Evaluation of the relationship between pulmonary artery volume and quantitative voxel based flow parameters in patients with and without pulmonary hypertension using 4D flow MRI

Abstract Purpose Four-dimensional (4D) magnetic resonance imaging (MRI) is used to determine abnormal blood flow in patients with pulmonary hypertension (PH), but the relationship between abnormal blood flow and pulmonary artery volume is unclear. This study aimed to quantify pulmonary artery volume and flow parameters using 4D flow MRI, and to evaluate their relationship in patients with PH and in those without PH. Methods We retrospectively studied 177 patients at our institution who underwent cardiac contrast-enhanced MRI to investigate cardiomyopathy or cardiac dysfunction. The patients were divided into the non-PH group (n = 162) with systolic pulmonary artery pressure 40 mmHg. We performed 4D flow MRI to quantitively assess volume, energy loss (EL), vorticity (Vor), and helicity (Hel) in the pulmonary artery. Results Pulmonary artery volume, EL average, Vor average, Hel right screw average, and Hel left screw average were significantly lower in the non-PH group than in the PH group (all p < 0.05). The pulmonary artery volume was significantly correlated with EL average (R = 0.4140, p < 0.0001), Vor average (R = 0.7561, p < 0.0001), and Hel right and left screw averages in the non-PH group (R = 0.5105, p < 0.0001; R = −0.5349, p < 0.0001, respectively). The pulmonary artery volume was significantly correlated with Vor average in the PH group (R= 0.6152, p = 0.0146). However, the pulmonary artery volume was not correlated with EL average or Hel right and left screw averages in the PH group. Conclusion EL and Hel may reflect PH in voxel-based evaluation of blood flow in the pulmonary artery.