Visualization Of Microvessels Research Articles

Ultrahigh-Resolution Visualization of Vascular Heterogeneity in Brain Tumors via Magnetic Nanoparticles-Enhanced Susceptibility-Weighted Imaging.

The precise assessment of vascular heterogeneity in brain tumors is vital for diagnosing, grading, predicting progression, and guiding treatment decisions. However, currently, there is a significant shortage of high-resolution imaging approaches. Herein, we propose a contrast-enhanced susceptibility-weighted imaging (CE-SWI) utilizing the minimalist dextran-modified Fe3O4 nanoparticles (Dextran@Fe3O4 NPs) for ultrahigh-resolution mapping of vasculature in brain tumors. The Dextran@Fe3O4 NPs are prepared via a facile coprecipitation method under room temperature, and exhibit small hydrodynamic size (28 nm), good solubility, excellent biocompatibility, and high transverse relaxivity (r2*, 159.7 mM-1 s-1) under 9.4 T magnetic field. The Dextran@Fe3O4 NPs-enhanced SWI can increase the contrast-to-noise ratio (CNR) of cerebral vessels to 2.5 times that before injection and achieves ultrahigh-spatial-resolution visualization of microvessels as small as 0.1 mm in diameter. This advanced imaging capability not only allows for the detailed mapping of both enlarged peritumoral drainage vessels and the intratumoral microvessels, but also facilitates the sensitive imaging detection of vascular permeability deterioration in a C6 cells-bearing rat glioblastoma model. Our proposed Dextran@Fe3O4 NPs-enhanced SWI provides a powerful imaging technique with great clinical translation potential for the precise theranostics of brain tumors.

Ultrasound Microvessel Visualization in Cervical Cancer: Association Between Novel Ultrasound Techniques and Histologic Microvessel Densities.

The aim of the work described here was to evaluate the feasibility of superb microvascular imaging (SMI) and vascular endothelial growth factor receptor 2 (VEGFR2)-targeted microbubble (MBVEGFR2)-based ultrasound molecular imaging (USMI) for visualizing microvessels in cervical cancer. Hela cells were used to establish subcutaneous cervical cancer models. SMI and MBVEGFR2-based USMI were performed, and the results were compared with intratumoral microvessel density (MVD) in four groups based on tumor diameter (<3 mm, 3-5 mm, 5-7 mm and ≥7 mm). The vascularization index (VI, %) was evaluated for SMI, and the normalized intensity difference (NID) for USMI. Tumors with diameters ranging from 3 to 5 mm had the highest VI (39.07 ± 1.58) in SMI, and VI significantly decreased with increasing tumor size (all p values <0.001). The strongest signal intensity was observed in very early tumors (d < 3 mm: 43.80 ± 3.58%) after MBVEGFR2 administration; the NID gradually decreased with increasing diameter of tumors (all p values=0.007). However, no significant differences were observed in NID after administration of non-targeted (control) microbubbles (MBCon) (all p values=0.125). MBVEGFR2-based USMI had the strongest correlation with MVD in displaying microvessels of cervical cancer compared with SMI and MBCon (R2=0.78 vs. R2=0.40 and R2=0.38). These findings validate the superiority and accuracy of MBVEGFR2-based USMI for microvessel imaging and monitoring of angiogenesis in cervical cancer compared with SMI and MBCon. Nonetheless, SMI remains an alternative to microvessel imaging when ultrasonic contrast agent use is contraindicated.

Time–frequency analysis of laser speckle contrast for transcranial assessment of cerebral blood flow

Improving noninvasive approaches to monitoring blood microcirculation is an urgent topic in modern biomedical engineering. One of the actively developing methods is laser speckle contrast imaging (LSCI), which allows not only the visualization of microvessels but also the quantitative measurements of microcirculatory blood flow. This work shows the application of LSCI for mapping the cerebral vessels of a laboratory animal, and also presents the time–frequency processing of the registered signal. Thus, we expand the capabilities of the existing LSCI approach and demonstrate spatial mapping of blood flow rhythms. The proposed technology makes it possible not only to measure the relative cerebral blood flow but also to expand diagnostic capabilities for a detailed analysis of the physiological mechanisms of changes in blood flow.

