Deep Learning-based Segmentation of CT Scans Predicts Disease Progression and Mortality in IPF.

RATIONALE: Despite evidence demonstrating a prognostic role for CT scans in IPF, image-based biomarkers are not routinely used in clinical practice or trials. OBJECTIVES: Develop automated imaging biomarkers using deep learning based segmentation of CT scans. METHODS: We developed segmentation processes for four anatomical biomarkers which were applied to a unique cohort of treatment-naive IPF patients enrolled in the PROFILE study and tested against a further UK cohort. The relationship between CT biomarkers, lung function, disease progression and mortality were assessed. MEASUREMENTS AND MAIN RESULTS: Data was analysed from 446 PROFILE patients. Median follow-up was 39.1 months (IQR 18.1-66.4) with cumulative incidence of death of 277 over 5 years (62.1%). Segmentation was successful on 97.8% of all scans, across multiple imaging vendors at slice thicknesses 0.5-5mm. Of 4 segmentations, lung volume showed strongest correlation with FVC (r=0.82, p<0.001). Lung, vascular and fibrosis volumes were consistently associated across cohorts with differential five-year survival, which persisted after adjustment for baseline GAP score. Lower lung volume (HR 0.98, CI 0.96-0.99, p=0.001), increased vascular volume (HR 1.30, CI 1.12-1.51, p=0.001) and increased fibrosis volume (HR 1.17, CI 1.12-1.22, p=<0.001) were associated with reduced two-year progression-free survival in the pooled PROFILE cohort. Longitudinally, decreasing lung volume (HR 3.41; 95% CI 1.36-8.54; p=0.009) and increasing fibrosis volume (HR 2.23; 95% CI 1.22-4.08; p=0.009) were associated with differential survival. CONCLUSIONS: Automated models can rapidly segment IPF CT scans, providing prognostic near and long-term information, which could be used in routine clinical practice or as key trial endpoints. This article is open access and distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).

Seven Pillars of Small Airways Disease in Asthma and COPD: Supporting Opportunities for Novel Therapies.

Identification of pathologic changes in early and mild obstructive lung disease has shown the importance of the small airways and their contribution to symptoms. Indeed, significant small airways dysfunction has been found prior to any overt airway obstruction being detectable by conventional spirometry techniques. However, most therapies for the treatment of obstructive lung disease target the physiological changes and associated symptoms that result from chronic lung disease, rather than directly targeting the specific underlying causes of airflow disruption or the drivers of disease progression. In addition, although spirometry is the current standard for diagnosis and monitoring of response to therapy, the most widely used measure, FEV1 , does not align with the pathologic changes in early or mild disease and may not align with symptoms or exacerbation frequency in the individual patient. Newer functional and imaging techniques allow more effective assessment of small airways dysfunction; however, significant gaps in our understanding remain. Improving our knowledge of the role of small airways dysfunction in early disease in the airways, along with the identification of novel end points to measure subclinical changes in this region (ie, those not captured as symptoms or identified through standard FEV1), may lead to the development of novel therapies that directly combat early airways disease processes with a view to slowing disease progression and reversing damage. This expert opinion paper discusses small airways disease in the context of asthma and COPD and highlights gaps in current knowledge that impede earlier identification of obstructive lung disease and the development and standardization of novel small airways-specific end points for use in clinical trials.

Quantitative Assessment of Regional Mucociliary Clearance in Smokers with Mild-to-Moderate Chronic Obstructive Pulmonary Disease and Chronic Bronchitis from Planar Radionuclide Imaging.

