansen²  Naomi Larsen²  Mariya S. Pravdivtseva³  Mona Salehi Ravesh³  Patricia Ulloa³  Jan-Bernd Hövener³ 

[1] Department of Fluid Dynamics and Technical Flows, Research Campus STIMULATE, Magdeburg University, 39106 Magdeburg, Germany;Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Kiel University, 24105 Kiel, Germany;Department of Radiology and Neuroradiology, University Medical Center Schleswig-Holstein (UKSH), Section Biomedical Imaging, Molecular Imaging North Competence Center (MOIN CC), Kiel University, 24105 Kiel, Germany;

关键词: intracranial aneurysm;    4D flow MRI;    compressed sensing;    intracranial vessels;    flow;    partial volume effect;   

DOI  :  10.3390/tomography8010038

来源: DOAJ

【 摘 要 】

Four-dimensional (4D) flow MRI allows quantifying flow in blood vessels–non invasively and in vivo. The clinical use of 4D flow MRI in small vessels, however, is hampered by long examination times and limited spatial resolution. Compressed SENSE (CS-SENSE) is a technique that can accelerate 4D flow dramatically. Here, we investigated the effect of spatial resolution and CS acceleration on flow measurements by using 4D flow MRI in small vessels in vitro at 3 T. We compared the flow in silicon tubes (inner diameters of 2, 3, 4, and 5 mm) measured with 4D flow MRI, accelerated with four CS factors (CS = 2.5, 4.5, 6.5, and 13) and three voxel sizes (0.5, 1, and 1.5 mm³) to 2D flow MRI and a flow sensor. Additionally, the velocity field in an aneurysm model acquired with 4D flow MRI was compared to the one simulated with computational fluid dynamics (CFD). A strong correlation was observed between flow sensor, 2D flow MRI, and 4D flow MRI (rho > 0.94). The use of fewer than seven voxels per vessel diameter (nROI) resulted in an overestimation of flow in more than 5% of flow measured with 2D flow MRI. A negative correlation (rho = −0.81) between flow error and nROI were found for CS = 2.5 and 4.5. No statistically significant impact of CS factor on differences in flow rates was observed. However, a trend of increased flow error with increased CS factor was observed. In an aneurysm model, the peak velocity and stagnation zone were detected by CFD and all 4D flow MRI variants. The velocity difference error in the aneurysm sac did not exceed 11% for CS = 4.5 in comparison to CS = 2.5 for all spatial resolutions. Therefore, CS factors from 2.5–4.5 can appear suitable to improve spatial or temporal resolution for accurate quantification of flow rate and velocity. We encourage reporting the number of voxels per vessel diameter to standardize 4D flow MRI protocols.

【 授权许可】

Unknown