Evaluation of Takayasu's arteritis activity by ultrasound localization microscopy

Abstract Objectives Use of sulphur hexafluoride microbubbles (MB) with ultrasound can provide arterial wall enhancement. The use of ultrafast imaging with MB super-localization offers the possibility of ultrasound localization microscopy (ULM) and thus a visualization of in vivo carotid vasa vasorum. We aim to perform in vivo Vasa vasorum imaging in the carotid wall in Takayasu's arteritis and to provide a correlation with the disease's activity. Methods Patients with Takayasu arteritis were consecutively included in the national referral centre. Assessment of activity was performed by NIH activity index, with measurement of biological inflammation, morphological evaluation by computed tomography (CT) angiography, and 18-fluorodeoxyglucose CT scan. Ultrafast ultrasound imaging was performed with a 7 MHz central frequency linear probe. A dedicated contrast imaging sequence (plane waves with 8 angles, frame rate 500 Hz, voltage 8 V, duration of 8 s), coupled with the intravenous injection of sulphur hexafluoride MB allow us to store the raw radio frequency data of the MB passage. After a pre-processing step to accumulate frames properly including a frames selection and a movement correction, the MB were localized then tracked, allowing reconstruction of the vasa vasorum. The inflammation was quantified through MB tracked and normalized for inter acquisition comparison. Results 16 patients were included. 5 patients (median age 35.8 [24.5–46.0] years, 3 women) had active disease and 11 patients (37.2 [31.7–47.3] years, 9 women) had quiescent disease. The passage of MB allowed the visualisation of microvessels within the arterial wall for active cases. The number of MB detected per second in the wall was 118 [80–169] for active cases vs. 13 [10–15] for quiescent cases (p=0.0005). Conclusion ULM allows visualization of microvessels within the carotid wall, with significantly greater MB passage in active Takayasu arteritis. ULM provides for the first time a precise visualization in vivo of the vasa vasorum and gives access to quantification of the vascularity of the arterial wall. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Société française de cardiologie

Development of an Imaging Framework for Visualization of Cutaneous Micro-Vasculature by using High Frequency Ultrafast Ultrasound Imaging.

Visualization of cutaneous micro-vasculatures is a determined approach in the diagnosis of skin vascular disorders. Clinically, high frequency ultrasound (HFUS) modalities have been used for cutaneous morphological and structural imaging, but visualization of micro-vessels has always been remained a daunting task. These tiny structures might be visualized by devising a highly sensitive Doppler technique for HFUS systems. In this study, we proposed an imaging framework using HFUS (30 MHz) ultrafast Doppler imaging along with SVD clutter filtering that is proficient in detection of micro-scale circulation. The performance of the devised framework was examined on a 200-micron flow phantom made of poly-vinyl alcohol under four different flow rates (56 - 18 ul/min) and visualized the micro-structure with averaged detected diameter of 93 - 170 µm. The results indicated that the devised framework has sufficient sensitivity and resolvability to visualize the micro-vasculatures in dermis layer of skin (depth ≤ 4 mm). Clinical Relevance - This study brings an insight to visualize in-vivo cutaneous micro-vasculatures with ultrafast Doppler imaging in clinical applications for better assessment of cutaneous disorders.

Improved Ultrafast Power Doppler Imaging by Using Spatiotemporal Non-Local Means Filtering.

The change of microvasculature is associated with the occurrence and development of many diseases. Ultrafast power Doppler imaging (uPDI) is an emerging technology for the visualization of microvessels due to the development of ultrafast plane wave (PW) imaging and advanced clutter filters. However, the low signal-to-noise ratio (SNR) caused by unfocused transmit of PW imaging deteriorates the subsequent imaging of microvasculature. Nonlocal means (NLM) filtering has been demonstrated to be effective in the denoising of both natural and medical images, including ultrasound power Doppler images. However, the feasibility and performance of applying an NLM filter on the ultrasound radio frequency (RF) data have not been investigated so far. In this study, we propose to apply an NLM filter on the spatiotemporal domain of clutter filtered blood flow RF data (St-NLM) to improve the quality of uPDI. Experiments were conducted to compare the proposed method with three different methods (under various similarity window sizes), including conventional uPDI without NLM filtering (Non-NLM), NLM filtering on the obtained power Doppler images (PD-NLM), and NLM filtering on the spatial domain of clutter filtered blood flow RF data (S-NLM). Phantom experiments, in vivo contrast-enhanced human spinal cord tumor experiments, and in vivo contrast-free human liver experiments were performed to demonstrate the superiority of the proposed St-NLM method over the other three methods. Qualitative and quantitative results show that the proposed St-NLM method can effectively suppress the background noise, improve the contrast between vessels and background, and preserve the details of small vessels at the same time. In the human liver study, the proposed St-NLM method achieves 31.05-, 24.49-, and 11.15-dB higher contrast-to-noise ratios (CNRs) and 36.86-, 36.86-, and 15.22-dB lower noise powers than Non-NLM, PD-NLM, and S-NLM, respectively. In the human spinal cord tumor, the full-width at half-maximums (FWHMs) of vessel cross Section are 76, 201, and [Formula: see text] for St-NLM, Non-NLM, and S-NLM, respectively. The proposed St-NLM method can enhance the microvascular visualization in uPDI and has the potential for the diagnosis of many microvessel-change-related diseases.

