Efficacy of High Temporal Frequency Photoacoustic Guidance of Laser Ablation Procedures

2021 ◽  
Vol 43 (3) ◽  
pp. 149-156
Author(s):  
Yan Yan ◽  
Samuel John ◽  
Jurgita Meiliute ◽  
Loay Kabbani ◽  
Mohammad Mehrmohammadi
Keyword(s):  
Laser Ablation ◽  
Temporal Resolution ◽  
Ex Vivo ◽  
Temporal Frequency ◽  
Frame Rate ◽  
Ablation Catheter ◽  
Temperature Feedback ◽  
Catheter Tip ◽  
Rapid Temperature ◽  
Excised Tissue

Inaccurate placement of the ablation catheter and the inability to monitor the real-time temperature within the tissue of interest such as veins curbs the treatment efficacy of laser ablation procedures during thermal therapies. Our previous studies have validated the efficacy of photoacoustic (PA) imaging during endovenous laser ablation (EVLA) procedures. However, the PA-guided therapies suffer from low temporal resolution, due to the low pulse repetition rates of pulsed lasers, which could cause a problem during fast catheter motion and rapid temperature changes. Herein, to enhance the accuracy and sensitivity for tracking the ablation catheter tip and temperature monitoring, we proposed to develop a high frame rate (500 Hz), combined ultrasound (US), and PA-guided ablation system. The proposed PA-guided ablation system was evaluated in a set of ex vivo tissue studies. The developed system provides a 2 ms temporal resolution for tracking and monitoring the ablation catheter tip’s location and temperature, which is 50 times higher temporal resolution compared to the previously proposed 10 Hz system. The proposed system also provided more accurate feedback about the temperature variations during rapid temperature increments of 10°C per 250 ms. The co-registered US and PA images have an imaging resolution of about 200 μm and a field of view of 45 × 40 mm2. Tracking the ablation catheter tip in an excised tissue layer shows higher accuracy during a relatively fast catheter motion (0.5–3 mm/s). The fast US/PA-guided ablation system will potentially enhance the outcome of ablation procedures by providing location and temperature feedback.

Creating a cumulative equivalent thermal isoeffect dosimetry model in several ex vivo tissue models mimicking focal laser ablation treatment of the prostate

2021 ◽  
Vol 79 ◽  
pp. S604
Author(s):  
L.A.M.J.G. Van Riel ◽  
R.A.A. Van Kollenburg ◽  
T.M. De Reijke ◽  
C.D. Savci - Heijink ◽  
R. Zweije ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Ex Vivo ◽  
Ex Vivo Tissue ◽  
Tissue Models

scholarly journals Speckle-Tracking Echocardiography With Novel High Frame-Rate Imaging

2021 ◽  
Author(s):  
Kana Fujikura ◽  
Mohammed Makkiya ◽  
Muhammad Farooq ◽  
Yun Xing ◽  
Wayne Humphrey ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Speckle Tracking ◽  
Speckle Tracking Echocardiography ◽  
Myocardial Strain ◽  
Left Ventricular ◽  
Frame Rate ◽  
High Frame Rate ◽  
Echocardiographic Images ◽  
The Impact ◽  
Normal Lvef

Background: global longitudinal strain (GLS) measures myocardial deformation and is a sensitive modality for detecting subclinical myocardial dysfunction and predicting cardiac outcomes. The accuracy of speckle-tracking echocardiography (STE) is dependent on temporal resolution. A novel software enables relatively high frame rate (Hi-FR) (~200 fps) echocardiographic images acquisition which empowers us to investigate the impact of Hi-FR imaging on GLS analysis. The goal of this pilot study was to demonstrate the feasibility of Hi-FR for STE. Methods: In this prospective study, we acquired echocardiographic images using clinical scanners on patients with normal left ventricular systolic function using Hi-FR and conventional frame rate (Reg-FR) (~50 FPS). GLS values were evaluated on apical 4-, 2- and 3-chamber images acquired in both Hi-FR and Reg-FR. Inter-observer and intra-observer variabilities were assessed in Hi-FR and Reg-FR. Results: There were 143 resting echocardiograms with normal LVEF included in this study. The frame rate of Hi-FR was 190 ± 25 and Reg-FR was 50 ± 3, and the heart rate was 71 ± 13. Strain values measured in Hi-FR were significantly higher than those measured in Reg-FR (all p < 0.001). Inter-observer and intra-observer correlations were strong in both Hi-FR and Reg-FR. Conclusions: We demonstrated that strain values were significantly higher using Hi-FR when compared with Reg-FR in patients with normal LVEF. It is plausible that higher temporal resolution enabled the measurement of myocardial strain at desired time point. The result of this study may inform clinical adoption of the novel technology. Further investigations are necessary to evaluate the value of Hi-FR to assess myocardial strain in stress echocardiography in the setting of tachycardia.

