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Intracoronary Imaging
摘要： Coronary angiography represents both the gold standard for diagnosis of coronary artery disease and the main guidance for percutaneous coronary intervention (PCI). Yet, coronary angiography is well known to not be optimal in appreciating the whole spectrum of lesions that may cause clinical problems in patients with coronary artery disease. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) represent the 2 contemporary invasive intracoronary imaging modalities aimed at improving the detection of coronary details. Their potential is extraordinary but their use for improving coronary disease diagnosis is not standardized. Moving from diagnosis to treatment, PCI based on drug-eluting stent (DES) implantation often requires a series of manipulations with different techniques and devices. Last generation DES types have similar technical features and share a comparable ability to scaffold coronary lesions. Not surprisingly, lesion complexity is known to be associated with increased procedure challenges that may be tackled by different strategies. The selection of devices and the assessment of appropriate DES implantation may be based on either angiography or intracoronary imaging techniques like IVUS or OCT. Both techniques have evolved over time and offer the possibility to see details of coronary lesions and stent/vessel interactions that are impossible to be captured and measured by angiography. So far, thousands of studies with different designs have been performed, but they have not been able to make interventional cardiologists act in a homogeneous way. Consequently, intravascular imaging is selected on the basis of individual yield, with an impressive variability across different countries and operators. Reimbursement issues are part of the game but do not entirely explain the overall underutilization of intravascular imaging (especially in Western countries where a lot of expensive devices are routinely incorporated in interventional practice). In reality, the application of intracoronary imaging adds complexity to PCI, requires adequate technical skills, and by itself does not necessarily improve the clinical outcome. As compared with angiography guidance, IVUS and OCT are able to provide (in real time) many more coronary details. Such angiographically invisible details need to be recognized by the operator to properly react to improve the clinical outcome of treated patients. Because of the impressive amount of details and possible measures/cutoffs, the identification of both impactful features (deserving attention) and best reactions (additional technical steps with corrective efficacy) is pivotal. Yet, data collected by IVUS studies have not been concordant and this has resulted in overall limited clinical penetration: many catheterization laboratories are actually working without any access to intracoronary imaging. Furthermore, although rare, imaging catheter-related complications may occur so that a safety issue has to be considered any time the expected benefit is not well established in clinical practice. On the bases of these concepts, it is evident that the intracoronary imaging clinical impact may come from the correct identification and appropriate processing of those details that may help (1) to improve the PCI strategy (technique/device selection, that is, PCI planning) and (2) to facilitate the achievement of improved stenting result (ie, PCI optimization). As shown in the Figure, among all the information captured by intracoronary imaging, a limited series of imaging-based pre-PCI findings can be easily incorporated in the PCI planning (lesion preparation and stent selection). Similarly, some key intra-PCI findings (stent underexpansion, stent edge dissections, and strut malapposition) can be searched in order to optimize the stent implantation result. The feasibility of this approach is supported by the daily experience of many high volume centers. Yet, the overall clinical impact of image guidance in PCI is still unrecognized, and large studies in the field are needed. Recently-collected data started shedding new light on both IVUS and OCT. The large study by Maehara et al, although not randomized, allowed to run a propensity-matched comparison between thousands of IVUS-guided and angiography-guided procedures. IVUS use was associated with different procedure conduction and reduced major adverse events incidence at up to 2 years. Of note, the clinical benefit comprised significant improvements of hard end points, namely stent thrombosis, myocardial infarction, and cardiac mortality. Such results fit well with the recent ULTIMATE prospective randomized trial (Intravascular Ultrasound Guided Drug Eluting Stents Implantation in 'All-Comers' Coronary Lesions). The ULTIMATE investigators randomized 1448 all-comer patients who required DES implantation to either IVUS guidance or angiography guidance. As compared with angiography, randomization to IVUS guidance was associated with different procedure course (higher contrast administration, larger and longer stents, and higher inflation pressures) and warranted lower target vessel failures with IVUS at 12 months. OCT, as compared with IVUS, represents a younger technique, but data are growingly been collected because it has the appeal of offering higher resolution. The specific image generation process of OCT translates into the need of dedicated experience but has the potential for shorter learning curve. The possible clinical impact of OCT use in PCI guidance has been started to be highlighted by the results of the CLI-OPCI II study (Centro per la Lotta Contro l'Infarto-Optimisation of Percutaneous Coronary Intervention II). In this large registry, specific definitions for OCT features of suboptimal stent results were found to be independently associated with adverse clinical outcome after PCI. For sure, more complex PCIs (where the risk of stent thrombosis and restenosis is higher), are expected to benefit more from PCI refinements. Thus, two large prospectively randomized trials (OCTOBER, and ILUMIEN IV, and URL: https://www.clinicaltrials.gov. Unique identifier: NCT03507777) comparing OCT and angiographic guidance are actually ongoing and have been powered to explore the benefit of OCT guidance (using rigorous OCT-based PCI optimization algorithms) in, respectively, bifurcated lesions and complex patients. In conclusion, intravascular imaging modalities are entering a new era because the recently collected data seem to show new thresholds and targets for PCI planning and optimization. Thus, IVUS and OCT are going to become the ideal glasses that interventional cardiologists should wear anytime something looks unclear before, during or after PCI. Appropriate education, standardization of operative protocols and definitions of best clinical settings for application represent the future challenges for the intravascular imaging clinical implementation.
