13 Weeks Gestation

3D Ultrasound Atlas

Weeks of gestation

Comparative fetal anatomy

Case 1

Below are annotated images of a healthy fetus – 13 weeks and 5 days (13 + 5 weeks) gestation – imaged ex-vivo using 3D ultrasound with CrystalVue™ and RealisticVue™ rendering. Thereafter, the specimen was imaged using contrast-enhanced microCT which was used as an anatomical reference standard. The ultrasound and microCT images are directly compared, allowing for validation and annotation of the the structures visualised in 3D ultrasound imaging. 

Left hand and fingers
Umbilical cord (cut)
Ribs
Parietal bone
Frontal bone
Right eye
Ribs
Umbilical cord (cut)
Lens of right eye
Umbilical cord (cut)
Right femur
  1. – C.  Increasing levels of CrystalVue™ complexity and transparency are applied to the 3D ultrasound volume thereby highlighting different (internal) structures. 
Right ear
Right eye
Left hand and fingers
Right forearm
Left hand and fingers
Right forearm
Right eye
Right internal ear (cochlea)
Left hand and fingers
Right forearm
  1. 3D ultrasound volume with CrystalVue™ and Realistic Vue™ applied.
  2. 2D ultrasound image of the left hand from the 3D ultrasound volume, using the multiplanar mode. 
  3. MicroCT image of a matching imaging plane selected from the same specimen.
Posterior Fontanel
Parietal Bone
Frontal Bone
Temporal Bone
Sphenoidal Fontanel
Lens
Zygomatic Bone
Femur
  1. 3D ultrasound volume with CrystalVue™ and RealisticVue™ applied. 
  2. Overlay of a schematic illustration of the skeletal the structures visualised in the 3D ultrasound volume and the original image.
Spinal canal*
Rib
Vertebral Arch
Vertebral ossification centre
Ilium
Spinal Cord within the spinal canal*
Rib
Vertebral Arches
Ilium
Vertebral ossification centre
Cross section of vertebral bodies
Rib
Rib
Vertebral ossification centre
Vertebral arch
Vertebral arch
Vertebral arch
Vertebral arch
Rib
Rib
Rib
  1. 3D ultrasound volume with CrystalVue™ and RealisticVue™ applied. The volume has been sectioned in the coronal plane to visualise the fetal spine.
  2. MicroCT image slice corresponding to the 3D ultrasound section in image A to validate the the structures visualised*.

*Note that 3D imaging with CrystalVue™ rendering allows visualisation of multiple structures at different depths in a single imaging plane unlike microCT slices. As such, the vertebral bodies are visible in the ultrasound volume, whereas they are obstructed by the spinal cord in the microCT image even though the images have been acquired and displayed in the same imaging plane. Also note in image B that the spinal cord reaches all the way down to the bottom of the spinal canal at this stage of development.

Spinal canal*
Vertebral arch
Vertebral arch
Vertebral arch
Vertebral body
Vertebral body
Vertebral body
Sacral vertebrae**
Sacral Vertebrae**
Spinal cord located within the spinal canal*
Vertebral arch
Vertebral arch
Vertebral arch
Vertebral body
Vertebral body
Vertebral body
Sacral vertebrae**
  1. 3D ultrasound volume with CrystalVue™ and RealisticVue™ rendering. The volume has been sectioned in the sagittal plane to visualise the fetal spine.
  2. 2D ultrasound image of the spine in the coronal plane from the 3D ultrasound volume, using the multiplanar mode. 
  3. MicroCT image slice corresponding to the 3D ultrasound section in image A to validate the the structures visualised*.

*Note that the spinal cord appears translucent in the 3D ultrasound volume whereas the spinal cord can be clearly discerned in the microCT image. The spinal cord reaches down all the way down to the bottom of the spinal canal at this stage in development.

**Note that the sacral vertebrae do not fuse during fetal development.

Spine
Acoustic shadow from rib
Acoustic shadow from rib
Acoustic shadow from rib
Right renal pelvis
Right kidney
Right ilium
Spine
Right renal pelvis
Right kidney
Right ilium
  1. 3D ultrasound volume with CrystalVue™ and RealisticVue™ rendering. The volume has been sectioned in a coronal plane to visualise kidneys.
  2. MicroCT image slice corresponding to the 3D ultrasound section in image.
Ductus venosus
Liver
Umbilical vein
Umbilical cord
Small intestine
Liver
Ductus venosus
Umbilical vein
Umbilical cord
Small intestine
  1. 3D ultrasound volume with CrystalVue™ and RealisticVue™ rendering. The volume has been sectioned in a sagittal plane to visualise ductus venosus, umbilical vein and cord insertion.
  2.  MicroCT image slice corresponding to the 3D ultrasound section in image A to validate the the structures visualised.

Comparative fetal anatomy

Case 2

Below are annotated 3D in-utero ultrasound images of a fetus – 13+1 weeks’ gestation – with CrystalVue™ and RealisticVue™ rendering as part of the PRECISE study.  The ventricular system as shown on the 3D ultrasound volume was compared to a 3D model of the ventricular system of a Carnegie Stage (CS) 23 embryo, adapted from de Bakker et al., 2016, with permission.

  1. 3D ultrasound image in the coronal plane of the ventricular system at 13 weeks gestation with CrystalVue™ and RealisticVue™ rendering applied (in-utero volume from the PRECISE study).
  2. Digital reconstruction of the ventricular system of a stage 23 human embryo from the 3D Atlas of Human Embryology.
  3. 3D ultrasound image in the sagittal plane with CrystalVue™ and RealisticVue™ software applied.
  4. Schematic drawing of the ventricular system as presented in the sagittal plane.

H. Shah et al., Novel first-trimester fetal CNS ultrasonography. Am J Obstet Gynecol 2017.