scholarly journals Electro-optic imaging enables efficient wide-field fluorescence lifetime microscopy

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Adam J. Bowman ◽  
Brannon B. Klopfer ◽  
Thomas Juffmann ◽  
Mark A. Kasevich
Keyword(s):  
Temporal Resolution ◽  
Single Molecule ◽  
Fluorescence Lifetime ◽  
Collection Efficiency ◽  
Frame Rate ◽  
Optical Systems ◽  
Wide Field ◽  
Pockels Cell ◽  
Low Light ◽  
Optical Efficiency

Abstract Nanosecond temporal resolution enables new methods for wide-field imaging like time-of-flight, gated detection, and fluorescence lifetime. The optical efficiency of existing approaches, however, presents challenges for low-light applications common to fluorescence microscopy and single-molecule imaging. We demonstrate the use of Pockels cells for wide-field image gating with nanosecond temporal resolution and high photon collection efficiency. Two temporal frames are obtained by combining a Pockels cell with a pair of polarizing beam-splitters. We show multi-label fluorescence lifetime imaging microscopy (FLIM), single-molecule lifetime spectroscopy, and fast single-frame FLIM at the camera frame rate with 103–105 times higher throughput than single photon counting. Finally, we demonstrate a space-to-time image multiplexer using a re-imaging optical cavity with a tilted mirror to extend the Pockels cell technique to multiple temporal frames. These methods enable nanosecond imaging with standard optical systems and sensors, opening a new temporal dimension for wide-field low-light microscopy.

Peripheral bronchial luminal conspicuity on dynamic-ventilation computed tomography: association with radiation doses and temporal resolution by using an ex vivo porcine lung phantom

2020 ◽  
Vol 61 (12) ◽  
pp. 1608-1617
Author(s):  
Yukihiro Nagatani ◽  
Makoto Yoshigoe ◽  
Shinsuke Tsukagoshi ◽  
Noritoshi Ushio ◽  
Kohei Ohashi ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Temporal Resolution ◽  
Ex Vivo ◽  
Reconstruction Algorithm ◽  
Radiation Doses ◽  
Reconstruction Algorithms ◽  
Movement Velocity ◽  
Full Reconstruction ◽  
Luminal Area ◽  
Lung Phantom

Background It is still unclear which image reconstruction algorithm is appropriate for peripheral bronchial luminal conspicuity (PBLC) on dynamic-ventilation computed tomography (DVCT). Purpose To assess the influence of radiation doses and temporal resolution (TR) on the association between movement velocity (MV) and PBLC on DVCT. Material and Methods An ex vivo porcine lung phantom with simulated respiratory movement was scanned by 320-row CT at 240 mA and 10 mA. Peak and dip CT density and luminal area adjusted by values at end-inspiration (CTDpeak and CTDdip, luminal area ratio [LAR]) for PBLC and MVs were measured and visual scores (VS) were obtained at 12 measurement points on 13 frame images obtained at half and full reconstructions (TR 340 and 190 ms) during expiration. Size-specific dose estimate (SSDE) was applied to presume radiation dose. VS, CTDpeak, CTDdip, LAR, and their cross-correlation coefficients with MV (CCC) were compared among four methods with combinations of two reconstruction algorithms and two doses. Results The dose at 10 mA was presumed as 26 mA by SSDE for standard proportion adults. VS, CTDdip, CTDpeak, and LAR with half reconstruction at 10 mA (2.52 ± 0.59, 1.016 ± 0.221, 0.948 ± 0.103, and 0.990 ± 0.527) were similar to those at 240 mA except for VS, and different from those with full reconstruction at both doses (2.24 ± 0.85, 0.830 ± 0.209, 0.986 ± 0.065, and 1.012 ± 0.438 at 240 mA) ( P < 0.05). CCC for CTDdip with half reconstruction (–0.024 ± 0.552) at 10 mA was higher compared with full reconstruction (–0.503 ± 0.291) ( P < 0.05). Conclusion PBLC with half reconstruction at 10 mA was comparable to that at 240 mA and better than those with full reconstruction on DVCT.

scholarly journals Integrated Multifunctional Laryngoscope for Medical Diagnosis and Treatment

2020 ◽  
Vol 10 (21) ◽  
pp. 7491
Author(s):  
Shanshan Liang ◽  
Xinyu Li ◽  
Jiajing Kang ◽  
Jiebin Zou ◽  
Faya Liang ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Early Diagnosis ◽  
White Light ◽  
Ex Vivo ◽  
Imaging Evaluation ◽  
Cross Sectional ◽  
White Light Endoscopy ◽  
Common Path ◽  
Path Design ◽  
Laryngeal Tumors

