Prediction of Protumorigenic Effects after Image-Guided Radiofrequency Ablation of Hepatocellular Carcinoma Using Biomarkers.

PURPOSE: To perform radiofrequency (RF) ablation of hepatocellular carcinoma (HCC) and to assess serological and histopathological markers of tumorigenesis in distant untreated tumors to determine whether these were associated with unfavorable outcomes such as early relapse and increased biological aggressiveness. MATERIALS AND METHODS: The study cohort comprised 13 patients from a prospective single-arm study. All patients underwent 2 ablation sessions of multifocal HCC nodules 14 days apart. Core biopsy samples of untreated tumors were acquired at baseline and at the time of the second ablation session. Samples were stained immunohistochemically with Ki-67 (proliferation) and CD34 (microvasculature). Blood plasma was obtained at baseline and 2 days after the initial ablation session and analyzed for hepatocyte growth factor (HGF), vascular endothelial growth factor C, and angiopoietin-2 using an enzyme-linked immunosorbent assay. The clinical follow-up period ranged from 7 to 25 months. Patients were stratified as responders (complete remission or limited and delayed recurrence at >6 months; n = 6) or nonresponders (any recurrence within 6 months or >3 new tumors or any new tumor of >3 cm thereafter; n = 7). RESULTS: In 3 of 7 nonresponders, the Ki-67 index markedly increased in untreated tumors, whereas Ki-67 was stable in all responders. Microvascular density strongly increased in a single nonresponder only. HGF and angiopoietin-2 increased by >30% in 3 of 7 and 4 of 7 nonresponders, respectively, whereas they were stable or decreased in responders. Overall, ≥2 biomarkers were elevated in 6 of 7 (85.7%) nonresponders, whereas 4 of 6 responders demonstrated no increased biomarker and 2 patients demonstrated increase in 1 biomarker only (P = .002). CONCLUSIONS: RF ablation of HCC can produce protumorigenic factors that induce effects in distant untreated tumors. These may potentially function as biomarkers of clinical outcome.

3D-Non-destructive Imaging through Heavy-Metal Eosin Salt Contrast Agents.

Conventional histology is a destructive technique based on the evaluation of 2D slices of a 3D biopsy. By using 3D X-ray histology these obstacles can be overcome, but their application is still restricted due to the inherently low attenuation properties of soft tissue. In order to solve this problem, the tissue can be stained before X-ray computed tomography imaging (CT) to enhance the soft tissue X-ray contrast. Evaluation of brominated fluorescein salts revealed a mutual influence of the number of bromine atoms and the cations applied on the achieved contrast enhancement. The dibromo fluorescein barium salt turned out to be the ideal X-ray contrast agent, allowing for 3D imaging and subsequent complementing counterstaining applying standard histological techniques.

Three-dimensional virtual histology enabled through cytoplasm-specific X-ray stain for microscopic and nanoscopic computed tomography.

Many histological methods require staining of the cytoplasm, which provides instrumental details for diagnosis. One major limitation is the production of 2D images obtained by destructive preparation of 3D tissue samples. X-ray absorption micro- and nanocomputed tomography (microCT and nanoCT) allows for a nondestructive investigation of a 3D tissue sample, and thus aids to determine regions of interest for further histological examinations. However, application of microCT and nanoCT to biological samples (e.g., biopsies) is limited by the missing contrast within soft tissue, which is important to visualize morphological details. We describe an eosin-based preparation overcoming the challenges of contrast enhancement and selectivity for certain tissues. The eosin-based staining protocol is suitable for whole-organ staining, which then enables high-resolution microCT imaging of whole organs and nanoCT imaging of smaller tissue pieces retrieved from the original sample. Our results demonstrate suitability of the eosin-based staining method for diagnostic screening of 3D tissue samples without impeding further diagnostics through histological methods.

Targeting Endothelin Receptors in a Murine Model of Myocardial Infarction Using a Small Molecular Fluorescent Probe.

