Quantification of regional blood volumes by rapid <i>T</i><sub>1</sub> mapping

Schwarzbauer, Christian; Syha, Jutta; Haase, Axel

doi:10.1002/mrm.1910290521

Cited by 92 publications

(77 citation statements)

References 15 publications

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“…Recirculation presents a particularly difficult challenge for measurement of CBV by bolus tracking techniques, especially when CBV is low and the mean transit time is prolonged so that extrapolation of the bolus curve is particularly uncertain. On the other hand, steady-state experiments require 20 min for complete dispersal into the entire volume of distribution for the contrast agent, giving rise to issues such as subject sedation, crossing of small contrast molecules across the blood-brain barrier, and glomerular filtration (13,14,(32)(33)(34). These problems are avoided by use of the short infusion.…”

Section: Discussionmentioning

confidence: 99%

Cerebral blood volume measurements by rapid contrast infusion and T‐weighted echo planar MRI

Tudorica

Li²,

Hospod³

et al. 2002

Magnetic Resonance in Med

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Cerebral blood volume (CBV) provides information complementary to that of cerebral blood flow in cerebral ischemia, tumors, and other conditions. We have developed an alternative theory and method for measuring CBV based on dynamic imaging by MRI or CT during a short contrast infusion. This method avoids several limitations of traditional approaches that involve waiting for steady state or measuring the area under the curve (AUC) during bolus contrast injection. Anesthetized dogs were studied by T* 2 -weighted echo planar imaging during gadolinium-DTPA infusions lasting 30 -60 sec. CBV was calculated from the ratio of the signal changes in tissue and artery. Method responsiveness was compared to AUC measurements using the vasodilator acepromazine. The ratio of signal change in tissue to that in artery rapidly approached an asymptotic value even while the amount of contrast in artery continued to increase. Using 30-sec infusions, the mean (؎SD) of CBV for control animals was 3.6 ؎ 0.9 ml blood/100 g tissue in gray matter and 2.3 ؎ 0.8 ml blood/100 g tissue in white matter (ratio ‫؍‬ 1.6). Acepromazine increased CBV to 5.7 ؎ 1.5 ml blood/100 g tissue in gray matter and 3.1 ؎ 0.8 ml blood/100 g tissue in white matter (ratio ‫؍‬ 2.0). AUC measurements after bolus injection yielded similar values for control animals but failed to demonstrate any change after acepromazine. It is possible to measure CBV using dynamic MRI or CT during 30 -60-sec contrast infusions. This method may be more sensitive to changes in CBV than traditional AUC methods.

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Section: Discussionmentioning

confidence: 99%

Cerebral blood volume measurements by rapid contrast infusion and T‐weighted echo planar MRI

Tudorica

Li²,

Hospod³

et al. 2002

Magnetic Resonance in Med

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“…Typically, studies of fractional blood volume (V b ) assume that the exchange rate between compartments is either very high (fast exchange) (6,8) or insignificant (no exchange) (7,9 -12). Since most living tissues do not exhibit such extreme exchange characteristics (6,(12)(13)(14), neither of these assumptions accurately describes the biological system.…”

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confidence: 99%

Water exchange and inflow affect the accuracy of T₁‐GRE blood volume measurements: Implications for the evaluation of tumor angiogenesis

Kim

Rebro

Schmainda

2002

Magnetic Resonance in Med

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The goal of this study was to determine the degree to which vascular water exchange and blood flowing into an imaging slice affect the accuracy of blood volume measurements of brain and tumor tissue when using intravascular T 1 contrast agents. The study was performed using 2D and 3D gradientecho imaging sequences, since these are two of the most commonly used MRI methods used to evaluate tissue blood volume fraction. Computer simulations were performed and measurements made in a rat 9L gliosarcoma brain tumor model. The computer simulations demonstrate that, with either water exchange or inflow effects alone, the dependence on the physiologic and imaging parameters can be well characterized and therefore potentially offset. In the exchange only case, the parametric dependence of 3D simulations suggest that the best accuracy is achieved with high flip angles, short TR, and low blood contrast agent concentrations. However, for a 2D GRE sequence which is influenced by both water exchange and inflow, the simulations predict that the error trend as a function of the imaging and physiologic parameters is unpredictable and therefore difficult to compensate. With both 2D and 3D GRE the measured blood volume data in rat brain and tumor tissue demonstrate tissue-specific trends, which reflect differences in the considered physiologic parameters. The experimental data strongly support the computer simulations and also indicate that minimization of the physiological effects by proper selection of imaging parameters, contrast concentration, and volume calculation methods is crucial for accurate assessment of absolute blood volume fraction. Magn Reson Med 47: 1110 -1120, 2002.

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“…Under the assumption of water being in the fast exchange regime between all the tumor compartments, the concentration of the high MW contrast agent within a voxel is proportional to the changes in relaxation rate (1/T 1 ) before and after administration of the contrast agent. Relaxation rates can then be computed directly using either dynamic [94], or steady-state T 1 MRI [95] and spatial maps of tumor vascular volume and PS constructed after fitting to the appropriate kinetic model. Assuming negligible reflux of the contrast agent and constant blood concentrations of the agent for the duration of the MR experiment, the contrast agent uptake within the tissue of interest can be modeled as a linear function of time.…”

Section: Magnetic Resonance Imagingmentioning

confidence: 99%

Circulating and imaging markers for angiogenesis

Pathak

Hochfeld

et al. 2008

Angiogenesis

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Abundant preclinical and indirect clinical data have for several decades convincingly supported the notion that anti-angiogenesis is an effective strategy for the inhibition of tumor growth. The recent success achieved in patients with metastatic colon carcinoma using a neutralizing antibody directed against vascular endothelial growth factor (VEGF) has translated preclinical optimism into a clinical reality.With this transformation in the field of angiogenesis has come a need for reliable surrogate markers. A surrogate marker by definition serves as a substitute for the underlying process in question, and in the case of angiogenesis, microvessel density (usually in so-called "hot-spots") has until now been the most widely used parameter. However, this parameter is more akin to a static "snapshot" and does not lend itself either to the dynamic in situ assessment of the status of the tumor microvasculature or to the molecular factors that regulate its growth and involution. This has led to an acute need for developing circulating and imaging markers of angiogenesis that can be monitored in vivo at repeated intervals in large number of patients with a variety of tumors in a non-invasive manner. Such markers of angiogenesis are the subject of this review.

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Quantification of regional blood volumes by rapid T₁ mapping

Cited by 92 publications

References 15 publications

Cerebral blood volume measurements by rapid contrast infusion and T‐weighted echo planar MRI

Cerebral blood volume measurements by rapid contrast infusion and T‐weighted echo planar MRI

Water exchange and inflow affect the accuracy of T₁‐GRE blood volume measurements: Implications for the evaluation of tumor angiogenesis

Circulating and imaging markers for angiogenesis

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Quantification of regional blood volumes by rapid T1 mapping

Cited by 92 publications

References 15 publications

Cerebral blood volume measurements by rapid contrast infusion and T‐weighted echo planar MRI

Cerebral blood volume measurements by rapid contrast infusion and T‐weighted echo planar MRI

Water exchange and inflow affect the accuracy of T1‐GRE blood volume measurements: Implications for the evaluation of tumor angiogenesis

Circulating and imaging markers for angiogenesis

Contact Info

Product

Resources

About

Quantification of regional blood volumes by rapid T₁ mapping

Water exchange and inflow affect the accuracy of T₁‐GRE blood volume measurements: Implications for the evaluation of tumor angiogenesis