Browsing by Author "Li, Meng-Lin"

Now showing 1 - 10 of 10

A novel multifunctional nano-platform with enhanced anti-cancer and photoacoustic imaging modalities using gold-nanorod-filled silica nanobeads
(2013)
Chen, Po-Jung
;
Hu, Shang-Hsiu
;
Fan, Chih-Tai
;
Li, Meng-Lin
;
Chen, You-Yin
The novel nano-seaurchin structure is characteristic of high-density and well-dispersed gold nanorods in one mesoporous silica nanobead. This nanoplatform provided increased photothermal stability, stable photoacoustic signal and highly efficient hyperthermia effect both in vitro and in vivo, indicating a powerful theranostic modality.
Functional photoacoustic micro-imaging of rat cerebral hemodynamic response function in single vessels during forepaw electrical stimulation
(2012)
Liao, Lun-De
;
Chen, You-Yin
;
Lin, Chin-Teng
;
Chang, Jyh-Yeong
;
Li, Meng-Lin
The specificity of the hemodynamic response function (HRF) is determined spatially by the vascular architecture and temporally by the evolution of hemodynamic changes. Here, we used functional photoacoustic microscopy (fPAM) to investigate the spatiotemporal evolution of the HRFs of hemoglobin concentration (HbT), cerebral blood volume (CBV) and hemoglobin oxygen saturation (SO2) in single cerebral vessels to rat left-forepaw stimulation. The HRF changes in specific cerebral vessels responding to different stimulation intensities and durations were bilaterally imaged with 36 x 65-mu m spatial resolution. Various electrical stimulations were applied with stimulation intensities at 1, 2, 6 and 10-mA combined with 5-s and 15-s stimulation durations, respectively. Our main findings were as follows: 1) the functional HbT and SO2 increased sub-linearly with increasing stimulus intensities and 2) the results suggested that the CBV changes are more linearly correlated with arterioles than HbT and SO2 within a limited dynamic range of stimulation intensities and duration. The findings in this study indicate that the regulation of hemodynamic changes in single cerebral vessels can be reliable studied by the fPAM technique without the use of contrast agents.
Functional transcranial photoacoustic micro-imaging of mouse cerebrovascular cross-section and hemoglobin oxygenation changes during forepaw electrical stimulation
(2011)
Liao, Lun-De
;
Chen, You-Yin
;
Lin, Chin-Teng
;
Chang, Jyh-Yeong
;
Li, Meng-Lin
In this study, we report on using a 50-MHz functional photoacoustic microscopy (PAM) to transcranially image the cross-section and hemoglobin oxygenation (SO(2)) changes of single mouse cortical vessels in response to left forepaw electrical stimulation. Three difference levels of the cortical vessels (i.e., with different-sized diameters of 350, 100 and 55 mu m) on activated regions were marked to measure their functional cross-section and SO(2) changes as a function of time. Electrical stimulation of the mouse left forelimb was applied to evoke functional changes in vascular dynamics of the mouse somatosensory cortex. The applied current pulses were with a pulse frequency of 3 Hz, pulse duration of 0.2 ms, and pulse amplitude of 2 mA. The cerebrovascular cross-section changes, which indicate changes in cerebral blood volume (CBV), were probed by images acquired at 570 nm, a hemoglobin isosbestic point, while SO(2) changes were monitored by the derivatives of 560-nm images normalized to 570-nm ones. The results show that vessel diameter and SO(2) were significantly dilated and increased when compared with those of the controlled ones. In summary, the PAM shows its promise as a new imaging modality for transcranially functional quantification of single vessel diameter (i.e., CBV) and SO(2) changes without any contrast agents applied during stimulation.
Imaging brain hemodynamic changes during rat forepaw electrical stimulation using functional photoacoustic microscopy
(2010-08-15)
Liao, Lun-De
;
Li, Meng-Lin
;
Lai, Hsin-Yi
;
Shih, Yen-Yu I.
;
Lo, Yu-Chun
The present study reported the development of a novel functional photoacoustic microscopy (fPAM) system for investigating hemodynamic changes in rat cortical vessels associated with electrical forepaw stimulation. Imaging of blood optical absorption by fPAM at multiple appropriately-selected and distinct wavelengths can be used to probe changes in total hemoglobin concentration (HbT, i.e., cerebral blood volume [CBV]) and hemoglobin oxygen saturation (SO(2)). Changes in CBV were measured by images acquired at a wavelength of 570 nm (lambda(570)), an isosbestic point of the molar extinction spectra of oxy- and deoxy-hemoglobin, whereas SO(2) changes were sensed by pixel-wise normalization of images acquired at lambda(560) or lambda(600) to those at lambda(570). We demonstrated the capacity of the fPAM system to image and quantify significant contralateral changes in both SO(2) and CBV driven by electrical forepaw stimulation. The fPAM system complements existing imaging techniques, with the potential to serve as a favorable tool for explicitly studying brain hemodynamics in animal models. (C) 2010 Elsevier Inc. All rights reserved.
