Goal: To assess flow quantitation with multi-directional (ICOSA6) high-moment 4D-flow in a compliant type-B aortic dissection model that provides complex flow and a large velocity range. An in vitro flow setup was designed to acquire prolonged 4D-flow imaging in a flow- and pressure-controlled environment. ICOSA6 4D-flow data was acquired with a highly-sampled stack-of-stars scheme, reconstructed with varying under-sampling factors (R=5-65), and compared to a four-point Cartesian-sampled 4D-flow sequence. Results showed average net flow difference within the ±5% margin for ICOSA6 data under-sampled with up to R=40. Peak velocity, however, differed greatly for all ICOSA6 data when compared to four-point Cartesian.