Search

Abstract Background Fractional flow reserve (FFR) can be estimated by analysis of intravascular imaging in a coronary artery; however, there are no data for estimated FFR in an extremity artery. The aim of this concept-generating study was to determine whether it is possible to estimate the value of peripheral FFR (PFFR) by intravascular ultrasound (IVUS) analysis also in femoropopliteal artery lesions. Methods Between April 2022 and February 2023, PFFR was measured before endovascular therapy in 31 stenotic femoropopliteal artery lesions. High-definition IVUS measurement was simultaneously performed in automatic pullback mode in 6 of those 31 lesions. IVUS-derived PFFR was calculated by an algorithm based on fluid dynamics as the following equation: ΔP = FV + SV2. F is the coefficient of pressure loss because of viscous friction (Poiseuille’s equation) and S is the coefficient of local pressure loss because of flow separation (Bernoulli’s equation). The values of F and S were calculated by analysis of IVUS. V is velocity and the value of V was obtained from previously reported data in a duplex ultrasound study. The mean pressure was assumed to be 80 mmHg, and IVUS-derived PFFR was calculated by the following equation: IVUS-derived PFFR = (80 – ΔP) / 80. Results The values of IVUS-derived PFFR and actual PFFR were similar: 0.73 and 0.72, 0.87 and 0.92, 0.90 and 0.92, 0.66 and 0.73, and 0.79 and 0.72, respectively. In one case in which run-off of the below-the-knee artery was poor, PFFR (0.91) was higher than the IVUS-derived PFFR (0.73). Conclusion Virtual PFFR in the superficial femoral artery can be estimated from IVUS analysis.

Background: Fractional flow reserve (FFR) can be estimated by analysis of intravascular imaging in a coronary artery; however, there are no data for estimated FFR in an extremity artery. The aim of this concept-generating study was to determine whether it is possible to estimate the value of peripheral FFR (PFFR) by intravascular ultrasound (IVUS) analysis also in femoropopliteal artery lesions. Methods: Between April 2022 and February 2023, PFFR was measured before endovascular therapy in 31 stenotic femoropopliteal artery lesions. High-definition IVUS measurement was simultaneously performed in automatic pullback mode in 6 of those 31 lesions. IVUS-derived PFFR was calculated by an algorithm based on fluid dynamics as the following equation: ΔP = FV + SV2. F is the coefficient of pressure loss because of viscous friction (Poiseuille's equation) and S is the coefficient of local pressure loss because of flow separation (Bernoulli's equation). The values of F and S were calculated by analysis of IVUS. V is velocity and the value of V was obtained from previously reported data in a duplex ultrasound study. The mean pressure was assumed to be 80 mmHg, and IVUS-derived PFFR was calculated by the following equation: IVUS-derived PFFR = (80 – ΔP) / 80. Results: The values of IVUS-derived PFFR and actual PFFR were similar: 0.73 and 0.72, 0.87 and 0.92, 0.90 and 0.92, 0.66 and 0.73, and 0.79 and 0.72, respectively. In one case in which run-off of the below-the-knee artery was poor, PFFR (0.91) was higher than the IVUS-derived PFFR (0.73). Conclusion: Virtual PFFR in the superficial femoral artery can be estimated from IVUS analysis. [ABSTRACT FROM AUTHOR]

The recent developments in artificial intelligence have the potential to facilitate new research methods in ecology. Especially Deep Convolutional Neural Networks (DCNNs) have been shown to outperform other approaches in automatic image analyses. Here we apply a DCNN to facilitate quantitative wood anatomical (QWA) analyses, where the main challenges reside in the detection of a high number of cells, in the intrinsic variability of wood anatomical features, and in the sample quality. To properly classify and interpret features within the images, DCNNs need to undergo a training stage. We performed the training with images from transversal wood anatomical sections, together with manually created optimal outputs of the target cell areas. The target species included an example for the most common wood anatomical structures: four conifer species; a diffuse-porous species, black alder (Alnus glutinosa L.); a diffuse to semi-diffuse-porous species, European beech (Fagus sylvatica L.); and a ring-porous species, sessile oak (Quercus petraea Liebl.). The DCNN was created in Python with Pytorch, and relies on a Mask-RCNN architecture. The developed algorithm detects and segments cells, and provides information on the measurement accuracy. To evaluate the performance of this tool we compared our Mask-RCNN outputs with U-Net, a model architecture employed in a similar study, and with ROXAS, a program based on traditional image analysis techniques. First, we evaluated how many target cells were correctly recognized. Next, we assessed the cell measurement accuracy by evaluating the number of pixels that were correctly assigned to each target cell. Overall, the “learning process” defining artificial intelligence plays a key role in overcoming the issues that are usually manually solved in QWA analyses. Mask-RCNN is the model that better detects which are the features characterizing a target cell when these issues occur. In general, U-Net did not attain the other algorithms’ performance, while ROXAS performed best for conifers, and Mask-RCNN showed the highest accuracy in detecting target cells and segmenting lumen areas of angiosperms. Our research demonstrates that future software tools for QWA analyses would greatly benefit from using DCNNs, saving time during the analysis phase, and providing a flexible approach that allows model retraining.

