1,834 research outputs found
Aerosol optical properties at Lampedusa (Central Mediterranean). 1. Influence of transport and identification of different aerosol types
Aerosol optical depth and Ångström exponent were obtained from multi filter rotating shadowband radiometer (MFRSR) observations carried out at the island of Lampedusa, in the Central Mediterranean, in the period July 2001–September 2003. The average aerosol optical depth at 495.7 nm, τ, is 0.24±0.14; the average Ångström exponent, α, is 0.86±0.63. The observed values of τ range from 0.03 to 1.13, and the values of α vary from −0.32 to 2.05, indicating a large variability in aerosol content and size. In cloud-free conditions, 36% of the airmasses come from Africa, 25% from Central-Eastern Europe, and 19% from Western France, Spain and the North Atlantic. In summer, 42% of the airmasses is of African origin. In almost all cases African aerosols display high values of τ and low values of α, typical of Saharan dust (average values of τ and α are 0.36 and 0.42, respectively). Particles originating from Central-Eastern Europe show relatively large average values of τ and α (0.23 and 1.5, respectively), while particles from Western France, Spain and the North Atlantic show the lowest average values of τ (0.15), and relatively small values of α (0.92). Intermediate values of α are often connected with relatively fast changes of the airmass originating sector, suggesting the contemporary presence of different types of particles in the air column. Clean marine conditions are rare at Lampedusa, and are generally associated with subsidence of the airmasses reaching the island. Average values of τ and α for clean marine conditions are 0.11 and 0.86, respectively. The largest values of α (about 2) were observed in August 2003, when large scale forest fires in Southern Europe produced consistent amounts of fine combustion particles, that were transported to the Central Mediterranean by a persistent high pressure system over Central Europe. Smoke particles in some cases mix with desert dust, producing intermediate values of α. The seasonal distribution of the meteorological patterns over the Mediterranean, the efficiency of the aerosol production mechanisms, and the variability of the particles' residence time produce a distinct seasonal cycle of aerosol optical depths and Ångström exponent values. Particles originating from all sectors show a summer maximum in aerosol optical depth. The summer increase in optical depth for European aerosols is linked with an increment in the values of α, that indicates an enhancement in the number of fine particles. The summer maximum of τ for African particles is associated with a weak reduction in the Ångström exponent, suggesting an increase in the total number of particles and a relatively more intense transport of large particles. The observations were classified according to the aerosol optical properties, and two main classes have been identified: desert dust and biomass burning/urban-industrial aerosols. Values of τ and α averaged over the whole observing period are 0.37 and 0.15 for desert dust, and 0.27 and 1.77 for urban-industrial/biomass burning aerosols
Anatomic feasibility of in-situ fenestration for isolate left subclavian artery preservation during thoracic endovascular aortic repair using an adjustable needle puncturing system
Objectives: To evaluate the feasibility of thoracic endovascular aortic repair (TEVAR) using the AnkuraTM device (Lifetech Scientific, Shenzhen, China) with left subclavian artery (LSA) in-situ fenestration (ISF) using an adjustable puncture device system.
Methods: It is a single center, retrospective, financially unsupported cohort study of TEVAR performed from 16 February 2007 to 10 January 2023. Inclusion criteria were isolate LSA revascularization for elective or urgent/emergent âzone 2â TEVAR, and the availability of the preoperative computed tomography angiography.
Results: Post-hoc analysis identified 52 TEVARs. There were 39 (75.0%) males, and 13 (25.0%) females: median age was 74.5 years (IQR, 65.5â78). Index TEVAR was performed for atherosclerotic aneurysm in 27 (51.9%) cases, dissection-related diseases in 18 (34.6%), penetrating aortic ulcer in 5 (9.6%), and blunt traumatic aortic injury in 2 (3.8%). Access-vessel feasibility rate of TEVAR using the AnkuraTM device would have been 98.1% (51/52). Considering the morphology of the aortic arch, ISF TEVAR feasibility would have been 61.5% (32/52). Binary logistic regression analysis identified LSA angulation (OR: 1.1, 95%CI: 1.03â1.14, p = 0.003) to be associated with ISF feasibility using this endograft and a self-centering adjustable needle-based puncture device.
