The usefulness of perfluorocarbon nanoemulsions for the imaging of experimental myocarditis has been demonstrated in a high-field 9.4 Tesla MRI scanner. Our proof-of-concept study investigated the imaging capacity of PFC-based 19F/1H MRI in an animal myocarditis model using a clinical field strength of 1.5 Tesla. To induce experimental myocarditis, five male rats (weight ~300 g, age ~50 days) were treated with one application per week of doxorubicin (2 mg/kg BW) over a period of six weeks. Three control animals received the identical volume of sodium chloride 0.9% instead. Following week six, all animals received a single 4 ml injection of an 20% oil-in-water perfluorooctylbromide nanoemulsion 24 hours prior to in vivo1H/19F imaging on a 1.5 Tesla MRI. After euthanasia, cardiac histology and immunohistochemistry using CD68/ED1 macrophage antibodies were performed, measuring the inflamed myocardium in μm2 for further statistical analysis to compare the extent of the inflammation with the 19F-MRI signal intensity. All animals treated with doxorubicin showed a specific signal in the myocardium, while no myocardial signal could be detected in the control group. Additionally, the doxorubicin group showed a significantly higher SNR for 19F and a stronger CD68/ED1 immunhistoreactivity compared to the control group. This proof-of-concept study demonstrates that perfluorocarbon nanoemulsions could be detected in an in vivo experimental myocarditis model at a currently clinically relevant field strength.

Comprehension about the behavior of the Planet Boundary Layer (PBL) is an important factor in several fields, from analysis about air quality until modeling. However, monitoring the PBL evolution is a complex problem, because few instruments can provide continuous atmospheric measurements with enough spatial and temporal resolution. Inside this scenario lidar systems appear as an important tool, because it complies with all these capabilities-However, PBL observations are not a direct measure, being necessary to use complex mathematic algorithms. Recently, wavelet covariance transforms have been applied in this field.The objective of this work is to compare the performing of distinct types of algorithms: a structured on Haar wavelet and other based on first derivative of Gaussian and Mexican Hat wavelets, and the results were compared with two Hysplit modelling. For this aim, two campaigns were carried out. From the results were possible to infer that both algorithms provide coherent results as the expected, but the Haar algorithm separates the sub-layers more efficiently, so it is the most appropriate to complex situations.

We compare the performance of some available atmospheric models for the atmosphere of Sao Paulo (Brazil) to be used in case of absence of radio-sounding data for the given day. We developed our own model (SPm) from historic radio-sounding data in order to create a local model. By performing inversions of lidar signals (distributed over a year), we could benchmark the performance of the models against radio-sounding data. SPm and ISA-15N show the smallest deviation and represent, therefore, the best fallback models for this southern latitude.

Este trabalho aborda a identificacao da altura da CLP a partir de uma nova tecnica intitulada Metodo das Imagens. Tal metodo foi empregado a partir de dados do sistema LIDAR, obtidos na campanha do projeto CHUVA-SUL e validado a partir de dados de radiossondagem.

The main objective of this work is to obtain methods that automatically allow qualitative detections of Atmospheric Boundary Layer heights from LIDAR data. Case studies will be used to describe the more relevant days of a campaign carried out in July of 2012 in Vitoria, Espirito Santo, Brazil. The data analysis compares three mathematical algorithms that automatically provide the ABL height: Gradient Method (GM), using the derivative of the Range Corrected Signal (RCS) logarithm, WCT (Wavelet Covariance Transform), and Bulk Richardson's Number, which was used to validate the methods mentioned above. The comparison between the methods has shown that as the presence of clouds and the aerosol sublayer increased, the more sensitive was the refinement needed to choose the "right" parameters, whereas even Richardson's method had ambiguities in finding a good estimate of the ABL top.

This paper presents a methodology to calculate lidar ratios for distinct cirrus clouds that has been developed and implemented for a site located in the Southern Hemisphere. The cirrus cloud lidar data processing aims to consider a large cloud variability and cirrus cloud monitoring through a robust retrieval process. Among cirrus features estimates for complex scenes that lidar systems can provide, we highlight cloud geometrical information and extinction-to-backscatter ratio (known as lidar ratio or LR). In general, direct information on cirrus cloud microphysics is difficult to derive because LR depends on the presence of ice crystals and their properties such as shape, size, composition and orientation of particles. An iterative process to derive a stable LR value has been proposed. One of the keys is to restrict the analysis to conditions allowing accurate multilayer events. This method uses nonparametric statistical approaches to identify stationary periods according to cloud features and variability. Measurements performed in the region of the metropolitan city of São Paulo (MSP) have been used to implement and test the methodology developed for cirrus cloud characterization. Good results are represented by examining specific cases with multilayer cirrus cloud occurrence. In addition to the geometrical parameters obtained, cirrus LR values were calculated for a single day ranging from 19 ± 01 sr to 74 ± 13 sr for 2 observed layers. This large difference in LR can indicate a mixture of ice crystal particles with different sizes and shapes in both layers of the cirrus clouds. Trajectory analyses indicate that both of these cloud layers can be associated with different air mass and should be considered as 2 distinct clouds in climatology.

