Current Imaging Methods Research Articles

UPLC-HRMS-based Plasma Metabolomics Study of Thymoma and Thymic Hyperplasia.

Thymoma is a rare malignant tumor but it is the most common primary tumor of the anterior mediastinum. The current imaging methods for thymoma screening suffer from false positive rate problem, and thymoma pathogenesis remains elusive. Study of thymoma metabolic characteristics could provide clues for improving the diagnosis and understanding the pathogenesis of thymoma. Metabolic profiling of sera from thymoma and thymic hyperplasia patients was performed using UPLC-HRMS in both positive and negative ionization modes. After pre- and post-processing, the dataset was divided into three age groups and statistical analysis was performed to select differential metabolites of thymoma. For feature identification, experimental MS/MS spectra were matched to those of databases and available chemical standards, and also manually annotated with plausible chemical structures to ensure high identification confidence. A total of 47 differential metabolites were identified in thymoma. Significant higher levels of histidine, sphinganine 1-phosphate, lactic acid dimer, phenylacetylglutamine, LPC (18:3) and LPC (16:1), and significant lower levels of phenylalanine, indole-3-propionic acid (IPA), hippuric acid and mesobilirubinogen were associated with thymoma. Tryptophan level in thymoma-associated myasthenia gravis (TAMG) was significantly lower than that of the MG (-) group. IPA and hippuric acid abundances exhibited increasing trends from indolent to aggressive thymoma. Our study revealed aberrant aromatic amino acid metabolism and fatty acid oxidation might be associated with thymoma. The identified unique metabolic characteristics of thymoma may provide valuable information for study of the molecular mechanism of thymoma pathogenesis, and improvement of diagnosis and discovery of new therapeutic strategies for thymoma.

Dose Images Reconstruction Based on X-ray-Induced Acoustic Computed Tomography

The accurate reconstruction of the in vivo dose is a critical step in radiation therapy. X-ray-induced acoustic imaging is a promising technology for in vivo dose reconstruction, as it enables the nonradiative and noninvasive monitoring of radiation dose. However, current X-ray acoustic imaging methods suffer from several limitations, including high signal-to-noise ratio, poor imaging quality and massive loss of structural information. To address these limitations, we propose a dose image reconstruction method based on tensor sparse dictionary learning. Specifically, we combine tensor coding with compressed sensing data, extend two-dimensional dictionary learning to three-dimensional by using tensor product, and then utilize the spatial information of X-ray acoustic signal more efficiently. To reduce the artifacts of reconstruction images caused by spare sampling, we design the alternate iterative solution of the tensor sparse coefficient and tensor dictionary. In addition, we build the X-ray-induced acoustic dose images reconstruction system, simulate the X-ray acoustic signals based on patients’ information from Sichuan Cancer Hospital, and then create the simulated datasets. Compared to some typical state-of-the art imaging methods, the experimental results demonstrate that our method can significantly improve the quality of reconstructed images and the accuracy of dose distribution.

Rapid imaging of unsaturated lipids at isomer level using photoepoxidation

Unsaturated lipids play an essential role in living organisms, and their different isomers show significant functional differences. Therefore, in situ characterization of unsaturated lipids in tissues needs to be extended to isomer level. However, the exposure of tissue sections to an open environment for a long time may cause cell autolysis or corruption, and current unsaturated lipid imaging methods still face challenges in efficiency. This paper proposes an imaging method based on photoepoxidation coupled with air-flow-assisted desorption electrospray ionization mass spectrometry (AFADESI-MS) to rapidly realize the spatial characterization of unsaturated lipids at the isomer level. The technique has a fast response speed, high epoxide yield (>80%), and high diagnostic ion abundance. After 0.5 min of photoepoxidation, the derivation product yield ratio reached 24.6%. This method rapidly identified six glycerophospholipid isomers containing an 18:1 acyl chain in normal rat liver tissue. Then the imaging method was applied in nude mice lung cancer tissue and human thyroid cancer tissue, with only 3 min photoepoxidation. Results successfully characterized the location and range of unsaturated lipid isomers and revealed their enrichment in tumor tissue. In addition, the experiment shows that the variational trend of the ratio of unsaturated lipid isomers in different types of tumor samples is different. Based on the advantages of efficiency and convenience, this method is prospective for screening unsaturated lipid markers and pathological research of related diseases.

