Identification of impactful imaging biomarker: Clinical applications for breast and prostate carcinoma

BACKGROUND

 Imaging biomarkers are quantitative parameters from imaging modalities, which are collected noninvasively, allow conclusions about physiological and pathophysiological processes, and may consist of single (monoparametric) or multiple parameters (bi- or multiparametric).

METHOD

 This review aims to present the state of the art for the quantification of multimodal and multiparametric imaging biomarkers. Here, the use of biomarkers using artificial intelligence will be addressed and the clinical application of imaging biomarkers in breast and prostate cancers will be explained. For the preparation of the review article, an extensive literature search was performed based on Pubmed, Web of Science and Google Scholar. The results were evaluated and discussed for consistency and generality.

RESULTS AND CONCLUSION

 Different imaging biomarkers (multiparametric) are quantified based on the use of complementary imaging modalities (multimodal) from radiology, nuclear medicine, or hybrid imaging. From these techniques, parameters are determined at the morphological (e. g., size), functional (e. g., vascularization or diffusion), metabolic (e. g., glucose metabolism), or molecular (e. g., expression of prostate specific membrane antigen, PSMA) level. The integration and weighting of imaging biomarkers are increasingly being performed with artificial intelligence, using machine learning algorithms. In this way, the clinical application of imaging biomarkers is increasing, as illustrated by the diagnosis of breast and prostate cancers.

KEY POINTS

· Imaging biomarkers are quantitative parameters to detect physiological and pathophysiological processes.. · Imaging biomarkers from multimodality and multiparametric imaging are integrated using artificial intelligence algorithms.. · Quantitative imaging parameters are a fundamental component of diagnostics for all tumor entities, such as for mammary and prostate carcinomas..

CITATION FORMAT

· Bäuerle T, Dietzel M, Pinker K et al. Identification of impactful imaging biomarker: Clinical applications for breast and prostate carcinoma. Fortschr Röntgenstr 2024; 196: 354 - 362.

[Emergency diagnoses in the gastrointestinal tract]

Gastrointestinal emergencies are a frequent reason for presentation in the emergency department and involve patients of all ages. The patients must undergo an immediate cross-sectional imaging as in many cases the underlying pathology is a life-threatening condition, which often needs surgical or in some cases also interventional radiological treatment. In this overview, the most important differential diagnoses and their characteristics on cross-sectional imaging are presented.

CT-guided High-Dose-Rate Brachytherapy versus Transarterial Chemoembolization in Patients with Unresectable Hepatocellular Carcinoma

Background CT-guided high-dose-rate (HDR) brachytherapy (hereafter, HDR brachytherapy) has been shown to be safe and effective for patients with unresectable hepatocellular carcinoma (HCC), but studies comparing this therapy with other local-regional therapies are scarce. Purpose To compare patient outcomes of HDR brachytherapy and transarterial chemoembolization (TACE) in patients with unresectable HCC. Materials and Methods This multi-institutional retrospective study included consecutive treatment-naive adult patients with unresectable HCC who underwent either HDR brachytherapy or TACE between January 2010 and December 2022. Overall survival (OS) and progression-free survival (PFS) were compared between patients matched for clinical and tumor characteristics by propensity score matching. Not all patients who underwent TACE had PFS available; thus, a different set of patients was used for PFS and OS analysis for this treatment. Hazard ratios (HRs) were calculated from Kaplan-Meier survival curves. Results After propensity matching, 150 patients who underwent HDR brachytherapy (median age, 71 years [IQR, 63-77 years]; 117 males) and 150 patients who underwent TACE (OS analysis median age, 70 years [IQR, 63-77 years]; 119 male; PFS analysis median age, 68 years [IQR: 63-76 years]; 119 male) were analyzed. Hazard of death was higher in the TACE versus HDR brachytherapy group (HR, 4.04; P < .001). Median estimated PFS was 32.8 months (95% CI: 12.5, 58.7) in the HDR brachytherapy group and 11.6 months (95% CI: 4.9, 22.7) in the TACE group. Hazard of disease progression was higher in the TACE versus HDR brachytherapy group (HR, 2.23; P < .001). Conclusion In selected treatment-naive patients with unresectable HCC, treatment with CT-guided HDR brachytherapy led to improved OS and PFS compared with TACE. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Chapiro in this issue.

Myocardial Late Gadolinium Enhancement (LGE) in Cardiac Magnetic Resonance Imaging (CMR)-An Important Risk Marker for Cardiac Disease

Cardiovascular magnetic resonance (CMR) has significantly revolutionized the comprehension and diagnosis of cardiac diseases, particularly through the utilization of late gadolinium enhancement (LGE) imaging for tissue characterization. LGE enables the visualization of expanded extracellular spaces in conditions such as fibrosis, fibrofatty tissue, or edema. The growing recognition of LGE's prognostic capacity underscores its importance, evident in the increasing explicit recommendations within guidelines. Notably, the contemporary characterization of cardiomyopathies relies on LGE-based scar assessment by CMR to a large extent. This review describes the pattern and prognostic value of LGE in detail for various cardiac diseases. Despite its merits, establishing LGE as a reliable risk marker encounters challenges. Limitations arise from the fact that not all diseases show LGE, and it should always be analyzed in the context of all CMR sequences and the patient's medical history. In summary, LGE stands as a robust indicator of adverse outcomes in diverse cardiovascular diseases. Its further integration into routine practice is desirable, necessitating widespread availability and application to accumulate both individual and scientific experience.

