Innovative Imaging Techniques Used to Evaluate Borderline-Resectable Pancreatic Adenocarcinoma.

A diagnosis of pancreatic cancer carries a 5-y survival rate of less than 10%. Furthermore, the detection of pancreatic cancer occurs most often in later stages of the disease due to its location in the retroperitoneum and lack of symptoms (in most cases) until tumors become more advanced. Once diagnosed, cross-sectional imaging techniques are heavily utilized to determine the tumor stage and the potential for surgical resection. However, a major determinant of resectability is the extent of local vascular involvement of the mesenteric vessels and critical tributaries; current imaging techniques have limited capacity to accurately determine vascular involvement. Surrounding inflammation and fibrosis can be difficult to discriminate from viable tumor, making determination of the degree of vascular involvement unreliable. New innovations in fluorescence and optoacoustic imaging techniques may overcome these limitations and make determination of resectability more accurate. These imaging modalities are able to more clearly discern between viable tumor tissue and non-neoplastic inflammation or desmoplasia, allowing clinicians to more reliably characterize vascular involvement and develop individualized treatment plans for patients. This review will discuss the current imaging techniques used to diagnose pancreatic cancer, the barriers that current techniques raise to accurate staging, and novel fluorescence and optoacoustic imaging techniques that may provide more accurate clinical staging of pancreatic cancer.

Advances in Imaging of Inflammation, Fibrosis, and Cancer in the Gastrointestinal Tract.

Gastrointestinal disease is prevalent and broad, manifesting itself in a variety of ways, including inflammation, fibrosis, infection, and cancer. However, historically, diagnostic technologies have exhibited limitations, especially with regard to diagnostic uncertainty. Despite development of newly emerging technologies such as optoacoustic imaging, many recent advancements have focused on improving upon pre-existing modalities such as ultrasound, computed tomography, magnetic resonance imaging, and endoscopy. These advancements include utilization of machine learning models, biomarkers, new technological applications such as diffusion weighted imaging, and new techniques such as transrectal ultrasound. This review discusses assessment of disease processes using imaging strategies for the detection and monitoring of inflammation, fibrosis, and cancer in the context of gastrointestinal disease. Specifically, we include ulcerative colitis, Crohn's disease, diverticulitis, celiac disease, graft vs. host disease, intestinal fibrosis, colorectal stricture, gastric cancer, and colorectal cancer. We address some of the most recent and promising advancements for improvement of gastrointestinal imaging, including unique discussions of such advancements with regard to imaging of fibrosis and differentiation between similar disease processes.

Diabetes, Obesity, and Inflammation: Impact on Clinical and Radiographic Features of Breast Cancer.

Obesity, diabetes, and inflammation increase the risk of breast cancer, the most common malignancy in women. One of the mainstays of breast cancer treatment and improving outcomes is early detection through imaging-based screening. There may be a role for individualized imaging strategies for patients with certain co-morbidities. Herein, we review the literature regarding the accuracy of conventional imaging modalities in obese and diabetic women, the potential role of anti-inflammatory agents to improve detection, and the novel molecular imaging techniques that may have a role for breast cancer screening in these patients. We demonstrate that with conventional imaging modalities, increased sensitivity often comes with a loss of specificity, resulting in unnecessary biopsies and overtreatment. Obese women have body size limitations that impair image quality, and diabetes increases the risk for dense breast tis-sue. Increased density is known to obscure the diagnosis of cancer on routine screening mammography. Novel molecu-lar imaging agents with targets such as estrogen receptor, human epidermal growth factor receptor 2 (HER2), pyrimi-dine analogues, and ligand-targeted receptor probes, among others, have potential to reduce false positive results. They can also improve detection rates with increased resolution and inform therapeutic decision making. These emerg-ing imaging techniques promise to improve breast cancer diagnosis in obese patients with diabetes who have dense breasts, but more work is needed to validate their clinical application.

Squaraine Dyes: Molecular Design for Different Applications and Remaining Challenges.

