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Neuroimaging Clinics of North America May 2024Cerebrovascular surgery has many intraoperative imaging modalities available. Modern technologies include intraoperative digital subtraction angiogram, indocyanine green... (Review)
Review
Cerebrovascular surgery has many intraoperative imaging modalities available. Modern technologies include intraoperative digital subtraction angiogram, indocyanine green (ICG) angiography, relative fluorescent measurement with ICG, and ultrasound. Each of these can be used effectively in the treatment of open aneurysm and arteriovenous malformation surgeries, in addition to arteriovenous fistula surgery, and cerebral bypass surgery.
Topics: Humans; Indocyanine Green; Neurosurgery; Angiography, Digital Subtraction; Cerebral Angiography; Neurosurgical Procedures
PubMed: 38604710
DOI: 10.1016/j.nic.2024.01.005 -
Optics Letters Aug 2023This study develops a handheld optical coherence tomography angiography (OCTA) system that uses a high-speed (200 kHz) swept laser with a dual-reference common-path...
This study develops a handheld optical coherence tomography angiography (OCTA) system that uses a high-speed (200 kHz) swept laser with a dual-reference common-path configuration for stable and fast imaging. The common-path design automatically avoids polarization and dispersion mismatches by using one circulator as the primary system element, ensuring a cost-effective and compact design for handheld probe use. With its stable envelope (i.e., sub-µm shifts) and phase variation (corresponding to nm changes in axial displacement), the minimum detectable flow velocity is ∼ 0.08 mm/s in our experiment, which gives the common-path setup a high potential for application in a handheld OCTA system for clinical skin screening. In vivo skin structures and microvasculature networks on the dorsum of the hand and cheek of a healthy human are imaged successfully.
Topics: Humans; Tomography, Optical Coherence; Angiography; Skin; Microvessels; Lasers; Fluorescein Angiography
PubMed: 37527081
DOI: 10.1364/OL.488786 -
Journal of Reconstructive Microsurgery Mar 2022The benefits of preoperative perforator imaging for microsurgical reconstruction have been well established in the literature. (Review)
Review
BACKGROUND
The benefits of preoperative perforator imaging for microsurgical reconstruction have been well established in the literature.
METHODS
An extensive literature review was performed to determine the most commonly used modalities, and their applicability, advantages and disadvantages.
RESULTS
The review demonstrated varioius findings including decreases in operative time and cost with the use of CT angiography to identification of perforators for inclusion in flap design with hand-held Doppler ultrasound. Modalities like MR angiography offer alternatives for patients with contrast allergies or renal dysfunction while maintaining a high level of clarity and fidelity. Although the use of conventional angiography has decreased due to the availability of less invasive alternatives, it continues to serve a role in the preoperative evaluation of patients for lower extremity reconstruction. Duplex ultrasonography has been of great interest recently as an inexpensive, risk free, and extraordinarily accurate diagnostic tool. Emerging technologies such as indocyanine green fluorescence angiography and dynamic infrared thermography provide real-time information about tissue vascularity and perfusion without requiring radiation exposure.
CONCLUSION
This article presents an in-depth review of the various imaging modalities available to reconstructive surgeons and includes hand held Doppler ultrasound, CT angiography, MR angiography, conventional angiography, duplex ultrasonography, Indocyanine Green Fluorescence Angiography and Dynamic Infrared Thermography.
