Optical coherence Doppler tomography quantifies laser speckle contrast imaging for blood flow imaging in the rat cerebral cortex

Luo, Zhongchi; Wang, Zhenguo; Yuan, Zhijun; Du, Congwu; Pan, Yingtian

doi:10.1364/ol.33.001156

Cited by 19 publications

(13 citation statements)

References 9 publications

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“…LSCI has been compared with other applicable techniques like LDF and DOCT. [22,23] To the best of our knowledge, only 1 study has previously aimed LSCI to measure GTR in pigs. [13] The speckle-derived flow data, as reported in the porcine study, show that perfusion is greatest at the base of the gastric tube and progressively decreases towards the anastomosis and gastric tube tip area; this was also shown in other (non-LSCI) studies.…”

Section: Discussionmentioning

confidence: 99%

Laser speckle contrast imaging identifies ischemic areas on gastric tube reconstructions following esophagectomy

et al. 2016

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Gastric tube reconstruction (GTR) is a high-risk surgical procedure with substantial perioperative morbidity. Compromised arterial blood supply and venous congestion are believed to be the main etiologic factors associated with early and late anastomotic complications. Identifying low blood perfusion areas may provide information on the risks of future anastomotic leakage and could be essential for improving surgical techniques. The aim of this study was to generate a method for gastric microvascular perfusion analysis using laser speckle contrast imaging (LSCI) and to test the hypothesis that LSCI is able to identify ischemic regions on GTRs.Patients requiring elective laparoscopy-assisted GTR participated in this single-center observational investigation. A method for intraoperative evaluation of blood perfusion and postoperative analysis was generated and validated for reproducibility. Laser speckle measurements were performed at 3 different time pointes, baseline (devascularized) stomach (T0), after GTR (T1), and GTR at 20° reverse Trendelenburg (T2).Blood perfusion analysis inter-rater reliability was high, with intraclass correlation coefficients for each time point approximating 1 (P < 0.0001). Baseline (T0) and GTR (T1) mean blood perfusion profiles were highest at the base of the stomach and then progressively declined towards significant ischemia at the most cranial point or anastomotic tip (P < 0.01). After GTR, a statistically significant improvement in mean blood perfusion was observed in the cranial gastric regions of interest (P < 0.05). A generalized significant decrease in mean blood perfusion was observed across all GTR regions of interest during 20° reverse Trendelenburg (P < 0.05).It was feasible to implement LSCI intraoperatively to produce blood perfusion assessments on intact and reconstructed whole stomachs. The analytical design presented in this study resulted in good reproducibility of gastric perfusion measurements between different investigators. LSCI provides spatial and temporal information on the location of adequate tissue perfusion and may thus be an important aid in optimizing surgical and anesthesiological procedures for strategically selecting anastomotic site in patients undergoing esophagectomy with GTR.

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Section: Discussionmentioning

confidence: 99%

Laser speckle contrast imaging identifies ischemic areas on gastric tube reconstructions following esophagectomy

et al. 2016

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“…To minimize this confound and make it relevant to fMRI studies we chose α-chloralose, which has been widely used for rodent fMRI studies because (i) it preserves metabolic coupling for somatosensory stimulation (21), (ii) it provides a normal CBF baseline close to that measured in the awake state compared with other anesthetic agents such as isoflurane (22), and (iii) it preserves cerebrovascular reactivity (23). In addition, because of the slow Ca 2+ i acquisition rate used, we cannot rule out the possibility that the "slow" Ca 2+ i oscillations might be due to folding over from higher- (49). It may be that changes in RBC velocity are not reflecting changes in total blood flow through the capillary bed.…”

Section: Discussionmentioning

confidence: 99%

Low-frequency calcium oscillations accompany deoxyhemoglobin oscillations in rat somatosensory cortex