A Machine Learning Framework Reduces the Manual Workload for Systematic Reviews of the Diagnostic Performance of Prostate Magnetic Resonance Imaging

Prostate magnetic resonance imaging has become the imaging standard for prostate cancer in various clinical settings, with interpretation standardized according to the Prostate Imaging Reporting and Data System (PI-RADS). Each year, hundreds of scientific studies that report on the diagnostic performance of PI-RADS are published. To keep up with this ever-increasing evidence base, systematic reviews and meta-analyses are essential. As systematic reviews are highly resource-intensive, we investigated whether a machine learning framework can reduce the manual workload and speed up the screening process (title and abstract). We used search results from a living systematic review of the diagnostic performance of PI-RADS (1585 studies, of which 482 were potentially eligible after screening). A naïve Bayesian classifier was implemented in an active learning environment for classification of the titles and abstracts. Our outcome variable was the percentage of studies that can be excluded after 95% of relevant studies have been identified by the classifier (work saved over sampling: WSS@95%). In simulation runs of the entire screening process (controlling for classifier initiation and the frequency of classifier updating), we obtained a WSS@95% value of 28% (standard error of the mean ±0.1%). Applied prospectively, our classification framework would translate into a significant reduction in manual screening effort.

Patient summary

Systematic reviews of scientific evidence are labor-intensive and take a lot of time. For example, many studies on prostate cancer diagnosis via MRI (magnetic resonance imaging) are published every year. We describe the use of machine learning to reduce the manual workload in screening search results. For a review of MRI for prostate cancer diagnosis, this approach reduced the screening workload by about 28%.

Development, synthesis and evaluation of novel fluorescent Endothelin-B receptor probes

The endothelin (ET) signaling system is comprised of three endothelin peptides (ET-1, -2 and -3) and two corresponding endothelin-A and -B receptors (ET_AR and ET_BR), which belong to the G-protein coupled receptor (GPCR) superfamily. The endothelin axis, as this system is also referred to, contributes to the maintenance of vascular tone, functions as regulator of inflammation and proliferation and helps in balancing water homeostasis. In pathological settings, the ET axis is known to contribute to endothelial activation in cardiovascular diseases, to cell proliferation, chemoresistance and metastasis in cancer and to inflammation and fibrosis in renal disease. Antagonists of ET_AR and ET_BR, either subtype-specific compounds or substances with high affinity to both receptors, have been developed for more than 30 years. In the preclinical context, in vivo imaging of endothelin receptor expression has been utilized to assess ET-axis contribution to e.g. cancer or myocardial infarction. In this work, we present the development and synthesis of two novel ET_BR-specific fluorescent probes, based on the available antagonists BQ788 and IRL2500 and their preliminary evaluation in a breast cancer context.

Vascular response patterns to targeted therapies in murine breast cancer models with divergent degrees of malignancy

BACKGROUND

Response assessment of targeted cancer therapies is becoming increasingly challenging, as it is not adequately assessable with conventional morphological and volumetric analyses of tumor lesions. The tumor microenvironment is particularly constituted by tumor vasculature which is altered by various targeted therapies. The aim of this study was to noninvasively assess changes in tumor perfusion and vessel permeability after targeted therapy in murine models of breast cancer with divergent degrees of malignancy.

METHODS

Low malignant 67NR or highly malignant 4T1 tumor-bearing mice were treated with either the multi-kinase inhibitor sorafenib or immune checkpoint inhibitors (ICI, combination of anti-PD1 and anti-CTLA4). Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with i.v. injection of albumin-binding gadofosveset was conducted on a 9.4 T small animal MRI. Ex vivo validation of MRI results was achieved by transmission electron microscopy, immunohistochemistry and laser ablation-inductively coupled plasma-mass spectrometry.

RESULTS

Therapy-induced changes in tumor vasculature differed between low and highly malignant tumors. Sorafenib treatment led to decreased tumor perfusion and endothelial permeability in low malignant 67NR tumors. In contrast, highly malignant 4T1 tumors demonstrated characteristics of a transient window of vascular normalization with an increase in tumor perfusion and permeability early after therapy initiation, followed by decreased perfusion and permeability parameters. In the low malignant 67NR model, ICI treatment also mediated vessel-stabilizing effects with decreased tumor perfusion and permeability, while ICI-treated 4T1 tumors exhibited increasing tumor perfusion with excessive vascular leakage.

CONCLUSION

DCE-MRI enables noninvasive assessment of early changes in tumor vasculature after targeted therapies, revealing different response patterns between tumors with divergent degrees of malignancy. DCE-derived tumor perfusion and permeability parameters may serve as vascular biomarkers that allow for repetitive examination of response to antiangiogenic treatment or immunotherapy.

Low bone mineral density is a prognostic factor for elderly patients with HCC undergoing TACE: results from a multicenter study

OBJECTIVES

Low bone mineral density (BMD) was recently identified as a novel risk factor for patients with hepatocellular carcinoma (HCC). In this multicenter study, we aimed to validate the role of BMD as a prognostic factor for patients with HCC undergoing transarterial chemoembolization (TACE).

METHODS

This retrospective multicenter trial included 908 treatment-naïve patients with HCC who were undergoing TACE as a first-line treatment, at six tertiary care centers, between 2010 and 2020. BMD was assessed by measuring the mean Hounsfield units (HUs) in the midvertebral core of the 11^th thoracic vertebra, on contrast-enhanced computer tomography performed before treatment. We assessed the influence of BMD on median overall survival (OS) and performed multivariate analysis including established estimates for survival.

