Intrauterine sonographic measurement of the embryonic brain mantle.

Abstract

To evaluate embryonic brain mantle measurements using intrauterine sonography in the early first trimester. In 85 women about to undergo therapeutic termination at 6-11 weeks' gestation we studied the embryonic brain mantle using a specially developed 20-MHz, flexible, catheter-based, high-resolution, real-time, miniature (1.8 mm in outer diameter) ultrasound transducer. Thickness of the embryonic brain telencephalon, diencephalon, mesencephalon and rhombencephalon was measured. We found a linear relationship between gestational age and telencephalon thickness (R(2) = 51.9%, P < 0.0001), diencephalon thickness (R(2) = 62.2%, P < 0.0001), mesencephalon thickness (R(2) = 59.2%, P < 0.0001) and rhombencephalon thickness (R(2) = 47.8%, P = 0.0043). There was also a linear relationship between crown-rump length and telencephalon thickness (R(2) = 55.0%, P < 0.0001), diencephalon thickness (R(2) = 59.6%, P < 0.0001), mesencephalon thickness (R(2) = 55.0%, P < 0.0001) and rhombencephalon thickness (R(2) = 52.3%, P = 0.0025). Embryonic brain mantle measurements by intrauterine sonography are feasible, although the invasive nature of this technique limits its usefulness in routine clinical practice. It is possible, however, that further improvement in the resolution of transvaginal sonography will allow accurate and reproducible non-invasive imaging of embryonic brain mantle development in the near future.