ECG Gating Is More Precise Than Peripheral Pulse Gating When Quantifying Spinal CSF Pulsations Using Phase Contrast Cine MRI

Abstract

To compare accuracy of spinal cerebrospinal fluid (CSF) pulsatile flow measurements at cervical, thoracic, and lumbar levels using Phase Contrast Cine MRI (PCCMRI) with retrospective electrocardiogram (recg) vs. retrospective peripheral pulse gating (rppg) gating. We scanned 10 healthy volunteers, ages 23-46 years, using external recg-gated or rppg-gated 2D PCCCMRI at 3T. Transverse scans of CSF, arteries and veins scans were at C1/C4/T1/T7/L1-L3. Data were analyzed with custom Matlab-based software, measuring CSF, arterial (descending aorta, abdominal aorta, common carotid artery, ICA, and vertebral artery) and venous (internal jugular vein and inferior vena cava) flow, velocity and region of interest area. recgPCCMRI produced less quantitative and temporal statistical variation than pcgPCCMRI when analyzing CSF flow. The instantaneous recgPCCMRI CSF flows consistently decreased craniocaudally, while the results with rppgPCCMRI were less consistent. The recgPCCMRI root mean square error values were 6.04, 6.94, 4.81, 4.49, and 4.16 for C1, C4, T1, T7, and L2, compared with 7.24, 8.97, 7.9, 7.82, and 6.68 for rppgPCCMRI. Results were independent of analysts. Summations of standard errors produced similar results. RppgPCCMRI also showed increase variability of CSF flow correlations with arteries and veins compared to recgPCCMRI. None-the-less, when recgPCCMRI is considered the reference standard, there is good correlations between rppgPCCMRI and recgPCCMRIdata sets, when averaged over cohorts of at least five subjects. Our results indicated that recgPCCMRI is more quantitatively and temporally precise than rppgPCCMRI in CSF quantitative flow analysis. Pulse-gating CSF flow results are reasonable when averaged over cohorts of at least five subjects, but subtle conclusions should be interpreted with caution.