In this study, a mapping of the soot extinction coefficient in an oil refinery flare using a three-wavelength elastic backscatter lidar system is presented. A log-normal aerosol size distribution was assumed for the flare, and a homogenous refractive index was assumed along the nearly horizontal beam path through the atmosphere, excluding the flare volume. The optical depth was estimated for each wavelength and from this the Angstr¨om exponent was calculated. The results were comparable with the literature, demonstrating that it is possible to distinguish small from large particles by this technique in low wind conditions.

Non-invasive near-infrared fluorescence (NIRF) imaging is a powerful tool to study pathophysiology in a wide variety of animal disease models including brain diseases. However, especially in NIRF imaging of the brain or other deeper laying target sites, background fluorescence emitted from the scalp or superficial blood vessels can impede the detection of fluorescence in deeper tissue. Here, we introduce an effective method to reduce the impact of fluorescence from superficial layers. The approach uses excitation light at two different wavelengths generating two images with different depth sensitivities followed by an adapted subtraction algorithm. This technique leads to significant enhancement of the contrast and the detectability of fluorochromes located in deep tissue layers in tissue simulating phantoms and murine models with stroke.

High field magnetic resonance imaging (MRI) was performed to investigate the long-term effect of ezetimibe (eze), a cholesterol resorption blocker, on atherosclerotic lesion formation in the thoracic aorta of apolipoprotein E-deficient mice (apoE ( -/- )) in comparison to wild type mice (WT). Fifteen-month-old apoE ( -/- ) (Western type diet), apoE ( -/-eze ) (Western type diet with eze) which received eze (5 mc/kg/day) continuously, and age-matched WT (normal chow) were studied using contrast-enhanced 3D turbo-spin-echo sequences (RARE factor 2) on a 7 Tesla scanner. Vessel parameters were analyzed in the aortic root (AR) and aortic arch (AA) and compared to those found in histology. Plasma cholesterol levels were reduced at 15 months by 71% (P < 0.01) in apoE ( -/-eze ) compared to apoE ( -/- ). Vessel wall thickness was increased in the AR and AA in apoE ( -/- ) by 189.1 and 147.2%, respectively compared to WT. ApoE ( -/-eze ) showed reduced wall thickness in the AR (127.4%) and AA (102.8%, both P < 0.05 vs. apoE ( -/- )). A significant increase in total aortic vessel area was determined in the AR and AA in apoE ( -/- ) by 134.7 and 118.3%, respectively, compared to WT. This effect was inhibited in apoE ( -/-eze ) (AR: 126.7%, AA: 86.4%, both P < 0.05). Histological analysis confirmed the effect of eze observed by MRI and demonstrated a significant correlation between the two techniques (P < 0.001). MRI demonstrates that ezetimibe significantly reduces atherosclerotic disease in apoE ( -/- ). MRI is therefore a useful technique to perform in vivo interventional studies in experimental atherosclerosis.

Impairment of the blood–brain barrier (BBB) after cerebral ischemia leads to extravasation of plasma constituents into the brain parenchyma. We describe a novel method using non-invasive near-infrared fluorescence (NIRF) imaging and bovine serum albumin labeled with a NIRF dye (NIRF–BSA) to detect BBB impairment after middle cerebral artery occlusion (MCAO) in mice. We first explored the time course of BBB impairment after transient MCAO using Evans blue (EB), which binds to plasma albumin in vivo. An initial BBB impairment was observed at 4–8 h and a second impairment at 12–16 h after reperfusion. No EB extravasation was detected at 8–12 h. Non-invasive NIRF imaging with NIRF–BSA confirmed biphasic BBB impairment. Upon co-injection of NIRF–BSA with EB we found a strong correlation between the detected NIRF signal and the amount of extravasated EB (r = 0.857, P = 0.00178). When MCAO mice received NIRF–BSA together with gadolinium–diethylene triamine penta-acetic acid (Gd–DTPA), T1-weighted images showed Gd–DTPA enhancement at all times while NIRF imaging showed biphasic BBB impairment. In conclusion, NIRF–BSA is a suitable marker of plasma albumin extravasation in the mouse brain. Non-invasive NIRF imaging with NIRF–BSA is a useful tool to study BBB integrity in preclinical models of central nervous system pathology.