Conclusions: Potential feasibility of TEVAR using the AnkuraTM endograft with ISF using a self-centering adjustable needle system was 61.5%. Left subclavian artery angulation seems to be the most important and limiting anatomical constraint
Computed-Tomography-Guided Lung Biopsy: A Practice-Oriented Document on Techniques and Principles and a Review of the Literature
Computed tomography (CT)-guided lung biopsy is one of the oldest and most widely known minimally invasive percutaneous procedures. Despite being conceptually simple, this procedure needs to be performed rapidly and can be subject to meaningful complications that need to be managed properly. Therefore, knowledge of principles and techniques is required by every general or interventional radiologist who performs the procedure. This review aims to contain all the information that the operator needs to know before performing the procedure. The paper starts with the description of indications, devices, and types of percutaneous CT-guided lung biopsies, along with their reported results in the literature. Then, pre-procedural evaluation and the practical aspects to be considered during procedure (i.e., patient positioning and breathing) are discussed. The subsequent section is dedicated to complications, with their incidence, risk factors, and the evidence-based measures necessary to both prevent or manage them; special attention is given to pneumothorax and hemorrhage. After conventional CT, this review describes other available CT modalities, including CT fluoroscopy and cone-beam CT. At the end, more advanced techniques, which are already used in clinical practice, like fusion imaging, are included
Imaging-Guided Percutaneous Puncture and Embolization of Visceral Pseudoaneurysms: Feasibility and Outcomes
Visceral artery pseudoaneurysms (VAPAs) are the most frequently diagnosed pseudoa-neurysms (PSAs). PSAs can be asymptomatic or symptomatic. The aim of our study was to evaluate the safety and effectiveness of percutaneous embolization of VAPAs performed on patients with an unfeasible trans-arterial approach. Fifteen patients with fifteen visceral PSAs, with a median dimension of 21 mm (IQR 20â24 mm), were retrospectively analyzed. No patients were suitable for trans-arterial catheterization and therefore a percutaneous approach was chosen. During percutaneous treatments, two embolic agents were used, either N-butyl cyanoacrylate (NBCA) (Glubran II, GEM Milan, Italy) mixed with Lipiodol (Lipiodol, Guerbet, France) or thrombin. The outcomes of this study were technical success, primary clinical success, and secondary clinical success. In our population the 15 PSA were located as follows: 2 in the left gastric artery, 1 in the right gastric artery, 3 in the right hepatic artery, 2 in a jejunal artery, 1 in left colic artery branch, 1 in a right colic artery branch, 1 in the gastroepiploic artery, 1 in the dorsal pancreatic artery, 1 in an ileocolic artery branch, 1 in an iliac artery branch, and 1 in a sigmoid artery branch. 80% of PSAs (12/15) were treated with a NBCA:lipiodol mixture and 20% of PSAs (3/15) were treated with thrombin. Technical, primary, and secondary clinical successes were obtained in 100% of the cases. No harmful or life-threatening complications were observed. Minor complications were registered in 26.6% (4/15) of the patients. Percutaneous embolization of visceral PSA is a safe and effective treatment and should be considered as an option when the endovascular approach is unsuccessful or unfeasible
Could Maximum SUV be Used as Imaging Guidance in Large Lung Lesions Biopsies? Double Sampling Under PET-CT/XperGuide Fusion Imaging in Inhomogeneous Lung Uptaking Lesions to Show That it can Make a Difference
Introduction: The purpose of this study is to evaluate the diagnostic value of positron emission computed tomography-cone beam computed tomography (PET/CT-CBCT) fusion guided percutaneous biopsy, targeted to the maximum standardized uptake value (SUVmax) and minimum standardized uptake value (SUVmin) of large lung lesions. Materials and Methods: Inside a larger cohort of PET/CT-CBCT guided percutaneous lung biopsies, 10 patients with large pulmonary lesions (diameter > 30â