An advanced ultrasound application used to assess peripheral vascular diseases: superb microvascular imaging.

Over the past several years, a novel ultrasound imaging modality termed superb microvascular imaging (SMI) has enabled visualization of microvessels. SMI ultrasound studies of peripheral artery diseases have significantly extended our knowledge of tissue microcirculation and the arterial microenvironments of atherosclerotic lesions. We here present an overview of current knowledge on the utility of SMI assessment of vascular diseases and highlight certain peripheral microcirculation disorders for which SMI is particularly valuable. The evidence indicates that SMI can detect intraplaque neovascularization and usefully assess carotid plaque vulnerability; vascularization of the carotid arterial wall detected by SMI is a potential marker of disease activity in patients with Takayasu arteritis; SMI reveals the foot microcirculation and yields a quantitative vascular index (in line with the angiosome concept); and, SMI may serve as an auxiliary diagnostic modality for hereditary hemorrhagic telangiectasia and Raynaud syndrome. In general, microcirculatory evaluation by SMI is an attractive field for future research on therapeutic strategies for peripheral vascular diseases.

Visibility of microvessels in Optical Coherence Tomography angiography depends on angular orientation.

Optical Coherence Tomography angiography (OCTA) is a widespread tool for depth-resolved imaging of chorioretinal vasculature with single microvessel resolution. To improve the clinical interpretation of OCTA, the conditions affecting visualization of microvessels must be defined. Here we inject a scattering plasma tracer (Intralipid) during OCTA imaging of the anesthetized rat eye. In the retina, we find that interlaminar (vertical) vessels that connect laminae have one-fourth to one-third the OCTA red blood cell to tracer (RBC-to-tracer) signal ratio of intralaminar (horizontal) vessels. This finding suggests that the OCTA signal from microvessels depends on angular orientation, making vertically-oriented vessels more difficult to visualize using intrinsic contrast alone. Clinicians should be aware of this potential artifact when interpreting OCTA.

Imaging of Microhemodynamics in Peripheral Nerves by Contact Endoscope

Entrapment neuropathies include a wide field of locations. In most cases, the microsurgical decompression is still the therapy of choice. However, the role of venous stasis and ischemia is still discussed controversially. Here the authors evaluated the visualization of microvessels and the microperfusion at peripheral nerves with a contact endoscope during the surgical decompression for the first time. Eight patients were subjected to endoscopic or endoscopically assisted peripheral nerve decompression. In 3 patients with nerve tumors, the tumor carrying nerve was inspected endoscopically proximal and distal to the tumor site before and after resection. Microcirculation was assessed by a contact endoscope, allowing a 150-fold magnification, at superficial areas proximal and distal to the compression site. The electronically stored records were analyzed retrospectively using image processing software. Vessel diameter, red blood cell velocity, and blood flow, before and after decompression, were extracted. The contact endoscope was easy to handle intraoperatively without problems. All minimally invasive procedures were performed without complications. In the offline computer-assisted analysis, single arterioles and veins were visualized showing decreased red blood cell velocity prior to decompression. After surgical treatment, a statistically significant increase of blood flow was observed. Basically, the application of a contact endoscope for visualization of peripheral nerves' microcirculation is feasible. The observed effect of increased blood flow after decompression should be compared with the clinical outcome in a further prospective randomized study.