Imaging angiogenesis in an intracerebrally induced model of brain macrometastasis using αv β3 -targeted iron oxide microparticles.

Brain metastasis is responsible for a large proportion of cancer mortality, and there are currently no effective treatments. Moreover, the impact of treatments, particularly antiangiogenic therapeutics, is difficult to ascertain using current magnetic resonance imaging (MRI) methods. Imaging of the angiogenic vasculature has been successfully carried out in solid tumours using microparticles of iron oxide (MPIO) conjugated to a Arg-Gly-Asp peptide (RGD) targeting integrin αv β3 . The aim of this study was to determine whether RGD-MPIO could be used to identify angiogenic blood vessels in brain metastases in vivo. A mouse model of intracerebrally implanted brain macrometastasis was established through intracerebral injection of 4T1-GFP cells. T2 *-weighted imaging was used to visualise MPIO-induced hypointense voxels in vivo, and Prussian blue staining was used to visualise MPIO and endogenous iron histologically ex vivo. The RGD-MPIO showed target-specific binding in vivo, but the sensitivity of the agent for visualising angiogenic vessels per se was reduced by the presence of endogenous iron-laden macrophages in larger metastases, resulting in pre-existing hypointense areas within the tumour. Further, our data suggest that peptide-targeted MPIO, but not antibody-targeted MPIO, are taken up by perivascular macrophages within the macrometastatic microenvironment, resulting in additional nonspecific contrast. While pre-MPIO imaging will circumvent the issues surrounding pre-existing hypointensities and enable detection of specific contrast, our preliminary findings suggest that the use of antibodies rather than peptides as the targeting ligand may represent a preferable route forward for new angiogenesis-targeted molecular MRI agents.

An intelligent colony optimization imaging method for composites health monitoring using ultrasonic guided wave

Damage imaging technology based on ultrasonic guided wave can characterize and visualize structural damage. However, current imaging methods require high accuracy in wave packets information extraction, resulting in artifacts, large spots and false imaging. Therefore, an intelligent colony optimization imaging method is proposed to transform the damage imaging problem into the scattering sources search problem. The number of imaging trajectories through potential scattering sources is employed as the fitness function to assess the damage possibility in this individual. The fitness function is further implemented to particle swarm optimization algorithm for iterative search of actual scattering sources to find out the damage area with highest damage possibility. After the scattering sources search, the location of the damage can be identified through observing the distribution of the population. The experimental results illustrate that the proposed intelligent imaging method can accurately locate the crack damage of different lengths and delamination damage in composites, and the damage imaging effect is better than that of elliptic imaging.

DBCU-Net: deep learning approach for segmentation of coronary angiography images.

Coronary angiography (CAG) is the "gold standard" for diagnosing coronary artery disease (CAD). However, due to the limitation of current imaging methods, the CAG image has low resolution and poor contrast with a lot of artifacts and noise, which makes it difficult for blood vessels segmentation. In this paper, we propose a DBCU-Net for automatic segmentation of CAG images, which is an extension of U-Net, DenseNet with bi-directional ConvLSTM(BConvLSTM). The main contribution of our network is that instead of convolution in the feature extraction of U-Net, we incorporate dense connectivity and the bi-directional ConvLSTM to highlight salient features. We conduct our experiment on our private dataset, and achieve average Accuracy, Precision, Recall and F1-score for coronary artery segmentation of 0.985, 0.913, 0.847 and 0.879 respectively.

Atrial cardiomyopathy: Current and future imaging methods for assessment of atrial structure and function.

Changes in atrial size and function have historically been considered a surrogate marker of ventricular dysfunction. However, it is now recognized that atrial cardiomyopathy (ACM) may also occur as a primary myocardial disorder. Emerging evidence that ACM is a major risk factor for atrial fibrillation, heart failure, and thromboembolic stroke, has highlighted the significance of this disorder and the need for better assessment of atrial metrics in clinical practice. Key barriers in this regard include a lack of standardized criteria or hierarchy for the diagnosis of ACM and lack of consensus for the most accurate phenotyping methods. In this article we review existing literature on ACM, with a focus on current and future non-invasive imaging methods for detecting abnormalities of atrial structure and function. We discuss the relative advantages and disadvantages of transthoracic echocardiography and cardiac magnetic resonance imaging for assessing a range of parameters, including atrial size and contractile function, strain, tissue characteristics, and epicardial adipose tissue. We will also present the potential application of novel imaging methods such as sphericity index and four- or five-dimensional flow.