The endothelin (ET) axis plays a pivotal role in cardiovascular diseases. Enhanced levels of circulating ET-1 have been correlated with an inferior clinical outcome after myocardial infarction (MI) in humans. Thus, the evaluation of endothelin-A receptor (ETAR) expression over time in the course of myocardial injury and healing may offer valuable information toward the understanding of the ET axis involvement in MI. We developed an approach to track the expression of ETAR with a customized molecular imaging probe in a murine model of MI. The small molecular probe based on the ETAR-selective antagonist 3-(1,3-benzodioxol-5-yl)-5-hydroxy-5-(4-methoxyphenyl)-4-[(3,4,5-trimethoxyphenyl)methyl]-2(5H)-furanone (PD156707) was labeled with fluorescent dye, IRDye800cw. Mice undergoing permanent ligation of the left anterior descending artery (LAD) were investigated at day 1, 7, and 21 post surgery after receiving an intravenous injection of the ETAR probe. Cryosections of explanted hearts were analyzed by cryotome-based CCD, and fluorescence reflectance imaging (FRI) and fluorescence signal intensities (SI) were extracted. Fluorescence-mediated tomography (FMT) imaging was performed to visualize probe distribution in the target region in vivo. An enhanced fluorescence signal intensity in the infarct area was detected in cryoCCD images as early as day 1 after surgery and intensified up to 21 days post MI. FRI was capable of detecting significantly enhanced SI in infarcted regions of hearts 7 days after surgery. In vivo imaging by FMT localized enhanced SI in the apex region of infarcted mouse hearts. We verified the localization of the probe and ETAR within the infarct area by immunohistochemistry (IHC). In addition, neovascularized areas were found in the affected myocardium by CD31 staining. Our study demonstrates that the applied fluorescent probe is capable of delineating ETAR expression over time in affected murine myocardium after MI in vivo and ex vivo.

Experimental feasibility of spectral photon-counting computed tomography with two contrast agents for the detection of endoleaks following endovascular aortic repair.

OBJECTIVES: After endovascular aortic repair (EVAR), discrimination of endoleaks and intra-aneurysmatic calcifications within the aneurysm often requires multiphase computed tomography (CT). Spectral photon-counting CT (SPCCT) in combination with a two-contrast agent injection protocol may provide reliable detection of endoleaks with a single CT acquisition. METHODS: To evaluate the feasibility of SPCCT, the stent-lined compartment of an abdominal aortic aneurysm phantom was filled with a mixture of iodine and gadolinium mimicking enhanced blood. To represent endoleaks of different flow rates, the adjacent compartments contained either one of the contrast agents or calcium chloride to mimic intra-aneurysmatic calcifications. After data acquisition with a SPCCT prototype scanner with multi-energy bins, material decomposition was performed to generate iodine, gadolinium and calcium maps. RESULTS: In a conventional CT slice, Hounsfield units (HU) of the compartments were similar ranging from 147 to 168 HU. Material-specific maps differentiate the distributions within the compartments filled with iodine, gadolinium or calcium. CONCLUSION: SPCCT may replace multiphase CT to detect endoleaks without sacrificing diagnostic accuracy. It is a unique feature of our method to capture endoleak dynamics and allow reliable distinction from intra-aneurysmatic calcifications in a single scan, thereby enabling a significant reduction of radiation exposure. KEY POINTS: • SPCCT might enable advanced endoleak detection. • Material maps derived from SPCCT can differentiate iodine, gadolinium and calcium. • SPCCT may potentially reduce radiation burden for EVAR patients under post-interventional surveillance.

Targeting Elastase for Molecular Imaging of Early Atherosclerotic Lesions.

OBJECTIVE: Neutrophils accumulate in early atherosclerotic lesions and promote lesion growth. In this study, we evaluated an elastase-specific near-infrared imaging agent for molecular imaging using hybrid fluorescence molecular tomography/x-ray computed tomography. APPROACH AND RESULTS: Murine neutrophils were isolated from bone marrow and incubated with the neutrophil-targeted near-infrared imaging agent Neutrophil Elastase 680 FAST for proof of principle experiments, verifying that the elastase-targeted fluorescent agent is specifically cleaved and activated by neutrophil content after lysis or cell stimulation. For in vivo experiments, low-density lipoprotein receptor-deficient mice were placed on a Western-type diet and imaged after 4, 8, and 12 weeks by fluorescence molecular tomography/x-ray computed tomography. Although this agent remains silent on injection, it produces fluorescent signal after cleavage by neutrophil elastase. After hybrid fluorescence molecular tomography/x-ray computed tomography imaging, mice were euthanized for whole-body cryosectioning and histological analyses. The in vivo fluorescent signal in the area of the aortic arch was highest after 4 weeks of high-fat diet feeding and decreased at 8 and 12 weeks. Ex vivo whole-body cryoslicing confirmed the fluorescent signal to locate to the aortic arch and to originate from the atherosclerotic arterial wall. Histological analysis demonstrated the presence of neutrophils in atherosclerotic lesions. CONCLUSIONS: This study provides evidence that elastase-targeted imaging can be used for in vivo detection of early atherosclerosis. This imaging approach may harbor potential in the clinical setting for earlier diagnosis and treatment of atherosclerosis.