In vivo functional photoacoustic micro-imaging of the electrically stimulated rat brain with multi-wavelengths
(2010)
Liao, Lun-De
;
Li, Meng-Lin
;
Lai, Hsin-Yi
;
Chen, You-Yin
;
Chao, Paul C. -P.
In this study, we report on using multi-wavelength photoacoustic microscopy to image hemodynamic changes of total hemoglobin concentration (HbT) (i.e., blood volume) and oxygenation (SO(2)) in rat brain cortex vessels with electrical stimulation. Electrical stimulation of the rat left forelimb was applied to evoke changes in vascular dynamics of the rat somatosensory cortex. The applied current pulses were with a pulse frequency of 3 Hz, pulse duration of 0.2 ms, and pulse amplitude of 5 mA, respectively. The imaging target of rat brains was demarcated at AP 0 - -2.5 mm and ML +/-6 mm with respect to bregma. HbT changes were probed by images acquired at 570 nm, a hemoglobin isosbestic point while SO(2) changes were imaged by those acquired at 560 nm or 600 nm and their derivatives, which were normalized to those with 570 nm wavelengths. Correlation between the electrical stimulation paradigm and images acquired at 570, 560, and 600 nm in contralateral and ipsilateral vasculature was statistically analyzed, showing that the HbT and SO(2) changes revealed by multi-wavelength photoacoustic images spatially correlated with contralateral vasculature.
Investigation of the cerebral hemodynamic response function in single blood vessels by functional photoacoustic microscopy
(2012-06-01)
Liao, Lun-De
;
Lin, Chin-Teng
;
Shih, Yen-Yu I.
;
Lai, Hsin-Yi
;
Zhao, Wan-Ting
The specificity of the hemodynamic response function (HRF) is determined spatially by the vascular architecture and temporally by the evolution of hemodynamic changes. Here, we used functional photoacoustic microscopy (fPAM) to investigate single cerebral blood vessels of rats after left forepaw stimulation. In this system, we analyzed the spatiotemporal evolution of the HRFs of the total hemoglobin concentration (HbT), cerebral blood volume (CBV), and hemoglobin oxygen saturation (SO2). Changes in specific cerebral vessels corresponding to various electrical stimulation intensities and durations were bilaterally imaged with 36 x 65-mu m(2) spatial resolution. Stimulation intensities of 1, 2, 6, and 10 mA were applied for periods of 5 or 15 s. Our results show that the relative functional changes in HbT, CBV, and SO2 are highly dependent not only on the intensity of the stimulation, but also on its duration. Additionally, the duration of the stimulation has a strong influence on the spatiotemporal characteristics of the HRF as shorter stimuli elicit responses only in the local vasculature (smaller arterioles), whereas longer stimuli lead to greater vascular supply and drainage. This study suggests that the current fPAM system is reliable for studying relative cerebral hemodynamic changes, as well as for offering new insights into the dynamics of functional cerebral hemodynamic changes in small animals. (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [ DOI: 10.1117/1.JBO.17.6.061210]
Multitheragnostic Multi-GNRs Crystal-Seeded Magnetic Nanoseaurchin for Enhanced In Vivo Mesenchymal-Stem-Cell Homing, Multimodal Imaging, and Stroke Therapy
(2015-11-04)
Chen, Po-Jung
;
Kang, Yi-Da
;
Lin, Chen-Huan
;
Chen, San-Yuan
;
Hsieh, Chia-Hung
A multifunctional nanoseaurchin probe in which mesoporous silica nanobeads with iron oxide nanoparticles embedded and multi-gold nanorods crystal-seeded are fabricated and labeled with umbilical cord mesenchymal stem cells through endocytosis. This nanoplatform enables efficient magnetic remote-controlled guiding for stem cell homing, and provides dual modalities of photoacoustic imaging and magnetic resonance imaging for in situ tracking and long-term monitoring to achieve therapeutic efficacy.