Seeing plants as never before.

Imaging has long supported our ability to understand the inner life of plants, their development, and response to a dynamic environment. While optical microscopy remains the core tool for imaging, a suite of novel technologies is now beginning to make a significant contribution to visualize plant metabolism. The purpose of this review was to provide the scientific community with an overview of current imaging methods, which rely variously on either nuclear magnetic resonance (NMR), mass spectrometry (MS) or infrared (IR) spectroscopy, and to present some examples of their application in order to illustrate their utility. In addition to providing a description of the basic principles underlying these technologies, the review discusses their various advantages and limitations, reveals the current state of the art, and suggests their potential application to experimental practice. Finally, a view is presented as to how the technologies will likely develop, how these developments may encourage the formulation of novel experimental strategies, and how the enormous potential of these technologies can contribute to progress in plant science.

High resolution propagation-based lung imaging at clinically relevant X-ray dose levels

Absorption-based clinical computed tomography (CT) is the current imaging method of choice in the diagnosis of lung diseases. Many pulmonary diseases are affecting microscopic structures of the lung, such as terminal bronchi, alveolar spaces, sublobular blood vessels or the pulmonary interstitial tissue. As spatial resolution in CT is limited by the clinically acceptable applied X-ray dose, a comprehensive diagnosis of conditions such as interstitial lung disease, idiopathic pulmonary fibrosis or the characterization of small pulmonary nodules is limited and may require additional validation by invasive lung biopsies. Propagation-based imaging (PBI) is a phase sensitive X-ray imaging technique capable of reaching high spatial resolutions at relatively low applied radiation dose levels. In this publication, we present technical refinements of PBI for the characterization of different artificial lung pathologies, mimicking clinically relevant patterns in ventilated fresh porcine lungs in a human-scale chest phantom. The combination of a very large propagation distance of 10.7 m and a photon counting detector with 100,upmu hbox {m} pixel size enabled high resolution PBI CT with significantly improved dose efficiency, measured by thermoluminescence detectors. Image quality was directly compared with state-of-the-art clinical CT. PBI with increased propagation distance was found to provide improved image quality at the same or even lower X-ray dose levels than clinical CT. By combining PBI with iodine k-edge subtraction imaging we further demonstrate that, the high quality of the calculated iodine concentration maps might be a potential tool for the analysis of lung perfusion in great detail. Our results indicate PBI to be of great value for accurate diagnosis of lung disease in patients as it allows to depict pathological lesions non-invasively at high resolution in 3D. This will especially benefit patients at high risk of complications from invasive lung biopsies such as in the setting of suspected idiopathic pulmonary fibrosis (IPF).

Current Non-Invasive Imaging Techniques Used in the Diagnosis of Adenomyosis

Objective: This review aims to provide insights into the current non-invasive imaging methods used in the diagnosis of adenomyosis, as well as to highlight their diagnostic accuracy, advantages, disadvantages and limitations in the detection of this benign uterine condition. At the same time, this paper emphasizes the importance of using consensus-based terminology in the imaging description of these lesions. Mechanism: A search of PUBMED database was conducted for articles published between January 1998 and August 2022 and studies which compared non-invasive imaging methods with postoperative histology examination of uterine specimens were primarily selected. Transvaginal two-dimensional ultrasound was for a long time the main non-invasive imagistic method used for assessment of adenomyosis lesions. The introduction of Morphological Uterus Sonographic Assessment (MUSA) group criteria yielded a significantly better diagnostic outcome of adenomyosis in case of conventional ultrasonography, but the distinction of concomitant benign uterine conditions still remained challenging. Findings in Brief: The addition of three-dimensional ultrasound or elastosonography to conventional two-dimensional transvaginal ultrasound yielded higher diagnostic sensitivity. Qualitative elastography particularly proved useful in the diagnosis of adenomyosis due to its capacity to achieve differential diagnosis of benign uterine pathologies based on lesion stiffness. Magnetic resonance imaging (MRI) examination presents higher diagnostic specificity and sensitivity, can assess the endometrial and myometrial layers in detail, but its use has been shadowed by costs and significantly longer examination time. Conclusions: The imaging terminology established by consensus by the MUSA group in recent years has facilitated the description of adenomyosis-specific lesions. Two-dimensional transvaginal ultrasound in combination with three-dimensional ultrasound or combined with qualitative elastography offers similar diagnostic sensitivity and specificity to MRI. Despite some limitations, MRI remains a reliable diagnostic method for adenomyosis.

