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Table 1 Foetal IVIM parameters and their repeatability across the study population

From: Intra-voxel incoherent motion MRI of the living human foetus: technique and test–retest repeatability

Structure and number (n) of individuals where the structure was repeatedly imaged IVIM measurements Within-subject variability (VAR%) Subjects where bi-exponential fitting was insufficient, f and D* = 0 (n (%))
Perfusion fraction f Diffusion coefficient d (mm2/s) Pseudo-diffusion coefficient D* (mm2/s) Perfusion fraction f (%) Diffusion coefficient d (%) Pseudo- diffusion coefficient D* (%)  
Brain, frontal cortex (n = 11) 0.142 ± 0.133 (0–0.54)a 4.7 × 10–4 ± 9.9 × 10–5(2.9 × 10–4–7.7 × 10–4) 9.5 × 10–3 ± 2.9 × 10–2(1 × 10–3–1.5 × 10–1) 23.5 4.8 19.9 2 (18.2)
Brain, frontal white matter (n = 8) 0.087 ± 0.106 (0–0.377)a 5.2 × 10–4 ± 1.3 × 10–4(2.9 × 10–4–7.8 × 10–4) 7.3 × 10–3 ± 2.8 × 10–2(1 × 10–3–1.5 × 10–1) 33.6 12.8 27.9 5 (62.5)
Cerebellum (n = 9) 0.135 ± 0.122 (0–0.419)a 4.6 × 10–4 ± 1.1 × 10–4(2.3 × 10–4–6.9 × 10–4) 9.4 × 10–3 ± 3.0 × 10–2(1 × 10–3–1.5 × 10–1) 33.5 15.2 28.2 3 (33.3)
Placenta (n = 16) 0.28 ± 0.105 (0–0.479)a 5.4 × 10–4 ± 8.2 × 10–5(2.9 × 10–4–6.8 × 10–4) 4.7 × 10–3 ± 3.8 × 10–3(2.5 × 10–3–2.3 × 10–2) 16.9 12.2 17 1 (6.3)
Liver (n = 8) 0.346 ± 0.101 (0.149–0.479) 3.7 × 10–4 ± 8.7 × 10–5(2.3 × 10–4–5.9 × 10–4) 2.6 × 10–3 ± 2.4 × 10–3(0–9.9 × 10–3) 14.4 13.8 16.8 0 (0)
Lung (n = 9) 0.33 ± 0.112 (0.108–0.548) 5.5 × 10–4 ± 9.2 × 10–5(4 × 10–4–8.1 × 10–4) 2.5 × 10–3 ± 1.3 × 10–3(1 × 10–3–5.5 × 10–1) 20.4 14.1 25.3 0 (0)
Kidneys (n = 5) 0.153 ± 0.09 (0–0.307)a 4.2 × 10–4 ± 8.6 × 10–5(3.1 × 10–4–6.4 × 10–4) 1.7 × 10–2 ± 4.2 × 10–2(1 × 10–3–1.5 × 10–1) 36.2 17 30.1 2 (40)
  1. Data are given as mean ± SD and range, while repeatability is expressed as test–retest variability (VAR%, see Eq. 2) of repeated measurements
  2. aCases where the number for assessing the variability of f was further reduced due to the insufficient fitting of the bi-exponential curve (in such cases, f and D* were equal to zero); the number of missing data entries is given in the last column of the table