Background: Mucociliary clearance (MCC) rate from the lung has been shown to be reduced in chronic obstructive pulmonary disease (COPD). This study investigates the value of regional clearance measurements in assessing MCC in mild-to-moderate disease. Methods: Measurement of lung MCC using planar gamma camera imaging was performed in three groups: (i) healthy nonsmoking controls (NSCs) (n = 9), (ii) smoking controls (SCs) who were current smokers with normal lung function (n = 10), and (iii) current smokers with mild-to-moderate COPD and bronchitis (n = 15). The mean (±standard deviation) forced expiratory volumes at 1 second (FEV1) for the three groups were 109 (± 18), 94 (± 5), and 78 (± 12), respectively. After inhalation of a technetium-99m labeled aerosol, planar imaging was performed over 4 hours and then at 24 hours. Both lung clearance and tracheobronchial clearance (TBC) (normalized to 24 hours clearance) were calculated for inner and outer lung zones. Inner zone clearance was corrected for input from the outer zone. A novel parameter, the bronchial airways clearance index (BACI), which combined clearance data from both zones, was also evaluated. Regional results were compared with whole lung clearance in the same subjects. Results: Corrected inner zone clearance at 3 hours was not reduced compared with NSC in either SCs or COPD. Outer zone clearance was higher in COPD than in the other groups. Corrected inner zone TBC showed significant reductions in SC and COPD compared with NSC. BACI was significantly reduced in COPD compared with NSC and also correlated with FEV1. The mean BACI for SC was also reduced compared with NSC, but the distribution of results was bimodal, with a significant proportion of subjects having values in the NSC range. Conclusions: Regional MCC demonstrated differences between NSCs, SCs, and subjects with mild-to-moderate COPD, which were not apparent with whole lung measurements.

OptiJ: Open-source optical projection tomography of large organ samples.

The three-dimensional imaging of mesoscopic samples with Optical Projection Tomography (OPT) has become a powerful tool for biomedical phenotyping studies. OPT uses visible light to visualize the 3D morphology of large transparent samples. To enable a wider application of OPT, we present OptiJ, a low-cost, fully open-source OPT system capable of imaging large transparent specimens up to 13 mm tall and 8 mm deep with 50 µm resolution. OptiJ is based on off-the-shelf, easy-to-assemble optical components and an ImageJ plugin library for OPT data reconstruction. The software includes novel correction routines for uneven illumination and sample jitter in addition to CPU/GPU accelerated reconstruction for large datasets. We demonstrate the use of OptiJ to image and reconstruct cleared lung lobes from adult mice. We provide a detailed set of instructions to set up and use the OptiJ framework. Our hardware and software design are modular and easy to implement, allowing for further open microscopy developments for imaging large organ samples.

Quantitative Assessment of Mucociliary Clearance in Smokers with Mild-to-Moderate Chronic Obstructive Pulmonary Disease and Chronic Bronchitis from Planar Radionuclide Imaging Using the Change in Penetration Index.

Background: Mucociliary clearance (MCC) rate from the lung has been shown to be reduced in chronic obstructive pulmonary disease (COPD). This study compared the use of change in penetration index (PI) with conventional whole lung clearance in assessing MCC in mild-to-moderate disease. Methods: Measurement of lung MCC using planar gamma camera imaging was performed in three groups: (1) healthy nonsmoking controls (n = 9), (2) smoking controls who were current smokers with normal lung function (n = 10), and (3) current smokers with mild-to-moderate COPD and bronchitis (n = 15). The mean (±standard deviation) forced expiratory volume at 1 second (FEV1) for the three groups was 109 (±18), 94 (±5), and 78 (±12), respectively. Following inhalation of a technetium-99m labeled aerosol, planar imaging was performed over 4 hours and then at 24 hours. Total lung clearance and tracheobronchial clearance (TBC; normalized to 24-hour clearance) were calculated. A novel parameter, the normalized change in PI (NOCHIP), was also evaluated. PI is the ratio of counts between outer and inner lung zones normalized to lung volume. Results: More aerosol was deposited in central airways in COPD compared to nonsmoking controls, using 24-hour clearance measurements (p < 0.001). Smoking controls had intermediate values. The optimal endpoint for MCC assessment was chosen to be 3 hours, when intersubject variability was minimal, while preserving a measure of early clearance. There was no statistical difference between the three groups in mean total lung clearance, or TBC, at 3 hours. NOCHIP at 3 hours was reduced significantly, compared to nonsmoking controls, in both smoking controls (p = 0.007) and COPD (p < 0.0001). It also correlated with FEV1 (p = 0.003). A higher proportion of smoking control subjects had NOCHIP values in the nonsmoking control range than in the COPD group. Conclusions: NOCHIP was a more sensitive measure of MCC than whole lung clearance and TBC in mild-to-moderate COPD.

