In vivo 17 O MRS imaging – Quantitative assessment of regional oxygen consumption and perfusion rates in living brain

J Cereb Blood Flow Metab

Lee

Chen

2018

Self Cite

Cellular ATP energy metabolism and regulation are essential for brain function and health. Given the high ATP expenditure at resting-state, it is not yet clear how the human brain at working-state can effectively regulate ATP production to meet higher energy requirement. Through quantitative measurement of regional cerebral ATP production rates and associated neurophysiological parameters in human visual cortex at rest and during visual stimulation, we found significant stimulus-induced and highly correlated neuroenergetic changes, indicating distinctive and complementary roles of the ATP synthesis reactions in supporting evoked neuronal activity and maintaining ATP homeostasis. We also uncovered large individual variances in the neuroenergetic responses and significant reductions in intracellular [H] and free [Mg] during the stimulation. These results provide new insights into the mechanism underlying the brain ATP energy regulation and present a sensitive and much-needed neuroimaging tool for quantitatively assessing neuroenergetic state in healthy and diseased human brain.

Section: Introductionmentioning

confidence: 99%

Functional energetic responses and individual variance of the human brain revealed by quantitative imaging of adenosine triphosphate production rates

J Cereb Blood Flow Metab

Lee

Chen

2018

Self Cite

“…Overcoming these limitations will enable many potential applications that are previously unachievable. For example, 31 P and 17 O are two biologically important nuclei for studying brain energetics [1,2,20, 28–30]. The detection sensitivities of 31 P and 17 O relative to 1 H (assumed as 1) are 6.63 × 10 −2 and 1.08 × 10 −5 , respectively.…”

Section: Discussionmentioning

confidence: 99%

Large improvement of RF transmission efficiency and reception sensitivity for human in vivo 31 P MRS imaging using ultrahigh dielectric constant materials at 7 T

Lee

Magnetic Resonance Imaging

Rupprecht

et al. 2017

Self Cite

In vivo31P MRS provides a unique and important imaging tool for studying high-energy phosphate metabolism and bioenergetics noninvasively. However, compared to 1H MRS, 31P MRS with a relatively low gyromagnetic ratio (γ) has a lower and limited sensitivity even at ultrahigh field. The proof of concept has been recently demonstrated that the use of high dielectric constant (HDC) materials between RF coil and object sample could increase MRI signal and reduce required RF transmission power for reaching the same RF pulse flip angle in the region of interest. For low-γ MRS applications operated at relatively lower frequency, however, it demands the dielectric materials with a much higher permittivity for achieving optimal performance. We conducted a 31P MRS imaging study using ultra-HDC (uHDC; with a relative permittivity of ~1200) material blocks incorporated with an RF volume coil at ultrahigh field of 7.0 T. The experimental results from phantom and human calf muscle demonstrate that the uHDC technique significantly enhanced RF magnetic transmit field ( B1+) and reception field ( B1-) and the gain could reach up to two folds in the tissue near the uHDC blocks. The overall results indicate that the incorporation of the uHDC materials having an appropriate permittivity value with a RF coil can significantly increase detection sensitivity and reduces RF transmission power for X-nuclei MRS applications at ultrahigh field. The uHDC technology could provide an efficient, cost-effective engineering solution for achieving high detection sensitivity and concurrently minimizing tissue heating concern for human MRS and MRI applications.

“…The 17 O MR approach had been employed to assess the cerebral blood perfusion using the 17 O-labeled water as a perfusion tracer; however, the most important application of the in vivo 17 O MRS imaging technique is to noninvasively imaging CMRO 2 through detection of the metabolic end product of H 2 17 O water after an inhalation of 17 O-labeled O 2 gas [36-45] (also see review articles [17, 46, 47] and cited references therein). In this section, we discuss the method and utility of the 17 O based imaging for noninvasive and simultaneous measurement of CMRO 2 , CBF and OEF.…”

Section: In Vivo 17o Mrs Technique For Noninvasive Imaging Of Cmromentioning

confidence: 99%

Quantitative imaging of brain energy metabolisms and neuroenergetics using in vivo X-nuclear 2H, 17O and 31P MRS at ultra-high field

Journal of Magnetic Resonance

Lü

Chen

2018

Self Cite

Brain energy metabolism relies predominantly on glucose and oxygen utilization to generate biochemical energy in the form of adenosine triphosphate (ATP). ATP is essential for maintaining basal electrophysiological activities in a resting brain and supporting evoked neuronal activity under an activated state. Studying complex neuroenergetic processes in the brain requires sophisticated neuroimaging techniques enabling noninvasive and quantitative assessment of cerebral energy metabolisms and quantification of metabolic rates. Recent state-of-the-art in vivo X-nuclear MRS techniques, including H,O and P MRS have shown promise, especially at ultra-high fields, in the quest for understanding neuroenergetics and brain function using preclinical models and in human subjects under healthy and diseased conditions.