3D ultrasound in first and second trimester - Minnis Journals

3D ultrasound in first and second trimester – hype or helpful?Fig. 3: 3D surface image at 12wks demonstrates large omphalocoeleand shortish limbs. Trisomy 13.Fig. 4: 3D surface image at anatomy scan showing persistent subtleoverlapping fingers 2 and 3 right hand. Left hand and feet appearednormal. Trisomy 18.Fig. 5: 3D skeletal image spine shows lower thoracic hemivertebrawith rib disparity.Anatomy scanFacial features, especially cleft lip and hard palate are wellsuited for 3D imaging, particularly when trying to depictthese for the parents or clinicians. A well performed 2Danatomy scan should detect virtually all cleft lips, but sometimescleft of the hard palate can only be found using volumeimaging with either a reverse face 3D 2 or an extended midlinesagittal image acquisition 3D 1 .LimbsHand, wrist and foot anomalies, including clubfoot, polydactylyand clenching, may be very difficult to depict in 2Dimaging but are often well seen using 3D surface (Fig. 4).Skeletal assessmentIn particular, where spinal anomalies such as hemivertebraare detected, 3D imaging of the spine helps confirm the findingby depicting the hemivertebra, and also allows accuratecounting of ribs on either side (Fig. 5). Spina bifida, skulland long bones can also be further demonstrated with 3D.HeartThe Spatio-Temporal Image Correlation (STIC) volumeacquisition, can allow rapid depiction of the cardiac anatomy,and with an enthusiastic sonographer can give a quickFig. 6: 3D surface image face at anatomy scan showing descriptivefacial and hand expressions.and accurate depiction of the chambers and major vessels3,4,5,6 . STIC has many benefits both for screening in theroutine anatomy scan, and for further evaluating the heartwhere an abnormality is suspected. It improves resolution,offers unlimited images in any plane, allows simultaneouscorrelation between image planes that are perpendicular tothe acquisition plane and 3D rendered images can be reconstructed3 . With an experienced sonologist, evaluation timemay be shortened, especially with complex defects. It alsoallows all images in all planes to be reviewed in cine-loop,and the complete data volume can be stored, reviewed andmanipulated later. This means the data can be assessed at aremote site by a more expert clinician who is not limited bythe findings detected by the first examiner 3 . In conventional2D ultrasound review of the examination is generally limitedto the findings detected and documented by the sonologist.Some 3D/4D imaging can be incorporated into the routinescreening anatomy scan with not much effort or increasein scanning time in the majority of patients. Certainly, tolook at the face and limbs only takes a few moments, andwith enthusiasm and some practice, the heart and spine canoften be shown in a more useful way. Just as the developmentof reasonable technique for things such as NT scanning,nasal bone, tricuspid and ductus, requires 50–100 orAustralasian Journal of Ultrasound in Medicine August 2009; 12 (3)29