Non-Local Based Denoising Framework for In Vivo Contrast-Free Ultrasound Microvessel Imaging.

Vascular networks can provide invaluable information about tumor angiogenesis. Ultrafast Doppler imaging enables ultrasound to image microvessels by applying tissue clutter filtering methods on the spatio-temporal data obtained from plane-wave imaging. However, the resultant vessel images suffer from background noise that degrades image quality and restricts vessel visibilities. In this paper, we addressed microvessel visualization and the associated noise problem in the power Doppler images with the goal of achieving enhanced vessel-background separation. We proposed a combination of patch-based non-local mean filtering and top-hat morphological filtering to improve vessel outline and background noise suppression. We tested the proposed method on a flow phantom, as well as in vivo breast lesions, thyroid nodules, and pathologic liver from human subjects. The proposed non-local-based framework provided a remarkable gain of more than 15 dB, on average, in terms of contrast-to-noise and signal-to-noise ratios. In addition to improving visualization of microvessels, the proposed method provided high quality images suitable for microvessel morphology quantification that may be used for diagnostic applications.

Influence of Helicobacter pylori Infection on Endoscopic Findings of Gastric Adenocarcinoma of the Fundic Gland Type.

PurposeGastric adenocarcinoma of the fundic gland type (chief cell predominant type) (GA-FG-CCP) was first reported as a rare adenocarcinoma found in the normal fundic mucosa. Recent studies have proposed the possibility that GA-FG-CCPs were also generated in the atrophic mucosa after Helicobacter pylori (HP) eradication therapy. However, little is known on the endoscopic findings of GA-FG-CCP generated in the atrophic mucosa due to its extreme rarity.Materials and MethodsA total of 8 patients who underwent endoscopic submucosal resection and were diagnosed with GA-FG-CCP generated in the HP-uninfected mucosa (4 cases, HP-uninfected group) or HP-eradicated atrophic mucosa (4 cases, HP-eradicated group) were retrospectively analyzed, and their endoscopic findings, including magnifying endoscopy with narrow band imaging (M-NBI), and pathological features were compared.ResultsWhile GA-FG-CCPs in the 2 groups displayed similar macroscopic appearance, M-NBI demonstrated that characteristic microvessels (tapered microvessels like withered branches) were specifically identified in the HP-eradicated group. Pathological investigation revealed that a decreasing number of fundic glands and thinned foveolar epithelium covering tumor ducts were thought to lower the thickness of the covering layer over tumor ducts in the HP-eradicated group. Moreover, dilation of vessels just under the surface of the lesions contributed to the visualization of microvessels by M-NBI.ConclusionsThe change in background mucosa due to HP infection influenced the thickness of the covering layer over the tumor ducts and M-NBI finding of GA-FG-CCP.

Minimal Esophageal Lesions Detected by Digital Chromoendoscopy Using Optical Enhancement SystemTM Associated to High Definition Plus Optical Magnification in Non-Erosive Reflux Disease (NERD)