mm) were selected retrospectively. These patients have been subjected to double biopsy sampling respectively in the SUVmax area and in the SUVmin area of the lesion. Technical success has been calculated. For each sample, the percentage of neoplastic, inflammatory, and fibrotic cells was reported. Furthermore, the possibility of performing immunohistochemical or molecular biology investigations to specifically define the biomolecular tumor profile was analyzed. Results: Nine lesions were found to be malignant, one benign (inflammation). Technical success was 100% (10/10) in the SUVmax samples and 70% (7/10) in the SUVmin samples (P-value:.21). In the first group, higher percentages of neoplastic cells were found at pathologic evaluation, while in the second group areas of inflammation and fibrosis were more represented. The biomolecular profile was obtained in 100% of cases (9/9) of the first group, while in the second group only in 33.3% of cases (2/6), with a statistically significant difference between the 2 groups (P-value:.011). Conclusion: A correlation between the standardized uptake value value and the technical success of the biopsy sample has been identified. PET/CT-CBCT guidance allows to target the biopsy in the areas of the tumor which are richer in neoplastic cells, thus obtaining more useful information for the planning of patient-tailored cancer treatments
Percutaneous Application of High Power Microwave Ablation With 150â W for the Treatment of Tumors in Lung, Liver, and Kidney: A Preliminary Experience
Objective: The aim of this study is to evaluate the feasibility, safety, and short-term effectiveness of a high-power (150â
W) microwave ablation (MWA) device for tumor ablation in the lung, liver, and kidney. Methods: Between December 2021 and June 2022, patients underwent high-power MWA for liver, lung, and kidney tumors. A retrospective observational study was conducted in accordance with the Declaration of Helsinki. The MWA system utilized a 150-W, 2.45-GHz microwave generator (Emprintâą HP Ablation System, Medtronic). The study assessed technical success, safety, and effectiveness, considering pre- and post-treatment diameter and volume, lesion location, biopsy and/or cone beam computed tomography (CBCT) usage, MWA ablation time, MWA power, and dose-area product (DAP). Results: From December 2021 to June 2022, 16 patients were enrolled for high-power MWA. Treated lesions included hepatocellular carcinoma (10), liver metastasis from colon cancer (1), liver metastasis from pancreatic cancer (1), squamous cell lung carcinoma (2), renal cell carcinoma (1), and renal oncocytoma (1). Technical success rate was 100%. One grade 1 complication (6.25%) was reported according to CIRSE classification. Overall effectiveness was 92.8%. Pre- and post-treatment mean diameters for liver lesions were 19.9â
mm and 37.5â
mm, respectively; for kidney lesions, 34â
mm and 35â
mm; for lung lesions, 29.5â
mm and 31.5â
mm. Pre- and post-treatment mean volumes for liver lesions were 3.4â
ml and 24â
ml, respectively; for kidney lesions, 8.2â
ml and 20.5â
ml; for lung lesions, 10.2â
ml and 32.7â
ml. The mean ablation time was 48â
minutes for liver, 42.5â
minutes for lung, and 42.5â
minutes for renal ablation. The mean DAP for all procedures was 40.83 Gcm2. Conclusion: This preliminary study demonstrates the feasibility, safety, and effectiveness of the new 150â
W MWA device. Additionally, it shows reduced ablation times for large lesions
A long-term time series of global and diffuse photosynthetically active radiation in the Mediterranean: interannual variability and cloud effects
Abstract. Measurements of global and diffuse photosynthetically active
radiation (PAR) have been carried out on the island of Lampedusa, in the
central Mediterranean Sea, since 2002. PAR is derived from observations made
with multi-filter rotating shadowband radiometers (MFRSRs) by comparison with
a freshly calibrated PAR sensor and by relying on the on-site Langley plots.
In this way, a long-term calibrated record covering the period 2002â2016 is
obtained and is presented in this work. The monthly mean global PAR peaks in June, with about 160âWâmâ2, while
the diffuse PAR reaches 60âWâmâ2 in spring or summer. The global PAR
displays a clear annual cycle with a semi amplitude of about 52âWâmâ2.
