Optimizing Unanesthetized Cerebral Oxygen Consumption Measures: Comparison of NIRS and MRI Approaches in Neonates with Congenital Heart Disease

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.

Section: Discussionmentioning

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Vessel‐specific quantification of neonatal cerebral venous oxygenation

Jiang

Parkinson

et al. 2019

“…200 Note that oxygen is delivered to the fetus from the placenta through the umbilical vein, which was reported to have an average oxygenation of 84%. 202 For newborn infants, several MRI techniques have been adapted to measure OEF in the neonatal brain, including T 2 -based 57,62,[203][204][205] and phase-based 206…”

Section: Oef Across the Human Lifespanmentioning

confidence: 99%

Cerebral oxygen extraction fractionMRI: Techniques and applications

Jiang

2022

The human brain constitutes 2% of the body's total mass but uses 20% of the oxygen. The rate of the brain's oxygen utilization can be derived from a knowledge of cerebral blood flow and the oxygen extraction fraction (OEF). Therefore, OEF is a key physiological parameter of the brain's function and metabolism.OEF has been suggested to be a useful biomarker in a number of brain diseases.With recent advances in MRI techniques, several MRI-based methods have been developed to measure OEF in the human brain. These MRI OEF techniques are based on the T 2 of blood, the blood signal phase, the magnetic susceptibility of blood-containing voxels, the effect of deoxyhemoglobin on signal behavior in extravascular tissue, and the calibration of the BOLD signal using gas inhalation.Compared to 15 O PET, which is considered the "gold standard" for OEF measurement, MRI-based techniques are non-invasive, radiation-free, and are more widely available. This article provides a review of these emerging MRI-based OEF techniques. We first briefly introduce the role of OEF in brain oxygen homeostasis. We then review the methodological aspects of different categories of MRI OEF techniques, including their signal mechanisms, acquisition methods, and data analyses. The strengths and limitations of the techniques are discussed.Finally, we review key applications of these techniques in physiological and pathological conditions.

Assessing the effects of subject motion on T₂ relaxation under spin tagging (TRUST) cerebral oxygenation measurements using volume navigators

Stout

Tisdall

McDaniel

et al. 2017

Self Cite

Purpose Subject motion may cause errors in estimates of blood T2 when using the T2-relaxation under spin tagging (TRUST) technique on non-compliant subjects like neonates. By incorporating three-dimensional volume navigators (vNavs) into the TRUST pulse sequence, independent measurements of motion during scanning permit evaluation of these errors. Methods The effects of integrated vNavs on TRUST-based T2 estimates were evaluated using simulations and in vivo subject data. Two subjects were scanned with the TRUST+vNav sequence during prescribed movements. Mean motion scores were derived from vNavs and TRUST images, along with a metric of exponential fit quality. Regression analysis was performed between T2 estimates and mean motion scores. Also, motion scores were determined from independent neonatal scans. Results vNavs negligibly affected venous blood T2 estimates and better detected subject motion than fit quality metrics. Regression analysis showed that T2 is biased upwards by 4.1 ms per 1 mm of mean motion score. During neonatal scans, mean motion scores of 0.6–2.0 mm were detected. Conclusion Motion during TRUST causes an overestimate of T2, which suggests a cautious approach when comparing TRUST-based cerebral oxygenation measurements of noncompliant subjects.