Introduction: Patients with GERD have an increased number, dilation and tortuosity of microscopic intra-papillary capillary loops (IPCLs). Recently, an image-enhanced technology called Optical Enhancement system (OE systemTM) is equipped in Pentax video processor EPK-i7010. It improves visualization of microvessels. Also new high definition scopes with optical magnification (MagniviewTM) were developed (increase image >136 times). AIM: To evaluate diagnosis ability of OE systemTM +MagniviewTM scopes detecting minimal esophageal lesions IPCLs and predicting reflux in non-erosive reflux disease (NERD).Figure: Red ROC curve: pH-Impedanciometry. Blue ROC curve: Biopsy. UELS: Upper endoscopy low segment. UEMS: Upper endoscopy middle segment. UEUP: Upper endoscopy upper segment. UEG: Upper endoscopy in general.Table: Table. Contingency Table comparing Upper Endoscopy with Ph-Impedanciometry and histopathological BiopsyMethods: Prospective, non-randomized study. Patients enrolled had GERD symptoms. If esophagus was normal at endoscopy, pH-impedanciometry was performed to discriminate NERD patients (NG) from non reflux disease (Control group, CG). OE systemTM+MagniviewTM endoscopy was performed. Images were recorded and examined blindly by 3 endoscopists. Biopsies from each esophagus level were done. Images were compared to histology to predict inflammation. Inclusion Criteria: >18 years-old, >8 points at GERD questionnaire), abcense of Barrett's esophagus or erosive sign (Los Angeles classification grade A-D) by endoscopy (by neither white light nor I-ScanTM). Exclusion Criteria: History of esophagitis, achalasia, esophageal varices, esophageal cancer, PPI or NSAIDs consumption, coagulopathy, gastric lesions, gastroparesis, esophageal/gastric surgery, pregnancy. Results: 57 patients were analyzed [36 (63.2%) NG, 21 (36.9%) CG] [mean age 48 yo, 46 women (81%)]. Main symptom was regurgitation in 27 cases (47.3%). IPCLs was observed in 94.4% of NG, being lower third the most affected (P<0.05). In CG 8 patients (38%) had IPCLs (P<0.05 for NG). IPCLs dilatation was most common find (91.6%). Unlike IPCLs tortuosity, both dilatation and increased number of IPCLs showed a significant difference between groups. Also both lesions were more common (P<0.05) between patients with inflammation at histology. OE systemTM+Magniview scopes ability predicting GERD (gold standard: pH-Impedanciometry) reached sensitivity, specificity, PPV, NPV and accuracy of 94.4, 61.9, 91.4, 81.8 and 86.67% respectively. Lower third of esophagus had higher sensibility and accuracy (88.9 and 87.7%). Kappa inter and intra-observer value was 0.85 and 0.90 respectively. Conclusion: OE systemTM+MagniviewTM scopes can detect IPCLs and predict NERD with high sensitivity and accuracy.

A rotating cerium anode X-ray system allows visualization of intramural coronary vessels after cardiac stem cell therapy for myocardial infarction.

Conventional angiography is insufficient for evaluating the therapeutic effect of cardiac regeneration therapy. A microangiographic X-ray system using a cerium anode was developed. Cerium has a characteristic X-ray with a peak at 34.6keV, which allows visualization of tiny amounts of iodine. The performance of the cerium anode X-ray system was evaluated in two excised normal canine hearts and in excised ischemic canine hearts treated with c-kit-positive cardiac stem cells (5 canines) or without cells (5 control canines). In the normal canines, branches penetrating from the left anterior descending artery into the myocardium were visualized, down to third-order branches. In just the treated hearts treated with stem cells, small vessels characterized by irregular vessel walls were observed. The cerium anode X-ray system allowed visualization of microvessels in excised ischemic canine hearts, and may evaluate the effect of cardiac stem cell therapy.

Effects of voluntary exercise on structure and function of cortical microvasculature

Aerobic activity has been shown highly beneficial to brain health, yet much uncertainty still surrounds the effects of exercise on the functioning of cerebral microvasculature. This study used two-photon fluorescence microscopy to examine cerebral hemodynamic alterations as well as accompanying geometric changes in the cortical microvascular network following five weeks of voluntary exercise in transgenic mice endogenously expressing tdTomato in vascular endothelial cells to allow visualization of microvessels irrespective of their perfusion levels. We found a diminished microvascular response to a hypercapnic challenge (10% FiCO2) in running mice when compared to that in nonrunning controls despite commensurate increases in transcutaneous CO2 tension. The flow increase to hypercapnia in runners was 70% lower than that in nonrunners (p = 0.0070) and the runners’ arteriolar red blood cell speed changed by only half the amount seen in nonrunners (p = 0.0085). No changes were seen in resting hemodynamics or in the systemic physiological parameters measured. Although a few unperfused new vessels were observed on visual inspection, running did not produce significant morphological differences in the microvascular morphometric parameters, quantified following semiautomated tracking of the microvascular networks. We propose that voluntary running led to increased cortical microvascular efficiency and desensitization to CO2 elevation.

