Does Increased Echogenicity in the Caudothalamic Groove Always Indicate Hemorrhage in Early Infancy?

We aim to evaluate the diagnostic significance of caudothalamic groove (CTG) echogenicity on cranial ultrasonography (CUS) by examining its correlation with magnetic resonance imaging (MRI) findings, including susceptibility-weighted imaging (SWI). This retrospective study screened 131 neonatal intensive care unit neonatal intensive care unit infants with diagnostic-quality CUS and MRI (including SWI) performed between January 2019 and April 2022. Among these, 34 had CTG echogenicity on CUS; 18 of the 34 had no corresponding CTG hemorrhage on SWI and formed the analytic cohort. The final cohort included 18 infants (10 males, 8 females; mean gestational age 32.7 wk, range 25.3 to 39.3 wk). Five (27.8%) were term, 13 (72.2%) were preterm. Initial CUS demonstrating CTG echogenicity was performed at a mean of 15.7 postnatal days; echogenicity was bilateral in 9 (50%) and unilateral in 9 (50%), with teardrop-like morphology in 10 (55.6%). MRI with SWI was performed at a mean of 29 postnatal days (range 2 to 90 d). No hemorrhagic changes were observed in the CTG region on SWI. Three patients (16.7%) had normal MRI findings, 15 (83.3%) showed nonhemorrhagic abnormalities, including edema, thin corpus callosum, subependymal cysts, ventricular dilatation, or cortical malformations. This study demonstrates a discordance between CUS and SWI-MRI findings in infants with CTG echogenicity. The presence of term infants and bilateral involvement suggests that CTG echogenicity may be a nonspecific imaging finding that can reflect a variable pathophysiological process. Therefore, confirmatory MRI with SWI may be valuable for accurate diagnosis and clinical decision-making in both preterm and term neonates with isolated CTG echogenicity.