In 2010-2018, Northern Patagonia featured the longest severe drought of the last millennium. This extreme dry spell triggered widespread growth decline and forest dieback. Nonetheless, the roles played by the two major mechanisms driving dieback, hydraulic failure and carbon starvation, are still not clear and understudied in this seasonally dry region. Here, for the 1800-2017 period, we apply a retrospective analysis of radial growth, wood anatomical traits (lumen area, cell-wall thickness) and δ13C and δ18O stable isotopes to assess dieback causes of the iconic conifer Araucaria araucana. We selected three stands where declining (defoliated) and nondeclining (not defoliated) trees coexisted along a precipitation gradient from the warm-dry Coastal Range to the cool-wet Andes. At all sites declining trees showed lower radial growth and lower theoretical hydraulic conductivity, suggesting a long-lasting process of hydraulic deterioration in their water transport system compared to nondeclining, coexisting trees. Wood anatomical traits evidenced that this divergence between declining and nondeclining trees started at least seven decades before canopy dieback. In the drier stands, declining trees showed higher water-use efficiency (WUE) throughout the whole period, which we attributed to early stomatal closure, suggesting a greater carbon starvation risk consistent with thinner cell walls. In the wettest stand, we found the opposite pattern. Here, a reduction in WUE coupled with thicker cell walls suggested increased carbon assimilation rates and exposure to drought-induced hydraulic failure. The δ18O values indicated different strategies of gas exchange between sites, which are likely a consequence of microsite conditions and water sources. Multiproxy, retrospective quantifications of xylem anatomical traits and tree-ring isotopes provide a robust tool to identify and forecast, which stands or trees will show dieback or, on the contrary, which will likely withstand and be more resilient to future hotter droughts. [ABSTRACT FROM AUTHOR]

The recent developments in artificial intelligence have the potential to facilitate new research methods in ecology. Especially Deep Convolutional Neural Networks (DCNNs) have been shown to outperform other approaches in automatic image analyses. Here we apply a DCNN to facilitate quantitative wood anatomical (QWA) analyses, where the main challenges reside in the detection of a high number of cells, in the intrinsic variability of wood anatomical features, and in the sample quality. To properly classify and interpret features within the images, DCNNs need to undergo a training stage. We performed the training with images from transversal wood anatomical sections, together with manually created optimal outputs of the target cell areas. The target species included an example for the most common wood anatomical structures: four conifer species; a diffuse-porous species, black alder (Alnus glutinosa L.); a diffuse to semi-diffuse-porous species, European beech (Fagus sylvatica L.); and a ring-porous species, sessile oak (Quercus petraea Liebl.). The DCNN was created in Python with Pytorch, and relies on a Mask-RCNN architecture. The developed algorithm detects and segments cells, and provides information on the measurement accuracy. To evaluate the performance of this tool we compared our Mask-RCNN outputs with U-Net, a model architecture employed in a similar study, and with ROXAS, a program based on traditional image analysis techniques. First, we evaluated how many target cells were correctly recognized. Next, we assessed the cell measurement accuracy by evaluating the number of pixels that were correctly assigned to each target cell. Overall, the "learning process" defining artificial intelligence plays a key role in overcoming the issues that are usually manually solved in QWA analyses. Mask-RCNN is the model that better detects which are the features characterizing a target cell when these issues occur. In general, U-Net did not attain the other algorithms' performance, while ROXAS performed best for conifers, and Mask-RCNN showed the highest accuracy in detecting target cells and segmenting lumen areas of angiosperms. Our research demonstrates that future software tools for QWA analyses would greatly benefit from using DCNNs, saving time during the analysis phase, and providing a flexible approach that allows model retraining. [ABSTRACT FROM AUTHOR]