关键词： intravascular ultrasound,angiography,myocardial infarction,Editorials,diagnosis,optical coherence tomography,coronary artery disease,percutaneous coronary intervention
更新于2025-09-23 15:22:29
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Simultaneous Axial Multifocal Imaging using a Single Acoustical Transmission: a Practical Implementation
摘要： Standard ultrasound imaging techniques rely on sweeping a focused beam across a field of view; however, outside the transmission focal depth, image resolution and contrast are degraded. High-quality deep tissue in vivo imaging requires focusing the emitted field at multiple depths, yielding high resolution and high contrast ultrasound images but at the expense of a loss in frame rate. Recent developments in ultrasound technologies have led to user-programmable systems, which enable real-time dynamic control over the phase and apodization of each individual element in the imaging array. In this paper, we present a practical implementation of a method to achieve simultaneous axial multifoci using a single acoustical transmission. Our practical approach relies on the superposition of axial multifoci waveforms in a single transmission. The delay in transmission between different elements is set such that pulses constructively interfere at multiple focal depths. The proposed method achieves lateral resolution similar to successive focusing, but with an enhanced frame rate. The proposed method uses standard dynamic receive beamforming, identical to two-way focusing, and does not require additional post-processing. Thus, the method can be implemented in real-time on programmable ultrasound systems that allow different excitation signals for each element. The proposed method is described analytically and validated by laboratory experiments in phantoms and ex vivo biological samples.
关键词： beamforming,frame rate,multifoci,ultrasound imaging
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - Feasibility Study of a Coherent Multi-Transducer US Imaging System
摘要： Ultrasound images can be difficult to assess, because of the limited resolution and view-dependent artefacts that are inherent to the small aperture transducers used clinically. An extended aperture has the potential to greatly improve imaging performance. This work introduces a fully coherent multi-transducer ultrasound imaging system, formed by two ultrasound transducers that are synchronized, freely located in space with a common field of view and transmit plane waves. Through coherent combination of the different transducers, a larger effective aperture is obtained and then an improved final image. First phantom images produced using this technique are presented here.
关键词： Large Aperture,Beamforming,Image Resolution,Plane Waves,Ultrasound Imaging
更新于2025-09-23 15:22:29
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Automatic thyroid nodule recognition and diagnosis in ultrasound imaging with the YOLOv2 neural network
摘要： Background: In this study, images of 2450 benign thyroid nodules and 2557 malignant thyroid nodules were collected and labeled, and an automatic image recognition and diagnosis system was established by deep learning using the YOLOv2 neural network. The performance of the system in the diagnosis of thyroid nodules was evaluated, and the application value of artificial intelligence in clinical practice was investigated. Methods: The ultrasound images of 276 patients were retrospectively selected. The diagnoses of the radiologists were determined according to the Thyroid Imaging Reporting and Data System; the images were automatically recognized and diagnosed by the established artificial intelligence system. Pathological diagnosis was the gold standard for the final diagnosis. The performances of the established system and the radiologists in diagnosing the benign and malignant thyroid nodules were compared. Results: The artificial intelligence diagnosis system correctly identified the lesion area, with an area under the receiver operating characteristic (ROC) curve of 0.902, which is higher than that of the radiologists (0.859). This finding indicates a higher diagnostic accuracy (p = 0.0434). The sensitivity, positive predictive value, negative predictive value, and accuracy of the artificial intelligence diagnosis system for the diagnosis of malignant thyroid nodules were 90.5%, 95.22%, 80.99%, and 90.31%, respectively, and the performance did not significantly differ from that of the radiologists (p > 0.05). The artificial intelligence diagnosis system had a higher specificity (89.91% vs 77.98%, p = 0.026). Conclusions: Compared with the performance of experienced radiologists, the artificial intelligence system has comparable sensitivity and accuracy for the diagnosis of malignant thyroid nodules and better diagnostic ability for benign thyroid nodules. As an auxiliary tool, this artificial intelligence diagnosis system can provide radiologists with sufficient assistance in the diagnosis of benign and malignant thyroid nodules.