Modeling Gadoxetate Liver Uptake and Efflux Using Dynamic Contrast-Enhanced Magnetic Resonance Imaging Enables Preclinical Quantification of Transporter Drug-Drug Interactions.

OBJECTIVES: The aim of this study was to model the in vivo transporter-mediated uptake and efflux of the hepatobiliary contrast agent gadoxetate in the liver. The efficacy of the proposed technique was assessed for its ability to provide quantitative insights into drug-drug interactions (DDIs), using rifampicin as inhibitor. MATERIALS AND METHODS: Three groups of C57 mice were scanned twice with a dynamic gadoxetate-enhanced magnetic resonance imaging protocol, using a 3-dimensional spoiled gradient-echo sequence for approximately 72 minutes. Before the second magnetic resonance imaging session, 2 of the groups received a rifampicin dose of 20 (n = 7) or 40 (n = 7) mg/kg, respectively. Data from regions of interest in the liver were analyzed using 2 simplifications of a 2-compartment uptake and efflux model to provide estimates for the gadoxetate uptake rate (ki) into the hepatocytes and its efflux rate (kef) into the bile. Both models were assessed for goodness-of-fit in the group without rifampicin (n = 9), and the appropriate model was selected for assessing the ability to monitor DDIs in vivo. RESULTS: Seven of 9 mice from the group without rifampicin were assessed for model implementation and reproducibility. A simple 3 parameter model (ki, kef, and extracellular space, vecs) adequately described the observed liver concentration time series with mean ki = 0.47 ± 0.11 min and mean kef = 0.039 ± 0.016 min. Visually, the area under the liver concentration time profile was reduced for the groups receiving rifampicin. Furthermore, tracer kinetic modeling demonstrated a significant dose-dependent decrease in the uptake (5.9- and 17.3-fold decrease for 20 mg/kg and 40 mg/kg, respectively) and efflux rates (2.2- and 7.9-fold decrease) compared with the first scan for each group. CONCLUSIONS: This study presents the first in vivo implementation of a 2-compartment uptake and efflux model to monitor DDIs at the transporter-protein level, using the clinically relevant organic anion transporting polypeptide inhibitor rifampicin. The technique has the potential to be a novel alternative to other methods, allowing real-time changes in transporter DDIs to be measured directly in vivo.

The use of 18F-Fluoro-deoxy-glucose positron emission tomography (18F-FDG PET) as a non-invasive pharmacodynamic biomarker to determine the minimally pharmacologically active dose of AZD8835, a novel PI3Kα inhibitor.

BACKGROUND: The phosphatidyl inositol 3 kinase (PI3K), AKT and mammalian target of rapamycin (mTOR) signal transduction pathway is frequently de-regulated and activated in human cancer and is an important therapeutic target. AZD8835 is a PI3K inhibitor, with selectivity against PI3K α and δ isoforms, which is currently in Phase 1 clinical trials. 18F-Fluoro-deoxy-glucose positron emission tomography (18F-FDG PET) is a non-invasive pharmacodynamic imaging biomarker that has become an integral part of drug development. It has been used widely with PI3K inhibitors both clinically and pre-clinically because of the role of the PI3K pathway in glucose metabolism. In this study we investigated the potential of 18F-FDG PET as a non-invasive pharmacodynamic biomarker for AZD8835. We sought to understand if 18F-FDG PET could determine the minimally effective dose of AZD8835 and correlate with other pharmacodynamic biomarkers for validation of its use in clinical development. 18F-FDG PET scans were performed in nude mice in the BT474C breast xenograft model. Mice were fasted prior to imaging and static 18F-FDG PET was performed. Treatment groups received AZD8835 by oral gavage at a dose volume of 10ml/kg. Treatment groups received either 3, 6, 12.5, 25 or 50mg/kg AZD8835. Tumour growth was monitored throughout the study, and at the end of the imaging procedure, tumours were taken and a full pharmacodynamic analysis was performed. RESULTS: Results showed that AZD8835 reduced 18F-FDG uptake at a dose of 12.5, 25 and 50mg/kg with no significant reduction at doses of 3 and 6mg/kg. These results were consistent with other pharmacodynamics biomarkers measured and show 18F-FDG PET as a sensitive biomarker with the ability to determine the minimal effective dose of AZD8835. CONCLUSIONS: Our pre-clinical studies support the use of 18F-FDG PET imaging as a sensitive and non- invasive pharmacodynamic biomarker (understanding the role of PI3K signalling in glucose uptake) for AZD8835 with a decrease in 18F-FDG uptake observed at only two hours post treatment. The decrease in 18F-FDG uptake was dose dependent and data showed excellent PK/PD correlation. This data supports and parallels observations obtained with this class of compounds in patients.