Intravascular ultrasound (IVUS) has been widely used to capture cross sectional lumen frames of inner wall of coronary arteries. This kind of medical imaging modalities is capable of providing detailed and significant information of lumen contour shape, which is very important for clinical diagnosis and analysis of cardiovascular diseases. Numerous learning based techniques have recently become very popular for coronary artery segmentation due to their impressive results. In this work, a supervised machine learning method for coronary artery lumen segmentation with high accuracy and minimal user interaction is designed. The fully discriminative lumen segmentation method jointly learning a classifier the weak learners rely on and the features of the classifier is developed. Additionally, the theoretical supports of the Gradient Boosting framework used in this work and its quadratic approximation are presented. The proposed algorithm is tested on the public datasets of boundary detection of lumen in IVUS challenge held in MICCAI 2011 and achieves a higher average Jaccard similarity of 96.8% and a lower mean error distance of 0.55 (in Cartesian coordinates), which shows higher accuracy compared to the existing learning based methods. Moreover, three real patient IVUS datasets are used to evaluate the performance of the proposed coronary artery lumen segmentation algorithm, which is shown to achieve lower percent error of lumen area of 1.861% ± 0.965%, 1.968% ± 0.864%, and 1.671% ± 0.584%, respectively, compared to the manually measured lumen area (ground truth). The proposed lumen segmentation method is found to be superior to the latest learning based segmentation techniques. Given the efficiency and robustness, our method has great potential in IVUS images processing and coronary artery segmentation and quantification. Novelty Statement: The main contributions are summarized in the following aspects:A detailed review of related work about learning based coronary artery lumen segmentation in intravascular ultrasound images is presented.A fully discriminative lumen segmentation method jointly learning a classifier our weak learners rely on and the features of the classifier is developed.The theoretical supports of the Gradient Boosting framework and its quadratic approximation used in this work are presented. [ABSTRACT FROM AUTHOR]

The effects of climate change on high‐latitude forest ecosystems are complex, making forecasts of future scenarios uncertain. The predicted lengthening of the growing season under warming conditions is expected to increase tree growth rates. However, there is evidence of an increasing sensitivity of the boreal forest to drought stress. To assess the influence of temperature and precipitation on the growth of black spruce (Picea mariana), we investigated long‐term series of wood anatomical traits on 20 trees from four sites along 600 km, the latitudinal range of the closed boreal forest in Quebec, Canada. We correlated the anatomical traits resolved at intraring level with daily temperature, vapor pressure deficit (VPD), and precipitation during the 1943–2010 period. Tree‐ring width, number of cells per ring and cell wall thickness were positively affected by spring and summer daily mean and maximum temperature at the northern sites. These results agree with the well‐known positive effect of high temperatures on tree ring formation at high latitudes. However, we captured, for the first time in this region, the latent impact of water availability on xylem traits. Indeed, in all the four sites, cell lumen area showed positive correlations with daily precipitation (mostly at low latitude), and/or negative correlations with daily mean and maximum temperature and VPD (mostly at high latitude). We inferred that drought, due to high temperatures, low precipitations, or both, negatively affects cell enlargement across the closed boreal forest, including the northernmost sites. The production of tracheids with narrower lumen, potentially more resistant to cavitation, could increase xylem hydraulic safety under a warmer and drier climate. However, this would result in lower xylem conductivity, with consequent long‐term hydraulic deterioration, growth decline, and possibly lead to tree dieback, as observed in other forest ecosystems at lower latitudes. [ABSTRACT FROM AUTHOR]

Highlights • Rings formed during the defoliation had a significant and progressive loss of biomass. • Defoliation significantly reduced latewood density for black spruce and balsam fir. • Average ring density was reduced only in black spruce. • The changes in growth and density were associated with changes in anatomical features. • Significant reductions occurred in cell-wall thickness after 3rd year of defoliation. Abstract Spruce budworm (SBW – Choristoneura fumiferana Clem.) is one of the most damaging defoliating insects in the coniferous forests of eastern North America. In Canada, the widely distributed balsam fir (Abies balsamea L. (Mill)) and black spruce (Picea mariana B.S.P. (Mill)) are its most important hosts. Defoliation by SBW reduces growth in the host trees and can lead to host mortality. Although SBW impacts on growth are well documented, much less is known about changes in wood properties resulting from defoliation. To address this knowledge gap, we sampled 36 SBW-infested stands located in the boreal forest of Quebec (Canada) to determine whether defoliation modifies the wood quality of affected trees. The selected stands had been subjected to one to four years of SBW defoliation. For both species, we assessed ring growth, wood density, and the anatomical characteristics of stem wood formed during the outbreak years. We determined that rings formed during the SBW outbreak had a significant and progressive loss of biomass production with a longer duration of defoliation. SBW significantly reduced latewood density in the second and third year of defoliation for black spruce and the third and fourth year for balsam fir. Average ring density was reduced only in black spruce and only after four years of defoliation. The observed changes in growth and density were associated with changes in anatomical features. While the cellular characteristics of the earlywood remained fairly constant, significant reductions occurred in latewood cell-wall thickness after three years of defoliation. Our study shows that not only do SBW outbreaks reduce annual radial growth, but the cellular characteristics in latewood cells are also modified momentarily. Thus, SBW outbreaks affect wood density and quality in both black spruce and balsam fir. [ABSTRACT FROM AUTHOR]

