Fetal Transverse Thalamic Diameter and Assessment of Gestational Age as a Fetal Growth Parameter Using 2D Ultrasound

The thalamus is a nuclear complex which located in the diencephalon of the brain. Its main function is to relay messages which affect the sensory and motor functions in the body. A lot of behavioral functions are accredited to it such as memory, learning, attention and language. (Sridar P,et al 2020) There is an automatic thalamic diameter measurement to estimate the thalamic diameter, with the measurement accuracy as good as the clinical assessment.( Sridar P,et al 2016) Transverse thalamic diameter increased significantly with increasing gestational age, head circumference, and trans-cerebellar diameter linearly, and normal range thalamic charts are presented. The guitar shape provided good reproducibility of thalamic diameter measures. (Sridar P,et al 2020) Also the evaluation of echogenic thalamus is beneficial, and can be considered as a new marker of fetal lung maturity. ( Rasheed FA, et al 2012). Maternal hyperglycemia was significantly associated with an increase in the widths of fetal posterior lateral ventricles, cavum septum pellucidi, and cisterna magna and a decrease in fetal trans-cerebellar diameter with no difference was found between three groups in terms of fetal thalamus size (Ekin A. et al 2023). However, little is known about the growth pattern of thalami during fetal life, and virtually nothing is known about the possible association of deviations from the normal growth pattern with the abnormal conditions. There is a study published on fetal thalami which compare the volumes of cerebral structures, including thalami, between two group's normally growing and growth-restricted fetuses and reported lack of significant difference in thalamic volumes between the two groups. (Elshal RS.etal 2023). During fetal life, the thalamus increases in size between the ages of 20 to 43 weeks of gestation (Tutunji R et al 2018 ) The development of the thalamus is not a unified progress as it shows remarkable dynamism and heterogeneity ( Zheng et al., 2023) F