Topics: Angiography; Computed Tomography Angiography; Humans; Perforator Flap; Preoperative Care; Plastic Surgery Procedures; Surgical Flaps
PubMed: 34688218
DOI: 10.1055/s-0041-1736316 -
Developments in Ophthalmology 2016ZEISS Angioplex™ optical coherence tomography (OCT) angiography generates high-resolution three-dimensional maps of the retinal and choroidal microvasculature while... (Review)
Review
ZEISS Angioplex™ optical coherence tomography (OCT) angiography generates high-resolution three-dimensional maps of the retinal and choroidal microvasculature while retaining all of the capabilities of the existing CIRRUS™ HD-OCT Model 5000 instrument. Angioplex™ OCT angiographic imaging on the CIRRUS™ HD-OCT platform was made possible by increasing the scanning rate to 68,000 A-scans per second and introducing improved tracking software known as FastTrac™ retinal-tracking technology. The generation of en face microvascular flow images with Angioplex™ OCT uses an algorithm known as OCT microangiography-complex, which incorporates differences in both the phase and intensity information contained within sequential B-scans performed at the same position. Current scanning patterns for en face angiographic visualization include a 3 × 3 and a 6 × 6 mm scan pattern on the retina. A volumetric dataset showing erythrocyte flow information can then be displayed as a color-coded retinal depth map in which the microvasculature of the superficial, deep, and avascular layers of the retina are displayed together with the colors red, representing the superficial microvasculature; green, representing the deep retinal vasculature; and blue, representing any vessels present in the normally avascular outer retina. Each retinal layer can be viewed separately, and the microvascular layers representing the choriocapillaris and the remaining choroid can be viewed separately as well. In addition, readjusting the contours of the slabs to target different layers of interest can generate custom en face flow images. Moreover, each en face flow image is accompanied by an en face intensity image to help with the interpretation of the flow results. Current clinical experience with this technology would suggest that OCT angiography should replace fluorescein angiography for retinovascular diseases involving any area of the retina that can be currently scanned with the CIRRUS™ HD-OCT instrument and may replace fluorescein angiography and indocyanine green angiography for some choroidal vascular diseases.
Topics: Angiography; Animals; Choroid; Diagnostic Techniques, Ophthalmological; Fluorescein Angiography; Humans; Imaging, Three-Dimensional; Retinal Vessels; Tomography, Optical Coherence
PubMed: 27023249
DOI: 10.1159/000442773 -
Journal of Biophotonics May 2019A large-depth-of-field full-field optical angiography (LD-FFOA) method is developed to expand the depth-of-field (DOF) using a contrast pyramid fusion algorithm (CPFA)....
A large-depth-of-field full-field optical angiography (LD-FFOA) method is developed to expand the depth-of-field (DOF) using a contrast pyramid fusion algorithm (CPFA). The absorption intensity fluctuation modulation effect is utilized to obtain full-field optical angiography (FFOA) images at different focus positions. The CPFA is used to process these FFOA images with different focuses. By selecting high-contrast areas, the CPFA can highlight the characteristics and details of blood vessels to obtain LD-FFOA images. In the optimal case of the proposed method, the DOF for FFOA is more than tripled using 10 differently focused FFOA images. Both the phantom and animal experimental results show that the LD-FFOA resolves FFOA defocusing issues induced by surface and thickness inhomogeneities in biological samples. The proposed method can be potentially applied to practical biological experiments.
Topics: Angiography; Optical Imaging
PubMed: 30315638
DOI: 10.1002/jbio.201800329 -
Whole-brain arteriography and venography: Using improved velocity-selective saturation pulse trains.Magnetic Resonance in Medicine Apr 2018To develop velocity-selective (VS) MR angiography (MRA) protocols for arteriography and venography with whole-brain coverage.
PURPOSE
To develop velocity-selective (VS) MR angiography (MRA) protocols for arteriography and venography with whole-brain coverage.
METHODS
Tissue suppression using velocity-selective saturation (VSS) pulse trains is sensitive to radiofrequency field (B +) inhomogeneity. To reduce its sensitivity, we replaced the low-flip-angle hard pulses in the VSS pulse train with optimal composite (OCP) pulses. Additionally, new pulse sequences for arteriography and venography were developed by placing spatially selective inversion pulses with a delay to null signals from either venous or arterial blood. The VS MRA techniques were compared to the time-of-flight (TOF) MRA in six healthy subjects and two patients at 3T.