关键词： Thyroid nodules,Ultrasound,Artificial intelligence,Computer-aided diagnosis systems,YOLOv2 neural network
更新于2025-09-23 15:22:29
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A fast scheme for renal microvascular perfusion functional imaging: Assessed by an imaging quality evaluation model
摘要： Purpose: This study aimed to develop a fast scheme of multiparametric perfusion functional imaging (PFI) based on dynamic contrast-enhanced ultrasound (DCEUS) for assessing renal microvascular hemodynamics. Method: The flow process in the DCEUS-based PFI was modified step-by-step to improve its operational efficiency, which was validated through in vivo renal perfusion experiments. A multiparametric model with a comprehensive coefficient of imaging quality (CIQ) was then built on four terms of the average information entropy, contrast, gray, and noise coefficient of PFIs to evaluate the sacrifice of imaging quality during modifications of DCEUS-based PFI. Results: The multiparametric model successfully evaluated modifications of DCEUS-based PFI from multiple perspectives (R2 = 0.73, P < 0.01). Compared with the raw scheme in the renal sagittal and coronal planes, the fast PFI scheme significantly improved its operational efficiency by 62.82 ± 1.07% (P < 0.01) and the nine PFIs simultaneously maintained a similar CIQ of 0.26 ± 0.06. Conclusions: The inhomogeneous hemodynamic distributions with a ring-like feature in the renal microvasculature were accurately and efficiently characterized by the fast PFI scheme. The fast PFI scheme can be applied for early diagnosis, follow-up evaluation and monitoring treatment of chronic kidney disease.
关键词： modification,coefficient of imaging quality,perfusion functional imaging,multiparametric model,dynamic contrast-enhanced ultrasound
更新于2025-09-23 15:22:29
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Arterial Stiffness Assessment by Shear Wave Elastography and Ultrafast Pulse Wave Imaging: Comparison with Reference Techniques in Normotensives and Hypertensives
摘要： Shear wave elastography and ultrafast imaging of the carotid artery pulse wave were performed in 27 normotensive participants and 29 age- and sex-matched patients with essential hypertension, and compared with reference techniques: carotid–femoral pulse wave velocity (cfPWV) determined via arterial tonometry and carotid stiffness (carPWV) determined via echotracking. Shear wave speed in the carotid anterior (a-SWS) and posterior (p-SWS) walls were assessed throughout the cardiac cycle. Ultrafast PWV was measured in early systole (ufPWV-FW) and in end-systole (dicrotic notch, ufPWV-DN). Shear wave speed in the carotid anterior appeared to be the best candidate to evaluate arterial stiffness from ultrafast imaging. In univariate analysis, a-SWS was associated with carPWV (r = 0.56, p = 0.003) and carotid-to-femoral PWV (r = 0.66, p < 0.001). In multivariate analysis, a-SWS was independently associated with age (R2 = 0.14, p = 0.02) and blood pressure (R2 = 0.21, p = 0.004). Moreover, a-SWS increased with blood pressure throughout the cardiac cycle and did not differ between normotensive participants and patients with essential hypertension when compared at similar blood pressures.
关键词： Hypertension,Vascular ultrasound,Arterial stiffness,Pulse wave velocity,Shear wave elastography,Ultrafast imaging,Echotracking
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - High Voltage Excitation and Nonlinear Transmission of a 16 MHz AlN-Based Piezoelectric Micro-Machined Ultrasonic Transducer
摘要： This paper reports the performance of a 25 μm AlGaN-based micro-piezoelectric transducer (MPT) under high voltage excitation and determination. The proposed MPT array consists of 23×28 elements fabricated on a silicon-on-insulator (SOI) substrate with 1 μm AlGaN thin film on 24 μm silicon membrane. With all the array elements electrically connected together, the electric impedance of the MPT was 11.5–7.22 kΩ at 24.7 MHz resonance frequency in air and 3.21–7.24 kΩ at 22.8 MHz when the device was water charged. The laser Doppler vibrometer (LDV) measurements showed that the transmission efficiency and the bandwidth for free vibration were 1.6 nm/V and 1.0%, respectively. The resonance modes were specifically associated with the material parameters and the initial state of the device. Moreover, nonlinear behavior was observed when increasing the input mean power exceeded 24 mW. This strategy is potentially applied to CMOS-compatible high-resolution ultrasound imaging.
