Multi-level optical angiography for photodynamic therapy

Abstract

Blood flow imaging is widely applied in photodynamic therapy (PDT) to provide vascular morphological and statistical parameters. This approach relies on the intensity of time-domain signal differences between blood vessels and background tissues; therefore, it often ignores differences within the vasculature and cannot accommodate abundant structural information. This study proposes a multi-level optical angiography (MOA) method for PDT. It can enhance capillaries and image vessels at different levels by measuring the signal frequency shift associated with red blood cell motion. The experimental results regarding the PDT-induced chorioallantoic membrane model showed that the proposed method could not only perform multi-level angiography but also provide more accurate quantitative information regarding various vascular parameters. This MOA method has potential applications in PDT studies.

Lateralization of cortical activity, networks, and hemodynamic lag after stroke: A resting‐state fNIRS study

“…Because the time series of the middle 8-min (approximately equal to 500 s) was more stable compared to the first and last 1 min, the signal of the middle 8-min was chosen for subsequent analysis. The overall preprocessing steps were consistent with a previous study [29] and were briefly summarized:…”

“…Statistical analyses were performed at the level of all channels' mean value in cortical regions, as it can improve the results reliability compared to the singlechannel level [29]. For the comparison of metrics between the stroke group and the control group, such as WA and WA laterality, independent sample t test was applied.…”

“…CAR, common average reference; fNIRS, functional near-infrared spectroscopy; HbO 2 , hemoglobin; HbR, deoxyhemoglobin; HMS, hemodynamic modality separation; PCA, principal component analysis. between the two signals, which took the range of 0-1, with the larger value of the phase difference tended to be more constant, implying a higher level of functional connectivity [29]. The functional connectivity-based laterality was measured by the hemispheric autonomy coefficient:…”

Effects of different frequencies music on cortical responses and functional connectivity in patients with minimal conscious state

“…If a musical intervention activates a particular cortex, a corresponding hemodynamic response that can be observed by the fNIRS technique is produced. Although the discharge frequency of the auditory nerve varies with the frequency of the sound [28], the hemodynamic response that is transmitted to the auditory cortex and affects other cortical areas is still in the frequency range of less than 0.2 Hz [29] [30], and the sampling rate of 10 Hz or higher of commonly used fNIRS devices is sufficient to ensure the accuracy of this process measurement. We hypothesized that music interventions of different frequencies would evoke cortical responses at different locations and different degrees in MCS patients, as well as synergistic differences between cortical regions, which could be distinguished by changes in hemoglobin concentration monitored by fNIRS.…”