Transcranial imaging of functional cerebral hemodynamic changes in single blood vessels using in vivo photoacoustic microscopy
(2012-06-01)
Liao, Lun-De
;
Lin, Chin-Teng
;
Shih, Yen-Yu I.
;
Duong, Timothy Q.
;
Lai, Hsin-Yi
Optical imaging of changes in total hemoglobin concentration (HbT), cerebral blood volume (CBV), and hemoglobin oxygen saturation (SO2) provides a means to investigate brain hemodynamic regulation. However, high-resolution transcranial imaging remains challenging. In this study, we applied a novel functional photoacoustic microscopy technique to probe the responses of single cortical vessels to left forepaw electrical stimulation in mice with intact skulls. Functional changes in HbT, CBV, and SO2 in the superior sagittal sinus and different-sized arterioles from the anterior cerebral artery system were bilaterally imaged with unambiguous 36x65-mu m(2) spatial resolution. In addition, an early decrease of SO2 in single blood vessels during activation (i.e., 'the initial dip') was observed. Our results indicate that the initial dip occurred specifically in small arterioles of activated regions but not in large veins. This technique complements other existing imaging approaches for the investigation of the hemodynamic responses in single cerebral blood vessels. Journal of Cerebral Blood Flow & Metabolism (2012) 32, 938-951; doi:10.1038/jcbfm.2012.42; published online 4 April 2012
Ultrafast Plane Wave Imaging Based Pulsed Magnetomotive Ultrasound
(2014-01-01)
Ting, Pei-Hsien
;
Kang, Yi-Da
;
Chen, San-Yuan
;
Li, Meng-Lin
;
材料科學與工程學系
Recently, pulsed magnetomotive ultrasound (pMMUS) imaging has been introduced to detect magnetic nanoparticles (MNPs) which are not able to be visualized by conventional ultrasound. However, because of the used magnetic short pulse, the reported pMMUS only can use a single-element ultrasound transducer along with mechanical scanning to perform imaging, which significantly limits the imaging fame rate. To solve this problem, we propose an ultrafast plane wave imaging based pMMUS technique. The ultrafast frame rate of plane wave imaging is fast enough to track the magneto-motion of the excited MNPs during the period of the magnetic pulse being applied. Therefore, the proposed ultrafast plane wave pMMUS is capable of visualizing the dynamic response of the excited MNPs, which is highly correlated to tissue characteristics, to an externally-applied magnetic pulse. In our experiments, ultrafast plane wave imaging with a 5 kHz frame rate was used to implement the pMMUS where the MNP motion induced by an 8-ms magnetic pulse was tracked. The results showed that there were significant differences between the ultrafast plane wave pMMUS images of the phantoms with and without MNPs embedded. In addition, gelatin phantoms with 2%, 4% and 6% gelatin were used to mimic tissues with different elasticity. The dynamic responses of the excited MNPs in the three types of phantoms were distinguishable. Overall, it is demonstrated that the feasibility of our proposed ultrafast plane wave pMMUS imaging technique for the visualization of the magneto-motion and dynamic response of the MNPs under the excitation of a short magnetic pulse. More studies are required to further improve the magneto-motion tracking algorithm and explore the relationship between the dynamic response of the excited MNPs and the tissue viscosity and elasticity.
Ultrafast Pulsed Magnetomotive Ultrasound Imaging of Sentinel Lymph Nodes: Small Animal Study
(2015-01-01)
Huang, Yu-Chun
;
Houng, Jieh-Yuan
;
Kang, Yi-Da
;
Chen, San-Yuan
;
Li, Meng-Lin
Sentinel lymph nodes (SLNs) are the first draining lymph nodes while the metastatic cancer cells are spreading. A noninvasive imaging modality for SLN identification with fine needle aspiration biopsy (FNAB) would be beneficial for staging the axillary lymph nodes without surgical intervention. Here we propose a method - ultrafast pulsed magnetomotive ultrasound (pMMUS) for noninvasive SLN identification, which leverages the MRI superparamagnetic iron oxide nanoparticles (SPIOs) and potentially offers real-time imaging capability for SLN FNAB. Ultrafast pMMUS can localize the SPIOs drained to the SLNs and thus identify the SLNs. Experiments on rats were carried out to verify the feasibility. The SLN was identified in pMMUS images which was confirmed by the methylene blue assay while it is challenging to be localized in B-mode image. Overall, we demonstrated the feasibility of the proposed ultrafast pMMUS for noninvasive SLN identification. Proper SPIO particle size, time window of imaging, and motion-tracking algorithm will be studied to further improve the performance of the proposed method.