Validation of two accelerated 4D flow MRI sequences at 3 T: a phantom study

European Radiology Experimental

Table 4 Distribution of measurements of the flow volumes, mean velocity, and peak velocity for two different 2D flow phase-contrast acquisitions (orthogonal “through-plane” to the phantom vessel and misaligned) and two 4D flow phase-contrast sequences (GRAPPA2 and k-t-GRAPPA5) with angles between the longitudinal axis of the phantom vessel and the z-direction in 15° steps from 0 to 45°

Angle	Pump reference			2D flow PC			4D flow PC GRAPPA2			4D flow PC k-t-GRAPPA5
Angle	Flow volume, L/min	Mean velocity, cm/s	Peak velocity, cm/s	Flow volume, L/min	Mean velocity, cm/s	Peak velocity, cm/s	Flow volume, L/min	Mean velocity, cm/s	Peak velocity, cm/s	Flow volume, L/min	Mean velocity, cm/s	Peak velocity, cm/s
0°	5.3	70	70	5.4	71	93	5.4	71	90	5.4	71	96
15°	5.3	70	70	5.4	64	89	5.3	70	90	5.3	72	93
30°	5.3	70	70	5.1	60	82	5.3	70	87	5.3	70	87
45°	5.3	70	70	4.8	51	82	5.2	68	90	5.3	71	89

No significant differences between 4D flow measurements, orthogonal (“through-plane”) 2D flow measurements, and the pump reference (p = 0.999). In contrast, the misaligned 2D flow measurements demonstrated increasingly higher differences with the degree of misalignment
2D two-dimensional, 4D four-dimensional, cm/s centimetres per second, GRAPPA generalised autocalibrating partially parallel acquisition, L/min litres per minute, PC phase-contrast, V_enc velocity encoding