RESULTS
More uniform suppression of stationary tissue was observed when the hard pulses were replaced by OCP pulses in the VSS pulse trains, which improved contrast ratios between blood vessels and tissue background for both arteries (0.87 vs. 0.77) and veins (0.80 vs. 0.59). Both arteriograms and venograms depicted all major cervical and intracranial arteries and veins, respectively. Compared to TOF MRA, VS MRA not only offers larger spatial coverage but also depicts more small vessels. Initial clinical feasibility was shown in two patients with comparisons to TOF protocols.
CONCLUSION
Noncontrast-enhanced whole-brain arteriography and venography can be obtained without losing sensitivity to small vessel detection. Magn Reson Med 79:2014-2023, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
Topics: Adult; Angiography; Brain; Cerebral Angiography; Cerebrovascular Circulation; Computer Simulation; Female; Fourier Analysis; Humans; Image Interpretation, Computer-Assisted; Image Processing, Computer-Assisted; Imaging, Three-Dimensional; Male; Middle Aged; Models, Theoretical; Phlebography; Radio Waves
PubMed: 28799210
DOI: 10.1002/mrm.26864 -
Magma (New York, N.Y.) Oct 2020Coronary magnetic resonance angiography (coronary MRA) is advantageous in its ability to assess coronary artery morphology and function without ionizing radiation or... (Review)
Review
Coronary magnetic resonance angiography (coronary MRA) is advantageous in its ability to assess coronary artery morphology and function without ionizing radiation or contrast media. However, technical limitations including reduced spatial resolution, long acquisition times, and low signal-to-noise ratios prevent it from clinical routine utilization. Nonetheless, each of these limitations can be specifically addressed by a combination of novel technologies including super-resolution imaging, compressed sensing, and deep-learning reconstruction. In this paper, we first review the current clinical use and motivations for non-contrast coronary MRA, discuss currently available coronary MRA techniques, and highlight current technical developments that hold unique potential to optimize coronary MRA image acquisition and post-processing. In the final section, we examine the various research-based coronary MRA methods and metrics that can be leveraged to assess coronary stenosis severity, physiological function, and atherosclerotic plaque characterization. We specifically discuss how such technologies may contribute to the clinical translation of coronary MRA into a robust modality for routine clinical use.
Topics: Contrast Media; Coronary Angiography; Coronary Vessels; Heart; Magnetic Resonance Angiography
PubMed: 32242282
DOI: 10.1007/s10334-020-00834-8 -
Acta Neurologica Belgica Apr 2023
Topics: Humans; Angiography; Endovascular Procedures; Contrast Media
PubMed: 35859227
DOI: 10.1007/s13760-022-02034-8 -
Atherosclerosis Feb 2023
Topics: Humans; Computed Tomography Angiography; Artificial Intelligence; Carotid Arteries; Plaque, Atherosclerotic; Angiography; Carotid Stenosis; Coronary Angiography
PubMed: 36682983
DOI: 10.1016/j.atherosclerosis.2023.01.006 -
Ultrasound in Medicine & Biology Oct 2020Cancerous tumor growth is associated with the development of tortuous, chaotic microvasculature, and this aberrant microvascular morphology can act as a biomarker of... (Review)
Review
Cancerous tumor growth is associated with the development of tortuous, chaotic microvasculature, and this aberrant microvascular morphology can act as a biomarker of malignant disease. Acoustic angiography is a contrast-enhanced ultrasound technique that relies on superharmonic imaging to form high-resolution 3-D maps of the microvasculature. To date, acoustic angiography has been performed with dual-element transducers that can achieve high contrast-to-tissue ratio and resolution in pre-clinical small animal models. In this review, we first describe the development of acoustic angiography, including the principle, transducer design, and optimization of superharmonic imaging techniques. We then detail several preclinical applications of this microvascular imaging method, as well as the current and future development of acoustic angiography as a pre-clinical and clinical diagnostic tool.
Topics: Acoustics; Angiography; Animals; Contrast Media; Forecasting; Humans; Microvessels; Neoplasms; Neovascularization, Pathologic; Ultrasonography
PubMed: 32703659
DOI: 10.1016/j.ultrasmedbio.2020.06.009