关键词： AlGaN,CMOS-compatible,Ultrasound,High voltage,Micro-piezoelectric transducer
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - High Intensity Focused Ultrasound (HIFU) Combines Optical Coherence Tomography(OCT) for Biological Tissue Treatment and Evaluation
摘要： Light intensity focused ultrasound (LIFU) is an early stage medical technology that is in various stages of development to treat a range of disorders including super?cial diseases. Optical coherence tomography (OCT) is a rapid development imaging technique in recent ten years, which is a good way to monitor the tissue structure of super?cial diseases. In this study, OCT system is used to monitor the tissue structure of super?cial diseases during LIFU treatment. During the treatment, LIFU was performed on the lesion area of the sample with different energy levels for different times: 5s, 10s, 15s, 20s, 25s, 30s, respectively. During the treatment, the OCT system was working to monitor the tissue structure. The results showed that the light intensity of the lesion area increased with the treatment time, and the structure of the tissue changed. This study provides a new method for monitoring the treatment of super?cial diseases with LIFU.
关键词： Monitoring,Optical coherence tomography,Tissue structure,Super?cial diseases,Light intensity focused ultrasound
更新于2025-09-23 15:22:29
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Receive Beam-Steering and Clutter Reduction for Imaging the Speed-of-Sound Inside the Carotid Artery
摘要： Handheld imaging of the tissue’s speed-of-sound (SoS) is a promising multimodal addition to diagnostic ultrasonography for the examination of tissue composition. Computed ultrasound tomography in echo mode (CUTE) probes the spatial distribution of SoS, conventionally via scanning the tissue under a varying angle of ultrasound transmission, and quantifying—in a spatially resolved way—phase variations of the beamformed echoes. So far, this technique is not applicable to imaging the lumen of vessels, where blood ?ow and tissue clutter inhibit phase tracking of the blood echoes. With the goal to enable the assessment of atherosclerotic plaque composition inside the carotid artery, we propose two modi?cations to CUTE: (a) use receive (Rx) beam-steering as opposed to transmit (Tx) beam-steering to increase acquisition speed and to reduce ?ow-related phase decorrelation, and (b) conduct pairwise subtraction of data obtained from repetitions of the scan sequence, to highlight blood echoes relative to static echo clutter and thus enable the phase tracking of blood echoes. These modi?cations were tested in a phantom study, where the echogenicity of the vessel lumen was chosen to be similar to the one of the background medium, which allows a direct comparison of SoS images obtained with the different techniques. Our results demonstrate that the combination of Rx-steering with the subtraction technique results in an SoS image of the same quality as obtained with conventional Tx-steering. Together with the improved acquisition speed, this makes the proposed technique a key step towards successful imaging of the SoS inside the carotid artery.
关键词： atherosclerosis,clutter reduction,plaque characterisation,multimodal imaging,ultrasound tomography
更新于2025-09-23 15:22:29
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Technical notes Integrated image navigation system using head-mounted display in “RoboSurgeon” endoscopic radical prostatectomy
摘要： The safety and efficacy of minimally invasive surgery relies on visual information. We aimed to develop an integrated image navigation system (RoboSurgeon System) that combines head-mounted displays (HMDs) with multiple image modalities, and assessed its feasibility in 5 prostate cancer patients who underwent gasless single-port endoscopic radical prostatectomy. A robotically manipulated transrectal ultrasound (TRUS) system was used. In all cases, preoperative magnetic resonance (MR) images and intraoperative real-time images of an endoscope, TRUS, and HMD-mounted camera were integrated and displayed synchronously on each HMD in a four-split screen mode during the entire process. The TRUS helped identify the boundary with the adjacent structures endoscopically in reference to MR images. There were no negative incidents in intraoperative or postoperative courses. Integrated image navigation using HMDs as individualized monitors is feasible in the natural ergonomic position and may be beneficial to identify correct dissection planes. The efficacy of the RoboSurgeon System deserves further evaluation.
关键词： image navigation,prostate cancer,head-mounted display,minimally invasive surgery,transrectal ultrasound,radical prostatectomy
更新于2025-09-23 15:22:29