Novel non-invasive ECG imaging method based on the 12-lead ECG for reconstruction of ventricular activation: A proof-of-concept study.

Current non-invasive electrocardiographic imaging (ECGi) methods are often based on complex body surface potential mapping, limiting the clinical applicability. The aim of this pilot study was to evaluate the ability of a novel non-invasive ECGi method, based on the standard 12-lead ECG, to localize initial site of ventricular activation in right ventricular (RV) paced patients. Validation of the method was performed by comparing the ECGi reconstructed earliest site of activation against the true RV pacing site determined from cardiac computed tomography (CT). This was a retrospective study using data from 34 patients, previously implanted with a dual chamber pacemaker due to advanced atrioventricular block. True RV lead position was determined from analysis of a post-implant cardiac CT scan. The ECGi method was based on an inverse-ECG algorithm applying electrophysiological rules. The algorithm integrated information from an RV paced 12-lead ECG together with a CT-derived patient-specific heart-thorax geometric model to reconstruct a 3D electrical ventricular activation map. The mean geodesic localization error (LE) between the ECGi reconstructed initial site of activation and the RV lead insertion site determined from CT was 13.9 ± 5.6 mm. The mean RV endocardial surface area was 146.0 ± 30.0 cm2 and the mean circular LE area was 7.0 ± 5.2 cm2 resulting in a relative LE of 5.0 ± 4.0%. We demonstrated a novel non-invasive ECGi method, based on the 12-lead ECG, that accurately localized the RV pacing site in relation to the ventricular anatomy.

Assessment of nonalcoholic fatty liver function by photoacoustic imaging

SignificanceThe assessment of liver function plays an important role in the diagnosis of nonalcoholic fatty liver disease (NAFLD). Current noninvasive imaging methods have limited applicability in this regard.AimWe report an application of multispectral photoacoustic imaging (PAI), an emerging modality, to visualize lipid accumulation and liver function in NAFLD.ApproachWe first demonstrated the liver function reserve with indocyanine green (ICG) to verify the organ’s dysfunction due to NAFLD in a rabbit model. We then noninvasively quantified lipid content in the liver using multispectral PAI. The in vivo PAI results were compared and verified with photoacoustic ex vivo images and liver biopsy.ResultsA significant difference in the lipidmean value was observed [lipidmean = 0.081 ± 0.0161 arbitrary units (a.u.) control versus NAFLD 0.198 ± 0.048 a.u., P = 0.003]. Similar to in vivo analysis, a significant difference in lipidmean was observed (lipidmean = 0.0673 ± 0.0165 versus 0.486 ± 0.073 a.u., P < 0.0001) between control and NAFLD group ex vivo. For liver function, the control group showed a rapid decrease after the peak point, whereas the elimination of ICG for the NAFLD group was slower.ConclusionsOur study shows that PAI has the potential to provide a noninvasive biomarker for the assessment of liver function and lipid accumulation for NAFLD diagnosis and treatment.

Determining the value of early measurement of interleukin-10 in predicting the absence of brain lesions in CT scans of patients with mild traumatic brain injury

