Median and reference limits (5th and 95th centiles) for MR imaging traits between 20 and 24 completed weeks of gestation
| 20 Weeks | 21 Weeks | 22 Weeks | 23 Weeks | 24 Weeks | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 5th | 50th | 95th | 5th | 50th | 95th | 5th | 50th | 95th | 5th | 50th | 95th | 5th | 50th | 95th | |
| PCF | 23.3 | 26.3 | 29.3 | 24.6 | 27.8 | 31.1 | 25.9 | 29.3 | 32.9 | 27.2 | 30.8 | 34.7 | 28.5 | 32.4 | 36.5 |
| Cerebral FOD | 46.7 | 51.2 | 56.4 | 50.1 | 54.8 | 60.2 | 53.4 | 58.4 | 64.1 | 56.8 | 62.0 | 67.9 | 60.2 | 65.5 | 71.7 |
| Cerebral BPD | 36.2 | 38.7 | 41.6 | 37.8 | 40.9 | 44.5 | 39.4 | 43.0 | 47.4 | 40.9 | 45.2 | 50.5 | 42.4 | 47.3 | 53.6 |
| Vermian APD | 5.5 | 6.3 | 7.2 | 6.0 | 6.8 | 7.8 | 6.4 | 7.3 | 8.4 | 6.8 | 7.8 | 9.0 | 7.2 | 8.3 | 9.6 |
| Cerebellar LLD | 18.2 | 19.9 | 21.8 | 19.1 | 21.1 | 23.4 | 20.1 | 22.4 | 25.0 | 21.0 | 23.6 | 26.6 | 21.9 | 24.9 | 28.3 |
| Vermian CCD | 7.7 | 9.0 | 10.0 | 8.3 | 9.8 | 10.9 | 8.9 | 10.6 | 11.9 | 9.5 | 11.4 | 12.8 | 10.1 | 12.1 | 13.8 |
| CSA | 63.7 | 71.0 | 79.9 | 63.6 | 71.6 | 81.5 | 63.4 | 72.1 | 83.2 | 63.2 | 72.7 | 85.0 | 63.1 | 73.2 | 86.8 |
| LCC | 13.3 | 15.3 | 17.1 | 14.7 | 17.1 | 19.2 | 16.0 | 18.9 | 21.4 | 17.3 | 20.7 | 23.6 | 18.6 | 22.5 | 25.8 |
| LCC/cerebral FOD (%) | 27.3 | 29.9 | 32.5 | 27.8 | 31.1 | 34.3 | 28.3 | 32.3 | 36.1 | 28.7 | 33.5 | 38.0 | 29.1 | 34.7 | 39.9 |
| Thecal FOD | 53.4 | 57.5 | 62.1 | 56.7 | 61.3 | 66.6 | 60.0 | 65.2 | 71.2 | 63.2 | 69.0 | 75.7 | 66.4 | 72.8 | 80.4 |
| Thecal BPD | 42.1 | 45.7 | 49.9 | 44.4 | 48.3 | 52.9 | 46.7 | 50.9 | 56.0 | 49.0 | 53.6 | 59.1 | 51.3 | 56.2 | 62.1 |
| Mesencephalic APD | 3.6 | 4.4 | 5.2 | 3.7 | 4.5 | 5.2 | 3.8 | 4.5 | 5.3 | 3.8 | 4.6 | 5.3 | 3.9 | 4.6 | 5.3 |
| Pontine APD | 5.5 | 6.2 | 6.9 | 5.7 | 6.5 | 7.3 | 6.0 | 6.8 | 7.7 | 6.3 | 7.1 | 8.0 | 6.5 | 7.4 | 8.4 |
| Pontine CCD | 6.3 | 7.1 | 7.9 | 6.5 | 7.4 | 8.3 | 6.7 | 7.7 | 8.7 | 6.8 | 8.0 | 9.0 | 7.0 | 8.2 | 9.4 |
| Lateral ventricles | 5.7 | 7.0 | 8.4 | 5.3 | 6.8 | 8.4 | 5.0 | 6.6 | 8.4 | 4.7 | 6.4 | 8.5 | 4.5 | 6.3 | 8.5 |
Note:—APD indicates antero-posterior diameter; BPD, biparietal diameter; CCD, cranio-caudal diameter; CSA, clivosupraoccipital angle; LCC, length of the corpus callosum; LLD, latero-lateral diameter; FOD, fronto-occipital diameter; PCF, latero-lateral diameter of the posterior cranial fossa.