Abstract
The present study systemically investigated the influence of gated/non-gated sequences, velocity encoding (VENC), and spatial resolution on blood flow, wall shear stress (WSS), and artery area evaluations when scanning the common carotid artery (CCA) in rats using phase-contrast magnetic resonance imaging (PC-MRI). We first tested whether or not non-gated PC-MRI was appropriate for evaluating blood flow and WSS in rats. For both gated and non-gated techniques, VENC values in the range of 60–120 cm/s with an interval of 10 cm/s were also tested. Second, we optimized the in-plane resolution of PC-MRI for blood flow and WSS measurements. Results showed the usage of a gated instrument can provide more reproducible assessments, whereas VENC had an insignificant influence on all hemodynamic measurements (all P > 0.05). Lower resolutions, such as 0.63 mm, led to significant overestimations in blood flow and artery area quantifications and to an underestimation in WSS measurements (all P < 0.05). However, a higher resolution of 0.16 mm slightly increased measurement variation. As a tradeoff between accuracy and scan time, we propose a gated PC-MRI sequence with a VENC of 120 cm/s and a resolution of 0.21 mm to be used to extract hemodynamic information about rat CCA.
Highlights
Evaluating local flow profiles in vessels is a useful means to assess cardiovascular function and physiopathological conditions[1, 2]
Prior studies have shown that common carotid arteries (CCA) with a relatively low Wall shear stress (WSS) are prone to developing atherosclerosis[8] and are associated with other cerebrovascular diseases[9]
We first showed that the usage of cardiac-gated implementations in phase-contrast magnetic resonance imaging (PC-MRI) can provide more reproducible results; on the other hand, when including ECG gating, the derived blood flow, WSS, and artery area were not affected by the velocity encoding (VENC) settings
Summary
Evaluating local flow profiles in vessels is a useful means to assess cardiovascular function and physiopathological conditions[1, 2]. By using phase shifts in moving spins to quantify the velocity information in flowing vessels, PC-MRI enables the noninvasive assessment of blood rheology[4, 5]. Because it is user-independent and allows straightforward flow quantification, PC-MRI has had an immediate impact on various fields. Prior human studies have revealed that blood flow measurements using the PC-MRI technique were not affected by using electrocardiogram (ECG)-gated implementations[13]. Taking considerable difference in scan duration into account, non-gated PC-MRI has gained increasing popularity in human PC-MRI studies[20,21,22]. Given that accuracy and time efficiency are trade-offs, it is desirable to establish optimized scanning parameters for PC-MRI for the accurate quantification of hemodynamic characteristics in rats
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