MMTV insertional mutagenesis identifies genes, gene families and pathways involved in mammary cancer.

We performed a high-throughput retroviral insertional mutagenesis screen in mouse mammary tumor virus (MMTV)-induced mammary tumors and identified 33 common insertion sites, of which 17 genes were previously not known to be associated with mammary cancer and 13 had not previously been linked to cancer in general. Although members of the Wnt and fibroblast growth factors (Fgf) families were frequently tagged, our exhaustive screening for MMTV insertion sites uncovered a new repertoire of candidate breast cancer oncogenes. We validated one of these genes, Rspo3, as an oncogene by overexpression in a p53-deficient mammary epithelial cell line. The human orthologs of the candidate oncogenes were frequently deregulated in human breast cancers and associated with several tumor parameters. Computational analysis of all MMTV-tagged genes uncovered specific gene families not previously associated with cancer and showed a significant overrepresentation of protein domains and signaling pathways mainly associated with development and growth factor signaling. Comparison of all tagged genes in MMTV and Moloney murine leukemia virus-induced malignancies showed that both viruses target mostly different genes that act predominantly in distinct pathways.

Chondrosarcoma evaluation using hematein-based x-ray staining and high-resolution 3D micro-CT: a feasibility study.

BACKGROUND: Chondrosarcomas are rare malignant bone tumors diagnosed by analyzing radiological images and histology of tissue biopsies and evaluating features such as matrix calcification, cortical destruction, trabecular penetration, and tumor cell entrapment. METHODS: We retrospectively analyzed 16 cartilaginous tumor tissue samples from three patients (51-, 54-, and 70-year-old) diagnosed with a dedifferentiated chondrosarcoma at the femur, a moderately differentiated chondrosarcoma in the pelvis, and a predominantly moderately differentiated chondrosarcoma at the scapula, respectively. We combined a hematein-based x-ray staining with high-resolution three-dimensional (3D) microscopic x-ray computed tomography (micro-CT) for nondestructive 3D tumor assessment and tumor margin evaluation. RESULTS: We detected trabecular entrapment on 3D micro-CT images and followed bone destruction throughout the volume. In addition to staining cell nuclei, hematein-based staining also improved the visualization of the tumor matrix, allowing for the distinction between the tumor and the bone marrow cavity. The hematein-based staining did not interfere with further conventional histology. There was a 5.97 ± 7.17% difference between the relative tumor area measured using micro-CT and histopathology (p = 0.806) (Pearson correlation coefficient r = 0.92, p = 0.009). Signal intensity in the tumor matrix (4.85 ± 2.94) was significantly higher in the stained samples compared to the unstained counterparts (1.92 ± 0.11, p = 0.002). CONCLUSIONS: Using nondestructive 3D micro-CT, the simultaneous visualization of radiological and histopathological features is feasible. RELEVANCE STATEMENT: 3D micro-CT data supports modern radiological and histopathological investigations of human bone tumor specimens. It has the potential for being an integrative part of clinical preoperative diagnostics. KEY POINTS: • Matrix calcifications are a relevant diagnostic feature of bone tumors. • Micro-CT detects all clinically diagnostic relevant features of x-ray-stained chondrosarcoma. • Micro-CT has the potential to be an integrative part of clinical diagnostics.

Extracranial Vascular Anomalies Driven by RAS/MAPK Variants: Spectrum and Genotype-Phenotype Correlations.

