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Optical coherence tomography imaging of the basal ganglia: feasibility and brief review
摘要： Optical coherence tomography (OCT) is a promising medical imaging technique that uses light to capture real-time cross-sectional images from biological tissues in micrometer resolution. Commercially available optical coherence tomography systems are employed in diverse applications, including art conservation and diagnostic medicine, notably in cardiology and ophthalmology. Application of this technology in the brain may enable distinction between white matter and gray matter, and obtainment of detailed images from within the encephalon. We present, herein, the in vivo implementation of OCT imaging in the rat brain striatum. For this, two male 60-day-old rats (Rattus norvegicus, Albinus variation, Wistar) were stereotactically implanted with guide cannulas into the striatum to guide a 2.7-French diameter high-definition OCT imaging catheter (Dragonfly, St. Jude Medical, USA). Obtained images were compared with corresponding histologically stained sections to collect imaging samples. A brief analysis of OCT technology and its current applications is also reported, as well as intra-cerebral OCT feasibility on brain mapping during neurosurgical procedures.
关键词： Basal ganglia,Optical coherence tomography (OCT),Rat brain,Histology,Thalamus,Brain imaging
更新于2025-09-04 15:30:14
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Rotary photon drag in a Mach-Zehnder-type Sagnac interferometer
摘要： We theoretically investigate rotary photon drag in a Mach-Zehnder type Sagnac interferometer using a four level N-type atomic medium. Splitting of a single pulse of light into two pulses is observed at high strength of the control field both in absorption and dispersion spectra. Group index, relativistic velocities and rotary photon drag are examined as a function of probe field detuning Δp. Rotation angles of ± 2, ± 3, ± 4 and ± 6 micro radians are achieved for the two beams propagating in clockwise and counter clockwise direction by varying values of the probe field detuning as 0γ, 0.5γ and 1.5γ, respectively. The results obtained show potential applications in sensing technology, optical fibre communication technology as well as in perfect lens formation.
关键词： Rotary photon drag,Light propagation,Polarization,Quantum coherence,Interferometry,Electromagnetically induced transparency
更新于2025-09-04 15:30:14
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Progression of retinitis pigmentosa on multimodal imaging: the PREP‐1 study
摘要： Importance: It is important to establish reliable outcome measures to detect progression in retinitis pigmentosa (RP). Background: To evaluate progression of RP using multimodal imaging, including spectral-domain optical coherence tomography (SD-OCT), fundus autofluorescence (FAF) and microperimetry (MP). Design: Retrospective longitudinal study at a tertiary teaching hospital. Participants: 205 eyes of 106 patients with RP with 1-5 years of follow-up. Methods: Demographics and visual acuity (VA) were recorded, and each modality was graded at baseline and every annual follow-up. SD-OCT was graded for the width of ellipsoid zone (EZ), FAF was graded for the diameter and area of the hyperautofluorescent ring (if present), and MP was graded for mean, central and paracentral sensitivity. Spearman’s correlation was used to measure correlations at baseline. Mixed effects models were used to estimate the annual change of each parameter, adjusted for disease duration. Main outcome measures: Rate of progression. Results: The median VA at baseline was 75 letters and was positively correlated with mean and central sensitivity (r: 0.372 and 0.394; p=0.01 for both). All parameters (except paracentral sensitivity) were strongly correlated with each other (r: 0.673-0.991; p<0.001 for all). The annual rates of change for each parameter were as follows: VA, -2.3 letters (p<0.001); EZ, -151um (p<0.001); ring diameter, -132um (p<0.001); ring area, -0.4mm2 (p<0.001); mean sensitivity, -0.3 dB (p<0.001); central sensitivity, -0.7 dB (p<0.001); paracentral sensitivity, -0.4 dB (p<0.001). Conclusion and relevance: Structural and functional measures are well correlated in RP and can reliable measure disease progression within the course of a year.
关键词： Optical Coherence Tomography,Multimodal Imaging,Microperimetry,Fundus Autofluorescence,Disease Progression
更新于2025-09-04 15:30:14
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Intraoperative detection of blood vessels with an imaging needle during neurosurgery in humans
摘要： Intracranial hemorrhage can be a devastating complication associated with needle biopsies of the brain. Hemorrhage can occur to vessels located adjacent to the biopsy needle as tissue is aspirated into the needle and removed. No intraoperative technology exists to reliably identify blood vessels that are at risk of damage. To address this problem, we developed an “imaging needle” that can visualize nearby blood vessels in real time. The imaging needle contains a miniaturized optical coherence tomography probe that allows differentiation of blood flow and tissue. In 11 patients, we were able to intraoperatively detect blood vessels (diameter, >500 mm) with a sensitivity of 91.2% and a specificity of 97.7%. This is the first reported use of an optical coherence tomography needle probe in human brain in vivo. These results suggest that imaging needles may serve as a valuable tool in a range of neurosurgical needle interventions.
