ULTRASOUND OF THE CORPUS CALLOSUM

Growth of the corpus callosum is linear during pregnancy from 17 mm in length at 18 weeks' gestation to 44 mm at term. Thickness of the genu and the body increases from, respectively, 2 mm and 1 mm at 19 weeks' gestation to, respectively, 4-5 mm and 3 mm near term (1).

Mean length of corpus callosum : 44mm ( increased by 150% after 18 weeks).
Mean thickness of genu : 4.8mm at term.
Mean thickness of body : 2.6mm at term.
Mean thickness of splenium : 4.4mm at term.

Scan through the anterior fontanelle.

• Midline sagittal:
• 2 parallel echogenic lines.
• Upper line from longitudinal fissure.
• Lower line is roof of cavum septum pellucidum and vergae.
• 3-5 mm echolucent strip between them.
• Pericallosal artery follows the upper boundary of the corpus callosum.
• Coronal images:
• Semilunar shaped.

Ultrasound at 32 weeks of gestation – Sagittal view of Corpus callosum
MRI of Brain – Sagittal View at level of Corpus Callosum

REFERNCES

1. Malinger G, Zakut H. The corpus callosum: normal fetal development as shown by transvaginal sonography. AJR Am J Roentgenol 1993; 161: 1041-3