Quantitative Assessment of Liver Function Using Gadoxetate-Enhanced Magnetic Resonance Imaging: Monitoring Transporter-Mediated Processes in Healthy Volunteers.

OBJECTIVE: The objective of this study was to use noninvasive dynamic contrast-enhanced magnetic resonance imaging (MRI) techniques to study, in vivo, the distribution and elimination of the hepatobiliary contrast agent gadoxetate in the human body and characterize the transport mechanisms involved in its uptake into hepatocytes and subsequent efflux into the bile using a novel tracer kinetic model in a group of healthy volunteers. MATERIALS AND METHODS: Ten healthy volunteers (age range, 18-29 years), with no history of renal or hepatic impairment, were recruited via advertisement. Participants attended 2 MRI visits (at least a week apart) with gadoxetate as the contrast agent. Dynamic contrast-enhanced MRI data were acquired for approximately 50 minutes with a 3-dimensional gradient-echo sequence in the axial plane, at a temporal resolution of 6.2 seconds. Data from regions of interest drawn in the liver were analyzed using the proposed 2-compartment uptake and efflux model to provide estimates for the uptake rate of gadoxetate in hepatocytes and its efflux rate into the bile. Reproducibility statistics for the 2 visits were obtained to examine the robustness of the technique and its dependence in acquisition time. RESULTS: Eight participants attended the study twice and were included into the analysis. The resulting images provided the ability to simultaneously monitor the distribution of gadoxetate in multiple organs including the liver, spleen, and kidneys as well as its elimination through the common bile duct, accumulation in the gallbladder, and excretion in the duodenum. The mean uptake (ki) and efflux (kef) rates in hepatocytes, for the 2 visits using the 50-minute acquisition, were 0.22 ± 0.05 and 0.017 ± 0.006/min, respectively. The hepatic extraction fraction was estimated to be 0.19 ± 0.04/min. The variability between the 2 visits within the group level (95% confidence interval; ki: ±0.02/min, kef: ±0.004/min) was lower compared with the individual variability (repeatability; ki: ±0.06/min, kef: ±0.012/min). Data truncation demonstrated that the uptake rate estimates retained their precision as well as their group and individual reproducibility down to approximately 10 minutes of acquisition. Efflux rate estimates were underestimated (compared with the 50-minute acquisition) as the duration of the acquisition decreased, although these effects were more pronounced for acquisition times shorter than approximately 30 minutes. CONCLUSIONS: This is the first study that reports estimates for the hepatic uptake and efflux transport process of gadoxetate in healthy volunteers in vivo. The results highlight that dynamic contrast-enhanced MRI with gadoxetate can provide novel quantitative insights into liver function and may therefore prove useful in studies that aim to monitor liver pathology, as well as being an alternative approach for studying hepatic drug-drug interactions.

The use of (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) as a pathway-specific biomarker with AZD8186, a PI3Kß/δ inhibitor.