Blood-based biomarkers were recently proposed as predictors of traumatic brain injury (TBI) outcomes. This would be a critical step forward since the majority of TBI events are mild and structural brain damage in this group may be missed by current brain imaging methods. We sought to determine the performance of early measurement of interleukin-10 (IL-10) to distinguish computed tomography (CT)-positive from negative patients with mild TBI. We designed a single-center prospective observational study, which enrolled consecutive patients classed with mild TBI according to Glasgow Coma Scale [GCS] scores and appearance of at least one clinical symptom. Serum IL-10 levels were measured <3 h post hospital admission. The performance of IL-10 levels in correctly classifying patients was evaluated. IL-10 levels were significantly higher in the group with positive CT scans (p < 0.001). With sensitivity set at 100%, the specificity of IL-10 was only 38.1%. However, the specificities of IL-10 for prediction of negative and positive cases increased to 59% and 49%, respectively, when both parameters were assessed within 90 min of admission. For mild TBI patients between 36 and 66 years, classification performance increased significantly at the 100% sensitivity level with a specificity of 93%. Our results suggest that IL-10 may be an easily accessible clinically useful diagnostic biomarker that can distinguish between mild TBI patients with and without structural brain damage with higher effectiveness when lower times of blood sampling are employed and patients are between 36 and 66 years of age.

Optical-visualized photoacoustic tomographic navigation

The current preoperative vascular imaging methods cannot achieve noninvasive high-resolution imaging of deep-localized vessels. Photoacoustic tomography (PAT) can show microvessels with centimeter depth and submillimeter diameter without the use of contrast agents. Combined with PAT and optical projection technology, the Hessian-matrix-based skin removal algorithm and the target matching method were developed to spatially align the photoacoustic data of subcutaneous blood vessels with the anatomy of real patients and to realize three-dimensional (3D) visualization of blood vessels from the body surface. The optical projection navigation system based on PAT has high spatial resolution (∼135 μm) and temporal resolution (0.1 s). In the rabbit injection experiment, 3D distributions of needle and blood vessel (&amp;gt;100 μm) were obtained by image segmentation, which proved that the method can guide micro plastic injection. Furthermore, healthy volunteers' forehead imaging experiments show that 3D visualization and cross-sectional images of the human forehead clearly show the vascular network and ability of the system to image submillimeter blood vessels with penetration depth (∼10.2 mm). Our work confirms that the method of integrated photoacoustic imaging and optical projection has great potential for noninvasive diagnosis and treatment of clinical blood vessels, opening a path for the application of photonics in medical esthetics.

Diagnosis of fatigue cracks in structural elements manufactured by additive manufacturing

Recently, the production of metal structural elements using additive processes is gaining popularity. They allow the production of an element of any geometry and structure, while reducing the mass of the produced part. Unfortunately, the AM technology causes structural elements to be burdened with numerous defects in the form of porosity, unmelted powder, weak interlayer bonds or residual stresses, etc. These defects translate into the possibility of an early, uncontrolled fatigue crack. For this reason, it is important to find ways to quickly detect damage caused by random variable loads. The work presents methods of diagnosing cracks and fatigue damage in structural elements produced using 3D printing. The division of research methods allowing for the detection of defects in structural elements and the characteristics of the most popular methods, taking into account their advantages and limitations, were presented. Methods appropriate for a given type of material, test conditions and damages are indicated. The most important methods of diagnosing defects in printed elements include: penetrating, ultrasonic, radiographic, eddy current and thermal imaging methods.

Ferumoxytol-enhanced magnetic resonance imaging with volume rendering: A new approach for the depiction of internal placental structure in vivo

IntroductionPlacental function is vitally important, but placental assessment is limited by current imaging methods in vivo. The goal of this study is to determine if ferumoxytol-enhanced MR studies might be used to depict placental structure during pregnancy. MethodsTen pregnant women were referred for MRI evaluation of abnormal placentation. The study group was composed five of these patients whose placentas were normal at pathology. MR studies consisted of pre-contrast SSFSE (single-shot fast spin-echo), SSFP (steady-state free procession), diffusion, and ferumoxytol-enhanced acquisitions. The post-contrast sequences were compared to pre-contrast SSFSE, SSFP, and diffusion acquisitions for features of correspondence. MR images were also compared to histopathology for anatomic landmarks including the three-ring pattern of the functional vascular exchange unit (the placentone) created by this central cavity surrounded by a ring of clustered villi, and an outer ring of dispersed villi corresponding to the maternal venous outflow channel. The measured sizes of these features on MR were compared to reported sizes. ResultsPost-ferumoxytol images showed enhancement of the maternal blood within the placenta, notably the intervillous space and the myometrial vessels. The unenhanced fetal vessels were most visible on the MinIP (minimum intensity projection) images; the enhanced maternal vessels were most visible on the MIP (maximum intensity projection) images. Composite MIP/MinIP images show the relation of maternal and fetal circulations. The signal intensities replicate the relative contributions from enhanced maternal blood and unenhanced chorionic villi. DiscussionFerumoxytol-enhanced MR imaging can depict the internal anatomy of the placenta in vivo of clarity and detail. This could represent a new diagnostic approach to placental disorders.

