In vivo oxygen-17 nuclear magnetic resonance for the estimation of cerebral blood flow and oxygen consumption

Simplified Methods for Calculating Cerebral Metabolic Rate of Oxygen Based on 17O Magnetic Resonance Spectroscopic Imaging Measurement during a Short 17O2 Inhalation

“…This linear relationship was in fact shown in our previous experiments based on invasive methods that allowed the continuous in vivo measurement of C a (t) (Zhu et al, 2002). It is also supported by other studies (Arai et al, 1991;Pekar et al, 1991). Substituting Eq.…”

“…However, this is a complex measurement. It requires independent determinations of cerebral H 2 15 O content, CBF, and H 2 15 O present in the arterial supply to the brain (the arterial input function) (Mintun et al, 1984); in addition, it is necessary to experimentally determine (Mintun et al, 1984) or make assumptions (Ohta et al, 1992) (Arai et al, 1990(Arai et al, , 1991Fiat and Kang, 1992;Mateescu et al, 1989;Pekar et al, 1991Pekar et al, , 1995Zhu et al, 2002). This is analogous to the PET approach.…”

In vivo17O NMR approaches for brain study at high field

“…In vivo 17 O approaches can be potentially applied to measuring and imaging two important physiological parameters, namely CMRO 2 and CBF. 6,8,14,16,[37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] The 17 O NMR approaches for in vivo determinations of CMRO 2 and CBF involve the measurement of (i) the amount of 17 O-labeled water metabolically generated from the inhaled 17 O 2 gas through the oxidative pathway, and (ii) the washout rate of the 17 O-labeled water tracer introduced by a bolus injection, respectively. In terms of methodology, there is a close similarity between the in vivo 17 O approaches and PET approaches, especially for CBF measurements.…”

“…Another common and more straightforward approach for detecting the 17 Owing to the relatively low inherent NMR sensitivity of 17 O NMR detection and the small amount of metabolic water generated during an 17 O 2 inhalation, most of the early 17 O MR studies on oxidative metabolism detected the metabolic H 2 17 O from a large volume in living animal 42,49,50,82 and human brains, 8 as well as whole living insects. 83 To achieve a better spatial localization, techniques that are frequently applied for the proton MRI (e.g.…”

“…Therefore, most studies using direct in vivo 17 O NMR approaches have focused on still challenging but attainable goals for quantitatively imaging CBF 6,41,46,49,50 and, more importantly, CMRO 2 in living brains. 6,8,[41][42][43][46][47][48][49][50][51]82 Many previous studies were conducted at relatively low field strengths compared with what is available currently and demonstrated dramatic limitations imposed by the low inherent sensitivity of 17 O NMR. A few of these studies attempted to obtain a coarse CMRO 2 image ($0.8 ml voxel size) in the cat brain with a relatively long measurement time (15 min) at 4.7 T. 41,43 The limited 17 O sensitivity at low fields has hindered the developments of the direct 17 O approach for imaging CMRO 2 .…”