Lumen vessel sizing is important for optimization of interventional outcomes for treatment of vascular disease. The objective of this study is to develop an injection-less method to determine the lumen diameter, using multiple frequencies that eliminates the need for saline injections. We utilize the same electrical conductance devices developed for the two-injection method. A mathematical electrical model was devised to estimate the lumen area and diameter of the arteries. In vitro experiments were used to validate the method for various lumen diameters with both 5-5-5 (peripheral) and 2-2-2 (coronary) spacing conductance guidewires. The majority of 11 vessel data fall within one standard deviation and all the data fall within two standard deviations. The results indicate that the two-frequency model can reasonably predict the lumen diameter in an in-vitro test set-up. Our findings show that this approach can potentially translate to in vivo which would enable pull-back to reconstruct the lumen area profile of the vessel.

Purpose: To investigate in an in vitro model if secondary endobag filling can reduce gutter size during chimney endovascular aneurysm sealing (chEVAS).Materials and Methods: Nellix EVAS systems were deployed in 2 silicone juxtarenal aneurysm models with suprarenal aortic diameters of 19 and 24 mm. Four configurations were tested: EVAS with 6-mm balloon-expandable (BE) or self-expanding (SE) chimney grafts (CGs) in the renal branches of both models. Balloons were inflated simultaneously in the CGs and main endografts during primary and secondary endobag filling and polymer curing. Computed tomography (CT) was performed immediately after the primary and secondary fills. Cross-sectional lumen areas were measured on the CT images to calculate gutter volumes and percent change. CG compression was calculated as the reduction in lumen surface area measured perpendicular to the central lumen line. The largest gutter volume and highest compression were presented per CG configuration per model.Results: Secondary endobag filling reduced the largest gutter volumes from 99.4 to 73.1 mm3 (13.2% change) and 84.2 to 72.0 mm3 (27.6% change) in the BECG configurations and from 67.2 to 44.0 mm3 (34.5% change) and 92.7 to 82.3 mm3 (11.2% change) in the SECG configurations in the 19- and 24-mm models, respectively. Secondary endobag filling increased CG compression in 6 of 8 configurations. BECG compression changed by -0.2% and 5.4% and by -1.0% and 0.4% in the 19- and 24-mm models, respectively. SECG compression changed by 10.2% and 16.0% and by 7.2% and 7.3% in the 19- and 24-mm models, respectively.Conclusion: Secondary endobag filling reduced paragraft gutters; however, this technique did not obliterate them. Increased CG compression and prolonged renal ischemia time should be considered if secondary endobag filling is used. [ABSTRACT FROM AUTHOR]

Purpose: To investigate how 2-dimensional geometric parameters differ between ruptured and asymptomatic abdominal aortic aneurysms (AAAs) and provide a biomechanical explanation for the findings.Methods: The computed tomography angiography (CTA) scans of 30 patients (mean age 77±10 years; 23 men) with ruptured AAAs and 60 patients (mean age 76±8 years; 46 men) with asymptomatic AAAs were used to measure maximum sac diameter along the center lumen line, the cross-sectional lumen area, the total vessel area, the intraluminal thrombus (ILT) area, and corresponding volumes. The CTA data were segmented to create 3-dimensional patient-specific models for finite element analysis to compute peak wall stress (PWS) and the peak wall rupture index (PWRI). To reduce confounding from the maximum diameter, 2 diameter-matched groups were selected from the initial patient cohorts: 28 ruptured AAAs and another with 15 intact AAAs (diameters 74±12 vs 73±11, p=0.67). A multivariate model including the maximum diameter, the lumen area, and the ILT area of the 60 intact aneurysms was employed to predict biomechanical rupture risk parameters.Results: In the diameter-matched subgroup comparison, ruptured AAAs had a significantly larger cross-sectional lumen area (1954±1254 vs 1120±623 mm2, p=0.023) and lower ILT area ratio (55±24 vs 68±24, p=0.037). The ILT area (2836±1462 vs 2385±1364 mm2, p=0.282) and the total vessel area (3956±1170 vs 4338±1388 mm2, p=0.384) did not differ statistically between ruptured and intact aneurysms. The PWRI was increased in ruptured AAAs (0.80 vs 0.48, p<0.001), but the PWS was similar (249 vs 284 kPa, p=0.194). In multivariate regression analysis, lumen area was significantly positively associated with both PWS (p<0.001) and PWRI (p<0.01). The ILT area was also significantly positively associated with PWS (p<0.001) but only weakly with PWRI (p<0.01). The lumen area conferred a higher risk increase in both PWS and PWRI when compared with the ILT area.Conclusion: The lumen area is increased in ruptured AAAs compared to diameter-matched asymptomatic AAAs. Furthermore, this finding may in part be explained by a relationship with biomechanical rupture risk parameters, in which lumen area, irrespective of maximum diameter, increases PWS and PWRI. These observations thus suggest a possible method to improve prediction of rupture risk in AAAs by measuring the lumen area without the use of computational modeling. [ABSTRACT FROM AUTHOR]