We investigated whether in-vivo imaging of the CD40 receptor can be used for identification of inflammatory atherosclerotic lesions. Methods: Monoclonal antibodies against CD40 (CD40ab), IgGA2 (Coab) and Fab2 fragments (CD40Fab) were coupled to the near-infrared fluorescence (NIRF) dyes Cy5′5 or Cy7. Apolipoprotein E deficient mice (apoE−/−) and apoE−/−CD40−/− deficient mice (apoE−/−CD40−/−) were fed with high cholesterol diet for 8 –12 month. Antibody conjugates were injected into the tail vein and mice were investigated 6 to 48 hours after injection by conventional NIRF imaging, fluorescence microscopy of the aortic arch and in-vivo 3D fluorescence molecular tomography (FMT). Sudan staining and histological analysis were performed after imaging procedures. Results: Application of Cy5′5-labeled CD40ab resulted in accumulation of fluorescence signal intensity mainly in Sudan-positive areas of the thoracic aorta, which was also seen with the Coab at high concentrations. Fluorescence increased slightly after 24 hours compared to 6 hours after injection. In vivo imaging was not feasible using conjugated antibodies due to circulating intravasal fluorescence (>48h). Significant background fluorescence was detected after application of CD40ab and Coab in all mice, probably due to FC receptor-dependent binding. Application of Cy7-CD40Fab induced strong in-vivo fluorescence detected by FMT in projection to the aortic arch and carotid arteries of apoE−/− (n=4), but not in apoE−/−CD40−/− mice (n=4). No signal was observed in mice injected with unlabelled Cy7. Ex-vivo imaging of the thoracic aorta confirmed a Cy7 signal in atherosclerotic lesions of apoE−/−, but not in apoE−/−CD40−/− after application of CD40Fab. Data were also confirmed by microscopic fluorescence imaging of the aortic wall and atherosclerotic lesions. Conclusion: In vivo detection of CD40 in atherosclerotic plaques was feasible using antibody fragments but not with full anti-CD40 antibodies. The approach is applicable for detection of vascular inflammation, since CD40 is strongly associated with inflammatory lesion formation.

Matrix metalloproteinases (MMPs) have been implicated in the pathophysiology of cerebral ischemia. In this study, we explored whether MMP activity can be visualized by noninvasive near-infrared fluorescence (NIRF) imaging using an MMP-activatable probe in a mouse model of stroke. C57BI6 mice were subjected to transient middle cerebral artery occlusion (MCAO) or sham operation. Noninvasive NIRF imaging was performed 24 h after probe injection, and target-to-background ratios (TBRs) between the two hemispheres were determined. TBRs were significantly higher in MCAO mice injected with the MMP-activatable probe than in sham-operated mice and in MCAO mice that were injected with the nonactivatable probe as controls. Treatment with an MMP inhibitor resulted in significantly lower TBRs and lesion volumes compared to injection of vehicle. To test the contribution of MMP-9 to the fluorescence signal, MMP9-deficient (MMP9 −/- ) mice and wild-type controls were subjected to MCAO of different durations to attain comparable lesion volumes. TBRs were significantly lower in MMP9 −/- mice, suggesting a substantial contribution of MMP-9 activity to the signal. Our study shows that MMP activity after cerebral ischemia can be imaged noninvasively with NIRF using an MMP-activatable probe, which might be a useful tool to study MMP activity in the pathophysiology of the disease.

In vivo molecular fluorescence tomography of brain disease mouse models has two very specific demands on the optical setup: the use of pigmented furry mice does not allow for a purely noncontact setup, and a high spatial accuracy is required on the dorsal side of the animal due to the location of the brain. We present an optimized setup and tomographic scheme that meet these criteria through a combined CW reflectance-transmittance fiber illumination approach and a charge-coupled device contactless detection scheme. To consider the anatomy of the mouse head and take short source detector separations into account, the forward problem was evaluated by a Monte Carlo simulation input with a magnetic resonance image of the animal. We present an evaluation of reconstruction performance of the setup under three different condition. (i) Using a simulated dataset, with well-defined optical properties and low noise, the reconstructed position accuracy is below 0.5 mm. (ii) Using experimental data on a cylindrical tissue-simulating phantom with well-defined optical properties, a spatial accuracy of about 1 mm was found. (iii) Finally, on an animal model with a fluorescent inclusion in the brain, the target position was reconstructed with an accuracy of 1.6 mm.