BACKGROUND: The phosphatidylinositol 3 kinase (PI3K) signalling pathway is frequently altered in human cancer and a promising therapeutic target. AZD8186 (AstraZeneca) is a PI3Kß/δ inhibitor, currently in phase 1 clinical trials. (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) is often used as a biomarker for inhibitors targeting the PI3K axis because of the association of this pathway with glucose metabolism. In this study, we assessed if (18)F-FDG PET could be used as a pharmacodynamic marker to monitor PI3Kß inhibition by AZD8186, and hence have potential as a clinical biomarker of PI3Kß pathway activation, and for patient selection. (18)F-FDG PET scans were performed in nude mice bearing 786-0 renal, U87-MG glioma, and BT474C breast xenograft models. Mice were fasted prior to imaging and static (18)F-FDG PET imaging was performed. Tumour growth was monitored throughout each study, and at the end of the imaging procedure, tumours were taken and a full pharmacodynamic analysis performed. RESULTS: Results showed that in PTEN null tumour xenograft models, 786-0 and U87-MG, the PI3Kß inhibitor AZD8186 reduces (18)F-FDG uptake at a dose of 50 mg/kg, the same dose which causes tumour inhibition, while it has no impact in a PI3Kα mutant tumour xenograft BT474C. Consistent with the change in (18)F-FDG uptake, AZD8186 also modulated AKT and associated glucose pathway biomarkers in the PTEN null tumour xenografts but not in PTEN wild-type tumours. CONCLUSIONS: Our pre-clinical studies support the use of (18)F-FDG PET imaging as a sensitive and non-invasive pharmacodynamic biomarker for use in clinical studies with AZD8186.

Apparent diffusion coefficient is highly reproducible on preclinical imaging systems: Evidence from a seven-center multivendor study.

PURPOSE: To evaluate between-site agreement of apparent diffusion coefficient (ADC) measurements in preclinical magnetic resonance imaging (MRI) systems. MATERIALS AND METHODS: A miniaturized thermally stable ice-water phantom was devised. ADC (mean and interquartile range) was measured over several days, on 4.7T, 7T, and 9.4T Bruker, Agilent, and Magnex small-animal MRI systems using a common protocol across seven sites. Day-to-day repeatability was expressed as percent variation of mean ADC between acquisitions. Cross-site reproducibility was expressed as 1.96 × standard deviation of percent deviation of ADC values. RESULTS: ADC measurements were equivalent across all seven sites with a cross-site ADC reproducibility of 6.3%. Mean day-to-day repeatability of ADC measurements was 2.3%, and no site was identified as presenting different measurements than others (analysis of variance [ANOVA] P = 0.02, post-hoc test n.s.). Between-slice ADC variability was negligible and similar between sites (P = 0.15). Mean within-region-of-interest ADC variability was 5.5%, with one site presenting a significantly greater variation than the others (P = 0.0013). CONCLUSION: Absolute ADC values in preclinical studies are comparable between sites and equipment, provided standardized protocols are employed.

Sentinel lymph nodes fluorescence detection and imaging using Patent Blue V bound to human serum albumin.

Patent Blue V (PBV), a dye used clinically for sentinel lymph node detection, was mixed with human serum albumin (HSA). After binding to HSA, the fluorescence quantum yield increased from 5 × 10(-4) to 1.7 × 10(-2), which was enough to allow fluorescence detection and imaging of its distribution. A detection threshold, evaluated in scattering test objects, lower than 2.5 nmol × L(-1) was obtained, using a single-probe setup with a 5-mW incident light power. The detection sensitivity using a fluorescence imaging device was in the µmol × L(-1) range, with a noncooled CCD camera. Preclinical evaluation was performed on a rat model and permitted to observe inflamed nodes on all animals.

In vivo assessments of mucus dynamics in the rat lung using a Gd-Cy5.5-bilabeled contrast agent for magnetic resonance and optical imaging.