Quantification of coronary artery disease (CAD) from cardiac computed tomography angiography (CTA) is important both structurally (lumen area stenosis) and functionally (combined with computational fluid dynamics to determine fractional flow reserve) for assessment of ischemic stenosis and to guide treatment. Hence, it is important to have CTA image processing technique for segmentation and reconstruction of coronary arteries. In this study, we developed segmentation and reconstruction techniques, based on fast marching and Runge-Kutta methods for centerline extraction, and surface mesh generation. The accuracy of the reconstructed models was validated with direct intravascular ultrasound (IVUS) measurements in 1950 cross sections within 4 arteries. High correlation was found between CTA and IVUS measurements for lumen areas (r=0.993, p<0.001). Receiver-operating characteristic (ROC) curves showed excellent accuracies for detection of different cutoff values of cross-lumen area (5 mm2, 6 mm2, 7 mm2 and 8 mm2, all ROC values >0.99). We conclude that our technique has sufficient accuracy for quantifying coronary lumen area. The accuracy and efficiency demonstrated that our approach can facilitate quantitative evaluation of coronary stenosis and potentially help in real-time assessment of CAD. [ABSTRACT FROM AUTHOR]

Climate sensitivity of populations at the margins of their distribution range is of key importance to understand species’ responses to future warming conditions. Pinus cembra is of particular interest being a typical high-elevation taxon, spread with mostly scattered populations within its actual range, but still overlooked in traditional dendrochronological researches due to low tree-ring variability and climate sensitivity. With a different approach, we analyzed time series of xylem anatomical traits, split into intra-ring sectors, and used daily climate records over 89 years (1926-2014) aiming to improve the quality and time resolution of the climate/growth associations. From nine trees growing at their altitudinal limit and on 1.5 × 106 tracheids, we measured ring width (MRW), cell number per ring, lumen area (LA), and cell-wall thickness (CWT). We then computed correlations with monthly and fortnightly climate data. Late-spring and summer temperature emerged as the most important factors. LA and especially CWT showed a stronger temperature response than MRW, starting in mid-May and early June, respectively. CWT also evidenced the longest period of correlations with temperature and a significant difference between latewood radial and tangential walls. Analysis of xylem anatomical traits at intra-ring level and the use of daily temperature records proved to be useful for high resolution and detailed climate/growth association inferences in Pinus cembra. [ABSTRACT FROM AUTHOR]

Lumen vessel sizing is important for optimization of interventional outcomes for treatment of vascular disease. The objective of this study is to develop an injection-less method to determine the lumen diameter, using multiple frequencies that eliminates the need for saline injections. We utilize the same electrical conductance devices developed for the two-injection method. A mathematical electrical model was devised to estimate the lumen area and diameter of the arteries. In vitro experiments were used to validate the method for various lumen diameters with both 5-5-5 (peripheral) and 2-2-2 (coronary) spacing conductance guidewires. The majority of 11 vessel data fall within one standard deviation and all the data fall within two standard deviations. The results indicate that the two-frequency model can reasonably predict the lumen diameter in an in-vitro test set-up. Our findings show that this approach can potentially translate to in vivo which would enable pull-back to reconstruct the lumen area profile of the vessel. [ABSTRACT FROM AUTHOR]

