title: Three-dimensional extended imaging: a new display modality for three-dimensional ultrasound examination.
abstract: OBJECTIVE
  To describe Three-Dimensional eXtended Imaging (3DXI) as a new display modality for three-dimensional (3D) ultrasound examination of the fetus.
  
  
  METHODS
  The spine, palate, heart and brain were evaluated using 3D ultrasound examination at a mean gestational age of 22 weeks in 35, 31, 32 and 31 fetuses, respectively. The volume data captured were analyzed using the conventional orthogonal display mode (ODM), as well as the 3DXI, which includes the Multi-Slice View (MSV) mode and the Oblique View (OBV) mode. The MSV mode allows simultaneous display of multiple sequential parallel planes while the OBV mode allows examination of a non-standard straight or curved plane.
  
  
  RESULTS
  The MSV mode allowed a simultaneous display of multiple sequential parallel planes of the fetal structures, but we found some uncertainty if an isolated image in one of the multi-slice images represented the exact level of a fetal structure. The MSV mode was advantageous in one of the six cases of facial cleft by allowing the simultaneous display of bilateral clefts that were located in two different axial planes. The multi-slice images were helpful in making the diagnosis in one case of holoprosencephaly. The OBV mode allowed examination of the coronal plane across the curvature of the spine, and the 'in-plane' view of the interventricular septum in a non-gated study.
  
  
  CONCLUSIONS
  The 3DXI can display the volume data in a different manner from that which usually results from the use of more conventional ODM, and provide additional information over conventional two-dimensional sonography.
authors.affiliation: The University of Hong Kong, Queen Mary Hospital, Obstetrics & Gynaecology, Hong Kong SAR, China. Leungky1@ha.org.hk
authors.forename: K Y
authors.initials: KY
authors.lastname: Leung
authors.forename: C S W
authors.initials: CS
authors.lastname: Ngai
authors.forename: B C
authors.initials: BC
authors.lastname: Chan
authors.forename: W C
authors.initials: WC
authors.lastname: Leung
authors.forename: C P
authors.initials: CP
authors.lastname: Lee
authors.forename: M H Y
authors.initials: MH
authors.lastname: Tang
mesh_terms: D018376:Cardiovascular Abnormalities / Q000000981:diagnostic imaging; D002972:Cleft Palate / Q000000981:diagnostic imaging; D005240:Feasibility Studies; D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging*; D005318:Fetal Heart / Q000000981:diagnostic imaging; D016142:Holoprosencephaly / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D016135:Spinal Dysraphism / Q000000981:diagnostic imaging; D013131:Spine / Q000000981:diagnostic imaging; D016216:Ultrasonography, Prenatal / Q000379:methods*