Squaraine dyes are a class of organic dyes with strong and narrow absorption bands in the near-infrared. Despite high molar absorptivities and fluorescence quantum yields, these dyes have been less explored than other dye scaffolds due to their susceptibility to nucleophilic attack. Recent strategies in probe design including encapsulation, conjugation to biomolecules, and new synthetic modifications have seen squaraine dyes emerging into the forefront of biomedical imaging and other applications. Herein, we provide a concise overview of (1) the synthesis of symmetrical and unsymmetrical squaraine dyes, (2) the relationship between structure and photophysical properties of squaraine dyes, and (3) current applications of squaraine dyes in the literature. Given the recent successes at overcoming the limitations of squaraine dyes, they show high potential in biological imaging, in photodynamic and photothermal therapies, and as molecular sensors.

Imaging Inflammation and Infection in the Gastrointestinal Tract.

A variety of seemingly non-specific symptoms manifest within the gastrointestinal (GI) tract, particularly in the colon, in response to inflammation, infection, or a combination thereof. Differentiation between symptom sources can often be achieved using various radiologic studies. Although it is not possible to provide a comprehensive survey of imaging gastrointestinal GI tract infections in a single article, the purpose of this review is to survey several topics on imaging of GI tract inflammation and infections. The review discusses such modalities as computed tomography, positron emission tomography, ultrasound, endoscopy, and magnetic resonance imaging while looking at up-an-coming technologies that could improve diagnoses and patient comfort. The discussion is accomplished through examining a combination of organ-based and organism-based approaches, with accompanying selected case examples. Specific focus is placed on the bacterial infections caused by Shigella spp., Escherichia coli, Clostridium difficile, Salmonella, and inflammatory conditions of diverticulitis and irritable bowel disease. These infectious and inflammatory diseases and their detection via molecular imaging will be compared including the appropriate differential diagnostic considerations.

Small Molecule Optoacoustic Contrast Agents: An Unexplored Avenue for Enhancing In Vivo Imaging.

Almost every variety of medical imaging technique relies heavily on exogenous contrast agents to generate high-resolution images of biological structures. Organic small molecule contrast agents, in particular, are well suited for biomedical imaging applications due to their favorable biocompatibility and amenability to structural modification. PET/SPECT, MRI, and fluorescence imaging all have a large host of small molecule contrast agents developed for them, and there exists an academic understanding of how these compounds can be developed. Optoacoustic imaging is a relatively newer imaging technique and, as such, lacks well-established small molecule contrast agents; many of the contrast agents used are the same ones which have found use in fluorescence imaging applications. Many commonly-used fluorescent dyes have found successful application in optoacoustic imaging, but others generate no detectable signal. Moreover, the structural features that either enable a molecule to generate a detectable optoacoustic signal or prevent it from doing so are poorly understood, so design of new contrast agents lacks direction. This review aims to compile the small molecule optoacoustic contrast agents that have been successfully employed in the literature to bridge the information gap between molecular design and optoacoustic signal generation. The information contained within will help to provide direction for the future synthesis of optoacoustic contrast agents.

Orthotopic pancreatic tumors detected by optoacoustic tomography using Syndecan-1.

BACKGROUND: Advances in small animal imaging have improved the detection and monitoring of cancer in vivo; although with orthotopic models, precise localization of tumors remains a challenge. In this study, we evaluated multispectral optoacoustic tomography (MSOT) as an imaging modality to detect pancreatic adenocarcinoma in an orthotopic murine model. METHODS: In vitro binding of Syndecan-1 probe to the human pancreatic cancer cell line S2VP10 was evaluated on flow cytometry. For in vivo testing, S2VP10 cells were orthotopically implanted into the pancreas of severe combined immunodeficiency mice. At 7 d after implantation, the mice were intravenously injected with Syndecan-1 probe, and tumor uptake was evaluated with MSOT at multiple time points. Comparison was made with a free-dye control, indocyanine green (ICG). Probe uptake was verified ex vivo with fluorescent imaging. RESULTS: Syndecan-1 probe demonstrated partial binding to S2VP10 cells in vitro. In vivo, Syndecan-1 probe preferentially accumulated in the pancreas tumor (480 MSOT a.u.) compared with off-target organs, including the liver (67 MSOT a.u.) and kidney (96 MSOT a.u.). Syndecan-1 probe accumulation peaked at 6 h (480 MSOT a.u.), whereas the ICG control dye failed to demonstrate similar retention within the tumor bed (0.0003 MSOT a.u.). At peak accumulation, signal intensity was 480 MSOT a.u., resulting in several times greater signal in the tumor bed than in the kidney or liver. Ex vivo fluorescent imaging comparing tumor signal with that within off-target organs confirmed the in vivo results. CONCLUSIONS: MSOT demonstrates successful accumulation of Syndecan-1 probe within pancreatic tumors, and provides high-resolution images, which allow noninvasive, real-time comparison of signal within individual organs. Syndecan-1 probe preferentially accumulates within a pancreatic adenocarcinoma model, with minimal off-target effects.