Compensation for z-directional non-uniformity of a monopole antenna at 7T MRI

The research was conducted to find ways to compensate for z-directional non-uniformity at a monopole antenna array (MA) coil by using a tilted optimized non-saturating excitation (TONE) pulse and to evaluate the feasibility of using the MA coil with the TONE pulse for anatomical and angiographic imaging. The sensitivity of a MA coil along the z-direction was measured by using an actual flip angle imaging pulse sequence with an oil phantom to evaluate the flip angle distributions of the MA coil for 7T magnetic resonance imaging (MRI). The effects on the z-directional uniformity were examined by using slow and fast TONE pulses, i.e., TONE SLOW and TONE FAST. T1- and T2* -weighted images of the human brain were also examined. The z-directional profiles of the TONE pulses were analyzed by using the average signal intensity throughout the brain. The effect of the TONE pulses on cerebral vessels was further examined by analyzing maximal intensity projections of T1-weighted images. With increasing the applied flip angles, the sensitivity slope slightly increased (0.044 per degree). For the MA coil, the TONE SLOWpulse yielded a compensated profile along the z-direction while the TONE HIGH pulse, which has a flat excitation profile along the z-direction, exhibited a tilted signal intensity toward the coil end, clearly indicating an intrinsic property of the MA coil. Similar to the phantom study, human brain images revealed z-directional symmetry around the peak value for the averaged signal intensity of the TONE SLOW pulse while the TONE HIGH pulse exhibited a tilted signal intensity toward the coil end. In vascular system imaging, the MA coil also clearly demonstrated a beneficial effect on the cerebral vessels, either with or without the TONE pulses. This study demonstrates that TONE pulses could compensate for the intrinsic z-directional non-uniformity of MA coils that exhibit strong uniformity in the x-y plane. Furthermore, tilted pulses, such as TONE pulses, were utilized for visualizing small vessels. Appropriately combining MA coils and TONE pulses could help advance micro-vessel visualization.

Calibrating Doppler imaging of preterm intracerebral circulation using a microvessel flow phantom.

Introduction: Preterm infants are born during critical stages of brain development, in which the adaptive capacity of the fetus to extra-uterine environment is limited. Inadequate brain perfusion has been directly linked to preterm brain damage. Advanced high-frequency ultrasound probes and processing algorithms allow visualization of microvessels and depiction of regional variation. To assess whether visualization and flow velocity estimates of preterm cerebral perfusion using Doppler techniques are accurate, we conducted an in vitro experiment using a microvessel flow phantom.Materials and Methods: An in-house developed flow phantom containing two microvessels (inner diameter 200 and 700 μm) with attached syringe pumps, filled with blood-mimicking fluid, was used to generate non-pulsatile perfusion of variable flow. Measurements were performed using an Esaote MyLab70 scanner.Results: Microvessel mimicking catheters with velocities as low as 1 cm/s were adequately visualized with a linear ultrasound probe. With a convex probe, velocities <2 cm/s could not be depicted. Within settings, velocity and diameter measurements were highly reproducible [intra-class correlation 0.997 (95% CI 0.996–0.998) and 0.914 (0.864–0.946)]. Overall, mean velocity was overestimated up to threefold, especially in high velocity ranges. Significant differences were seen in velocity measurements when using steer angle correction and in vessel diameter estimation (p < 0.05).Conclusion: Visualization of microvessel-size catheters mimicking small brain vessels is feasible. Reproducible velocity and diameter results can be obtained, although important overestimation of the values is observed. Before velocity estimates of microcirculation can find its use in clinical practice, calibration of the ultrasound machine for any specific Doppler purpose is essential. The ultimate goal is to develop a sonographic tool that can be used for objective study of regional perfusion in routine practice.

Visualization of microvessels by angiography using inverse-Compton scattering X-rays in animal models

The fundamental performance of microangiography has been evaluated using the S-band linac-based inverse-Compton scattering X-ray (iCSX) method to determine how many photons would be required to apply iCSX to human microangiography. ICSX is characterized by its quasi-monochromatic nature and small focus size which are fundamental requirements for microangiography. However, the current iCSX source does not have sufficient flux for microangiography in clinical settings. It was determined whether S-band compact linac-based iCSX can visualize small vessels of excised animal organs, and the amount of X-ray photons required for real time microangiography in clinical settings was estimated. The iCSX coupled with a high-gain avalanche rushing amorphous photoconductor camera could visualize a resolution chart with only a single iCSX pulse of ∼3 ps duration; the resolution was estimated to be ∼500 µm. The iCSX coupled with an X-ray cooled charge-coupled device image sensor camera visualized seventh-order vascular branches (80 µm in diameter) of a rabbit ear by accumulating the images for 5 and 30 min, corresponding to irradiation of 3000 and 18000 iCSX pulses, respectively. The S-band linac-based iCSX visualized microvessels by accumulating the images. An iCSX source with a photon number of 3.6 × 10(3)-5.4 × 10(4) times greater than that used in this study may enable visualizing microvessels of human fingertips even in clinical settings.

