23 kHz MEMS based swept source for optical coherence tomography imaging

Vuong, Barry; Sun, Cuiru; Harduar, Mark K.; Mariampillai, Adrian; Isamoto, Keiji; Chong, Changho; Standish, Beau A.; Yang, Victor X. D.

doi:10.1109/iembs.2011.6091515

“…where z w is the roll-off function and was measured to be 3 mm by translating a mirror in the sample arm until the amplitude had decreased to 8 dB [120]. Linearization of the intensity signal was achieved by logarithmic compression [113] i…”

Section: Optical Coherence Tomography -Optical Attenuation Imagingmentioning

confidence: 99%

Development of an Intravascular Doppler Optical Coherence Tomography Imaging Technique for Neurovascular Applications

Vuong¹

2022

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The rupture of an intracranial aneurysm can cause spontaneous subarachnoid hemorrhage and result in sudden death. A large portion of intracranial aneurysms occurs near the center of the head, at the skull base, which poses significant technical challenge to neurosurgeons due to limited accessibility. The utilization of angiography is prominent during the treatment of intracranial aneurysms. However, malapposition of stent or incomplete packing of the intracranial aneurysm can be difficult to assess with angiography, and could lead to severe postoperative complications. As a result, angiography may not be sufficient in determining the risk of rupture as the compensatory mechanisms are known to occur at the microstructural level due to the local hemodynamics in the arterial lumen, as well as in evaluating the intraoperative treatment. In this work, we describe a method for assessing intracranial aneurysm through the evaluation of blood flow within the lumen and morphological structures of the arterial wall with optical coherence tomography (OCT). Sterile intravascular fiber-optic catheters can be introduced in the artery to detect blood flow. Prior to this work, limited investigations of catheter based Doppler OCT (DOCT) were reported. A novel signal processing technique was developed to further reduce the effect of Doppler noise within a catheter based DOCT system. This technique consisted of splitting the interferogram of an OCT signal prior to estimating the Doppler shift. This split spectrum DOCT (ssDOCT) method was evaluated through flow models and porcine models, as well as through the correlation between ssDOCT algorithm and computational fluid dynamic (CFD) models. It was observed that ssDOCT provided improved Doppler artefact suppression over the conventional DOCT technique. ssDOCT also provided the ability to estimate lower velocities within the DOCT image to measure the hemodynamic patterns around stent struts in both the internal carotid and patient specific flow phantoms. An OCT imaging study was also conducted consisting of surgically resected human intracranial aneurysms. Further enhancement of the detection of these key morphological structures was demonstrated by an optical-attenuation imaging variant of OCT. The presented techniques could provide further insights to the cause of intracranial aneurysm rupture and vascular healing mechanisms.

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“…where the position of the beam waist was z o ⇡ 19.4 µm and the Rayleigh length was z R ⇡ 1 mm. The where z w is the roll-o↵ function and was measured to be 3 mm by translating a mirror in the sample arm until the amplitude had decreased to 8 dB [120]. Linearization of the intensity signal was achieved by logarithmic compression [113] Thresholding was used to detect the surface of the tissue and a least square fit was performed on Equation 5.4 with a variable minimum window length of the following model [113],…”

Section: Optical Coherence Tomography -Optical Attenuation Imagingmentioning

confidence: 99%

Development of an Intravascular Doppler Optical Coherence Tomography Imaging Technique for Neurovascular Applications

Vuong¹

2021

Preprint

0

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The rupture of an intracranial aneurysm can cause spontaneous subarachnoid hemorrhage and result in sudden death. A large portion of intracranial aneurysms occurs near the center of the head, at the skull base, which poses significant technical challenge to neurosurgeons due to limited accessibility. The utilization of angiography is prominent during the treatment of intracranial aneurysms. However, malapposition of stent or incomplete packing of the intracranial aneurysm can be difficult to assess with angiography, and could lead to severe postoperative complications. As a result, angiography may not be sufficient in determining the risk of rupture as the compensatory mechanisms are known to occur at the microstructural level due to the local hemodynamics in the arterial lumen, as well as in evaluating the intraoperative treatment. In this work, we describe a method for assessing intracranial aneurysm through the evaluation of blood flow within the lumen and morphological structures of the arterial wall with optical coherence tomography (OCT). Sterile intravascular fiber-optic catheters can be introduced in the artery to detect blood flow. Prior to this work, limited investigations of catheter based Doppler OCT (DOCT) were reported. A novel signal processing technique was developed to further reduce the effect of Doppler noise within a catheter based DOCT system. This technique consisted of splitting the interferogram of an OCT signal prior to estimating the Doppler shift. This split spectrum DOCT (ssDOCT) method was evaluated through flow models and porcine models, as well as through the correlation between ssDOCT algorithm and computational fluid dynamic (CFD) models. It was observed that ssDOCT provided improved Doppler artefact suppression over the conventional DOCT technique. ssDOCT also provided the ability to estimate lower velocities within the DOCT image to measure the hemodynamic patterns around stent struts in both the internal carotid and patient specific flow phantoms. An OCT imaging study was also conducted consisting of surgically resected human intracranial aneurysms. Further enhancement of the detection of these key morphological structures was demonstrated by an optical-attenuation imaging variant of OCT. The presented techniques could provide further insights to the cause of intracranial aneurysm rupture and vascular healing mechanisms.

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“…In an OFDR system, the scan rate is limited by the frequency of laser wavelength scanning, the range of the scan determines the resolution, and the wavelength resolution of the scan and of the detector determines the scan range. Swept-source OCT constitutes demonstration of swept-source interferometry at a bandwidth of many kHz 20 …”

Section: Design Principlesmentioning

confidence: 99%

Multiplexed neural recording along a single optical fiber via optical reflectometry

Rodriques

¹

,

Marblestone

²

,

Scholvin

³

et al. 2016

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Abstract. We introduce the design and theoretical analysis of a fiber-optic architecture for neural recording without contrast agents, which transduces neural electrical signals into a multiplexed optical readout. Our sensor design is inspired by electro-optic modulators, which modulate the refractive index of a waveguide by applying a voltage across an electro-optic core material. We estimate that this design would allow recording of the activities of individual neurons located at points along a 10-cm length of optical fiber with 40-μm axial resolution and sensitivity down to 100 μV using commercially available optical reflectometers as readout devices. Neural recording sites detect a potential difference against a reference and apply this potential to a capacitor. The waveguide serves as one of the plates of the capacitor, so charge accumulation across the capacitor results in an optical effect. A key concept of the design is that the sensitivity can be improved by increasing the capacitance.To maximize the capacitance, we utilize a microscopic layer of material with high relative permittivity. If suitable materials can be found-possessing high capacitance per unit area as well as favorable properties with respect to toxicity, optical attenuation, ohmic junctions, and surface capacitance-then such sensing fibers could, in principle, be scaled down to few-micron cross-sections for minimally invasive neural interfacing. We study these material requirements and propose potential material choices. Custom-designed multimaterial optical fibers, probed using a reflectometric readout, may, therefore, provide a powerful platform for neural sensing.

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23 kHz MEMS based swept source for optical coherence tomography imaging

Cited by 7 publications

References 17 publications

Development of an Intravascular Doppler Optical Coherence Tomography Imaging Technique for Neurovascular Applications

Development of an Intravascular Doppler Optical Coherence Tomography Imaging Technique for Neurovascular Applications

Development of an Intravascular Doppler Optical Coherence Tomography Imaging Technique for Neurovascular Applications

Multiplexed neural recording along a single optical fiber via optical reflectometry

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