Theoretical and experimental investigation of the VASO contrast mechanism

Donahue, Manus J.; Lu, Hanzhang; Jones, Craig K.; Edden, Richard A.E.; Pekar, James J.; Zijl, Peter C.M. van

doi:10.1002/mrm.21072

Cited by 147 publications

(264 citation statements)

References 38 publications

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“…Note that the ATT reduction should reduce both the t a and t d terms equally. For VASO-FLAIR, the CBV quantification procedure has been outlined previously (Donahue et al, 2006); however, the salient aspects of this procedure and required assumptions are briefly reproduced here. The signal in the VASO-FLAIR experiment can be written,…”

Section: Interpreting Cerebral Blood Flow-weighted Arterial Spin Labementioning

confidence: 99%

“…where C GM = 0.89 mL water/mL gray matter and C b = 0.87 mL water/mL blood are the gray matter parenchyma and blood water densities, respectively (Donahue et al, 2006); CBV GM is the gray matter parenchymal CBV, TE = 40 milliseconds is the echo time, T base 2;GM = 70.8 milliseconds and T act 2;GM = 71.4 milliseconds are the transverse relaxation times of gray matter at 3.0T as measured previously (Donahue et al, 2006), and M z,GM is the longitudinal magnetization of blood water in the steadystate double inversion recovery VASO-FLAIR experiment,…”

Section: Interpreting Cerebral Blood Flow-weighted Arterial Spin Labementioning

confidence: 99%

“…In this model, we have neglected the effect of exchange and fresh blood water inflow, which have both been shown to be small at TR = 5,000 milliseconds (Donahue et al, 2006(Donahue et al, , 2009b. Finally, the CBV change can be estimated from the measured signal change,…”

Section: Interpreting Cerebral Blood Flow-weighted Arterial Spin Labementioning

confidence: 99%

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Visualization of Altered Neurovascular Coupling in Chronic Stroke Patients using Multimodal Functional MRI

Blicher

Stagg

O’Shea

et al. 2012

J Cereb Blood Flow Metab

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Evaluation of cortical reorganization in chronic stroke patients requires methods to accurately localize regions of neuronal activity. Blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is frequently employed; however, BOLD contrast depends on specific coupling relationships between the cerebral metabolic rate of oxygen (CMRO 2 ), cerebral blood flow (CBF), and volume (CBV), which may not exist following stroke. The aim of this study was to understand whether CBF-weighted (CBFw) and CBV-weighted (CBVw) fMRI could be used in sequence with BOLD to characterize neurovascular coupling mechanisms poststroke. Chronic stroke patients (n = 11) with motor impairment and age-matched controls (n = 11) performed four sets of unilateral motor tasks (60 seconds/30 seconds off/on) during CBFw, CBVw, and BOLD fMRI acquisition. While control participants elicited mean BOLD, CBFw, and CBVw responses in motor cortex (P < 0.01), patients showed only mean changes in CBF (P < 0.01) and CBV (P < 0.01), but absent mean BOLD responses (P = 0.20). BOLD intersubject variability was consistent with differing coupling indices between CBF, CBV, and CMRO 2 . Thus, CBFw and/or CBVw fMRI may provide crucial information not apparent from BOLD in these patients. A table is provided outlining distinct vascular and metabolic uncoupling possibilities that elicit different BOLD responses, and the strengths and limitations of the multimodal protocol are summarized.

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Section: Interpreting Cerebral Blood Flow-weighted Arterial Spin Labementioning

confidence: 99%

Section: Interpreting Cerebral Blood Flow-weighted Arterial Spin Labementioning

confidence: 99%

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Visualization of Altered Neurovascular Coupling in Chronic Stroke Patients using Multimodal Functional MRI

Blicher

Stagg

O’Shea

et al. 2012

J Cereb Blood Flow Metab

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“…For GMN technique, the signal from CSF leads to an underestimated signal change in CBV, because the CSF signal is of the same sign as the blood signal. Contamination of CSF signal in VASO fMRI causes an overestimation of CBV because of the opposite sign to the detected parenchymal MRI signal (Donahue et al, 2006b). The CSF effect is proportionally larger in GMN fMRI than in VASO, because shorter TI is used that leads to a large negative CSF signal in the former technique.…”

Section: Discussionmentioning

confidence: 99%

A Functional Magnetic Resonance Imaging Technique Based on Nulling Extravascular Gray Matter Signal