Tumor specific liposomes improve detection of pancreatic adenocarcinoma in vivo using optoacoustic tomography.

BACKGROUND: Pancreatic cancer often goes undiagnosed until late stage disease due in part to suboptimal early detection. Our goal was to develop a Syndecan-1 tagged liposome containing fluorescent dye as an improved contrast agent for detection of pancreatic adenocarcinoma in vivo using multispectral optoacoustic tomography. RESULTS: The diagnostic capabilities and specificity to pancreatic adenocarcinoma of Syndecan-1 targeted liposomes were evaluated both in vitro and in vivo. Immunocytochemistry showed that liposomes preferentially bound to and released their contents into cells expressing high levels of insulin-like growth factor 1 receptor. We determined that the contents of the liposome were released into the cell as noted by the change in propidium iodide fluorescence from green to red based upon nucleic acid binding. In an orthotopic mouse model, the liposomes preferentially targeted the pancreatic tumor with little off-target binding in the liver and spleen. Peak accumulation of the liposomes in the tumor occurred at 8 h post-injection. Multispectral optoacoustic tomographic imaging was able to provide high-resolution 3D images of the tumor and liposome location. Ex vivo analysis showed that non-targeted liposomes accumulated in the liver, suggesting that specificity of the liposomes for pancreatic adenocarcinoma was due to the presence of the Syndecan-1 ligand. CONCLUSIONS: This study demonstrated that Syndecan-1 liposomes were able to release cargo into IGF1-R expressing tumor cells. The Syndecan-1 liposomes demonstrated tumor specificity in orthotopic pancreatic cancer as observed using multispectral optoacoustic tomography with reduced kidney and liver uptake. By targeting the liposome with Syndecan-1, this nanovehicle has potential as a targeted theranostic nanoparticle for both drug and contrast agent delivery to pancreatic tumors.

Predictive modeling of in vivo response to gemcitabine in pancreatic cancer.

A clear contradiction exists between cytotoxic in-vitro studies demonstrating effectiveness of Gemcitabine to curtail pancreatic cancer and in-vivo studies failing to show Gemcitabine as an effective treatment. The outcome of chemotherapy in metastatic stages, where surgery is no longer viable, shows a 5-year survival <5%. It is apparent that in-vitro experiments, no matter how well designed, may fail to adequately represent the complex in-vivo microenvironmental and phenotypic characteristics of the cancer, including cell proliferation and apoptosis. We evaluate in-vitro cytotoxic data as an indicator of in-vivo treatment success using a mathematical model of tumor growth based on a dimensionless formulation describing tumor biology. Inputs to the model are obtained under optimal drug exposure conditions in-vitro. The model incorporates heterogeneous cell proliferation and death caused by spatial diffusion gradients of oxygen/nutrients due to inefficient vascularization and abundant stroma, and thus is able to simulate the effect of the microenvironment as a barrier to effective nutrient and drug delivery. Analysis of the mathematical model indicates the pancreatic tumors to be mostly resistant to Gemcitabine treatment in-vivo. The model results are confirmed with experiments in live mice, which indicate uninhibited tumor proliferation and metastasis with Gemcitabine treatment. By extracting mathematical model parameter values for proliferation and death from monolayer in-vitro cytotoxicity experiments with pancreatic cancer cells, and simulating the effects of spatial diffusion, we use the model to predict the drug response in-vivo, beyond what would have been expected from sole consideration of the cancer intrinsic resistance. We conclude that this integrated experimental/computational approach may enhance understanding of pancreatic cancer behavior and its response to various chemotherapies, and, further, that such an approach could predict resistance based on pharmacokinetic measurements with the goal to maximize effective treatment strategies.

Targeting of BRAF resistant melanoma via extracellular matrix metalloproteinase inducer receptor.