Anatomical parameters can be considered as a sensitive indicator of environmental changes on the intra-annual level. Methods of quantitative wood anatomy were used to study the dynamics of xylem traits for spruce growing in so called „Black Triangle” region where the fossil fuel emissions caused one of the globally highest pollutant depositions (SO2, NOx, F) in the 1970s and 1980s. The Klínovec study area was selected as a model area considering the combination of harsh climate and long-term air pollution load. The series of anatomical features such as number of tracheids, lumen area and cell wall thickness together with ring widths were examined for the entire tree life span. We obtained a unique, more than hundred years long sequence of anatomical parameters covering the period before, during and after the extreme air pollution load. Number of cells and tree-ring widths were detected as the most responsive features, while lumen area and cell-wall thickness were only slightly affected during the peak time of pollution concentration. For the future research, we suggest studying the anatomical features of early wood and late wood cells separately to verify the differences in their response. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To evaluate the plaque distribution and composition pattern in the left main coronary artery (LMCA) disease using intracoronary ultrasound. PATIENTS AND METHODS: Intravascular ultrasound data of 50 patients from the January 2010 to December 2015 with significant LMCA bifurcation lesions, with angiographic diameter stenosis >50%, and requiring revascularization, were evaluated. Plaque burden and percentage of necrotic core (% NC) at the minimal lumen area site and maximal % NC site were measured in different segments. The segments that were included in the study are as follows: segment 1: proximal LMCA, segment 2: left anterior descending (LAD) ostium, segment 3: left circumflex branch (LCX) ostium, segment 4: proximal LAD, segment 5: proximal LCX. According to its relationship with the bifurcation ridge, the blood vessel wall was divided into the contralateral bifurcation ridge blood vessel wall and bifurcation ridge blood vessel wall. RESULTS: Plaque burden results showed that the plaque eccentricity index of segment 2 and segment 3 was significantly higher than that of the other segments at sites of the minimal lumen area and maximal % NC with a statistically significant difference (p<0.05). Plaque eccentricity index of contralateral bifurcation ridge was significantly higher than that of the bifurcation ridge, and the difference was statistically significant (p<0.05). Analysis of plaque composition showed the fibrous tissue percentage of segment 2 and segment 3 was significantly higher than the other segments that at the sites of minimal lumen area and the maximal % NC site. The fibrous percentage of the contralateral bifurcation ridge was significantly lower than that of the bifurcation ridge. CONCLUSIONS: Intravascular ultrasound is an effective way for detecting the distribution and composition of the atherosclerotic plaque at the left main coronary artery bifurcation and is of great significance to adjuvant interventional therapy. [ABSTRACT FROM AUTHOR]

Background: Although previous observational studies have documented late luminal enlargement and expansive remodeling following implantation of a bioresorbable vascular scaffold (BVS), no comparison with metallic stents has been conducted in a randomized fashion.Objectives: This study sought to compare vessel remodeling patterns after either Absorb BVS or Xience metallic drug-eluting stent (DES) implantation (Abbott Vascular, Santa Clara, California) and determine the independent predictors of remodeling.Methods: In the ABSORB II randomized trial, 383 lesions (n = 359) were investigated by intravenous ultrasound both post-procedure and at 3-year follow-up. According to vessel and lumen area changes over 3 years, we categorized 9 patterns of vessel remodeling that were beyond the reproducibility of lumen and vessel area measurements.Results: The relative change in mean vessel area was significantly greater with the BVS compared to the DES (6.7 ± 12.6% vs. 2.9 ± 11.5%; p = 0.003); the relative change in mean lumen area was significantly different between the 2 arms (1.4 ± 19.1% vs. -1.9 ± 10.5%, respectively; p = 0.031). Multivariate analysis indicated that use of the BVS, female sex, balloon-artery ratio >1.25, expansion index ≥0.8, previous percutaneous coronary intervention, and higher level of low-density lipoprotein cholesterol were independent predictors of expansive remodeling. Furthermore, in the BVS arm, necrotic core pre-procedure was an independent determinant of expansive remodeling.Conclusions: Expansive vessel wall remodeling was more frequent and intense with the BVS than the metallic DES and could be determined by patient baseline characteristics and periprocedural factors. The clinical effect of the observed lumen and vessel remodeling must be investigated in further large clinical studies to optimize the clinical outcome of patients and lesions treated by bioresorbable scaffolds. (ABSORB II Randomized Controlled Trial; NCT01425281). [ABSTRACT FROM AUTHOR]