Dysfunctions in mucociliary clearance are associated with the accelerated loss of lung function in several respiratory diseases. Approaches enabling the in vivo visualization of mucus dynamics in rodents at high resolution and sensitivity would be beneficial for experimental lung research. We describe the synthesis and characterization of two bilabeled amino dextran-based probes binding specifically to mucin. Labeling of secreted mucus and of mucin in goblet cells in the lungs of lipopolysaccharide-challenged rats has been demonstrated in vivo with near-infrared fluorescence and MRI and confirmed by histology. The effects of uridine triphosphate were then studied in lipopolysaccharide-challenged rats by simultaneously administering the imaging probe and the compound. The data suggest that uridine triphosphate increased the mucociliary clearance, but at the same time induced a release of mucin from goblet cells, thus not contributing to the overall reduction of mucus in the lung. The approach outlined here enables one to derive information on mucus clearance, as well as secretion. Such a global view on mucus dynamics may prove invaluable when testing new pharmacological agents aimed at improving mucociliary clearance.

In vivo visualization of macrophage infiltration and activity in inflammation using magnetic resonance imaging.

Because macrophages play a key role on host defense, visualization of the migration of these cells is of high relevance for both diagnostic purposes and the evaluation of therapeutic interventions. The present article addresses the use of iron oxide and gadolinium-based particles for the noninvasive in vivo detection of macrophage infiltration into inflamed areas by magnetic resonance imaging (MRI). A general introduction on the functions and general characteristics of macrophages is followed by a discussion of some of the agents and acquisition schemes currently used to track the cells in vivo. Attention is then devoted to preclinical and clinical applications in the following disease areas: atherosclerosis and myocardial infarction, stroke, multiple sclerosis, rheumatoid arthritis, and kidney transplantation.

Allergen-induced lung inflammation in actively sensitized mice assessed with MR imaging.

PURPOSE: To demonstrate the feasibility of using proton magnetic resonance (MR) imaging to noninvasively detect extravascular and luminal fluid in a murine model of allergen-induced airway inflammation. MATERIALS AND METHODS: The Basel Veterinary Authority approved this experiment. Actively sensitized female Balb/c mice received ovalbumin or saline and underwent MR imaging (a) once 24 hours after the fourth administration of ovalbumin or saline (n = 25) or (b) several times between and after ovalbumin or saline administrations (n = 22) to determine the volume of fluid signal induced by an allergen. Images were acquired in spontaneously breathing animals, without cardiac or respiratory gating. Signal detected with a gradient-echo sequence was compared with bronchoalveolar lavage (BAL) fluid parameters and with perivascular and peribronchial edema and mucus observed at histologic analysis. RESULTS: Up to 24 hours after the fourth administration of ovalbumin, intense and continuous fluid signals (volume, 40-50 microL) were detected in proximal lung regions. At 72 hours after the fourth administration of ovalbumin, remaining signals (21.1 microL +/- 3.8) had a discontinuous texture. The number of eosinophils in the BAL fluid at 24 and 72 hours and their activation were higher in mice that received ovalbumin than in those that received saline. Histologic analysis revealed edema and secreted mucus in the early phase, whereas only mucus was encountered in the late phase. CONCLUSION: These findings suggest that the main component of the early response was plasma leakage (edema), while the main component of the late response was secreted mucus. With the technique validated, the basis for pharmacologic studies in this murine model of lung inflammation with use of MR imaging as a noninvasive readout was provided.

Lung MRI for experimental drug research.

Current techniques to evaluate the efficacy of potential treatments for airways diseases in preclinical models are generally invasive and terminal. In the past few years, the flexibility of magnetic resonance imaging (MRI) to obtain anatomical and functional information of the lung has been explored with the scope of developing a non-invasive approach for the routine testing of drugs in models of airways diseases in small rodents. With MRI, the disease progression can be followed in the same animal. Thus, a significant reduction in the number of animals used for experimentation is achieved, as well as minimal interference with their well-being and physiological status. In addition, under certain circumstances the duration of the observation period after disease onset can be shortened since the technique is able to detect changes before these are reflected in parameters of inflammation determined using invasive procedures. The objective of this article is to briefly address MRI techniques that are being used in experimental lung research, with special emphasis on applications. Following an introduction on proton techniques and MRI of hyperpolarized gases, the attention is shifted to the MRI analysis of several aspects of lung disease models, including inflammation, ventilation, emphysema, fibrosis and sensory nerve activation. The next subject concerns the use of MRI in pharmacological studies within the context of experimental lung research. A final discussion points towards advantages and limitations of MRI in this area.