RESULTS

The median BMD was 145 HU (IQR, 115-175 HU). Patients with a high BMD (≥ 114 HU) had a median OS of 22.2 months, while patients with a low BMD (< 114 HU) had a lower median OS of only 16.2 months (p < .001). Besides albumin, bilirubin, tumor number, and tumor diameter, BMD remained an independent prognostic factor in multivariate analysis.

CONCLUSIONS

BMD is an independent predictive factor for survival in elderly patients with HCC undergoing TACE. The integration of BMD into novel scoring systems could potentially improve survival prediction and clinical decision-making.

KEY POINTS

• Bone mineral density can be easily assessed in routinely acquired pre-interventional computed tomography scans. • Bone mineral density is an independent predictive factor for survival in elderly patients with HCC undergoing TACE. • Thus, bone mineral density is a novel imaging biomarker for prognosis prediction in elderly patients with HCC undergoing TACE.

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 K_trans 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 K_trans 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 90^th 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.

In vivo imaging of microenvironmental and anti-PD-L1-mediated dynamics in cancer using S100A8/S100A9 as an imaging biomarker

PURPOSE

As a promotor of tumor invasion and tumor microenvironment (TME) formation, the protein complex S100A8/S100A9 is associated with poor prognosis. Our aim was to further evaluate its origin and regulatory effects, and to establish an imaging biomarker for TME activity.

METHODS

S100A9-/-cells (ko) were created from syngeneic murine breast cancer 4T1 (high malignancy) and 67NR (low malignancy) wildtype (wt) cell lines and implanted into either female BALB/c wildtype or S100A9-/- mice (n = 10 each). Anti-S100A9-Cy5.5-targeted fluorescence reflectance imaging was performed at 0 h and 24 h after injection. Potential early changes of S100A9-presence under immune checkpoint inhibition (anti-PD-L1, n = 7 vs. rat IgG2b as isotype control, n = 3) were evaluated.

RESULTS

In S100A9-/-mice contrast-to-noise-ratios were significantly reduced for wt and S100A9-/-tumors. No significant differences were detected for 4T1 ko and 67NR ko cells as compared to wildtype cells. Under anti-PD-L1 treatment S100A9 presence significantly decreased compared with the control group.

CONCLUSION

Our results confirm a secretion of S100A8/S100A9 by the TME, while tumor cells do not apparently release the protein. Under immune checkpoint inhibition S100A9-imaging reports an early decrease of TME activity. Therefore, S100A9-specific imaging may serve as an imaging biomarker for TME formation and activity.

Tumor Burden in Patients With Hepatocellular Carcinoma Undergoing Transarterial Chemoembolization: Head-to-Head Comparison of Current Scoring Systems

Objectives

Recently, several scoring systems for prognosis prediction based on tumor burden have been promoted for patients with hepatocellular carcinoma (HCC) undergoing transarterial chemoembolization (TACE). This multicenter study aimed to perform the first head-to-head comparison of three scoring systems.

Methods

We retrospectively enrolled 849 treatment-naïve patients with HCC undergoing TACE at six tertiary care centers between 2010 and 2020. The tumor burden score (TBS), the Six-and-Twelve score (SAT), and the Seven-Eleven criteria (SEC) were calculated based on the maximum lesion size and the number of tumor nodes. All scores were compared in univariate and multivariate regression analyses, adjusted for established risk factors.

Results

The median overall survival (OS) times were 33.0, 18.3, and 12.8 months for patients with low, medium, and high TBS, respectively (p<0.001). The median OS times were 30.0, 16.9, and 10.2 months for patients with low, medium, and high SAT, respectively (p<0.001). The median OS times were 27.0, 16.7, and 10.5 for patients with low, medium, and high SEC, respectively (p<0.001). In a multivariate analysis, only the SAT remained an independent prognostic factor. The C-Indexes were 0.54 for the TBS, 0.59 for the SAT, and 0.58 for the SEC.

Conclusion

In a direct head-to-head comparison, the SAT was superior to the TBS and SEC in survival stratification and predictive ability. Therefore, the SAT can be considered when estimating the tumor burden. However, all three scores showed only moderate predictive power. Therefore, tumor burden should only be one component among many in treatment decision making.

[Mediastinal lesions : The most common pathologies in chest X-rays and their correlations in computed tomography]

BACKGROUND

Many pathologies of the mediastinum can be diagnosed using standard radiographs. Correlation of radiographic findings with computed tomography (CT) is instructive for a better understanding and can help improve detection rates of mediastinal lesions.

OBJECTIVES

To identify the most common mediastinal lesions and to correlate their features in chest radiographs and CT.

METHODS

The International Thymic Malignancy Interest Group (ITMIG) classification in the anterior, middle, and posterior mediastinum is based on anatomic landmarks. Used as a tool to characterize mediastinal lesions this classification is applied in this article.

RESULTS

The most common lesions include mediastinal goiter, germ cell and thymic neoplasms in the anterior mediastinum, lymphadenopathy in the middle mediastinum, and neurogenic neoplasms in the posterior mediastinum. Other lesions of neoplastic or non-neoplastic origin can be distinguished in the three compartments and should be considered in the differential diagnosis.

CONCLUSIONS

Knowledge of the most common pathologies in the three mediastinal compartments can accelerate differential diagnosis. Understanding the normal mediastinal lines is key in anatomic localization and detection of many lesions in chest radiographs.