Objective: Choroidal anastomosis (ChA) has been implicated as the main indicator of an increased hemorrhagic risk in adult moyamoya disease. In this retrospective study, the authors aimed to identify the potential risk factors that can influence the rupture of ChA., Methods: The authors evaluated the clinical and radiological data on brain hemispheres positive for ChA from September 2019 to March 2023. The rupture status of the ChA was determined using previously described methods. Two independent raters quantitatively investigated the lumen diameter (LD) and lumen area (LA) of the ChA using high-resolution vessel wall imaging (VWI). Multivariate logistic regression analysis was conducted to identify the risk factors for ruptured ChA., Results: Ruptured and unruptured ChAs were identified in 16 and 60 hemispheres, respectively. Univariate analysis showed that the mean values of the LD (1.251 ± 0.241 vs 0.967 ± 0.214 mm, p < 0.001) and LA (1.607 ± 0.445 vs 0.945 ± 0.372 mm2, p < 0.001) of ChAs were significantly greater in the ruptured group than in the unruptured group. A periventricular anastomosis (PA) score of 1, indicating the angiographic presence of ChA alone, was more prevalent in the ruptured group than in the unruptured group (43.8% vs 11.7%, p = 0.003). Multivariate analysis demonstrated that a larger LA of the ChA (OR 37.01, 95% CI 5.787-236.7, p < 0.001) and PA score 1 (OR 6.661, 95% CI 1.260-35.21, p = 0.026) were independently associated with ruptured ChA hemispheres. Receiver operating characteristic curve analysis revealed that the optimal cutoff point for the LA was 1.285 mm2 (sensitivity 81.3%, specificity 86.7%)., Conclusions: A larger LA (> 1.285 mm2) of the ChA and the angiographic presence of ChA alone are independent risk factors for a ruptured ChA. Revascularization surgery for the prevention of future hemorrhage may be indicated for hemispheres with a high-risk unruptured ChA. These characteristics may help to determine treatment strategies for patients with an unruptured ChA.

Computed tomographic measures of central airway morphology have been used in clinical, epidemiologic, and genetic investigation as an inference of the presence and severity of small-airway disease in smokers. Although several association studies have brought us to believe that these computed tomographic measures reflect airway remodeling, a careful review of such data and more recent evidence may reveal underappreciated complexity to these measures and limitations that prompt us to question that belief. This Perspective offers a review of seminal papers and alternative explanations of their data in the light of more recent evidence. The relationships between airway morphology and lung function are observed in subjects who never smoked, implying that native airway structure indeed contributes to lung function; computed tomographic measures of central airways such as wall area, lumen area, and total bronchial area are smaller in smokers with chronic obstructive pulmonary disease versus those without chronic obstructive pulmonary disease; and the airways are smaller as disease severity increases. The observations suggest that (1) native airway morphology likely contributes to the relationships between computed tomographic measures of airways and lung function; and (2) the presence of smaller airways in those with chronic obstructive pulmonary disease versus those without chronic obstructive pulmonary disease as well as their decrease with disease severity suggests that smokers with chronic obstructive pulmonary disease may simply have smaller airways to begin with, which put them at greater risk for the development of smoking-related disease. [ABSTRACT FROM AUTHOR]

Climate change can induce substantial modifications in xylem structure and water transport capacity of trees exposed to environmental constraints. To elucidate mechanisms of xylem plasticity in response to climate, we retrospectively analysed different cell anatomical parameters over tree-ring series in Norway spruce (Picea abies L. Karst.). We sampled 24 trees along an altitudinal gradient (1200, 1600 and 2100 m above sea level, a.s.l.) and processed 2335 ± 1809 cells per ring. Time series for median cell lumen area (MCA), cell number (CN), tree-ring width (RW) and tree-ring-specific hydraulic conductivity (Kr) were crossed with daily temperature and precipitation records (1926-2011) to identify climate influence on xylem anatomical traits. Higher Kr at the low elevation site was due to higher MCA and CN. These variables were related to different aspects of intra-seasonal climatic variability under different environmental conditions, with MCA being more sensitive to summer precipitation. Winter precipitation (snow) benefited most parameters in all the sites. Descending the gradient, sensitivity of xylem features to summer climate shifted mostly from temperature to precipitation. In the context of climate change, our results indicate that higher summer temperatures at high elevations will benefit cell production and xylem hydraulic efficiency, whereas reduced water availability at lower elevations could negatively affect tracheids enlargement and thus stem capacity to transport water. [ABSTRACT FROM AUTHOR]

