Purpose: Noninvasive measurement of cerebral venous oxygenation (Y v ) in neonates is important in the assessment of brain oxygen extraction and consumption, and may be useful in characterizing brain development and neonatal brain diseases.This study aims to develop a rapid method for vessel-specific measurement of Y v in neonates. Methods: We developed a pulse sequence, named accelerated T 2 -relaxation-underphase-contrast (aTRUPC), which consists of velocity-encoding phase-contrast module to isolate pure blood signal, flow-insensitive T 2 -preparation to quantify blood T 2 , and turbo-field-echo (TFE) scheme for rapid image acquisition, which is critical for neonatal MRI. A series of studies were conducted. First, the pulse sequence was optimized in terms of TFE factor, velocity encoding (VENC), and slice thickness for best sensitivity. Second, to account for the influence of TFE acquisition on T 2 quantification, simulation and experiments were conducted to establish the relationship between TFE-T 2 and standard T 2 . Finally, the complete aTRUPC sequence was applied on a group of healthy neonates and normative Y v values were determined. Results: Optimal parameters of aTRUPC in neonates were found to be a TFE factor of 15, VENC of 5 cm/s, and slice thickness of 10 mm. The TFE-T 2 was on average 3.9% lower than standard T 2 . These two measures were strongly correlated (R 2 = 0.86); thus their difference can be accounted for by a correction equation, T 2,standard = 1.2002 × T 2,TFE − 10.6276. Neonatal Y v values in veins draining cortical brain and those draining central brain were 64.8 ± 2.9% and 70.2 ± 3.3%, respectively, with a significant difference (P =.02).
Conclusion:The aTRUPC MRI has the potential to provide vessel-specific quantification of cerebral Y v in neonates.
|JIANG et Al.