Bleomycin-induced lung injury assessed noninvasively and in spontaneously breathing rats by proton MRI.

PURPOSE: To apply proton magnetic resonance imaging (MRI) techniques to assess noninvasively and in spontaneously breathing rats, structural changes following a single intratracheal administration of bleomycin (BLM). MATERIALS AND METHODS: Rats were scanned by MRI prior to BLM or vehicle administration and at six hours, 24 hours, week 1, and at weeks 2, 3, 6, and 8 after treatment. Bronchoalveolar lavage (BAL) fluid and histological analyses were performed at 24 hours, and at weeks 1 and 8 (histology only). RESULTS: Prominent MRI fluid signals were detected in the lungs of BLM-treated rats one week after challenge. These signals correlated with increased inflammatory parameters in BAL fluid and with marked perivascular and parenchymal infiltration with inflammatory cells in histological slices. At week 2 the MRI signals due to edema resolved, but nevertheless an increase in MRI signal intensity from the lung parenchyma was apparent. In some areas of the right lung the MRI signal intensity in the parenchyma decreased between weeks 2 and 8. These observations were in line with histology demonstrating collagen deposition and atelectasis (hallmarks of fibrosis) at week 1 and a partial recovery of the lung parenchyma at week 8. CONCLUSION: The data demonstrate the ability of proton MRI to detect BLM-induced lung fibrosis as well as the acute inflammatory response caused by the agent.

In vivo mouse imaging and spectroscopy in drug discovery.

Imaging modalities such as micro-computed tomography (micro-CT), micro-positron emission tomography (micro-PET), high-resolution MRI, optical imaging, and high-resolution ultrasound have become invaluable tools in preclinical pharmaceutical research. They can be used to non-invasively investigate, in vivo, rodent biology and metabolism, disease models, and pharmacokinetics and pharmacodynamics of drugs. The advantages and limitations of each approach usually determine its application, and therefore a small-rodent imaging laboratory in a pharmaceutical environment should ideally provide access to several techniques. In this paper we aim to illustrate how these techniques may be used to obtain meaningful information for the phenotyping of transgenic mice and for the analysis of compounds in murine models of disease.

Lung inflammation and vascular remodeling after repeated allergen challenge detected noninvasively by MRI.

Magnetic resonance imaging (MRI) has been used previously to follow noninvasively inflammatory processes in rat acute models of lung inflammation. Here the technique was applied to a model involving repeated intratracheal administration of ovalbumin (OA). Anatomical MRI was performed at different time points with respect to a single or multiple OA challenges in Brown Norway rats actively sensitized to the allergen. Vascular permeability was assessed using dynamic contrast-enhanced MRI (DCE-MRI). Bronchoalveolar lavage (BAL) fluid analysis and histology were performed to validate the MRI data. The time course of MRI signals after a single OA challenge reached a maximum at 48 h and decreased significantly at 96 h. After the second and subsequent challenges, the maximum signal occurred at 6 h with a time-dependent decline over the remainder of the time course. A reduction of the inflammatory response following repeated administration of OA was also detected by BAL fluid analysis. The decrease in vascular permeability assessed by DCE-MRI in repeatedly OA-challenged rats was consistent with the thickening of the vascular wall for vessels of diameter up to 300 microm revealed by histology. Angiogenesis of vessels smaller than 30 microm was also detected histologically. These results suggest that MRI can be used to detect the inflammatory response and vascular remodeling associated with chronic airway inflammation in rat models involving repeated administration of allergen. As the contrast agent used in the DCE-MRI experiments is approved for clinical use, there is potential to translate the approach to patients.