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Table 2 Distribution of two measurements of the mean velocity for 2D flow and two 4D flow phase-contrast sequences (GRAPPA2 and k-t-GRAPPA5) with different rotational frequencies of the blood pump

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

Rotational pump output, rpm Venc, cm/s Pump reference mean velocity 2D flow PC mean velocity 4D flow PC GRAPPA2 mean velocity 4D flow PC k-t-GRAPPA5 mean velocity
cm/s cm/s (difference from the pump reference) cm/s cm/s (difference from the pump reference) cm/s cm/s (difference from the pump reference) cm/s
Exam 1 Exam 2 Mean ± SD Exam 1 Exam 2 Mean ± SD Exam 1 Exam 2 Mean ± SD Exam 1 Exam 2 Mean ± SD
1,500 40 22 22 22 ± 0.0 22 (+ 0) 23 (+ 0) 22.5 ± 0.7 23 (+ 1) 23 (+ 1) 23 ± 0.0 23 (+ 1) 22 (+ 0) 22.5 (± 0.7)
2,000 50 31 30 31 ± 0.7 32 (+ 1) 32 (+ 2) 32 ± 0.0 32 (+ 1) 32 (+ 2) 32 ± 0.0 31 (+ 0) 31 (+ 1) 31 (± 0.0)
2,500 60 39 39 39 ± 0.0 41 (+ 2) 41 (+ 2) 41 ± 0.0 41 (+ 2) 41 (+ 2) 41 ± 0.0 41 (+ 2) 42 (+ 3) 41.5 (± 0.7)
3,000 70 50 50 50 ± 0.0 50 (+ 0) 50 (+ 0) 50 ± 0.0 49 (-1) 50 (+ 0) 49.5 ± 0.7 50 (+ 0) 52 (+ 2) 51 (± 1.4)
3,500 85 59 59 59 ± 0.0 60 (+ 1) 60 (+ 1) 60 ± 0.0 58 (-1) 59 (+ 0) 58.5 ± 0.7 60 (+ 1) 62 (+ 3) 61 (± 1.4)
4,000 100 70 70 70 ± 0.0 71 (+ 1) 70 (+ 0) 70.5 ± 0.7 68 (-2) 70 (+ 0) 69 ± 1.4 71 (+ 1) 72 (+ 2) 71.5 (± 0.7)
4,500 110 80 80 80 ± 0.0 81 (+ 1) 82 (+ 2) 81.5 ± 0.7 79 (-1) 80 (+ 0) 79.5 ± 0.7 81 (+ 1) 83 (+ 3) 82 (± 1.4)
5,000 125 91 91 91 ± 0.0 92 (+ 1) 93 (+ 2) 92.5 ± 0.7 91 (+ 0) 91 (+ 0) 91 ± 0.0 92 (+ 1) 94 (+ 3) 93 (± 1.4)
5,500 140 101 101 101 ± 0.0 103 (+ 2) 103 (+ 2) 103 ± 0.0 100 (-1) 101 (+ 0) 100.5 ± 0.7 103 (+ 2) 104 (+ 3) 103.5 (± 0.7)
  1. No significant differences between measurements and pump reference were observed (p = 0.998)
  2. 2D two-dimensional, 4D four-dimensional, cm/s centimetres per second, GRAPPA generalised autocalibrating partially parallel acquisition; PC phase-contrast, SD standard deviation of the mean, Venc velocity encoding