Identification of intratumour low frequency microvascular components via BOLD signal fractal dimension mapping

Wardlaw, Graeme; Wong, Raimond; Noseworthy, Michael D.

doi:10.1016/j.ejmp.2008.01.006

Cited by 15 publications

(7 citation statements)

References 14 publications

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“…It has been previously shown that evaluation of the BOLD signal temporal complexity highlights regions of potentially increased microvascular activity (vasodilation, flow, pO 2 fluctuations) using a frequency-based fractal dimension (FD) calculation. 50 Not only has this application proven useful for tumor evaluation, but it has also shown promise in studying brain microvasculature, 51,52 and in direct measurements of blood flow/oxygenation using implanted probes in murine tumors. [53][54][55] Recently we have shown that BOLD signal FD mapping is sensitive enough to show changes in muscle microvasculature, with only a moderate exercise challenge.…”

Section: Physiological Understanding Of Bold Signalmentioning

confidence: 99%

Advanced MR Imaging Techniques for Skeletal Muscle Evaluation

Noseworthy

Davis²,

Elzibak³

2010

Semin Musculoskelet Radiol

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Diagnostic imaging procedures for muscle evaluation have typically provided basic information concerning gross anatomical change resulting from pathology. Up until recently the musculoskeletal radiologist has been fairly limited to using simple proton-density weighted fat-saturated and short tau inversion recovery magnetic resonance imaging scans for assessment of skeletal muscle. Recent advances, however, have resulted in development of newer scans and postprocessing methods that provide much more than gross muscle structure. Scans providing fine structure, muscle function, and metabolism can easily be done using clinical scanners. Here we describe how diffusion tensor imaging (DTI) and blood oxygenation level-dependent (BOLD) imaging together can provide detailed information on muscle structural and functional changes. DTI is useful for visualizing muscle tears, and BOLD can be used for vascular insufficiency (e.g., compartment syndrome). In clinical sites that are gaining experience using these techniques, imaging of muscle pathology is becoming increasingly thorough. In the future, these methods will reduce the need for invasive approaches to study muscle pathology.

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Section: Physiological Understanding Of Bold Signalmentioning

confidence: 99%

Advanced MR Imaging Techniques for Skeletal Muscle Evaluation

Noseworthy

Davis²,

Elzibak³

2010

Semin Musculoskelet Radiol

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“…Stroke, transient ischemic attacks or other factors reducing regional perfusion increase the low-frequency vasomotion amplitude and reduce the dominant frequency (Hudetz et al, 1995; Liu et al, 2007). A lack of endothelium in tumor neovasculature induces extended hypoxic states that are also reflected in a BOLD signal as low-frequency events altering the temporal signal properties (Baudelet et al, 2006; Wardlaw et al, 2008). These metrics may reveal new pathological mechanisms and enable the detection of areas at risk of cerebrovascular incidents.…”

Section: Discussionmentioning

confidence: 99%

“…Indeed recently, the valuation of the microvascular state of rectal tumors have shown promising results (Wardlaw et al, 2008). As some of the changes in physiological low-frequency factors tend to occur over a wide range of low frequencies, instead of one single frequency, variables related to PSD trends and other features extracted from a temporal BOLD signal could be used as an improved marker of neurovascular integrity in tissue.…”

Section: Discussionmentioning

confidence: 99%

Mapping transient hyperventilation induced alterations with estimates of the multi-scale dynamics of BOLD signal.

Kiviniemi

Remes

Starck

et al. 2009

Front. Neuroinform.

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Temporal blood oxygen level dependent (BOLD) contrast signals in functional MRI during rest may be characterized by power spectral distribution (PSD) trends of the form 1/fα. Trends with 1/f characteristics comprise fractal properties with repeating oscillation patterns in multiple time scales. Estimates of the fractal properties enable the quantification of phenomena that may otherwise be difficult to measure, such as transient, non-linear changes. In this study it was hypothesized that the fractal metrics of 1/f BOLD signal trends can map changes related to dynamic, multi-scale alterations in cerebral blood flow (CBF) after a transient hyperventilation challenge. Twenty-three normal adults were imaged in a resting-state before and after hyperventilation. Different variables (1/f trend constant α, fractal dimension Df, and, Hurst exponent H) characterizing the trends were measured from BOLD signals. The results show that fractal metrics of the BOLD signal follow the fractional Gaussian noise model, even during the dynamic CBF change that follows hyperventilation. The most dominant effect on the fractal metrics was detected in grey matter, in line with previous hyperventilation vaso-reactivity studies. The α was able to differentiate also blood vessels from grey matter changes. Df was most sensitive to grey matter. H correlated with default mode network areas before hyperventilation but this pattern vanished after hyperventilation due to a global increase in H. In the future, resting-state fMRI combined with fractal metrics of the BOLD signal may be used for analyzing multi-scale alterations of cerebral blood flow.

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“…Significant disease-related changes in microvascular structure have been measured in the coronary circulation in cardiac hypertrophy and heart failure [24][25][26][27][28], pulmonary arterial hypertension [29], diabetic retinopathy and glaucoma [10,30], as well as in the liver, lung, and heart with aging [31][32][33]. Microvascular structure also has predictive diagnostic value, including distinguishing ischemic from non-ischemic tissue [34], differentiating healthy from cancerous tissue [35][36][37][38][39][40] or benign from malignant lesions [41], and in monitoring tumor treatment response [42][43][44]. Retinal vasculature fractal analysis was even shown to predict future coronary heart disease mortality [45].…”

Section: The Importance Of Vascular Complexity In Vascular-parenchymamentioning

confidence: 99%

Biofabrication strategies for creating microvascular complexity

2019

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Design and fabrication of effective biomimetic vasculatures constitutes a relevant and yet unsolved challenge, lying at the heart of tissue repair and regeneration strategies. Even if cell growth is achieved in 3D tissue scaffolds or advanced implants, tissue viability inevitably requires vascularization, as diffusion can only transport nutrients and eliminate debris within a few hundred microns. This engineered vasculature may need to mimic the intricate branching geometry of native microvasculature, referred to herein as vascular complexity, to efficiently deliver blood and recreate critical interactions between the vascular and perivascular cells as well as parenchymal tissues. This review first describes the importance of vascular complexity in labs-and organs-on-chips, the biomechanical and biochemical signals needed to create and maintain a complex vasculature, and the limitations of current 2D, 2.5D, and 3D culture systems in recreating vascular complexity. We then critically review available strategies for design and biofabrication of complex vasculatures in cell culture platforms, labs-and organs-on-chips, and tissue engineering scaffolds, highlighting their advantages and disadvantages. Finally, challenges and future directions are outlined with the hope of inspiring researchers to create the reliable, efficient and sustainable tools needed for design and biofabrication of complex vasculatures.

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Identification of intratumour low frequency microvascular components via BOLD signal fractal dimension mapping

Cited by 15 publications

References 14 publications

Advanced MR Imaging Techniques for Skeletal Muscle Evaluation

Advanced MR Imaging Techniques for Skeletal Muscle Evaluation

Mapping transient hyperventilation induced alterations with estimates of the multi-scale dynamics of BOLD signal.

Biofabrication strategies for creating microvascular complexity

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