Artificial Intelligence-based CT Assessment of Bronchiectasis: The COPDGene Study.

Background CT is the standard method used to assess bronchiectasis. A higher airway-to-artery diameter ratio (AAR) is typically used to identify enlarged bronchi and bronchiectasis; however, current imaging methods are limited in assessing the extent of this metric in CT scans. Purpose To determine the extent of AARs using an artificial intelligence-based chest CT and assess the association of AARs with exacerbations over time. Materials and Methods In a secondary analysis of ever-smokers from the prospective, observational, multicenter COPDGene study, AARs were quantified using an artificial intelligence tool. The percentage of airways with AAR greater than 1 (a measure of airway dilatation) in each participant on chest CT scans was determined. Pulmonary exacerbations were prospectively determined through biannual follow-up (from July 2009 to September 2021). Multivariable zero-inflated regression models were used to assess the association between the percentage of airways with AAR greater than 1 and the total number of pulmonary exacerbations over follow-up. Covariates included demographics, lung function, and conventional CT parameters. Results Among 4192 participants (median age, 59 years; IQR, 52-67 years; 1878 men [45%]), 1834 had chronic obstructive pulmonary disease (COPD). During a 10-year follow-up and in adjusted models, the percentage of airways with AARs greater than 1 (quartile 4 vs 1) was associated with a higher total number of exacerbations (risk ratio [RR], 1.08; 95% CI: 1.02, 1.15; P = .01). In participants meeting clinical and imaging criteria of bronchiectasis (ie, clinical manifestations with ≥3% of AARs >1) versus those who did not, the RR was 1.37 (95% CI: 1.31, 1.43; P < .001). Among participants with COPD, the corresponding RRs were 1.10 (95% CI: 1.02, 1.18; P = .02) and 1.32 (95% CI: 1.26, 1.39; P < .001), respectively. Conclusion In ever-smokers with chronic obstructive pulmonary disease, artificial intelligence-based CT measures of bronchiectasis were associated with more exacerbations over time. Clinical trial registration no. NCT00608764 © RSNA, 2022 Supplemental material is available for this article. See also the editorial by Schiebler and Seo in this issue.

Oxidation of hyperpolarized [1-13 C]pyruvate in isolated rat kidneys.

Kidneys play a central role in numerous disorders but current imaging methods have limited utility to probe renal metabolism. Hyperpolarized (HP) 13 C magnetic resonance imaging is uniquely suited to provide metabolite-specific information about key biochemical pathways and it offers the further advantage that renal imaging is practical in humans. This study evaluated the feasibility of hyperpolarization examinations in a widely used model for analysis of renal physiology, the isolated kidney, which enables isolation of renal metabolism from the effects of other organs and validation of HP results by independent measurements. Isolated rat kidneys were supplied with either HP [1-13 C]pyruvate only or HP [1-13 C]pyruvate plus octanoate. Metabolic activity in both groups was confirmed by stable renal oxygen consumption. HP [1-13 C]pyruvate was readily metabolized to [13 C]bicarbonate, [1-13 C]lactate, and [1-13 C]alanine, detectable seconds after HP [1-13 C]pyruvate was injected. Octanoate suppressed but did not eliminate the production of HP [13 C]bicarbonate from [1-13 C]pyruvate. Steady-state flux analyses using non-HP 13 C substrates validated the utilization of HP [1-13 C]pyruvate, as observed by HP 13 C NMR. In the presence of octanoate, lactate is generated from a tricarboxylic acid cycle intermediate, oxaloacetate. The isolated rat kidney may serve as an excellent model for investigating and establishing new HP 13 C metabolic probes for future kidney imaging applications.

Fibrin-Targeted Nanoparticles for Finding, Visualizing and Characterizing Blood Clots in Acute Ischemic Stroke.