Summary Purpose To evaluate the effects of photodynamic therapy (PDT) on chronic central serous chorioretinopathy (CCSC) by measuring the mean choroidal thickness (MCT) and the lumen area of abnormal choroidal vessels (LAACV). Methods A total of 36 eyes of 18 patients with monocular CCSC were included in this study. The CCSC eyes received PDT with a half dose (3 mg/m 2 ) of verteporfin and follow-up examinations were carried out for 3 months after PDT. The boundary of choroids and abnormal choroidal vessels (round or ovoid dark regions) were characterized using enhanced depth imaging optical coherence tomography. The MCT and LAACV were analyzed by two investigators masked to the diagnosis and the treatment of CCSC using the Image Pro Plus 6.0 software. Results The MCT of CCSC eyes was significantly greater than that of normal eyes at baseline ( P < 0.0001), but it significantly decreased at the last follow-up examination after PDT ( P < 0.0001). The LAACV of the last follow-up examination was significantly smaller than that of the first follow-up examination ( P < 0.0001). Moreover, the LAACV showed a significant correlation with the MCT in CCSC eyes. Conclusions The MCT and LAACV are useful for quantitative evaluation of the effects of PDT on CCSC. [ABSTRACT FROM AUTHOR]

The evaluation of new techniques for 2-D and 3-D intravascular ultrasound (US) imaging (IVUS) often requires the use of a pulsating coronary phantom. This study describes the design, construction and evaluation of a phantom simulating the pulsation of a human coronary artery for IVUS studies. Polyvinyl alcohol (PVA) cryogel was used as a tissue mimic for the coronary vessel, which was incorporated in a custom-built assembly. The phantom was programmed to pulsate under servomotor control, to model the pulsation of a normal coronary artery and 2-D IVUS images were obtained using an IVUS imaging catheter. To evaluate the performance of the phantom, the lumen area variation of the phantom was determined and compared with the programmed pulsation waveforms. Our results showed that phantom pulsation correlated well with the programmed pulsation waveform (r = 0.97). The deviation of the least squares line from the line of identity was calculated to be < 4%. (E-mail: afenster@irus.rri.ca) [Copyright &y& Elsevier]

: ObjectivesThe goal of this study was to evaluate the dose-dependency of morphometric changes in the coronary arterial wall after radioactive stenting.: BackgroundRadioactive stents have been found to reduce intrastent intimal hyperplasia (IIH) but lead to a characteristic type of restenosis occurring predominantly at the stent edges.: MethodsFifteen patients underwent intravascular ultrasound (IVUS) examination after implantation of a P-32 radioactive stent and at the six-month follow-up. The post-stent IVUS measurements on seven predefined locations of each lesion were subjected to a computer algorithm for the development of dose-volume histograms (DVH). Thus, we derived the radiation doses delivered to at least 10% and 90% of the adventitia (DV10, DV90). The IIH and vascular remodeling at follow-up were correlated with the doses in each segment.: ResultsThe IIH was most pronounced at the stent edges and lowest in the stent-body, whereas we detected a significant expansive remodeling within the stent body. The delivered doses correlated with a decreased IIH (r = 0.52, p < 0.001 for DV10 and r = 0.62, p < 0.001 for DV90) and with expansive remodeling (r = 0.48, p = 0.009 for DV10 and r = 0.50, p = 0.006 for DV90). A DV10 >90 Gy or a DV90 >15 Gy reduced IIH and induced expansive remodeling. Plaque growth was not reduced by radioactive stents.: ConclusionsThe DVH analysis reveals a dose-dependent increase of external elastic lamina area behind radioactive stents, whereas plaque growth is not reduced but inverted into an outward direction from the stent. A DV10 >90 Gy or a DV90 >15 Gy results in a beneficial long-term outcome after radioactive stenting. [Copyright &y& Elsevier]

[Display omitted] • A first investigation on peatland pines growth in the Alpine region. • Quantitative wood anatomy allows to detect changes in the xylem structure. • Summer temperature and precipitation resulted the major drivers of the xylem formation of peatland trees. Long-term climate reconstructions are frequently based on tree-ring high-resolution proxies extracted from subfossil peatland trees. Peatlands are peculiar ecosystems characterized by high moisture in the upper soil part which creates a harsh living environment for trees. The climate mostly indirectly influences tree growth determining seasonal variations in the water table level. Within this framework, the aim of this study was to investigate climate responses of trees (Pinus sylvestris L.) growing inside and outside a Southern Alpine peat bog, by using tree-ring and wood anatomical traits (e.g. tracheid number and dimension, cell-wall thickness). Our results showed differences in the xylem structure and climate signal recorded by peatland and mineral soil trees. Peatland trees were characterized by narrow rings and tracheids with thinner cell wall. Summer temperature and precipitation were the major drivers of xylem formation in peatland trees. At intra-annual level wood anatomical traits revealed a complex within-ring signal during the growing season. The multi-parameters approach together with the high-resolution gained by using tree-ring sectors allowed us to obtain new detailed information on the xylem development of peatland trees and climate drivers that influenced it. [ABSTRACT FROM AUTHOR]