How Different Albumin-Binders Drive Probe Distribution of Fluorescent RGD Mimetics

The biodistribution of medical imaging probes depends on the chemical nature of the probe and the preferred metabolization and excretion routes. Especially targeted probes, which have to reach a certain (sub)cellular destination, have to be guided to the tissue of interest. Therefore, small molecular probes need to exhibit a well-balanced polarity and lipophilicity to maintain an advantageous bioavailability. Labelled antibodies circulate for several days due to their size. To alter the biodistribution behavior of probes, different strategies have been pursued, including utilizing serum albumin as an inherent transport mechanism for small molecules. We describe here the modification of an existing fluorescent RGD mimetic probe targeted to integrin α_vβ₃ with three different albumin binding moieties (ABMs): a diphenylcyclohexyl (DPCH) group, a p-iodophenyl butyric acid (IPBA) and a fatty acid (FA) group with the purpose to identify an optimal ABM for molecular imaging applications. All three modifications result in transient albumin binding and a preservation of the target binding capability. Spectrophotometric measurements applying variable amounts of bovine serum albumin (BSA) reveal considerable differences between the compounds concerning their absorption and emission characteristics and hence their BSA binding mode. In vivo the modified probes were investigated in a murine U87MG glioblastoma xenograft model over the course of 1 wk by fluorescence reflectance imaging (FRI) and fluorescence mediated tomography (FMT). While the unmodified probe was excreted rapidly, the albumin-binding probes were accumulating in tumor tissue for at least 5 days. Considerable differences between the three probes in biodistribution and excretion characteristics were proved, with the DPCH-modified probe showing the highest overall signal intensities, while the FA-modified probe exhibits a low but more specific fluorescent signal. In conclusion, the modification of small molecular RGD mimetics with ABMs can precisely fine-tune probe distribution and offers potential for future clinical applications.

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.

Initial experience with [18F]DPA-714 TSPO-PET to image inflammation in primary angiitis of the central nervous system

Purpose

Primary angiitis of the central nervous system (PACNS) is a heterogeneous, rare, and poorly understood inflammatory disease. We aimed at non-invasive imaging of activated microglia/macrophages in patients with PACNS by PET-MRI targeting the translocator protein (TSPO) with [¹⁸F]DPA-714 to potentially assist differential diagnosis, therapy monitoring, and biopsy planning.

Methods

In total, nine patients with ischemic stroke and diagnosed or suspected PACNS underwent [¹⁸F]DPA-714-PET-MRI. Dynamic PET scanning was performed for 60 min after injection of 233 ± 19 MBq [¹⁸F]DPA-714, and MRI was simultaneously acquired.

Results

In two PACNS patients, [¹⁸F]DPA-714 uptake patterns exceeded MRI correlates of infarction, whereas uptake was confined to the infarct in four patients where initial suspicion of PACNS could not be confirmed. About three patients with PACNS or cerebral predominant lymphocytic vasculitis showed no or only faintly increased uptake. Short-term [¹⁸F]DPA-714-PET follow-up in a patient with PACNS showed reduced lesional [¹⁸F]DPA-714 uptake after anti-inflammatory treatment. Biopsy in the same patient pinpointed the source of tracer uptake to TSPO-expressing immune cells.

Conclusions

[¹⁸F]DPA-714-PET imaging may facilitate the diagnosis and treatment monitoring of PACNS. Further studies are needed to fully understand the potential of TSPO-PET in deciphering the heterogeneity of the disease.

Electronic supplementary material

The online version of this article (10.1007/s00259-019-04662-4) contains supplementary material, which is available to authorized users.

Optical and Optoacoustic Imaging Probes

Tissue has characteristic properties when it comes to light absorption and scattering. For optical (OI) and optoacoustic imaging (OAI) these properties can be utilised to visualise biological tissue characteristics, as, for example, the oxygenation state of haemoglobin alters the optical and optoacoustic properties of the molecule.

Introducing Specificity to Iron Oxide Nanoparticle Imaging by Combining 57Fe-Based MRI and Mass Spectrometry

Iron oxide nanoparticles (ION) are highly sensitive probes for magnetic resonance imaging (MRI) that have previously been used for in vivo cell tracking and have enabled implementation of several diagnostic tools to detect and monitor disease. However, the in vivo MRI signal of ION can overlap with the signal from endogenous iron, resulting in a lack of detection specificity. Therefore, the long-term fate of administered ION remains largely unknown, and possible tissue deposition of iron cannot be assessed with established methods. Herein, we combine nonradioactive ⁵⁷Fe-ION MRI with ex vivo laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) imaging, enabling unambiguous differentiation between endogenous iron (⁵⁶Fe) and iron originating from applied ION in mice. We establish ⁵⁷Fe-ION as an in vivo MRI sensor for cell tracking in a mouse model of subcutaneous inflammation and for assessing the long-term fate of ⁵⁷Fe-ION. Our approach resolves the lack of detection specificity in ION imaging by unambiguously recording a ⁵⁷Fe signature.

Use of Multispectral Optoacoustic Tomography to Diagnose Vascular Malformations

Importance

Differential diagnosis of congenital vascular anomalies is challenging, and misdiagnosis is frequent. Vascular malformations are considered one of the most difficult vascular diseases to treat. A new imaging approach that visualizes anatomical features and quantitatively assesses molecular biomarkers noninvasively would aid diagnosis and monitoring of treatment response of vascular malformations.

Objective

To evaluate multispectral optoacoustic tomography (MSOT) for noninvasive assessment of molecular biomarkers for diagnosis and therapeutic monitoring of vascular malformations.