BACKGROUND: The BRAF inhibitor vemurafenib (PLX) has shown promise in treating metastatic melanoma, but most patients develop resistance to treatment after 6 mo. We identified a transmembrane protein, extracellular matrix metalloproteinase inducer (EMMPRIN) as a cell surface receptor highly expressed by PLX-resistant melanoma. Using an S100A9 ligand, we created an EMMPRIN targeted probe and liposome that binds to melanoma cells in vivo, thus designing a novel drug delivery vehicle. METHODS: PLX-resistant cells were established through continuous treatment with PLX-4032 over the course of 1 y. Both PLX-resistant and sensitive melanoma cell lines were evaluated for the expression of unique cell surface proteins, which identified EMMPRIN as an overexpressed protein in PLX0-resistant cells and S100A9 is a ligand for EMMPRIN. To design a probe for EMMPRIN, S100A9 ligand was conjugated to a CF-750 near-infrared (NIR) dye. EMMPRIN targeted liposomes were created to encapsulate CF-750 NIR dye. Liposomes were characterized by scanning electron microscopy, flow cytometry, and in vivo analysis. A2058PLX and A2058 cells were subcutaneously injected into athymic mice. S100A9 liposomes were intravenously injected and tumor accumulation was evaluated using NIR fluorescent imaging. RESULTS: Western blot and flow cytometry demonstrated that PLX sensitive and resistant A2058 and A375 melanoma cells highly express EMMPRIN. S100A9 liposomes were 200 nm diameter and uniformly sized. Flow cytometry demonstrated 100X more intracellular dye uptake by A2058 cells treated with S100A9 liposomes compared with untargeted liposomes. In vivo accumulation of S100A9 liposomes within subcutaneous A2058 and A2058PLX tumors was observed from 6-48 h, with A2058PLX accumulating significantly higher levels (P = 0.001626). CONCLUSIONS: EMMPRIN-targeted liposomes via an S100A9 ligand are a novel, targeted delivery system which could provide improved EMMPRIN specific drug delivery to a tumor.

Chloroquine-mediated cell death in metastatic pancreatic adenocarcinoma through inhibition of autophagy.

CONTEXT: Cells in the interior of pancreatic tumors are believed to undergo continual autophagy to maintain homeostasis during unregulated growth in hypoxia caused by impaired vascularity. We hypothesize that treating metastatic cells with chloroquine, an inhibitor of autophagy, in hypoxia will decrease cell viability and induce cell death. DESIGN: MiaPaCa2 (non-metastatic) and S2VP10 (metastatic) cell lines were treated with 25 and 50 µM chloroquine for 24 and 48 hours in normoxia and hypoxia (5-10% O2). Viability was measured using ATPlite™. After treatment, the cell stress was analyzed, and protein was lysed and quantified using the Bradford assay. Autophagy-associated protein levels were determined by Western blot. RESULTS: S2VP10 cells treated for 48 hours with 50 µM chloroquine in hypoxia had 24% viability compared to normoxia control, with loss of 10% viability caused by low O2 alone. MiaPaCa2 cells under these conditions had 60% viability compared to normoxia control, with loss of 25% viability caused by low O2 alone. Analysis of cell stress pathways and dosimetry of Western blot data suggest that chloroquine inhibits the autophagy pathway in the metastatic S2VP10 cells. CONCLUSION: Autophagy blockage with chloroquine or similar-acting drugs may serve as a viable therapy for highly metastatic pancreatic cancers.

Correction: Garza-Morales et al. Temozolomide Enhances Triple-Negative Breast Cancer Virotherapy In Vitro. Cancers 2018, 10, 144.

Error in Figure [...].

Influence of structural moieties in squaraine dyes on optoacoustic signal shape and intensity.

Optoacoustic imaging has grown in clinical relevance due to inherent advantages in sensitivity, resolution, and imaging depth, but the development of contrast agents is lacking. This study assesses the influence of structural features of squaraine dyes on optoacoustic activity through computational models, in vitro testing, and in vivo experimentation. The squaraine scaffold was decorated with halogens and side-chain extensions. Extension of side chains and heavy halogenation of squaraines both increased optoacoustic signals individually, although they had a more significant effect in tandem. Density functional theory models suggest that the origin of the increased optoacoustic signal is the increase in transition dipole moment and vibrational entropy, which manifested as increased absorbance in near-infrared region (NIR) wavelengths and decreased fluorescence quantum yield. This study provides insight into the structure-function relationships that will lead guiding principles for optimizing optoacoustic contrast agents. Further developments of squaraines and other agents will further increase the relevance of optoacoustic imaging in a clinical setting.

