Template:Ultrasound terms

From Embryology

Ultrasound

  • Biparietal diameter - (BPD) used to determine fetal age and normal development (small/large/abnormal) parameters. Measured as the diameter between the 2 sides of the head, measurements after 13 weeks (2.4 cm) to term (9.5 cm).
  • Crown-Rump Length - (CRL) measurement used in embryology to more accurately stage the early embryo and fetus. Measured from the curvature at the top (crown) to the curvature at the bottom (rump) of the "C-shaped" early embryo. Used in clinical ultrasound as a measurement between the periods of 7 to 13 weeks as an accurate estimation of the gestational age GA.
  • DICOM - (ISO standard 12052:2006) Acronym for Digital Imaging and Communications in Medicine, a clinical standard for handling, storing, printing, and transmitting imaging information.
  • Femur length - (FL) is used to determine fetal age and normal development (small/large/abnormal) parameters. The femur is the longest bone in the body and measurements and reflects the longitudinal growth of the fetus (approximately 14 weeks 1.5 cm - term 7.8 cm). It is one of the four typical ultrasound assessments of fetal size and age: Biparietal Diameter (BPD), |Head Circumference (HC), Abdominal Circumference (AC), and Femur Length (FL).
  • Fetal size and age - typically measured using 4 ultrasound assessments: Biparietal Diameter (BPD), Head Circumference (HC), Abdominal Circumference (AC), and Femur Length (FL).
  • Functional linear discriminant analysis - (FLDA) new growth assessment technique using serial measurements to discriminate between normal and abnormal fetal growth during 2nd and 3rd trimester.
  • Head Circumference - (HC) Measured as an ellipse in a horizontal section at the level of the thalamus and the cavum septi pellucidi. 2nd trimester Fetal head growth
  • Gestational sac - (GS) size formed initially by the chorionic cavity, after the embryonic period (week 8, GA W10) the amniotic cavity expands and fuses with the chorion. Measured by mean gestation sac diameter.
  • inversion mode - an ultrasound processing method of volume analysis for the visualization of fluid-filled fetal structures such as; heart chambers, vessel lumen, stomach, gallbladder, renal pelvis, and the bladder. Post-processing inverts the gray scale of the volume voxels showing the normally anechoic structures in 3D or 4D renderings. This technique has been used to identify cardiac anomalies.
  • Linear discriminant analysis - (LDA) to longitudinal data (James and Hastie, 2001)
  • Mean gestation sac diameter - (MSD) = (length + height + width)/3. At week 3 (GAweek 5) MSD measures 2-3 mm. Normal MSD (in mm) + 30 = days of pregnancy.
  • Mean yolk sac diameter - (MYD) can be used as marker for subsequent embryonic death or abnormalities (PMID 22215774).
  • Spatiotemporal image correlation (STIC) - an image acquisition method used mainly for fetal heart analysis. Requires two steps; an automatic volume sweep, then image data analysis according to spatial and temporal domain generating an online dynamic 3D image sequence.
  • Transabdominal scan - the ultrasound probe is placed on the external abdomen wall to scan pelvic region structures, conceptus and placenta. Also used to guide prenatal diagnostic techniques of chorionic villus sampling and amniocentesis.
  • Transvaginal scan - (TVS) the ultrasound probe is placed inside the vagina and scans for female genital (uterus, ovary) and ectopic pregnancy.
  • Termination of pregnancy - (TOP)
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