Laryngeal lesions can cause great inconvenience to patients. Early diagnosis and corresponding treatments are critical to the survival of patients. However, the diagnosis and precise removal of tumors remain a challenge under the use of a white light laryngoscope. In this work, an integrated, multifunctional laryngoscope was designed and tested for the imaging evaluation and precision laser surgery for laryngeal tissue. This integrated diagnostic and therapeutic endoscopic system included two imaging modes (i.e., optical coherence tomography and white light endoscopy) and a laser ablation treatment mode. The endoscope had a common-path design to ensure that the same position could be imaged and treated simultaneously. The ex vivo porcine larynx experimental results showed that the system imaging modes could simultaneously acquire both superficial and cross-sectional images of the sample tissue, and the ablation treatment could be performed under imaging guidance. This multifunctional laryngoscope has great potential for the early diagnosis of and accurate laser ablation surgery for laryngeal tumors.

scholarly journals Light-In-Flight Imaging by a Silicon Image Sensor: Toward the Theoretical Highest Frame Rate

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2247 ◽  
Author(s):  
Takeharu Etoh ◽  
Tomoo Okinaka ◽  
Yasuhide Takano ◽  
Kohsei Takehara ◽  
Hitoshi Nakano ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
High Speed ◽  
Streak Camera ◽  
Image Sensor ◽  
Pulse Neutron ◽  
Frame Rate ◽  
Neutron Tomography ◽  
Single Shot ◽  
Resolution Limit ◽  
Lifetime Measurements

Light in flight was captured by a single shot of a newly developed backside-illuminated multi-collection-gate image sensor at a frame interval of 10 ns without high-speed gating devices such as a streak camera or post data processes. This paper reports the achievement and further evolution of the image sensor toward the theoretical temporal resolution limit of 11.1 ps derived by the authors. The theoretical analysis revealed the conditions to minimize the temporal resolution. Simulations show that the image sensor designed following the specified conditions and fabricated by existing technology will achieve a frame interval of 50 ps. The sensor, 200 times faster than our latest sensor will innovate advanced analytical apparatuses using time-of-flight or lifetime measurements, such as imaging TOF-MS, FLIM, pulse neutron tomography, PET, LIDAR, and more, beyond these known applications.

Evaluating ex vivo fluorescence confocal microscopy images of basal cell carcinomas in M ohs excised tissue

2014 ◽  
Vol 171 (3) ◽  
pp. 561-570 ◽  
Author(s):  
C. Longo ◽  
M. Rajadhyaksha ◽  
M. Ragazzi ◽  
K. Nehal ◽  
S. Gardini ◽  
...  
Keyword(s):  
Confocal Microscopy ◽  
Basal Cell ◽  
Ex Vivo ◽  
Fluorescence Confocal Microscopy ◽  
Basal Cell Carcinomas ◽  
Excised Tissue ◽  
Microscopy Images

Temporal frequency responsivity shows multiple maturational phases: State-dependent visual evoked potential luminance flicker fusion from birth to 9 months

1993 ◽  
Vol 10 (6) ◽  
pp. 1007-1018 ◽  
Author(s):  
Patricia Apkarian
Keyword(s):  
Temporal Resolution ◽  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Temporal Frequency ◽  
Slow Phase ◽  
Behavioral State ◽  
Structural Factors ◽  
Rapid Phase ◽  
Flickering Light ◽  
Visual Evoked

AbstractMaturation of temporal resolution was investigated in a visual evoked potential study in 77 infants from birth to 9 months of age. Luminance evoked potential measures in response to homogeneous sinusoidal flickering light (1–64 Hz) were recorded under behavioral state-defined conditions. Behavioral state was determined by direct observation and by polygraphic recording of the electroencephalogram (EEG), eye movements (EOG), muscle activity (EMG), heart rate (ECG), and respiration. Temporal-frequency functions of the amplitude of the fundamental response across the temporal-frequency range were recorded during sleep and wakefulness. The highest temporal-frequency response recorded during wakefulness was accepted as a measure for inclusion in a growth function of temporal-frequency responsiveness. The resulting temporal resolution frequency vs. age function showed three separate maturational phases. Maturational phases were defined as (1) an initial slow phase from 1–32 days postnatal during which maturation of temporal vision is unremarkable; (2) an intermediate rapid phase of improvement from age 26 to 170 days; and (3) an overlapping but final slow phase from 151 to at least 270 days during which adult-like flicker resolution is approximated. This study suggests that the multiple maturational phases of the infant's responses to flickering light are due to maturational differences, which correspond with maturation of structural factors of brain function. Finally, across the age span tested, high-frequency responsivity was influenced significantly by the degree of infant arousal.

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