Design, Setting, and Participants

This pilot study examined 6 patients with arteriovenous malformation (AVM) and 6 patients with venous malformation (VM) diagnosed according to the classification system of the International Society for the Study of Vascular Anomalies. All patients underwent clinical hybrid MSOT/ultrasonographic (US) imaging before and after treatment at an interdisciplinary vascular malformations clinic by trained MSOT and US examiners. Examiners were blinded to the patient history and stage of disease. Data were collected from April 11 to 25, 2017, and analyzed from May 1 to October 31, 2017.

Interventions

Clinical hybrid MSOT/US imaging was performed before or within 1 week after endovascular embolization (for AVM) or percutaneous sclerotherapy (for VM).

Main Outcomes and Measures

Region-of-interest analysis of the lesion and contralateral healthy tissue revealed quantitative values for oxygenated (HbO2) and deoxygenated (HbR) hemoglobin by spectral unmixing of optoacoustic data acquired at multiple wavelengths. The HbO2:HbR ratio was calculated for healthy tissue and for AVM and VM before and after treatment.

Results

Twelve patients (9 female and 3 male; mean [SD] age, 23 [18] years; age range, 6-59 years) with vascular malformations (6 with AVMs and 6 with VMs) were included. Significantly higher HbO2:HbR ratios for AVMs (mean [SEM], 1.82 [0.08] vs 0.89 [0.03]; P < .001) and for VMs (mean [SEM], 1.12 [0.04] vs 0.89 [0.03]; P = .001) were found on MSOT tissue compared with healthy tissue. Significantly higher HbO2:HbR ratios for AVMs compared with VMs (mean [SEM], 1.82 [0.08] vs 1.12 [0.04]; P < .001) were also found. Therefore, MSOT provided intrinsic biomarker patterns to distinguish both vascular malformations. After therapy, the HbO2:HbR ratio dropped in correlation to treatment success validated by magnetic resonance imaging or angiography.

Conclusions and Relevance

This study suggests that different types of vascular malformations are clearly distinguished by MSOT-based, noninvasive assessment of hemoglobin levels in vascular malformations. The therapy effects found in this study could be instantly visualized, and this may offer a new tool for noninvasive diagnosis and monitoring of vascular malformations.

Multispectral Optoacoustic Tomography of Benign and Malignant Thyroid Disorders: A Pilot Study

This study aimed at evaluating hybrid multispectral optoacoustic tomography/ultrasound for imaging of thyroid disorders, including Graves' disease and thyroid nodules. Methods: The functional biomarkers and tissue parameters deoxygenated hemoglobin, oxygenated hemoglobin, total hemoglobin, saturation of hemoglobin, fat content, and water content were analyzed in thyroid lobes affected by Graves' disease (n = 6), thyroid lobes with healthy tissue (n = 8), benign thyroid nodules (n = 13), and malignant thyroid nodules (n = 3). Results: In Graves' disease, significantly higher deoxygenated hemoglobin (3.18 ± 0.52 vs. 2.13 ± 0.62; P = 0.0055) and total hemoglobin (8.34 ± 0.88 vs. 6.59 ± 1.16; P = 0.0084) and significantly lower fat content (0.64 ± 0.37 vs. 1.69 ± 1.25; P = 0.0293) were found than in healthy controls. Malignant thyroid nodules showed significantly lower saturation of hemoglobin (55.4% ± 2.6% vs. 60.8% ± 7.2%; P = 0.0393) and lower fat content (0.62 ± 0.19 vs. 1.46 ± 0.87; P = 0.1295) than benign nodules. Conclusion: This pilot study showed the applicability and the potential of hybrid multispectral optoacoustic tomography/ultrasound to semiquantitatively provide tissue characterization and functional parameters in thyroid disorders for improved noninvasive diagnostics of thyroid diseases.

Multispectral Optoacoustic Tomography: Intra- and Interobserver Variability Using a Clinical Hybrid Approach

Multispectral optoacoustic tomography (MSOT) represents a new imaging approach revealing functional tissue information without extrinsic contrast agents. Using a clinical combined ultrasound (US)/MSOT device, we investigated the interindividual robustness and impact of intra- and interobserver variability of MSOT values in soft tissue (muscle and subcutaneous fat) of healthy volunteers. Semiquantitative MSOT values for deoxygenated (Hb), oxygenated (HbO₂) and total hemoglobin (HbT), as well as oxygen saturation (sO₂), were calculated for both forearms in transversal and longitudinal probe orientation (n = 3, 8 measurements per subject). For intraobserver reproducibility, the same examiner investigated three subjects twice. Mean values of left vs. right forearm and transversal vs. longitudinal probe orientation were compared using an unpaired Student’s t test. Bland Altmann plots with 95% limits of agreement for absolute averages and differences were calculated. Intraclass correlation coefficients (ICC 2,k) were computed for three different examiners. We obtained reproducible and consistent MSOT values with small-to-moderate deviation for muscle and subcutaneous fat tissue. Probe orientation and body side had no impact on calculated MSOT values (p > 0.05 each). Intraobserver reproducibility revealed equable mean values with small-to-moderate deviation. For muscular tissue, good ICC was obtained for sO₂. Measurements of subcutaneous tissue revealed good-to-excellent ICCs for all calculated values. Thus, in this preliminary study on healthy individuals, clinical MSOT provided consistent and reproducible functional soft tissue characterization, independent on the investigating personnel.