BACKGROUND: We aimed to correlate alterations in the rat sarcoma virus (RAS)/mitogen-activated protein kinase pathway in vascular anomalies to the clinical phenotype for improved patient and treatment stratification. METHODS AND RESULTS: This retrospective multicenter cohort study included 29 patients with extracranial vascular anomalies containing mosaic pathogenic variants (PVs) in genes of the RAS/mitogen-activated protein kinase pathway. Tissue samples were collected during invasive treatment or clinically indicated biopsies. PVs were detected by the targeted sequencing of panels of genes known to be associated with vascular anomalies, performed using DNA from affected tissue. Subgroup analyses were performed according to the affected genes with regard to phenotypic characteristics in a descriptive manner. Twenty-five vascular malformations, 3 vascular tumors, and 1 patient with both a vascular malformation and vascular tumor presented the following distribution of PVs in genes: Kirsten rat sarcoma viral oncogene (n=10), neuroblastoma ras viral oncogene homolog (n=1), Harvey rat sarcoma viral oncogene homolog (n=5), V-Raf murine sarcoma viral oncogene homolog B (n=8), and mitogen-activated protein kinase kinase 1 (n=5). Patients with RAS PVs had advanced disease stages according to the Schobinger classification (stage 3-4: RAS, 9/13 versus non-RAS, 3/11) and more frequent progression after treatment (RAS, 10/13 versus non-RAS, 2/11). Lesions with Kirsten rat sarcoma viral oncogene PVs infiltrated more tissue layers compared with the other PVs including other RAS PVs (multiple tissue layers: Kirsten rat sarcoma viral oncogene, 8/10 versus other PVs, 6/19). CONCLUSIONS: This comparison of patients with various PVs in genes of the RAS/MAPK pathway provides potential associations with certain morphological and clinical phenotypes. RAS variants were associated with more aggressive phenotypes, generating preliminary data and hypothesis for future larger studies.

Post-therapeutic microRNA-146a in liquid biopsies may determine prognosis in metastatic gastrointestinal cancer patients receiving 90Y-radioembolization.

PURPOSE: The role of microRNA-146a (miR-146a) in defining the tumor immune microenvironment (TIME) is well established. The aim of this study was to evaluate circulating miR-146a as an early prognostic marker of 90Y-radioembolization (90Y-RE) in metastatic liver cancer and to assess the correlation between circulating miR-146a and TIME cellular composition in distant, yet untreated metastases. METHODS: Twenty-one patients with bilobar liver lesions from gastro-intestinal cancer underwent lobar 90Y-RE. Biopsy of contralateral lobe abscopal tumors was acquired at the onset of a second treatment session at a median of 21 days after initial RE, immediately prior to ablation therapy of the contralateral lobe tumor. miR-146a was measured by RT-qPCR in plasma collected 24 h before (T1) and 48 h after (T2) initial unilobar 90Y-RE. The level of miR-146a was correlated with the infiltration of CD4 + , CD8 + , FoxP3 T cells, CD163 + M2 macrophages and immune-exhausted T cells in the abscopal tumor tissue acquired before the second treatment session. RESULTS: Plasma samples collected at T2 showed a higher concentration of miR-146a with respect to T1 in 43% of the patients (p = 0.002). In these patients, tumors revealed a pro-tumorigenic immune composition with enrichment of Tim3 + immune exhausted cells (p = 0.021), in combination with a higher infiltration of CD163 + M2 macrophages and a lower infiltration of CD8 + T cells. Patients with a higher level of miR-146a after 90Y-RE showed a trend to shorter OS (p = 0.055). CONCLUSION: miR-146a may represent a novel prognostic biomarker for 90Y-radioembolization in metastatic liver cancer.

Peripheral blood-based cell signature indicates response to interstitial brachytherapy in primary liver cancer.

PURPOSE: Biomarkers are essential to implement personalized therapies in cancer treatment options. As primary liver tumors are increasing and treatment is coupled to liver function and activation of systemic cells of the immune system, we investigated blood-based cells for their ability to predict response to local ablative therapy. METHODS: We analyzed peripheral blood cells in 20 patients with primary liver cancer at baseline and following brachytherapy. In addition to platelets, leukocytes, lymphocytes, monocytes, neutrophils and most common ratios PLR, LMR, NMR and NLR, we investigated T cell and NKT cell populations of 11 responders and 9 non-responders using flow cytometry. RESULTS: We have found a peripheral blood cell signature that differed significantly between responders and non-responders treated with interstitial brachytherapy (IBT). At baseline, non-responders featured higher numbers of platelets, monocytes and neutrophils, a higher platelet-to-lymphocyte ratio and an increase in the NKT cell population with a concurrent reduction in CD16 + NKT cells. Simultaneously, a lower percentage of CD4 + T cells was present in non-responders, as also reflected in a lower CD4/8 ratio. CD45RO + memory cells were lower in both, CD4 + and CD8 + T cell populations whereas PD-1 + T cells were only present in the CD4 + T cell population. CONCLUSION: Baseline blood-based cell signature may function as a biomarker to predict response following brachytherapy in primary liver cancer.

