Determination of Oxygen Extraction Ratios by Magnetic Resonance Imaging

Oja, Joni M. E.; Gillen, Joseph; Kauppinen, Risto A.; Kraut, Michael A.; Zijl, Peter C.M. van

doi:10.1097/00004647-199912000-00001

Cited by 96 publications

(148 citation statements)

References 35 publications

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“…First, BOLD measurements are mainly sensitive to the vascular space and therefore are not suitable for assessment of tissue oxygenation in the absence of functional erythrocyte perfused blood vessels, such as within necrotic tumor cores, which may often be present within metastatic H&N lymph nodes. In addition, there is uncertainty with regard to the appropriate value for the vascular factor (f vas ) used in the quadratic model of

T_{2}^{*}

dependence on fractional blood oxygenation 24, 26. Second, the measured

T_{2}^{*}

repeatability disregards the presence of true physiological fluctuations in blood flow within the tumor capillary network that lead to transient or cyclical hypoxia, which has been reported in a number of studies 16, 38.…”

Section: Discussionmentioning

confidence: 99%

“…In our simulations, a “tissue hematocrit” (H tiss ) was used, incorporating the BV fraction and a vascular factor (f vas = 0.85) to account for differences between erythrocyte concentration in large vessels and the tissue capillary network24, 26:

{normalH}_{tiss} = Hct \times BV \times {normalf}_{vas}

…”

Section: Methodsmentioning

confidence: 99%

“…In addition to the tumor vascular microenvironment, quantitation of

T_{2}^{*}

is also dependent on physiochemical and methodological parameters 14, 26, 27. Macroscopic magnetic field homogeneity resulting from the iterative shimming process affects the repeatability of

T_{2}^{*}

measurements.…”

mentioning

confidence: 99%

“…The measured

T_{2}^{*}

value within a voxel is a composite of spin relaxation rates within the intra‐ and extravascular tissue spaces, a consequence of the scanning spatial resolution. Spin relaxation in the extravascular space has a much weaker and variable dependency on blood oxygenation than that for the intravascular space within a tumor 10, 26…”

mentioning

confidence: 99%

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Repeatability and sensitivity of measurements in patients with head and neck squamous cell carcinoma at 3T

Panek

Welsh

Dunlop

et al. 2016

Magnetic Resonance Imaging

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PurposeTo determine whether quantitation of T2* is sufficiently repeatable and sensitive to detect clinically relevant oxygenation levels in head and neck squamous cell carcinoma (HNSCC) at 3T.Materials and MethodsTen patients with newly diagnosed locally advanced HNSCC underwent two magnetic resonance imaging (MRI) scans between 24 and 168 hours apart prior to chemoradiotherapy treatment. A multiple gradient echo sequence was used to calculate T2* maps. A quadratic function was used to model the blood transverse relaxation rate as a function of blood oxygenation. A set of published coefficients measured at 3T were incorporated to account for tissue hematocrit levels and used to plot the dependence of fractional blood oxygenation (Y) on T2* values, together with the corresponding repeatability range. Repeatability of T2* using Bland–Altman analysis, and calculation of limits of agreement (LoA), was used to assess the sensitivity, defined as the minimum difference in fractional blood oxygenation that can be confidently detected.Results T2* LoA for 22 outlined tumor volumes were 13%. The T2* dependence of fractional blood oxygenation increases monotonically, resulting in increasing sensitivity of the method with increasing blood oxygenation. For fractional blood oxygenation values above 0.11, changes in T2* were sufficient to detect differences in blood oxygenation greater than 10% (Δ T2* > LoA for ΔY > 0.1).ConclusionQuantitation of T2* at 3T can detect clinically relevant changes in tumor oxygenation within a wide range of blood volumes and oxygen tensions, including levels reported in HNSCC. J. Magn. Reson. Imaging 2016;44:72–80.

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T_{2}^{*}

dependence on fractional blood oxygenation 24, 26. Second, the measured

T_{2}^{*}

Section: Discussionmentioning

confidence: 99%

{normalH}_{tiss} = Hct \times BV \times {normalf}_{vas}

…”

Section: Methodsmentioning

confidence: 99%

“…In addition to the tumor vascular microenvironment, quantitation of

T_{2}^{*}

is also dependent on physiochemical and methodological parameters 14, 26, 27. Macroscopic magnetic field homogeneity resulting from the iterative shimming process affects the repeatability of

T_{2}^{*}

measurements.…”

mentioning

confidence: 99%

“…The measured

T_{2}^{*}

mentioning

confidence: 99%

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Repeatability and sensitivity of measurements in patients with head and neck squamous cell carcinoma at 3T

Panek

Welsh

Dunlop

et al. 2016

Magnetic Resonance Imaging

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show abstract

“…The flow and transverse relaxation data have been incorporated into a model of deoxyhemoglobin concentration, oxygen extraction, and consumption by numerous workers (Ogawa et al, 1993;Davis et al, 1998;Hoge et al, 1999;Oja et al, 1999) expressed in equation (1). The blood susceptibility-induced transverse relaxation rate, R 2 0 , is calculated from the time reversible gradient echo relaxation rate, R 2 *, and time irreversible spin echo intrinsic relaxation rate, R 2intrinsic , corrected by the loss of signal from B o homogeneity (An and Lin, 2002;Yablonskiy, 2002).…”

Section: Discussionmentioning

confidence: 99%

Human Cerebral Blood Flow and Metabolism in Acute Insulin-Induced Hypoglycemia

Kennan

Takahashi

Pan

et al. 2005

J Cereb Blood Flow Metab

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How the human brain functions under conditions of acute hypoglycemia remains a complex question by virtue of the potential simultaneous shifts in processes of perfusion, metabolism, and changing demand. We examined this issue by measuring cerebral blood flow (CBF) and oxidative metabolism (CMRO 2 ) in insulin-induced hypoglycemic (HG) and euglycemic (EG) conditions at rest and during motor activation in normal human subjects using magnetic resonance (MR). Experiments were performed on 12 subjects (9M, 3F). The protocol consisted of insulin-induced hypoglycemia (targeting a HG of 60 mg/dL) followed by euglycemia, or in reverse order, each phase lasting approximately 1.5 h. Euglycemia was performed with the same insulin infusion rate so as to match the hypoglycemic phase. Magnetic resonance data were acquired 30 mins after the target plasma glucose was achieved so as to minimize any acute effects. Although the depth of hypoglycemia achieved in the present study was relatively small, the present data found a significant increase in flow in motor cortex with mild hypoglycemia, from 56.4713.6 mL/100 g min (euglycemia) to 64.37 7.6 mL/100 g min (hypoglycemia). Using the Renkin-Crone exponential model of oxygen extraction with MR models of susceptibility-based relaxation, analysis of the flow measurements, relaxation and BOLD data also implied that throughout the studies, metabolism and flow remained coupled. Elementary motor task activation was not associated with any consistent larger activated flows. Thus it remains that although mild hypoglycemia induced an increase in basal flow and metabolism, a similar increase was not seen in task activation.

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Functional MRI

Jezzard¹,

Ramsey²

2003

Quantitative MRI of the Brain

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Determination of Oxygen Extraction Ratios by Magnetic Resonance Imaging

Cited by 96 publications

References 35 publications

Repeatability and sensitivity of measurements in patients with head and neck squamous cell carcinoma at 3T

Repeatability and sensitivity of measurements in patients with head and neck squamous cell carcinoma at 3T

Human Cerebral Blood Flow and Metabolism in Acute Insulin-Induced Hypoglycemia

Functional MRI

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