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
| 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) |
No significant differences between measurements and pump reference were observed (p = 0.998)
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