Erratum: Influence of structural moieties in squaraine dyes on optoacoustic signal shape and intensity.

[This corrects the article PMC11087056.].

Erratum: Influence of structural moieties in squaraine dyes on optoacoustic signal shape and intensity.

[This corrects the article PMC11087056.].

Lung resistance-related protein (LRP) expression in malignant ascitic cells as a prognostic marker for advanced ovarian serous carcinoma.

PURPOSE: Ovarian serous carcinoma is an aggressive cancer that often presents with metastatic disease. Although primary tumor and established metastatic foci in the omentum are generally compared to identify proteins involved in drug resistance, we investigated a potential bridge, the malignant cells from ascites, as facilitator of drug resistance and recurrence. METHODS: We evaluated the expression of drug resistance markers P-glycoprotein (P-gp), canalicular multispecific organic anion transporter (MRP2), and lung resistance-related protein (LRP) in malignant cells from ascites and matched omental metastasis from 25 patients with advanced-stage ovarian serous carcinoma who were chemotherapeutic naïve and undergoing initial cytoreductive surgery. Cell viability in vitro, patient response to chemotherapy, and patient survival were correlated with these biomarkers. RESULTS: Of the 25 patients evaluated for a correlation of LRP to 1-year recurrence, we correctly predicted the 1-year recurrence of 24 patients based solely on the presence of LRP in ascitic tumor cells (p=0.01). P-gp and MRP2 were not expressed in malignant cells of ascites or omental metastases. Malignant cells from ascites had higher expression of LRP and were found to be more resistant to carboplatin treatment than cells from omental metastasis (p=0.00375) by in vitro assay. LRP expression in the malignant cells of ascites correlated with carboplatin resistance (p=0.001) by in vitro assay and recurrence at 1 year (p=0.0125). CONCLUSIONS: LRP expression in malignant cells of ascites is a promising marker to predict response to first-line chemotherapy in patients with advanced ovarian serous carcinoma.

Inhibition of autophagy with chloroquine is effective in melanoma.

BACKGROUND: Cancer cells adapt to the stress resulting from accelerated cell growth and a lack of nutrients by activation of the autophagy pathway. Two proteins that allow cell growth in the face of metabolic stress and hypoxia are hypoxia-inducible factor-1α (HIF-1α) and heat shock protein 90 (Hsp 90). We hypothesize that chloroquine (CQ), an antimalarial drug that inhibits autophagosome function, in combination with either echinomycin, a HIF-1α inhibitor, or 17-dimethylaminoethylamino-17-dimethoxygeldanamycin (17-DMAG), an Hsp 90 inhibitor, will result in cytotoxicity in melanoma. MATERIALS AND METHODS: Multiple human melanoma cell lines (BRAF wild-type and mutant) were tested in vitro with CQ in combination with echinomycin or 17-DMAG. These treatments were performed in hypoxic (5% O2) and normoxic (18% O2) conditions. Mechanism of action was determined through Western blot of autophagy-associated proteins HIF-1α and Hsp 90. RESULTS: Chloroquine, echinomycin, and 17-DMAG each induced cytotoxicity in multiple human melanoma cell lines, in both normoxia and hypoxia. Chloroquine combined with echinomycin achieved synergistic cytotoxicity under hypoxic conditions in multiple melanoma cell lines (BRAF wild-type and mutant). Western blot analysis indicated that echinomycin reduced HIF-1α levels, both alone and in combination with CQ. Changes in LC3 flux indicated inhibition of autophagy at the level of the autophagosome by CQ therapy. CONCLUSIONS: Targeting autophagy with the antimalarial drug CQ may be an effective cancer therapy in melanoma. Sensitivity to chloroquine is independent of BRAF mutational status. Combining CQ with the HIF-1α inhibitor echinomycin improves cytotoxicity in hypoxic conditions.

Dynamic 2-deoxy-D-glucose-enhanced multispectral optoacoustic tomography for assessing metabolism and vascular hemodynamics of breast cancer.