Clinical Outcome and Quality of Life of Multimodal Treatment of Extracranial Arteriovenous Malformations: The APOLLON Study Protocol.

PURPOSE: Arteriovenous malformations (AVMs) as rare diseases are diagnostically and therapeutically challenging. Due to the limited evidence regarding treatment outcome, prospective data are needed on how different treatment regimens affect outcome. The aims of this prospective trial are to determine effectiveness, safety, and clinical outcome of multimodal treatment in patients with extracranial AVMs. MATERIALS AND METHODS: After clinical and magnetic resonance imaging (MRI)-based diagnosis and informed consent, 146 patients (> 4 years and < 70 years) undergoing multimodal therapy in tertiary care vascular anomalies centers will be included in this prospective observational trial. Treatment options include conservative management, medical therapy, minimally invasive image-guided procedures (embolization, sclerotherapy) and surgery as well as combinations of the latter. The primary outcome is the patient-reported QoL 6 months after completion of treatment using the short form-36 health survey version 2 (SF-36v2) and the corresponding short form-10 health survey (SF-10) for children. In addition, clinical presentation (physician-reported signs), MRI imaging (radiological assessment of devascularization), recurrence rate, and therapeutic safety will be analyzed. Further follow-up will be performed after 12, 24, and 36 months. Moreover, liquid biopsies are being obtained from peripheral blood at multiple time points to investigate potential biomarkers for therapy response and disease progression. DISCUSSION: The APOLLON trial is a prospective, multicenter, observational open-label trial with unequal study groups to generate prospective evidence for multimodal treatment of AVMs. A multicenter design with the potential to assess larger populations will provide an increased understanding of multimodal therapy outcome in this orphan disease. TRIAL REGISTRATION: German Clinical Trials Register (identification number: DRKS00021019) https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00021019 .

[X-Ray Dark-field radiography: Does this carry potential for diagnosing gout in exotic pets?] / Die Dunkelfeld-Radiografie ­ ein neuer Weg zur Diagnostik von Gichterkrankungen bei Vögeln und Reptilien?

OBJECTIVE: The aim of this study is to evaluate whether X-ray dark-field (DF) radiography is useful for the diagnosis of gout in birds and reptiles and whether this preclinical model could be helpful to establish this non-invasive imaging method in human medicine. MATERIAL AND METHODS: A total of 18 limbs originating from 11 birds (7 different species) and 7 reptiles (4 different species) with and without suspected joint gout were measured using a grating-based X-ray dark-field setup and conventional X-ray examination, respectively. Each image acquisition generated a dark-field and a conventional absorption x-ray image. The results of the individual scans were compared with the results of a pathological examination and arthrocentesis. RESULTS: In 5 of the birds and 4 of the reptiles examined, gout was detected by pathologic examination. In each group, uric acid crystals were found in the joints of 3 animals by means of arthrocentesis. The uric acid crystals were detectable in 2 bird and 2 reptile limbs in the dark-field image. CONCLUSION: The study demonstrated that the urate crystals evoke a clearly visible dark field signal, whereas this was not the case in the conventional radiographs. CLINICAL RELEVANCE: The results obtained show that uric acid crystal detection using less invasive imaging methods in an animal model with birds and reptiles may expand gout diagnostics not only in veterinary medicine but also in human medicine and possibly replace arthrocentesis if a DF signal is detectable. Preclinical scanners which use X-ray dark-field and phase-contrast radiography already exist for hands and mammography.

Early monocyte response following local ablation in hepatocellular carcinoma.

