Vessel‐specific quantification of neonatal cerebral venous oxygenation

Abstract

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.

Quantitative validation of MRI mapping of cerebral venous oxygenation with direct blood sampling: A graded‐O2 study in piglets

“…16 For aTRUPC, although changes in T 1 will affect the signal evolution during the TFE acquisition train, it has been shown that this effect is negligible on Y v quantification. 17 There are several limitations of this study. First, although TRUPC and aTRUPC can measure Y v in multiple veins, we only compared the Y v in the SSS of TRUPC and aTRUPC with blood gas oximetry.…”

“…In this study, we validated the accuracy of both TRUPC and aTRUPC techniques. The TRUPC 16,17 method can be used when regional information is required and scan time is not a compelling issue. In applications in which Y v is expected to alter globally, aTRUPC can be a faster surrogate for TRUPC.…”

“…The TRUPC technique aimed to provide a region-specific assessment of Y v and was acquired in the midsagittal plane (Figure 2, top panel) using the following parameters 17,24 : single slice, FOV = 80 × 80 × 5 mm 3 , acquisition matrix = 160 × 90, reconstruction voxel size = 0.5 × 0.5 × 5 mm 3 , recovery time = 460 ms, TE = 10.7 ms, flip angle = 90°, flowencoding direction = anterior-posterior, velocity encoding = 5 cm/s, three eTEs (0, 40, and 80 ms), one repetition, and scan time = 4.9 minutes.…”

“…Abbreviation: Acq, acquisition; eTE, effective TE; RT, recovery time Phase-errors induced by eddy current were corrected as detailed before. 17,24 For TRUPC, a preliminary region of interest covering the entire SSS (Figure 2, top panel) was manually drawn on the eTE = 0 ms complex-difference image. The 150 voxels with the highest intensities inside the preliminary region of interest were chosen as the final mask.…”

The Johns Hopkins Neurosciences Intensive Care Nursery Tenth Anniversary (2009-2019): A Historical Reflection and Vision for the Future

“…Our Neurosciences Intensive Care Nursery specialists work together to establish protocols to promote neuroprotection and brain recovery from injury such as hypoxic-ischemic encephalopathy, stroke, intracranial hemorrhage, seizures, and central nervous system infections while also initiating measures that might prevent further injury, that is, optimizing brain perfusion, cerebral autoregulation, and oxygenation. [12][13][14][15][16][17][18][19][20] Standardization of video EEG monitoring during therapeutic hypothermia has resulted in improved rapid seizure detection, optimization of EEG recording techniques, and reduced use of unnecessary antiseizure medications in this vulnerable population. 21 Additional collaborative research has identified key imaging and clinical signs associated with long-term outcomes among preterm children with post-hemorrhagic hydrocephalus.…”