Clinical tools for measuring tumor vascular hemodynamics, such as dynamic contrast-enhanced MRI, are clinically important to assess tumor properties. Here we explored the use of multispectral optoacoustic tomography (MSOT), which has a high spatial and temporal resolution, to measure the intratumoral pharmacokinetics of a near-infrared-dye-labeled 2-Deoxyglucose, 2-DG-800, in orthotropic 2-LMP breast tumors in mice. As uptake of 2-DG-800 is dependent on both vascular properties, and glucose transporter activity - a widely-used surrogate for metabolism, we evaluate hemodynamics of 2-DG-MP by fitting the dynamic MSOT signal of 2-DG-800 into two-compartment models including the extended Tofts model (ETM) and reference region model (RRM). We showed that dynamic 2-DG-enhanced MSOT (DGE-MSOT) is powerful in acquiring hemodynamic rate constants, including Ktrans and Kep, via systemically injecting a low dose of 2-DG-800 (0.5 µmol/kg b.w.). In our study, both ETM and RRM are efficient in deriving hemodynamic parameters in the tumor. Area-under-curve (AUC) values (which correlate to metabolism), and Ktrans and Kep values, can effectively distinguish tumor from muscle. Hemodynamic parameters also demonstrated correlations to hemoglobin, oxyhemoglobin, and blood oxygen level (SO2) measurements by spectral unmixing of the MSOT data. Together, our study for the first time demonstrated the capability of DGE-MSOT in assessing vascular hemodynamics of tumors.

Intraoperative Imaging in Hepatopancreatobiliary Surgery.

Hepatopancreatobiliary surgery belongs to one of the most complex fields of general surgery. An intricate and vital anatomy is accompanied by difficult distinctions of tumors from fibrosis and inflammation; the identification of precise tumor margins; or small, even disappearing, lesions on currently available imaging. The routine implementation of ultrasound use shifted the possibilities in the operating room, yet more precision is necessary to achieve negative resection margins. Modalities utilizing fluorescent-compatible dyes have proven their role in hepatopancreatobiliary surgery, although this is not yet a routine practice, as there are many limitations. Modalities, such as photoacoustic imaging or 3D holograms, are emerging but are mostly limited to preclinical settings. There is a need to identify and develop an ideal contrast agent capable of differentiating between malignant and benign tissue and to report on the prognostic benefits of implemented intraoperative imaging in order to navigate clinical translation. This review focuses on existing and developing imaging modalities for intraoperative use, tailored to the needs of hepatopancreatobiliary cancers. We will also cover the application of these imaging techniques to theranostics to achieve combined diagnostic and therapeutic potential.

Simultaneous Detection of Multiple Tumor-targeted Gold Nanoparticles in HER2-Positive Breast Tumors Using Optoacoustic Imaging.

Purpose To develop optoacoustic, spectrally distinct, actively targeted gold nanoparticle-based near-infrared probes (trastuzumab [TRA], TRA-Aurelia-1, and TRA-Aurelia-2) that can be individually identifiable at multispectral optoacoustic tomography (MSOT) of human epidermal growth factor receptor 2 (HER2)-positive breast tumors. Materials and Methods Gold nanoparticle-based near-infrared probes (Aurelia-1 and 2) that are optoacoustically active and spectrally distinct for simultaneous MSOT imaging were synthesized and conjugated to TRA to produce TRA-Aurelia-1 and 2. Freshly resected human HER2-positive (n = 6) and HER2-negative (n = 6) triple-negative breast cancer tumors were treated with TRA-Aurelia-1 and TRA-Aurelia-2 for 2 hours and imaged with MSOT. HER2-expressing DY36T2Q cells and HER2-negative MDA-MB-231 cells were implanted orthotopically into mice (n = 5). MSOT imaging was performed 6 hours following the injection, and the Friedman test was used for analysis. Results TRA-Aurelia-1 (absorption peak, 780 nm) and TRA-Aurelia-2 (absorption peak, 720 nm) were spectrally distinct. HER2-positive human breast tumors exhibited a significant increase in optoacoustic signal following TRA-Aurelia-1 (28.8-fold) or 2 (29.5-fold) (P = .002) treatment relative to HER2-negative tumors. Treatment with TRA-Aurelia-1 and 2 increased optoacoustic signals in DY36T2Q tumors relative to those in MDA-MB-231 controls (14.8-fold, P < .001; 20.8-fold, P < .001, respectively). Conclusion The study demonstrates that TRA-Aurelia 1 and 2 nanoparticles operate as a spectrally distinct HER2 breast tumor-targeted in vivo optoacoustic agent. Keywords: Molecular Imaging, Nanoparticles, Photoacoustic Imaging, Breast Cancer Supplemental material is available for this article. © RSNA, 2023.