Microvascular Glycocalyx Dimension Estimated by Automated SDF Imaging is not Related to Cardiovascular Disease

The EG regulates vascular homeostasis and has anti-atherogenic properties. SDF imaging allows for noninvasive visualization of microvessels and automated estimation of EG dimensions. We aimed to assess whether microcirculatory EG dimension is related to cardiovascular disease. Sublingual EG dimension was estimated by SDF imaging in healthy volunteers and in patients visiting an outpatient clinic for vascular medicine of a university hospital in Amsterdam, the Netherlands. EG dimension was compared among healthy volunteers, patients with CVD, and patients at low (<10%) or high risk (≥ 10%) of CVD according to the Framingham algorithm. In total 120 patients and 30 healthy volunteers were included. Patients had a mean age of 59 ± 14 years, 71 (59%) were men and 24 (20%) were black. Healthy volunteers were on average 28 ± 4 years and 19 (63%) were men. EG dimension was similar in healthy volunteers (2.04 ± 0.23 μm), low-risk patients (2.05 ± 0.24 μm, n = 39), high-risk patients (2.05 ± 0.23 μm, n = 30) and in patients with CVD (2.09 ± 0.21 μm, n = 51, p = 0.79). EG dimension was not correlated with cardiovascular risk factors. Microcirculatory EG dimension, as estimated by automated SDF imaging, is not associated with CVD, suggesting that this technique may not contribute to cardiovascular risk stratification.

Comparative study of 3D reconstruction of rat sciatic nerve microvessels using Evans blue and lead oxide

Background:The blood supply of peripheral nerve grafts is one of the important factors that affect nerve regeneration. Many investigators have studied how intraneural microvessels are distributed and ways to promote the angiogenesis of grafts. However, there still does not exist an ideal intraneural microvascular model. The purpose of this study was to compare the three-dimensional (3D) reconstruction of microvessels of the sciatic nerve in Sprague-Dawley (SD) rats after systemic perfusion with Evans blue (EB) or lead oxide.Methods:Ten adult SD rats were randomized to a fluorography group (EB) or radiography group (lead oxide). After administration of the perfusion agents, imaging information was obtained by fluorescence microscopy and micro-computed tomography (μCT). Three-dimensional reconstruction was performed, and the diameter of microvessels at a constant distance (a cross-section was taken every 1 mm), the vascular index, and volume were measured. Two-dimensional (2D) images were obtained by serial sectioning and μCT scanning using the two methods described.Results:In the EB group, the diameter, vascular area, and vascular index of microvessels were 11·79 ± 7·23 μm, 0.14 ± 0.05 mm2, and 24·19 ± 5·03%, respectively, and in the lead oxide group 26·45 ± 11·81 μm, 0.06 ± 0.02 mm2, and 10·73 ± 2·06%, respectively. Microvessels with diameters <20 μm were visualized better in the EB group than in the lead oxide group (P < 0·01). However, there was no significant difference between the groups in the visualization of microvessels with diameters 20–49 μm (P > 0·05).Conclusions:Both EB and lead oxide can be used for 2D study of intraneural microvessels and 3D observation after reconstruction. Lead oxide is easy to use, and though its resolution is lower than that of EB for smaller microvessels with diameters <20 μm, it is more suitable for studying a large sample volume.

A non-invasive technique for visualization of microvessels in asymptomatic patients with middle cerebral artery steno-occlusion

We determined whether 7T magnetic resonance angiography (MRA) could be used for clearly observing microvessels in a clinically asymptomatic patient with steno-occlusion of the middle cerebral artery (MCA). We utilized 3T magnetic resonance imaging to obtain the brain images of a clinically asymptomatic patient and noted MCA steno-occlusion. In comparison with 3T MRA, 7T MRA could clearly delineate the microvessels, including lenticulostriate arteries and presumed collaterals, and our observation was comparable to that with conventional digital subtraction angiography. We report an interesting case of a clinically asymptomatic patient with MCA steno-occlusion.