Local ablative therapies are established treatment modalities in the treatment of early- and intermediate-stage hepatocellular carcinoma (HCC). Systemic effects of local ablation on circulating immune cells may contribute to patients' response. Depending on their activation, myeloid cells are able to trigger HCC progression as well as to support anti-tumor immunity. Certain priming of monocytes may already occur while still in the circulation. By using flow cytometry, we analyzed peripheral blood monocyte cell populations from a prospective clinical trial cohort of 21 HCC patients following interstitial brachytherapy (IBT) or radiofrequency ablation (RFA) and investigated alterations in the composition of monocyte subpopulations and monocytic myeloid-derived suppressor cells (mMDSCs) as well as receptors involved in orchestrating monocyte function. We discovered that mMDSC levels increased following both IBT and RFA in virtually all patients. Furthermore, we identified varying alterations in the level of monocyte subpopulations following radiation compared to RFA. (A) Liquid biopsy liquid biopsy of circulating monocytes in the future may provide information on the inflammatory response towards local ablation as part of an orchestrated immune response.

Multiparametric MRI enables for differentiation of different degrees of malignancy in two murine models of breast cancer.

Objective: The objective of this study was to non-invasively differentiate the degree of malignancy in two murine breast cancer models based on identification of distinct tissue characteristics in a metastatic and non-metastatic tumor model using a multiparametric Magnetic Resonance Imaging (MRI) approach. Methods: The highly metastatic 4T1 breast cancer model was compared to the non-metastatic 67NR model. Imaging was conducted on a 9.4 T small animal MRI. The protocol was used to characterize tumors regarding their structural composition, including heterogeneity, intratumoral edema and hemorrhage, as well as endothelial permeability using apparent diffusion coefficient (ADC), T1/T2 mapping and dynamic contrast-enhanced (DCE) imaging. Mice were assessed on either day three, six or nine, with an i.v. injection of the albumin-binding contrast agent gadofosveset. Ex vivo validation of the results was performed with laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), histology, immunhistochemistry and electron microscopy. Results: Significant differences in tumor composition were observed over time and between 4T1 and 67NR tumors. 4T1 tumors showed distorted blood vessels with a thin endothelial layer, resulting in a slower increase in signal intensity after injection of the contrast agent. Higher permeability was further reflected in higher Ktrans values, with consecutive retention of gadolinium in the tumor interstitium visible in MRI. 67NR tumors exhibited blood vessels with a thicker and more intact endothelial layer, resulting in higher peak enhancement, as well as higher maximum slope and area under the curve, but also a visible wash-out of the contrast agent and thus lower Ktrans values. A decreasing accumulation of gadolinium during tumor progression was also visible in both models in LA-ICP-MS. Tissue composition of 4T1 tumors was more heterogeneous, with intratumoral hemorrhage and necrosis and corresponding higher T1 and T2 relaxation times, while 67NR tumors mainly consisted of densely packed tumor cells. Histogram analysis of ADC showed higher values of mean ADC, histogram kurtosis, range and the 90th percentile (p90), as markers for the heterogenous structural composition of 4T1 tumors. Principal component analysis (PCA) discriminated well between the two tumor models. Conclusions: Multiparametric MRI as presented in this study enables for the estimation of malignant potential in the two studied tumor models via the assessment of certain tumor features over time.

Animal Models of Neointimal Hyperplasia and Restenosis: Species-Specific Differences and Implications for Translational Research.

The process of restenosis is based on the interplay of various mechanical and biological processes triggered by angioplasty-induced vascular trauma. Early arterial recoil, negative vascular remodeling, and neointimal formation therefore limit the long-term patency of interventional recanalization procedures. The most serious of these processes is neointimal hyperplasia, which can be traced back to 4 main mechanisms: endothelial damage and activation; monocyte accumulation in the subintimal space; fibroblast migration; and the transformation of vascular smooth muscle cells. A wide variety of animal models exists to investigate the underlying pathophysiology. Although mouse models, with their ease of genetic manipulation, enable cell- and molecular-focused fundamental research, and rats provide the opportunity to use stent and balloon models with high throughput, both rodents lack a lipid metabolism comparable to humans. Rabbits instead build a bridge to close the gap between basic and clinical research due to their human-like lipid metabolism, as well as their size being accessible for clinical angioplasty procedures. Every different combination of animal, dietary, and injury model has various advantages and disadvantages, and the decision for a proper model requires awareness of species-specific biological properties reaching from vessel morphology to distinct cellular and molecular features.

In vivo optical molecular imaging of inflammation and immunity.