In a simultaneous electroencephalography (EEG) and near-infrared spectroscopy (NIRS) study, the predictive value of the individual alpha-frequency at rest (IAF) for the amplitude of neuronal and vascular responses to visual stimulation was investigated. Across subjects, we find (i) an inverse relationship between IAF and the amplitude of the alpha-rhythm at rest. The IAF also predicts (ii) the amplitude of the visual evoked potential (VEP), as well as (iii) the amplitude of the alpha-rhythm during stimulation. Most importantly, (iv) IAF correlates with the oxygenation response to visual stimulation: A high IAF predicts a low alpha-amplitude at rest, a small VEP amplitude and a small oxygenation response. Conversely, a low IAF predicts high alpha-amplitude and larger electrophysiological and vascular responses to stimulation. Based on these findings, we assume that the relationship between IAF and neuronal and vascular response stems from the size of the network recruited for visual processing. The relation between IAF, alpha-amplitude, evoked potential and vascular response is discussed in the framework of a simple heuristic model. The results may partly explain the large intersubject variability observed in recently published concurrent EEG-fMRI studies.

Fluorescence molecular brain imaging is a new modality allowing the detection of specific contrast agents down to very low concentration ranges (picomolar) in disease models. Here we demonstrate a first noninvasive application of fluorescence imaging in the human brain, where concentrations down to about 100 nM of a nonspecific dye were detected. We argue that due to its high sensitivity, optical molecular imaging of the brain is feasible, which – together with its bedside applicability – makes it a promising technique for use in patients.

Experimental and clinical evidence indicate that following stroke CD40 signalling is crucially involved in sustaining the inflammation and thereby contributes to the expansion of the lesion. Non-invasive imaging of CD40 receptor expression could provide a powerful tool to diagnose stroke-induced inflammation, to assess disease progression, to stratify patients for therapy, and to monitor response to therapeutic intervention. In the present study, we utilised non-invasive planar near-infrared fluorescence (NIRF) imaging to detect stroke-induced brain inflammation in a mouse stroke model. A monoclonal antibody against CD40 labelled with the NIRF dye Cy5.5 was injected intravenously 96 hours after transient middle cerebral artery occlusion (MCAO) in mice. NIRF imaging was performed 16 hours after injection of the compound. In MCAO-mice, high fluorescence intensities were detected through the skull and skin over the affected hemisphere. Corresponding ex-vivo NIRF images of the brain and brain sections confirmed localisation of the fluorescence in the ischemic territory. MCAO-mice receiving Cy5.5-labeled IgG as a control for non-specific accumulation did not show fluorescence enhancement over the ischemic hemisphere in-vivo. Single Plane Illumination Microscopy (SPIM) revealed the cellular localisation of the CD40 targeting contrast agent which was found to locate at activated microglia and endothelium after subsequent immunhistochemistry. Co-injection experiments with the green fluorescent cell tracker 6-carboxylfluorescein diacetate into the spleen of MCAO-mice revealed the presence of bloodderived mononuclear cells that were labelled with the CD40 targeting contrast agent. In conclusion, the results show that non-invasive NIRF imaging can be used to visualize stroke-induced brain inflammation in mice with high sensitivity and specificity.

Near-infrared fluorescence (NIRF) imaging has great potential for studying physiological and pathophysiological processes noninvasively in several locations of the body. In this study, we evaluated the feasibility of NIRF imaging to visualize fluorescent compounds within the brains of live mice commonly used in brain research. To simulate the presence of a molecular NIRF reporter agent at the site of a lesion, we developed a new in vivo phantom model wherein capsules containing different amounts of an NIRF dye (Cy5.5) were stereotactically implanted deep into the left hemispheres of living mice. To precisely locate the implanted capsules, magnetic resonance imaging (MRI) was performed. Fluorescence reflectance imaging (FRI) and transillumination fluorescence imaging (TFI) were conducted to analyze and compare sensitivity and target-to-background ratios of the two methods. The sensitivities of FRI and TFI to background fluorescence from circulating dye was tested by imaging fluorescent capsules in mice intravenously injected with increasing amounts of long-circulating Cy5.5-dextran. The results show that capsules containing dye amounts as low as 10 −12 mol can be detected. TFI yielded significantly higher target-to-background ratios than FRI at 10 −11 mol ( p < .05). Comparatively low amounts of fluorescence in the blood vessels can extinguish the signal. We conclude that keeping the signal from circulating NIRF dye low, NIRF imaging offers high sensitivity in detecting fluorochromes noninvasively within brains of mice, especially by using TFI. This encourages the application of NIRF for molecular imaging in the mouse brain using NIRF reporters.