关键词： intracranial hemorrhage,optical coherence tomography,neurosurgery,blood vessel detection,imaging needle
更新于2025-09-04 15:30:14
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Influence of uveitis on Bruch’s membrane opening minimum rim width and retinal nerve fibre layer thickness measurements
摘要： background/aims To assess the impact of papillary leakage and active inflammation on optical coherence tomography (OCT)-based retinal nerve fibre layer thickness (RNFLT) and Bruch’s membrane opening minimum rim width (BMO-MRW) measurements in uveitic eyes with and without secondary glaucoma. Methods Prospective, single-centre analysis of patients with uveitis. All patients included received a fluorescein angiography examination and an OCT scan measuring the BMO-MRW and the RNFLT in three concentric peripapillary ring scans. results Overall, 95 eyes of 56 patients were enrolled. Papillary leakage and active inflammation were present in 39 (41%) and 57 (60%) eyes, respectively. Twenty-one eyes were classified as glaucomatous; 10 of those glaucomatous eyes showed papillary leakage. Both BMO-MRW and RNFLT measurements were significantly increased in eyes with papillary leakage (BMO-MRW: p=0.0001; RNFL: first to third ring (p<0.0001)). Active inflammation led to a significantly thickened RNFLT (first ring: p=0.0026; second ring: p=0.0009; third ring: p=0.0002) while only a trend towards increased values could be observed in the BMO-MRW measurements (p=0.3063). Glaucomatous eyes with papillary leakage demonstrated significantly higher values on both BMO-MRW and RNFLT measurements than glaucomatous eyes without leakage (BMO-MRW: p=0.0159; RNFL: first ring: p=0.0062; second ring: p=0.0037; third ring: p=0.0197). No significant difference could be observed between glaucomatous eyes with leakage and non-glaucomatous eyes without leakage (BMO-MRW: p=0.4132; RNFL: first ring: p=0.5412; second ring: p=0.3208; third ring: p=0.1164). Conclusions The OCT scanning parameters BMO-MRW and RNFLT were significantly influenced by papillary leakage in uveitic eyes with and without glaucoma. RNFLT values were also significantly increased while active inflammation was present. In patients with uveitis, these OCT-based imaging tools should be interpreted with caution, especially in those with papillary leakage or active inflammation.
关键词： uveitis,optical coherence tomography,retinal nerve fibre layer thickness,Bruch’s membrane opening minimum rim width,glaucoma
更新于2025-09-04 15:30:14
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ST Elevation Infarction after Heart Transplantation Induced by Coronary Spasms and Mural Thrombus Detected by Optical Coherence Tomography
摘要： The case illustrates the possible link between coronary spasms, intraluminal thrombus formation, and widespread organized and layered thrombi in HTx patients. Furthermore, the case underlines the clinical value of OCT as a novel method for high-resolution vessel imaging in heart-transplanted (HTx) patients with coronary spasms and suspected coronary artery disease. Coronary spasms and sudden death are frequent complications after HTx. The underlying mechanisms leading to these complications are unknown. The present case displays the clinical course of a 19-year-old HTx patient who was hospitalized due to acute myocardial infarction induced by severe coronary spasms. The patients remained unstable on conservative therapy. Therefore, an optical coherence tomography (OCT) was performed and revealed massive, organized thrombi in the left main coronary artery, the circumflex coronary artery, and the left anterior descending coronary artery. The patient was stabilized after percutaneous coronary intervention. As a mural thrombus often goes undetected by coronary angiography, OCT may prove beneficial in HTx patients with myocardial infarction or suspected coronary spasms.
关键词： myocardial infarction,coronary spasms,optical coherence tomography,heart transplantation,mural thrombus
更新于2025-09-04 15:30:14
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Early Follow-Up Optical Coherence Tomographic Findings of Significant Drug-Eluting Stent Malapposition
摘要： BACKGROUND: Using optical coherence tomography, we evaluated early follow-up findings of significant stent malapposition (SSM) in patients treated with second-generation drug-eluting stent. METHODS AND RESULTS: From the DETECT-OCT randomized trial (Determination of the Duration of the Dual Antiplatelet Therapy by the Degree of the Coverage of the Struts on Optical Coherence Tomography From the Randomized Comparison Between Everolimus- Versus Biolimus-Eluting Stent), a total of 386 patients (390 lesions) who underwent both postintervention and 3-month follow-up optical coherence tomography examinations were included for the present analysis. SSM was defined as a stent that had a strut with a maximal wall-to-strut distance of ≥200 μm. Postintervention, SSM was detected in 175 lesions (44.9%), including 117 lesions with a maximal wall-to-strut distance of ≥200 to <400 μm and 58 lesions with a maximal wall-to-strut distance of ≥400 μm. As the implanted stent diameter-to-reference vessel diameter ratio grew, the risk of postintervention SSM dropped (odds ratio, 0.587; 95% CI, 0.367–0.941; P=0.0398). The optimal value that best separated SSM from non-SSM postintervention was a stent diameter-to-reference vessel diameter ratio of 1.0. At 3 months follow-up, the frequency of SSM decreased from 44.9% to 33.6% (131 lesions; P=0.0001), mainly driven by the decrease in lesions with a maximal wall-to-strut distance of ≥200 to <400 μm. As the maximal wall-to-strut distance on postintervention optical coherence tomography was larger, the risk of 3-month SSM increased (odds ratio, 1.607; 95% CI, 1.131–2.286; P=0.0284). The optimal value that best separated SSM from non-SSM at 3 months follow-up was a maximal wall-to-strut distance postintervention of 230 μm. CONCLUSIONS: A spontaneous decrease in SSM was observed early in this qualified study with a large number of study patients treated with second-generation drug-eluting stent.