Inflammation is the phenotypic form of various diseases. Recent development in molecular imaging provides new insights into the diagnostic and therapeutic evaluation of different inflammatory diseases as well as diseases involving inflammation such as cancer. While conventional imaging techniques used in the clinical setting provide only indirect measures of inflammation such as increased perfusion and altered endothelial permeability, optical imaging is able to report molecular information on diseased tissue and cells. Optical imaging is a quick, noninvasive, nonionizing, and easy-to-use diagnostic technology which has been successfully applied for preclinical research. Further development of optical imaging technology such as optoacoustic imaging overcomes the limitations of mere fluorescence imaging, thereby enabling pilot clinical applications in humans. By means of endogenous and exogenous contrast agents, sites of inflammation can be accurately visualized in vivo. This allows for early disease detection and specific disease characterization, enabling more rapid and targeted therapeutic interventions. In this review, we summarize currently available optical imaging techniques used to detect inflammation, including optical coherence tomography (OCT), bioluminescence, fluorescence, optoacoustics, and Raman spectroscopy. We discuss advantages and disadvantages of the different in vivo imaging applications with a special focus on targeting inflammation including immune cell tracking.

Tumor-Associated Macrophages-Implications for Molecular Oncology and Imaging.

Tumor-associated macrophages (TAMs) represent the largest group of leukocytes within the tumor microenvironment (TME) of solid tumors and orchestrate the composition of anti- as well as pro-tumorigenic factors. This makes TAMs an excellent target for novel cancer therapies. The plasticity of TAMs resulting in varying membrane receptors and expression of intracellular proteins allow the specific characterization of different subsets of TAMs. Those markers similarly allow tracking of TAMs by different means of molecular imaging. This review aims to provides an overview of the origin of tumor-associated macrophages, their polarization in different subtypes, and how characteristic markers of the subtypes can be used as targets for molecular imaging and theranostic approaches.

X-ray dark-field radiography for in situ gout diagnosis by means of an ex vivo animal study.

Gout is the most common form of inflammatory arthritis, caused by the deposition of monosodium urate (MSU) crystals in peripheral joints and tissue. Detection of MSU crystals is essential for definitive diagnosis, however the gold standard is an invasive process which is rarely utilized. In fact, most patients are diagnosed or even misdiagnosed based on manifested clinical signs, as indicated by the unchanged premature mortality among gout patients over the past decade, although effective treatment is now available. An alternative, non-invasive approach for the detection of MSU crystals is X-ray dark-field radiography. In our work, we demonstrate that dark-field X-ray radiography can detect naturally developed gout in animals with high diagnostic sensitivity and specificity based on the in situ measurement of MSU crystals. With the results of this study as a potential basis for further research, we believe that X-ray dark-field radiography has the potential to substantially improve gout diagnostics.

Application of High-Z Gold Nanoparticles in Targeted Cancer Radiotherapy-Pharmacokinetic Modeling, Monte Carlo Simulation and Radiobiological Effect Modeling.

High-Z gold nanoparticles (AuNPs) conjugated to a targeting antibody can help to improve tumor control in radiotherapy while simultaneously minimizing radiotoxicity to adjacent healthy tissue. This paper summarizes the main findings of a joint research program which applied AuNP-conjugates in preclinical modeling of radiotherapy at the Klinikum rechts der Isar, Technical University of Munich and Helmholtz Zentrum München. A pharmacokinetic model of superparamagnetic iron oxide nanoparticles was developed in preparation for a model simulating the uptake and distribution of AuNPs in mice. Multi-scale Monte Carlo simulations were performed on a single AuNP and multiple AuNPs in tumor cells at cellular and molecular levels to determine enhancements in the radiation dose and generation of chemical radicals in close proximity to AuNPs. A biologically based mathematical model was developed to predict the biological response of AuNPs in radiation enhancement. Although simulations of a single AuNP demonstrated a clear dose enhancement, simulations relating to the generation of chemical radicals and the induction of DNA strand breaks induced by multiple AuNPs showed only a minor dose enhancement. The differences in the simulated enhancements at molecular and cellular levels indicate that further investigations are necessary to better understand the impact of the physical, chemical, and biological parameters in preclinical experimental settings prior to a translation of these AuNPs models into targeted cancer radiotherapy.