Multispectral optoacoustic tomography of systemic sclerosis

The study aimed to evaluate the clinical feasibility of hybrid ultrasound/multispectral optoacoustic tomography (MSOT) for assessing microvascular dysfunction in systemic sclerosis (SSc). A handheld US/MSOT imaging system was applied for imaging patients diagnosed with SSc (n = 7) and healthy volunteers (n = 8). Semiquantitative MSOT values for deoxygenated (HbR), oxygenated (HbO₂ ) and total haemoglobin (HbT) were analysed for subcutaneous finger tissue of both hands (8 fingers per subject, 120 fingers in total) and used to assess disease activity (progressive vs stable). Grouped data were compared by one-way nested analysis of variance, Tukey post-hoc test as well as student's t test were used for statistical analysis.Subcutaneous finger tissue of patients with SSc provided significantly lower MSOT values for HbO₂ (26.16 ± 0.71 vs 38.2 ± 1.54, P = .023) and HbT (55.92 ± 1.62 vs 72.46 ± 1.90, P = .018) compared to healthy volunteers. Patients with progressive SSc had significantly lower MSOT values compared to patients with stable disease and healthy volunteers.This pilot study shows the feasibility of MSOT imaging to resolve microvascular dysfunction in SSc as a marker of disease activity. By providing biological tissue properties not revealed by other imaging modalities, MSOT might help to grade SSc non-invasively and monitor early therapy response.

Temporal window for detection of inflammatory disease using dynamic cell tracking with time-lapse MRI

Time-lapse MRI was implemented for dynamic non-invasive cell tracking of individual slowly moving intravascular immune cells. Repetitive MRI acquisition enabled dynamic observation of iron oxide nanoparticle (ION) labelled cells. Simulations of MRI contrast indicated that only cells moving slower than 1 µm/s were detectable. Time-lapse MRI of the brain was performed after either IONs or ION-labelled monocytes were injected intravenously into naïve and experimental autoimmune encephalomyelitis (EAE) bearing mice at a presymptomatic or symptomatic stage. EAE mice showed a reduced number of slow moving, i.e. patrolling cells before and after onset of symptoms as compared to naïve controls. This observation is consistent with the notion of altered cell dynamics, i.e. higher velocities of immune cells rolling along the endothelium in the inflamed condition. Thus, time-lapse MRI enables for assessing immune cell dynamics non-invasively in deep tissue and may serve as a tool for detection or monitoring of an inflammatory response.

Fluorescence-mediated Tomography for the Detection and Quantification of Macrophage-related Murine Intestinal Inflammation

Murine models of disease are indispensable to scientific research. However, many diagnostic tools such as endoscopy or tomographic imaging are not routinely employed in animal models. Conventional experimental readouts often rely on post mortem and ex vivo analyses, which prevent intra-individual follow-up examinations and increase the number of study animals needed. Fluorescence-mediated tomography enables the non-invasive, repetitive, quantitative, three-dimensional assessment of fluorescent probes. It is highly sensitive and permits the use of molecular makers, which allows for the specific detection and characterization of distinct molecular targets. In particular, targeted probes represent an innovative tool for analyzing gene activation and protein expression in inflammation, autoimmune disease, infection, vascular disease, cell migration, tumorigenesis, etc. In this article, we provide step-by-step instructions on this sophisticated imaging technology for the in vivo detection and characterization of inflammation (i.e., F4/80-positive macrophage infiltration) in a widely used murine model of intestinal inflammation. This technique might also be used in other research areas, such as immune cell or stem cell tracking.

Integrin-Targeted Hybrid Fluorescence Molecular Tomography/X-ray Computed Tomography for Imaging Tumor Progression and Early Response in Non-Small Cell Lung Cancer

Integrins play an important role in tumor progression, invasion and metastasis. Therefore we aimed to evaluate a preclinical imaging approach applying ανβ3 integrin targeted hybrid Fluorescence Molecular Tomography/X-ray Computed Tomography (FMT-XCT) for monitoring tumor progression as well as early therapy response in a syngeneic murine Non-Small Cell Lung Cancer (NSCLC) model. Lewis Lung Carcinomas were grown orthotopically in C57BL/6 J mice and imaged in-vivo using a ανβ3 targeted near-infrared fluorescence (NIRF) probe. ανβ3-targeted FMT-XCT was able to track tumor progression. Cilengitide was able to substantially block the binding of the NIRF probe and suppress the imaging signal. Additionally mice were treated with an established chemotherapy regimen of Cisplatin and Bevacizumab or with a novel MEK inhibitor (Refametinib) for 2 weeks. While μCT revealed only a moderate slowdown of tumor growth, ανβ3 dependent signal decreased significantly compared to non-treated mice already at one week post treatment. ανβ3 targeted imaging might therefore become a promising tool for assessment of early therapy response in the future.

The 5A apolipoprotein A-I (apoA-I) mimetic peptide ameliorates experimental colitis by regulating monocyte infiltration

BACKGROUND AND PURPOSE

New therapies for inflammatory bowel disease (IBD) are highly desirable. As apolipoprotein (apo)A-I mimetic peptides are beneficial in several animal models of inflammation, we hypothesized that they might be effective at inhibiting murine colitis.

EXPERIMENTAL APPROACH

Daily injections of 5A peptide, a synthetic bihelical apoA-I mimetic dissolved in PBS, or PBS alone were administered to C57BL/6 mice fed 3% (w v(-1) ) dextran sodium sulfate (DSS) in drinking water or healthy controls.