关键词： optical coherence tomography,drug-eluting stents,coronary artery disease
更新于2025-09-04 15:30:14
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Confocal Adaptive Optics Imaging of Peripapillary Nerve Fiber Bundles: Implications for Glaucomatous Damage Seen on Circumpapillary OCT Scans
摘要： To improve our understanding of glaucomatous damage as seen on circumpapillary disc scans obtained with frequency-domain optical coherence tomography (fdOCT), fdOCT scans were compared to images of the peripapillary retinal nerve fiber (RNF) bundles obtained with an adaptive optics-scanning light ophthalmoscope (AO-SLO). The AO-SLO images and fdOCT scans were obtained on 6 eyes of 6 patients with deep arcuate defects (5 points (cid:2)(cid:3)15 db) on 10-2 visual fields. The AO-SLO images were montaged and aligned with the fdOCT images to compare the RNF bundles seen with AO-SLO to the RNF layer thickness measured with fdOCT. All 6 eyes had an abnormally thin (1% confidence limit) RNF layer (RNFL) on regions of RNF bundles on AO-SLO in fdOCT and abnormal corresponding regions. However, regions of abnormal, but equal, RNFL thickness on fdOCT scans varied in appearance on AO-SLO images. These regions could be largely devoid of RNF bundles (5 eyes), have abnormal-appearing bundles of lower contrast (6 eyes), or have isolated areas with a few relatively normal-appearing bundles (2 eyes). There also were local variations in reflectivity of the fdOCT RNFL that corresponded to the variations in AO-SLO RNF bundle appearance. Relatively similar 10-2 defects with similar fdOCT RNFL thickness profiles can have very different degrees of RNF bundle damage as seen on fdOCT and AO-SLO. While the results point to limitations of fdOCT RNFL thickness as typically analyzed, they also illustrate the potential for improving fdOCT by attending to variations in local intensity.
关键词： optical coherence tomography,retinal nerve fiber layer,glaucoma,adaptive optics,optic disc
更新于2025-09-04 15:30:14
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The repeatability of superficial retinal vessel density measurements in eyes with long axial length using optical coherence tomography angiography
摘要： Background: To investigate the repeatability of superficial retinal vessel density measurements in healthy eyes with long axial length (AL) using optical coherence tomography angiography (OCTA). Methods: There were 60 eyes of 31 volunteers enrolled in this cross-sectional observational study. All subjects underwent OCTA, AL and refraction test. The enrolled eyes were divided into the long AL group (26 mm ≤ AL < 28 mm) and normal AL group (22 mm ≤ AL < 26 mm). The vessel length density (VLD), perfusion density (PD), and fovea avascular zone (FAZ) of the superficial retinal vessel were evaluated. Repeatability was assessed by intraclass correlation coefficients (ICCs) and Bland-Altman analysis. Pearson’s r correlation was used to analyze the relation of AL and the absolute difference between two measurements. Results: The 3 × 3 mm scan pattern showed good repeatability with all ICCs over 0.7. For all parameters of all scan patterns, the ICCs of the normal AL group were distinctly higher than those of the long AL group; this finding was also confirmed by Bland-Altman analysis. The correlation analysis of AL and repeatability of OCTA parameters showed significant negative correlations between the ALs and repeatability of VLD in 6 × 6 mm inner ring (r2 = 0.13, p = 0.01), VLD in 6 × 6 mm outer ring (r2 = 0.09, p = 0.02) and PD in 6 × 6 mm outer ring (r2 = 0.08, p = 0.03). Conclusions: The AL and the scanned area will both affect the repeatability of superficial retinal vessel density measurements in OCTA.
关键词： Fovea avascular zone,Vessel length density,Myopia,Optical coherence tomography angiography,Repeatability,Perfusion density
更新于2025-09-04 15:30:14
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Incoherent Shock and Collapse Singularities in Non-Instantaneous Nonlinear Media
摘要： We study the dynamics of a partially incoherent optical pulse that propagates in a slowly responding nonlinear Kerr medium. We show that irrespective of the sign of the dispersion (either normal or anomalous), the incoherent pulse as a whole exhibits a global collective behavior characterized by a dramatic narrowing and amplification in the strongly non-linear regime. The theoretical analysis based on the Vlasov formalism and the method of the characteristics applied to a reduced hydrodynamic model reveal that such a strong amplitude-incoherent pulse originates in the existence of a concurrent shock-collapse singularity (CSCS): The envelope of the intensity of the random wave exhibits a collapse singularity, while the momentum exhibits a shock singularity. The dynamic behavior of the system after the shock-collapse singularity is characterized through the analysis of the phase-space dynamics.
关键词： non-linear waves,optical turbulence,shockwaves,partially coherent beams and pulses,Vlasov formalism,coherence,rogue waves
更新于2025-09-04 15:30:14