The diffuse PAR annual cycle has a semi amplitude of about 12âWâmâ2. A simple method to retrieve the cloud-free PAR global and diffuse irradiances
in days characterized by partly cloudy conditions has been implemented and
applied to the dataset. This method allows retrieval of the cloud-free
evolution of PAR and calculation of the cloud radiative effect, CRE, for
downwelling PAR. The cloud-free monthly mean global PAR reaches
175âWâmâ2 in summer, while the diffuse PAR peaks at about
40âWâmâ2. The cloud radiative effect, CRE, on global and diffuse PAR is calculated as
the difference between all-sky and cloud-free measurements. The annual
average CRE is about â14.7âWâmâ2 for the global PAR and
+8.1âWâmâ2 for the diffuse PAR. The smallest CRE is observed in
July, due to the high cloud-free condition frequency. Maxima (negative for
the global, and positive for the diffuse component) occur in MarchâApril and
in October, due to the combination of elevated PAR irradiances and high
occurrence of cloudy conditions. Summer clouds appear to be characterized by
a low frequency of occurrence, low altitude, and low optical thickness,
possibly linked to the peculiar marine boundary layer structure. These
properties also contribute to produce small radiative effects on PAR in
summer. The cloud radiative effect has been deseasonalized to remove the influence
of annual irradiance variations. The monthly mean normalized CRE for global
PAR can be well represented by a multi-linear regression with respect to
monthly cloud fraction, cloud top pressure, and cloud optical thickness, as
determined from satellite MODIS observations. The behaviour of the normalized
CRE for diffuse PAR can not be satisfactorily described by a simple
multi-linear model with respect to the cloud properties, due to its non-linear dependency, in particular on the cloud optical depth. The analysis
suggests that about 77â% of the global PAR interannual variability may be
ascribed to cloud variability in winter
Relationship between methanesulphonate (MS-) in atmospheric particulate and remotely sensed phytoplankton activity in oligo-mesotrophic central Mediterranean Sea
Basic embolization techniques: tips and tricks
Good knowledge of the various approaches of embolization of peripheral bleedings and different embolic materials available is of paramount importance for successful and safe embolization. We review and illustrate the main endovascular and percutaneous techniques used for embolization, along with the characteristics of the different embolic materials, and the potential complications
Saharan dust aerosol over the central Mediterranean Sea: PM<sub>10</sub> chemical composition and concentration versus optical columnar measurements
This study aims to determine the mineral contribution to
PM<sub>10</sub> in the central Mediterranean Sea, based on 7 yr of daily PM<sub>10</sub>
samplings made on the island of Lampedusa (35.5° N, 12.6° E).
<br><br>
The chemical composition of the PM<sub>10</sub> samples was determined by ion
chromatography for the main ions, and, on selected samples, by particle-induced
X-ray emission (PIXE) for the total content of crustal markers.
Aerosol optical depth measurements were carried out in parallel to the
PM<sub>10</sub> sampling.
<br><br>
The average PM<sub>10</sub> concentration at Lampedusa over the period June
2004âDecember 2010 is 31.5 ÎŒg m<sup>â3</sup>, with low interannual
variability. The annual means are below the EU annual standard for
PM<sub>10</sub>, but 9.9% of the total number of daily data exceeds the daily
threshold value established by the European Commission for PM
(50 ÎŒg m<sup>â3</sup>, European Community, EC/30/1999).
<br><br>
The Saharan dust contribution to PM<sub>10</sub> was derived by calculating the
contribution of Al, Si, Fe, Ti, non-sea-salt (nss) Ca, nssNa, and nssK oxides
in samples in which PIXE data were available. Cases in which crustal content
exceeded the 75th percentile of the crustal oxide content distribution were
identified as elevated dust events. Using this threshold, we obtained 175
events. Fifty-five elevated dust events (31.6%) displayed PM<sub>10</sub> higher
than 50 ÎŒg m<sup>â3</sup>, with dust contributing by 33% on average.
<br><br>
The crustal contribution to PM<sub>10</sub> has an annual average value of 5.42 ÎŒg m<sup>â3</sup>,
and reaches a value as high as 67.9 ÎŒg m<sup>â3</sup> (corresponding
to 49% of PM<sub>10</sub>) during an intense Saharan dust event.
<br><br>
The crustal content estimated from a single tracer, such as Al or Ca, is in
good agreement with the one calculated as the sum of the metal oxides.
Conversely, larger crustal contents are derived by applying the EU guidelines
for demonstration and subtraction of exceedances in PM<sub>10</sub> levels due to
high background of natural aerosol. The crustal aerosol amount and
contribution to PM<sub>10</sub> showed a very small seasonal dependence;
conversely, the dust columnar burden displays an evident annual cycle, with a
strong summer maximum (monthly average aerosol optical depth at 500 nm up to
0.28 in JuneâAugust). We found that 71.3% of the dust events identified
from optical properties over the atmospheric column display a high dust
content at the ground level. Conversely, the remaining 28.7% of cases
present a negligible or small impact on the surface aerosol composition due
to the transport processes over the Mediterranean Sea, where dust frequently
travels above the marine boundary layer, especially in summer.
<br><br>
Based on backward trajectories, two regions, one in AlgeriaâTunisia, and one
in Libya, are identified as main source areas for intense dust episodes
occurring mainly in autumn and winter. Data on the bulk composition of mineral
aerosol arising from these two source areas are scarce; results on
characteristic ratios between elements show somewhat higher values of
Ca / Al and (Ca + Mg) / Fe (2.5 ± 1.0, and 4.7 ± 2.0, respectively) for
AlgeriaâTunisia than for Libyan origin (Ca / Al = 1.9 ± 0.7 and
(Ca + Mg) / Fe = 3.3 ± 1.1)
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