Abstract
Objective
Using transabdominal 2D ultrasonography, we aimed to establish nomograms for
fetal optic chiasm (OC) width, length, and area between 16–37 weeks of
gestation.
Materials and Methods
OC measurements were performed by a resident and a perinatologist. An
agreement was evaluated using intraclass correlation coefficients (ICCs)
with 95% confidence intervals. Then, nomogram tables of OC width, length,
and area measurements were derived using these measurements.
Results
A strong positive correlation was found between OC measurements and
gestational week (GW) (r=0.873 for width, r=0.827 for length, r=0.863 for
area; p<0.001). The regression equations obtained were: OC
width=1.164+0.206×GW, OC length=0.072+0.180×GW, OC area =–25.226+2.228×GW.
Interobserver agreement was high, with ICC values of 0.798 for width, 0.705
for length, and 0.758 for area, indicating consistent measurements between
observers.
Conclusion
This is the first study to establish normative data and nomograms for OC
dimensions. Our findings confirm that OC width, length, and area increase
linearly with advancing gestation. The high interobserver reliability
suggests that these measurements can be reliably used in clinical practice
and future research.
Keywords
Nomogram - optic chiasm - septo-optic dysplasia - two-dimensional ultrasound