Volkow

Koretsky

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Spontaneous low-frequency oscillations (LFOs) of blood-oxygenlevel-dependent (BOLD) signals are used to map brain functional connectivity with functional MRI, but their source is not well understood. Here we used optical imaging to assess whether LFOs from vascular signals covary with oscillatory intracellular calcium (Ca 2+ i ) and with local field potentials in the rat's somatosensory cortex. We observed that the frequency of Ca 2+ i oscillations in tissue (∼0.07 Hz) was similar to the LFOs of deoxyhemoglobin (HbR) and oxyhemoglobin (HbO 2 ) in both large blood vessels and capillaries. The HbR and HbO 2 fluctuations within tissue correlated with Ca 2+ i oscillations with a lag time of ∼5-6 s. The Ca 2+ i and hemoglobin oscillations were insensitive to hypercapnia. In contrast, cerebral-blood-flow velocity (CBFv) in arteries and veins fluctuated at a higher frequency (∼0.12 Hz) and was sensitive to hypercapnia. However, in parenchymal tissue, CBFv oscillated with peaks at both ∼0.06 Hz and ∼0.12 Hz. Although the higher-frequency CBFv oscillation (∼0.12 Hz) was decreased by hypercapnia, its lower-frequency component (∼0.06 Hz) was not. The sensitivity of the higher CBF V oscillations to hypercapnia, which triggers blood vessel vasodilation, suggests its dependence on vascular effects that are distinct from the LFOs detected in HbR, HbO 2 , Ca 2+ i , and the lower-frequency tissue CBFv, which were insensitive to hypercapnia. Hemodynamic LFOs correlated both with Ca 2+ i and neuronal firing (local field potentials), indicating that they directly reflect neuronal activity (perhaps also glial). These findings show that HbR fluctuations (basis of BOLD oscillations) are linked to oscillatory cellular activity and detectable throughout the vascular tree (arteries, capillaries, and veins).spontaneous low-frequency brain oscillations | resting-state functional connectivity | neuronal calcium | cerebral hemodynamic | neuroimaging M easures of resting-state functional connectivity with functional MRI (fMRI) are based on spontaneous low-frequency blood-oxygen-level-dependent (BOLD) oscillations that occur throughout the brain with the assumption that regions with correlated oscillations are functionally connected (1, 2). The networks that emerge from resting-state functional connectivity correspond roughly with neuroanatomical connectivity (3, 4) and are modified by brain diseases (5-7). BOLD signals in fMRI reflect the interplay between hemodynamics (including blood volume and velocity of blood flowing in the vessels) and cellular (neuronal and glial) metabolism, which affect the amount of deoxygenated hemoglobin (HbR) in brain tissue that leads to changes in BOLD fMRI (8,9). Human studies using near-infrared spectroscopy (NIRS) (10) have reported low-frequency oscillations (LFOs) of ∼0.04-0.1 Hz for oxygenated hemoglobin (HbO 2 ) and HbR in the brain consistent with those measured by BOLD (11). However, there is still no quantitative understanding of the relative direct contribution of spontaneous oscillations in cellular...

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“…More specifically, the long-lasting interruption in flow observed in some of the vessels, if it is exacerbated with repeated cocaine use could result in microischemic dysfunction and if prolonged could lead to neuronal death and loss of function. We had previously used Doppler OCT to show decreases in CBF after acute cocaine, 18, 21, 22 but the limited resolution and sensitivity did not allow us to measure the effects of cocaine on capillary beds. In the current study the enhanced capabilities of μOCA/μODT allowed us to document cocaine-induced microischemic events in capillaries and to show marked differences in the responses to cocaine between arterioles, venules and capillaries in the cerebrovascular networks (Figs.4–5).…”

Section: Discussionmentioning

confidence: 99%

Cocaine-induced cortical microischemia in the rodent brain: clinical implications

Ren

Yuan

et al. 2011

Mol Psychiatry

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Cocaine-induced stroke is among the most serious medical complications associated with its abuse. However the extent to which acute cocaine may induce silent microischemia predisposing the cerebral tissue to neurotoxicity has not been investigated; in part, because of limitations of current neuroimaging tools, i.e., lack of high spatiotemporal resolution and sensitivity to simultaneously measure cerebral blood flow (CBF) in vessels of different calibers (including capillaries) quantitatively and over a large field of view. Here we combine ultrahigh-resolution optical coherence tomography to enable tracker-free 3D microvascular angiography (μOCA) and a new phase-intensity-mapping algorithm to enhance the sensitivity of 3D optical Doppler tomography (μODT) for simultaneous capillary CBF quantization. We apply the technique to study the responses of cerebral microvascular networks to single and repeated cocaine administration in the mouse somatosensory cortex. We show that within 2–3 minutes after cocaine administration CBF markedly decreased (e.g., ~70%) but the magnitude and recovery differed for the various types of vessels; arterioles had the fastest recovery (~5min), capillaries varied drastically (from 4–20min) and venules showed relatively slower recovery (~12min). More importantly, we showed that cocaine interrupted CBF in some arteriolar branches for over 45min and this effect was exacerbated with repeated cocaine administration. These results provide evidence that cocaine doses within the range administered by drug abusers induces cerebral microischemia and that these effects are exacerbated with repeated use. Thus cocaine-induced microischemia is likely to be a contributor to its neurotoxic effects.

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Optical coherence Doppler tomography quantifies laser speckle contrast imaging for blood flow imaging in the rat cerebral cortex

Cited by 19 publications

References 9 publications

Laser speckle contrast imaging identifies ischemic areas on gastric tube reconstructions following esophagectomy

Laser speckle contrast imaging identifies ischemic areas on gastric tube reconstructions following esophagectomy

Low-frequency calcium oscillations accompany deoxyhemoglobin oscillations in rat somatosensory cortex

Cocaine-induced cortical microischemia in the rodent brain: clinical implications

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