Reference range of fetal cisterna magna volume by three-dimensional ultrasonography using the VOCAL method.
OBJECTIVE
To determine reference values for the fetal cisterna magna volume by three-dimensional ultrasonography (3DUS) using the virtual organ computer-aided analysis (VOCAL) method.


METHODS
A cross-sectional study was conducted with 224 healthy pregnant women between 17 and 29 completed weeks. Measurement of the fetal cisterna magna volume was performed in the standard axial plane of the transverse diameter of the cerebellum through the VOCAL method with a 30° angle. For the determination of reference values, polynomial regressions with adjustments by the coefficient of determination (R(2)) were held. The reliability and agreement were made by the intra-class correlation coefficient (ICC) and limits of agreement of the Bland-Altman graph.


RESULTS
The average of the fetal cisterna magna volume ranged from 0.73 ± 0.25 to 3.79 ± 1.10 cm(3) between 17 and 29 weeks, respectively. Correlation was observed between the fetal cisterna magna volume and the gestational age (GA), best represented by a quadratic equation: -1.918+0.0284 × GA + 0.0065 × GA(2) (R(2 )= 0.67). It was observed good reliability and intra-observer agreement, with ICC = 0.92 and 95% limits of agreement (-49.7; 48.4). There was low inter-observer reliability and agreement, with ICC = 0.58 and 95% limits of agreement (-114.0; 80.2).


CONCLUSIONS
Reference values for the fetal cisterna magna volume by 3DUS using the VOCAL method were determined and showed good agreement and intra-observer reliability.
Department of Obstetrics, Federal University of São Paulo (UNIFESP) , São Paulo-SP , Brazil and.
Edward
E
Araujo Júnior
Ana Paula
AP
Passos
Rafael Frederico
RF
Bruns
Luciano Marcondes Machado
LM
Nardozza
Antonio Fernandes
AF
Moron
D000465:Algorithms; D002946:Cisterna Magna / Q000000981:diagnostic imaging / Q000196:embryology*; D003430:Cross-Sectional Studies; D005260:Female; D047109:Fetal Development; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D015588:Observer Variation; D009929:Organ Size; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D012016:Reference Values; D015203:Reproducibility of Results; D016216:Ultrasonography, Prenatal / Q000379:methods*
Cisterna magna; VCAL; fetus; reference range; three-dimensional ultrasound