KEY RESULTS

Daily treatment with 5A peptide potently restricted DSS-induced inflammation, as indicated by improved disease activity indices and colon histology, as well as decreased intestinal tissue myeloperoxidase levels and plasma TNFα and IL-6 concentrations. Additionally, plasma levels of monocyte chemoattractant protein-1 and the monocyte expression of adhesion-mediating molecule CD11b were down-regulated, pro-inflammatory CD11b(+) /Ly6c(high) monocytes were decreased, and the number of intestinal monocytes was reduced in 5A peptide-treated animals as determined by intravital macrophage-related peptide-8/14-directed fluorescence-mediated tomography and post-mortem immunhistochemical F4/80 staining. Intravital fluorescence microscopy of colonic microvasculature demonstrated inhibitory effects of 5A peptide on leukocyte adhesion accompanied by reduced plasma levels of the soluble adhesion molecule sICAM-1. In vitro 5A peptide reduced monocyte adhesion and transmigration in TNFα-stimulated monolayers of human intestinal microvascular endothelial cells. Increased susceptibility to DSS-induced inflammation was noted in apoA-I(-/-) mice.

CONCLUSIONS AND IMPLICATIONS

The 5A peptide is effective at ameliorating murine colitis by preventing intestinal monocyte infiltration and activation. These findings point to apoA-I mimetics as a potential treatment approach for IBD.

Alarmin S100A8/S100A9 as a biomarker for molecular imaging of local inflammatory activity

Inflammation has a key role in the pathogenesis of various human diseases. The early detection, localization and monitoring of inflammation are crucial for tailoring individual therapies. However, reliable biomarkers to detect local inflammatory activities and to predict disease outcome are still missing. Alarmins, which are locally released during cellular stress, are early amplifiers of inflammation. Here, using optical molecular imaging, we demonstrate that the alarmin S100A8/S100A9 serves as a sensitive local and systemic marker for the detection of even sub-clinical disease activity in inflammatory and immunological processes like irritative and allergic contact dermatitis. In a model of collagen-induced arthritis, we use S100A8/S100A9 imaging to predict the development of disease activity. Furthermore, S100A8/S100A9 can act as a very early and sensitive biomarker in experimental leishmaniasis for phagocyte activation linked to an effective Th1-response. In conclusion, the alarmin S100A8/S100A9 is a valuable and sensitive molecular target for novel imaging approaches to monitor clinically relevant inflammatory disorders on a molecular level.

The use of molecular imaging combined with genomic techniques to understand the heterogeneity in cancer metastasis

Tumour heterogeneity has, in recent times, come to play a vital role in how we understand and treat cancers; however, the clinical translation of this has lagged behind advances in research. Although significant advancements in oncological management have been made, personalized care remains an elusive goal. Inter- and intratumour heterogeneity, particularly in the clinical setting, has been difficult to quantify and therefore to treat. The histological quantification of heterogeneity of tumours can be a logistical and clinical challenge. The ability to examine not just the whole tumour but also all the molecular variations of metastatic disease in a patient is obviously difficult with current histological techniques. Advances in imaging techniques and novel applications, alongside our understanding of tumour heterogeneity, have opened up a plethora of non-invasive biomarker potential to examine tumours, their heterogeneity and the clinical translation. This review will focus on how various imaging methods that allow for quantification of metastatic tumour heterogeneity, along with the potential of developing imaging, integrated with other in vitro diagnostic approaches such as genomics and exosome analyses, have the potential role as a non-invasive biomarker for guiding the treatment algorithm.

Visualization, imaging and new preclinical diagnostics in radiation oncology

Innovative strategies in cancer radiotherapy are stimulated by the growing knowledge on cellular and molecular tumor biology, tumor pathophysiology, and tumor microenvironment. In terms of tumor diagnostics and therapy monitoring, the reliable delineation of tumor boundaries and the assessment of tumor heterogeneity are increasingly complemented by the non-invasive characterization of functional and molecular processes, moving preclinical and clinical imaging from solely assessing tumor morphology towards the visualization of physiological and pathophysiological processes. Functional and molecular imaging techniques allow for the non-invasive characterization of tissues in vivo, using different modalities, including computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, positron emission tomography (PET) and optical imaging (OI). With novel therapeutic concepts combining optimized radiotherapy with molecularly targeted agents focusing on tumor cell proliferation, angiogenesis, and cell death, the non-invasive assessment of tumor microcirculation and tissue water diffusion, together with strategies for imaging the mechanisms of cellular injury and repair is of particular interest. Characterizing the tumor microenvironment prior to and in response to irradiation will help to optimize the outcome of radiotherapy. These novel concepts of personalized multi-modal cancer therapy require careful pre-treatment stratification as well as a timely and efficient therapy monitoring to maximize patient benefit on an individual basis. Functional and molecular imaging techniques are key in this regard to open novel opportunities for exploring and understanding the underlying mechanisms with the perspective to optimize therapeutic concepts and translate them into a personalized form of radiotherapy in the near future.

Doxycycline-induced expression of transgenic human tumor necrosis factor α in adult mice results in psoriasis-like arthritis

Objective

To generate doxycycline-inducible human tumor necrosis factor α (TNFα)–transgenic mice to overcome a major disadvantage of existing transgenic mice with constitutive expression of TNFα, which is the limitation in crossing them with various knockout or transgenic mice.

Methods

A transgenic mouse line that expresses the human TNFα cytokine exclusively after doxycycline administration was generated and analyzed for the onset of diseases.