Recanalization of the occluded artery is the gold standard treatment for acute ischemic stroke, which includes enzymatic fibrinolytic treatment with the use of recombinant tissue plasminogen activators (rtPAs) to disrupt the occluding clot, the use of mechanical thrombectomy to physically remove the clot, or a combination of both. Fibrin is one of the main components of blood clots causing ischemic stroke and is the target of rtPA upon activation of plasminogen in the clot. In addition, fibrin content also influences the efficacy of mechanical thrombectomy. Current imaging methods can successfully identify occlusions in large vessels; however, there is still a need for contrast agents capable of visualizing small thrombi in ischemic stroke patients. In this work, we describe the synthesis and the in vitro characterization of a new diagnostic nanoparticle, as well as the in vivo evaluation in an animal model of thromboembolic stroke. Gd-labeled KCREKA peptides were synthesized and attached onto the surface of PEGylated superparamagnetic nanoparticles. Magnetic resonance imaging (MRI) of blood clots was performed in vitro and in vivo in animal models of thromboembolic stroke. KCREKA-NPs were synthesized by attaching the peptide to the amino (N) termini of the PEG-NPs. The sizes of the nanoparticles, measured via DLS, were similar for both KCREKA-NPs and PEG-NPs (23 ± 4 nm, PDI = 0.11 and 25 ± 8 nm, PDI = 0.24, respectively). In the same line, r2 relaxivities were also similar for the nanoparticles (149 ± 2 mM Fe s−1 and 151 ± 5 mM Fe s−1), whereas the r1 relaxivity was higher for KCREKA-NPs (1.68 ± 0.29 mM Fe s−1 vs. 0.69 ± 0.3 mM Fe s−1). In vitro studies showed that blood clots with low coagulation times were disrupted by rtPA, whereas aged clots were almost insensitive to the presence of rtPA. MRI in vitro studies showed a sharp decrease in the T1 × T2 signals measured for aged clots incubated with KCREKA-NPs compared with fresh clots (47% [22, 80] to 26% [15, 51]). Furthermore, the control blood showed a higher value of the T1 × T2 signal (39% [20, 61]), being the blood clots with low coagulation times the samples with the lowest values measured by MRI. In vivo studies showed a significant T1 × T2 signal loss in the clot region of 24% after i.v. injection of KCREKA-NPs. The thrombus age (2.5% ± 6.1% vs. 81.3% ± 19.8%, p < 0.01) confirmed our ability to identify in vivo fresh blood clots. In this study, we developed and tested a dual MRI nanoparticle, acting as T1 and T2 contrast agents in MRI analyses. The developed KCREKA-NPs showed affinity for the fibrin content of blood clots, and the MRI signals provided by the nanoparticles showed significant differences depending on the clot age. The developed KCREKA-NPs could be used as a tool to predict the efficacy of a recanalization treatment and improve the triage of ischemic stroke patients.

Preclinical Safety Evaluation of Intraperitoneally Administered Cu-Conjugated Anti-EGFR Antibody NCAB001 for the Early Diagnosis of Pancreatic Cancer Using PET.

Detecting tumor lesions <1 cm in size using current imaging methods remains a clinical challenge, especially in pancreatic cancer. Previously, we developed a method to identify pancreatic tumor lesions ≥3 mm using positron emission tomography (PET) with an intraperitoneally administered 64Cu-labeled anti-epidermal growth factor receptor (EGFR) antibody (64Cu-NCAB001 ipPET). Here, we conducted an extended single-dose toxicity study of 64Cu-NCAB001 ipPET in mice based on approach 1 of the current ICH M3 [R2] guideline, as our new drug formulation contains 45 μg of the antibody. We used NCAB001 labeled with stable copper isotope instead of 64Cu. The total content of size variants was approximately 6.0% throughout the study. The relative binding potency of Cu-NCAB001 to recombinant human EGFR was comparable to that of cetuximab. The general and neurological toxicities of Cu-NCAB001 ipPET at 62.5 or 625 μg/kg were assessed in mice. The no-observed-adverse-effect level of Cu-NCAB001 was 625 μg/kg, a dose approximately 1000-fold higher at the μg/kg level than the dose of 64Cu-NCAB001 in our formulation (45 µg). The size variants did not affect the safety of the formulation. Therefore, clinical studies on the efficacy of 64Cu-NCAB001 ipPET for early detection of pancreatic cancer using PET imaging can be safely conducted.