Signal Intensity and Volume of Pituitary and Thyroid Glands in Preterm and Term Infants

Background Hypothalamic-pituitary-thyroid (HPT) maturation has not been extensively evaluated using neonatal MRI, even though both structures are visualized on MRI. Hypothesis That signal intensity and volume of pituitary and thyroid (T) glands on MRI in neonates may be interrelated. Study Type Retrospective. Subjects In all, 102 participants. Field Strength/Sequence 3.0T, T-1-weighted pointwise encoding time reduction with radial acquisition (PETRA). Assessment The volume of interest of the anterior pituitary (AP), posterior pituitary (PP), and T on MRI were defined on T-1-PETRA by two radiologists, and volumes of AP (AP_vol) and thyroid (T_vol) were calculated. Gestational age (GA), chronological age (CA), GA+CA, birth weight (BW), and thyroid function were recorded. Mean and maximum signal intensities of AP, PP, and T were normalized using signals from the pons and spinal cord as follows: signal ratio of anterior pituitary/pons (AP/pons), signal ratio of posterior pituitary/pons (PP/pons), and (signal ratio of thyroid/cord (T/cord)) T/cord, respectively. Statistical Tests Correlations between signal intensity and volume measures and GA, CA, GA+CA, and BW were assessed using Pearson's correlation coefficient or Spearman's rank correlation coefficient. Thyroid function analysis and T-mean/cord, T-max/cord, and T_vol were evaluated using the Steel-Dwass test. Results AP(mean)/pons correlated positively with GA (rho = 0.62,P <0.001) and BW (rho = 0.74,P <0.001), and negatively with CA (rho = -0.86,P <0.001) and GA+CA (rho = -0.46,P <0.001). PPmean/pons correlated positively with GA (rho = 0.49,P <0.001) and BW (rho = 0.63,P <0.001), and negatively with CA (rho = -0.70,P <0.001) and GA+CA (r = -0.38,P <0.001). T-mean/cord correlated positively with GA (rho = 0.48,P <0.001) and BW (rho = 0.55,P <0.001), and negatively with CA (rho = -0.59,P <0.001) and GA+CA (rho = -0.22,P =0.03). AP_vol correlated positively with GA (rho = 0.68,P <0.001) and BW (rho = 0.73,P <0.001), and negatively with CA (rho = -0.72,P <0.001). T_vol correlated positively with GA (rho = 0.50,P <0.001) and BW (rho = 0.61,P <0.001), and negatively with CA (rho = -0.54,P <0.001). AP(mean)/pons correlated positively with T-mean/cord (rho = 0.61,P <0.001). Data Conclusion Signal and volume of pituitary and thyroid glands correlated positively with GA and BW, and negatively with CA in neonates. Level of Evidence 4 Technical Efficacy Stage 5

Automated summary

In this study of 102 neonates, the signal intensity and volume of the pituitary and thyroid glands on MRI were found to be positively correlated with gestational age and birth weight, while negatively correlated with chronological age.