A mathematical analysis on the biological zero problem in laser Doppler flowmetry

Zhong, Jicun; Seifalian, AM; Salerud, Göran; Nilsson, Gert

doi:10.1109/10.661160

Cited by 48 publications

(14 citation statements)

References 6 publications

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“…This residue is possibly due to scatter motions in tissue that are not blood flow, such as random motions of red blood cells and other tissue organelles. A portion of these motions has been dubbed biological zero, because it is observed in freshly sacrificed model organisms, such as with laser Doppler flowmetry (82,83). The present study does not measure the true biological zero, because living tissues will have dynamic signals unrelated to blood flow, although the present study does place an upper bound of ~10% on this parameter.…”

Section: Discussionmentioning

confidence: 99%

Blood Flow Reduction in Breast Tissue due to Mammographic Compression

et al. 2014

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Rationale and objectives This study measures hemodynamic properties such as blood flow and hemoglobin concentration and oxygenation in the healthy human breast under a wide range of compressive loads. Because many breast-imaging technologies derive contrast from the deformed breast, these load-dependent vascular responses affect contrast agent–enhanced and hemoglobin-based breast imaging. Methods Diffuse optical and diffuse correlation spectroscopies were used to measure the concentrations of oxygenated and deoxygenated hemoglobin, lipid, water, and microvascular blood flow during axial breast compression in the parallel-plate transmission geometry. Results Significant reductions (P < .01) in total hemoglobin concentration (~30%), blood oxygenation (~20%), and blood flow (~87%) were observed under applied pressures (forces) of up to 30 kPa (120 N) in 15 subjects. Lipid and water concentrations changed <10%. Conclusions Imaging protocols based on injected contrast agents should account for variation in tissue blood flow due to mammographic compression. Similarly, imaging techniques that depend on endogenous blood contrasts will be affected by breast compression during imaging.

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Section: Discussionmentioning

confidence: 99%

Blood Flow Reduction in Breast Tissue due to Mammographic Compression

et al. 2014

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“…1), indicating the presence of a ‘biological zero' that needs to be taken into account when using the LSCI technique. The biological zero has been the subject of many studies using laser Doppler flow and has been suggested as consisting of Brownian motions of molecules as well as local redistribution of blood cells within vessels [22,23]. The interpretation and handling of the biological zero is still under debate, but it has been proposed that the underlying mechanism causing the biological zero may not be probed in the same way by the laser Doppler flow and LSCI techniques [24].…”

Section: Discussionmentioning

confidence: 99%

Laser Speckle Contrast Imaging for Monitoring Changes in Microvascular Blood Flow

et al. 2016

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Background/Aims: Microvascular blood flow is essential for healing and predicts surgical outcome. The aim of the current study was to investigate the relation between fluxes measured with the laser speckle contrast imaging (LSCI) technique and changes in absolute blood flow. In addition, we studied the reproducibility of the LSCI technique when assessing the intra-abdominal microcirculation of the pig. Methods: During trial 1, a fish gill arch was mechanically perfused with heparinized fish blood under controlled stepwise-altered flow rates alongside mechanically induced movement artefacts. The microcirculation of the fish gill was simultaneously assessed with the LSCI technique. In trial 2, microcirculation was measured in the stomach, liver, and small intestine of 10 pigs by two observers. Results: A linear correlation was observed between flux and volumetric flow. During conditions of no volumetric flow, the high recording speed with the LSCI technique registered the movement artefacts as flow signals. The LSCI measurements showed good correlation and agreement between the two observers when assessing microcirculation in the stomach, liver, and small intestine (r² = 0.857, 0.956, and 0.946; coefficients of variation = 6.0, 3.2, and 6.4%, respectively). Conclusion: Due to the non-contact and real-time assessment over large areas, LSCI is a promising technique for the intraoperative assessment of intra-abdominal microcirculation. A linear correlation between flux and volumetric flow was found, in accordance with previous experimental studies. However, movement artefacts affect flux measurements, and the choice of the sampling speed must be made with care, depending on the given setting.

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“… 40 How to interpret and handle the biological zero is under debate and needs to be investigated further. 55 , 56 …”

Section: Ldpimentioning

confidence: 99%

Non-invasive imaging of microcirculation: a technology review

Eriksson¹,

Nilsson²,

Sturesson³

2014

MDER

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Microcirculation plays a crucial role in physiological processes of tissue oxygenation and nutritional exchange. Measurement of microcirculation can be applied on many organs in various pathologies. In this paper we aim to review the technique of non-invasive methods for imaging of the microcirculation. Methods covered are: videomicroscopy techniques, laser Doppler perfusion imaging, and laser speckle contrast imaging. Videomicroscopy techniques, such as orthogonal polarization spectral imaging and sidestream dark-field imaging, provide a plentitude of information and offer direct visualization of the microcirculation but have the major drawback that they may give pressure artifacts. Both laser Doppler perfusion imaging and laser speckle contrast imaging allow non-contact measurements but have the disadvantage of their sensitivity to motion artifacts and that they are confined to relative measurement comparisons. Ideal would be a non-contact videomicroscopy method with fully automatic analysis software.

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A mathematical analysis on the biological zero problem in laser Doppler flowmetry

Cited by 48 publications

References 6 publications

Blood Flow Reduction in Breast Tissue due to Mammographic Compression

Blood Flow Reduction in Breast Tissue due to Mammographic Compression

Laser Speckle Contrast Imaging for Monitoring Changes in Microvascular Blood Flow

Non-invasive imaging of microcirculation: a technology review

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