Results

Doxycycline-inducible human TNFα–transgenic mice developed an inflammatory arthritis– and psoriasis-like phenotype, with fore and hind paws being prominently affected. The formation of “sausage digits” with characteristic involvement of the distal interphalangeal joints and nail malformation was observed. Synovial hyperplasia, enthesitis, cartilage and bone alterations, formation of pannus tissue, and inflammation of the skin epidermis and nail matrix appeared as early as 1 week after the treatment of mice with doxycycline and became aggravated over time. The abrogation of human TNFα expression by the removal of doxycycline 6 weeks after beginning stimulation resulted in fast resolution of the most advanced macroscopic and histologic disorders, and 3–6 weeks later, only minimal signs of disease were visible.

Conclusion

Upon doxycycline administration, the doxycycline-inducible human TNFα–transgenic mouse displays the major features of inflammatory arthritis. It represents a unique animal model for studying the molecular mechanisms of arthritis, especially the early phases of disease genesis and tissue remodeling steps upon abrogation of TNFα expression. Furthermore, unlimited crossing of doxycycline-inducible human TNFα–transgenic mice with various knockout or transgenic mice opens new possibilities for unraveling the role of various signaling molecules acting in concert with TNFα.

In vivo optical imaging of cellular inflammatory response in granuloma formation using fluorescence-labeled macrophages

Near-infrared imaging such as fluorescence reflectance imaging (FRI) and fluorescence-mediated tomography (FMT) yields high signal-to-noise ratios (SNRs) and should thus be well suited for cell-tracking studies. Extravasation of monocytes or macrophages (Ms) is one of the earliest events in inflammation. The purpose of this study was to assess whether FRI and FMT allow for the visualization and quantification of early inflammatory processes by tracing the migration of fluorescence-labeled murine Ms in a cutaneous granuloma model.

METHODS

Ms were labeled with a membrane-selective carbocyanine dye (1,1-dioctadecyl-3,3,3,3-tetramethylindotricarbocyanine iodide [DiR]). Cellular viability and function (nitric oxide production, phagocytosis, adherence) were assessed in vitro. Local inflammation was induced in mice by the subcutaneous injection of polyacrylamide gel pellets including or excluding a strong inflammatory stimulus (lipopolysaccharide). Labeled Ms were injected intravenously, and FRI and FMT were performed up to 7 d. SNRs were calculated for the pellets, and the 3-dimensional distribution of Ms was assessed using FMT. Cells were harvested from gel pellets and analyzed by flow cytometry.

RESULTS

DiR labeling did not affect cell viability or cell function. FRI revealed the migration of labeled Ms into gel pellets and the homing of Ms to different body compartments. The lipopolysaccharide-containing pellets exhibited significantly higher SNRs than did pellets without lipopolysaccharide. FMT showed that Ms distributed mainly in the periphery of the pellets. The cellular infiltrates extracted from the harvested pellets revealed the presence of approximately 10%-23% DiR-positive Ms-expressing typical markers, confirming the transendothelial migration of injected Ms.

CONCLUSION

The tagging of Ms with DiR allows the noninvasive tracking of inflammatory cells for several days in vivo. FRI and FMT are versatile techniques to monitor and quantify cellular inflammatory responses in vivo.

Bloodstream infections in neutropenic patients: early detection of pathogens and directed antimicrobial therapy due to surveillance blood cultures

Bloodstream infections (BSIs) are frequent infectious complications in neutropenic patients. In order to determine the efficacy of surveillance blood cultures (BCs) to detect BSIs prior to clinical manifestation we performed a prospective trial. One hundred patients with haematological malignancies and long-term neutropenia following intensive cytotoxic therapies were recruited. BCs were taken thrice weekly during neutropenia. Forty-two patients were diagnosed with BSI. In 18 (43%) of those patients surveillance BC results were positive and identified microorganisms prior to onset of fever. In patients with positive surveillance BCs modification of the clinical management (specific antimicrobial therapy, CVC removal) resulted in a shorter time to defervescence (median 1.5 days) compared with patients with BCs positive after onset of fever (median 3.5 days, P = 0.004). In conclusion we detected causative microorganisms in more than one-third of BSIs prior to onset of clinical manifestation. The impact of surveillance BCs on the outcome has to be assessed in randomized studies.

Seroprevalence of human granulocytic anaplasmosis in Berlin/Brandenburg, Germany: an 8-year survey

This study investigated the seroprevalence of antibodies against Anaplasma phagocytophilum in Berlin/Brandenburg, north-eastern Germany. During 1994-2001, 422 sera from patients with proven tick-exposure (specimens with antibodies against Borrelia burgdorferi) were compared with 249 control sera. Using indirect fluorescent antibody testing, significantly more positive samples were detected among Borrelia antibody-positive specimens (4.5%, 95% CI 2.5-6.5%) than among controls (1.2%, 95% CI 0.5-1.9%; p < 0.05). While six (2.2%, 95% CI 1.3-3.1%) samples were positive among Borrelia antibody-positive sera between 1994 and 1997, 13 (8.7%, 95% CI 6.9-10.5%) were positive between 1998 and 2001 (p < 0.01), indicating an uneven annual seroprevalence.

Isolation of Nocardia paucivorans from the cerebrospinal fluid of a patient with relapse of cerebral nocardiosis

Nocardia paucivorans represents a new species of the genus Nocardia that has recently been isolated from bronchial secretions of a patient with chronic lung disease. Here, we report on the course of a disseminated infection caused by this species: i.e., cerebral and subsequent meningeal manifestations, isolation from the cerebrospinal fluid, and in vitro susceptibility to various antimicrobial agents.