Shen

Kauppinen

Vidyasagar

et al. 2008

J Cereb Blood Flow Metab

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A new functional magnetic resonance imaging (fMRI) technique is proposed based on nulling the extravascular gray matter (GM) signal, using a spatially nonselective inversion pulse. The remaining MR signal provides cerebral blood volume (CBV) information from brain activation. A theoretical framework is provided to characterize the sources of GM-nulled (GMN) fMRI signal, effects of partial voluming of cerebrospinal fluid (CSF) and white matter, and behaviors of GMN fMRI signal during brain activation. Visual stimulation paradigm was used to explore the GMN fMRI signal behavior in the human brain at 3T. It is shown that the GMN fMRI signal increases by 7.2% ± 1.5%, which is two to three times more than that obtained with vascular space occupancy (VASO)-dependent fMRI (À3.2% ± 0.2%) or blood oxygenation level-dependent (BOLD) fMRI (2.9% ± 0.7%), using a TR of 3,000 ms and a resolution of 2¾2¾5 mm 3 . Under these conditions the fMRI signal-to-noise ratio (SNR fMRI ) for BOLD, GMN, and VASO images was 4.97 ± 0.76, 4.56 ± 0.86, and 2.43 ± 1.06, respectively. Our study shows that both signal intensity and activation volume in GMN fMRI depend on spatial resolution because of partial voluming from CSF. It is shown that GMN fMRI is a convenient tool to assess CBV changes associated with brain activation.

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“…[36][37][38][39][40][41][42][43][44] Additionally, concentration of other molecules relevant to lymphatic function will influence the water T 2 . It has been shown that in agarose phantoms water T 2 increases with increasing levels of NaCl.…”

Section: Physiology Of Deep and Superficial T 2 Changesmentioning

confidence: 99%

Bilateral Changes in Deep Tissue Environment After Manual Lymphatic Drainage in Patients with Breast Cancer Treatment-Related Lymphedema

Donahue

Crescenzi

Scott

et al. 2017

Lymphatic Research and Biology

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Background: Breast cancer treatment-related lymphedema (BCRL) arises from a mechanical insufficiency following cancer therapies. Early BCRL detection and personalized intervention require an improved understanding of the physiological processes that initiate lymphatic impairment. Here, internal magnetic resonance imaging (MRI) measures of the tissue microenvironment were paired with clinical measures of tissue structure to test fundamental hypotheses regarding structural tissue and muscle changes after the commonly used therapeutic intervention of manual lymphatic drainage (MLD). Methods and Results: Measurements to identify lymphatic dysfunction in healthy volunteers (n = 29) and patients with BCRL (n = 16) consisted of (1) limb volume, tissue dielectric constant, and bioelectrical impedance (i.e., non-MRI measures); (2) qualitative 3 Tesla diffusion-weighted, T 1 -weighted and T 2 -weighted MRI; and (3) quantitative multi-echo T 2 MRI of the axilla. Measurements were repeated in patients immediately following MLD. Normative control and BCRL T 2 values were quantified and a signed Wilcoxon Rank-Sum test was applied (significance: two-sided p < 0.05). Non-MRI measures yielded significant capacity for discriminating between arms with versus without clinical signs of BCRL, yet yielded no change in response to MLD. Alternatively, a significant increase in deep tissue T 2 on the involved (pre T 2 = 0.0371 -0.003 seconds; post T 2 = 0.0389 -0.003; p = 0.029) and contralateral (pre T 2 = 0.0365 -0.002; post T 2 = 0.0395 -0.002; p < 0.01) arms was observed. Trends for larger T 2 increases on the involved side after MLD in patients with stage 2 BCRL relative to earlier stages 0 and 1 BCRL were observed, consistent with tissue composition changes in later stages of BCRL manifesting as breakdown of fibrotic tissue after MLD in the involved arm. Contrast consistent with relocation of fluid to the contralateral quadrant was observed in all stages. Conclusion: Quantitative deep tissue T 2 MRI values yielded significant changes following MLD treatment, whereas non-MRI measurements did not vary. These findings highlight that internal imaging measures of tissue composition may be useful for evaluating how current and emerging therapies impact tissue function.

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Theoretical and experimental investigation of the VASO contrast mechanism

Cited by 147 publications

References 38 publications

Visualization of Altered Neurovascular Coupling in Chronic Stroke Patients using Multimodal Functional MRI

Visualization of Altered Neurovascular Coupling in Chronic Stroke Patients using Multimodal Functional MRI

A Functional Magnetic Resonance Imaging Technique Based on Nulling Extravascular Gray Matter Signal

Bilateral Changes in Deep Tissue Environment After Manual Lymphatic Drainage in Patients with Breast Cancer Treatment-Related Lymphedema

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