Phase-contrast MRI for Detection of Mild Systemic Hemodynamic Response after Segmental Allergen Challenge in Asthmatic Patients

Abstract

Detection of a systemic hemodynamic response in patients suffering from allergic asthma after segmental endobronchial allergen challenge using phase-contrast magnetic resonance imaging (MRI). Nine asthma patients and four healthy volunteers were examined using MRI (1.5T) before (0 hour), 6 hours, and 24 hours after segmental allergen challenge. Two-dimensional phase-contrast MRI measurements were performed in the aorta (AO) and in the pulmonary artery (PA). In addition, short-axis balanced steady state free precession cardiac cine MRI was performed. Maximum systolic flow, maximum flow acceleration, acceleration volume, acceleration time, distensibility, ejection fraction, stroke volume, end-systolic/diastolic volume, cardiac mass, heart rate (HR), and cardiac output (CO) were determined. Spirometry and bronchoalveolar lavage were also performed. In patients with asthma, maximal systolic flow and maximal flow acceleration increased 6 hours after provocation in the AO (112.3% and 118.9%, respectively) and PA (113.9% and 116.0%, respectively) compared to baseline (100%, P<.05). HR and CO increased significantly at 6 hours (115% and 118%, respectively) compared to baseline (100%, P=.003). In healthy subjects, almost all MRI-derived hemodynamic parameters did not significantly change at 6 hours and were significantly lower than baseline values at 24 hours (P<.02). Twenty-four hours after allergen challenge, all MRI-derived flow parameters were significantly lower in the control group compared to the asthma group (P<.05). HR, CO, and cardiac function parameters measured at 24 hours showed no significant difference comparing the two groups (P>.05). In asthmatic patients, MRI-derived hemodynamic parameters using phase-contrast MRI are slightly altered after segmental allergen provocation compared to normal controls indicating a mild systemic reaction to local allergen challenge.