Imaging and cancer: a review

Nano-Theranostics for the Sensing, Imaging and Therapy of Prostate Cancers

We highlight hereby recent developments in the emerging field of theranostics, which encompasses the combination of therapeutics and diagnostics in a single entity aimed for an early-stage diagnosis, image-guided therapy as well as evaluation of therapeutic outcomes of relevance to prostate cancer (PCa). Prostate cancer is one of the most common malignancies in men and a frequent cause of male cancer death. As such, this overview is concerned with recent developments in imaging and sensing of relevance to prostate cancer diagnosis and therapeutic monitoring. A major advantage for the effective treatment of PCa is an early diagnosis that would provide information for an appropriate treatment. Several imaging techniques are being developed to diagnose and monitor different stages of cancer in general, and patient stratification is particularly relevant for PCa. Hybrid imaging techniques applicable for diagnosis combine complementary structural and morphological information to enhance resolution and sensitivity of imaging. The focus of this review is to sum up some of the most recent advances in the nanotechnological approaches to the sensing and treatment of prostate cancer (PCa). Targeted imaging using nanoparticles, radiotracers and biomarkers could result to a more specialised and personalised diagnosis and treatment of PCa. A myriad of reports has been published literature proposing methods to detect and treat PCa using nanoparticles but the number of techniques approved for clinical use is relatively small. Another facet of this report is on reviewing aspects of the role of functional nanoparticles in multimodality imaging therapy considering recent developments in simultaneous PET-MRI (Positron Emission Tomography-Magnetic Resonance Imaging) coupled with optical imaging in vitro and in vivo, whilst highlighting feasible case studies that hold promise for the next generation of dual modality medical imaging of PCa. It is envisaged that progress in the field of imaging and sensing domains, taken together, could benefit from the biomedical implementation of new synthetic platforms such as metal complexes and functional materials supported on organic molecular species, which can be conjugated to targeting biomolecules and encompass adaptable and versatile molecular architectures. Furthermore, we include hereby an overview of aspects of biosensing methods aimed to tackle PCa: prostate biomarkers such as Prostate Specific Antigen (PSA) have been incorporated into synthetic platforms and explored in the context of sensing and imaging applications in preclinical investigations for the early detection of PCa. Finally, some of the societal concerns around nanotechnology being used for the detection of PCa are considered and addressed together with the concerns about the toxicity of nanoparticles–these were aspects of recent lively debates that currently hamper the clinical advancements of nano-theranostics. The publications survey conducted for this review includes, to the best of our knowledge, some of the most recent relevant literature examples from the state-of-the-art. Highlighting these advances would be of interest to the biomedical research community aiming to advance the application of theranostics particularly in PCa diagnosis and treatment, but also to those interested in the development of new probes and methodologies for the simultaneous imaging and therapy monitoring employed for PCa targeting.

The emerging role of photoacoustic imaging in clinical oncology

Clinical oncology can benefit substantially from imaging technologies that reveal physiological characteristics with multiscale observations. Complementing conventional imaging modalities, photoacoustic imaging (PAI) offers rapid imaging (for example, cross-sectional imaging in real time or whole-breast scanning in 10-15 s), scalably high levels of spatial resolution, safe operation and adaptable configurations. Most importantly, this novel imaging modality provides informative optical contrast that reveals details on anatomical, functional, molecular and histological features. In this Review, we describe the current state of development of PAI and the emerging roles of this technology in cancer screening, diagnosis and therapy. We comment on the performance of cutting-edge photoacoustic platforms, and discuss their clinical applications and utility in various clinical studies. Notably, the clinical translation of PAI is accelerating in the areas of macroscopic and mesoscopic imaging for patients with breast or skin cancers, as well as in microscopic imaging for histopathology. We also highlight the potential of future developments in technological capabilities and their clinical implications, which we anticipate will lead to PAI becoming a desirable and widely used imaging modality in oncological research and practice.

Iron–Gold Nanoflowers: A Promising Tool for Multimodal Imaging and Hyperthermia Therapy

The development of nanoplatforms prepared to perform both multimodal imaging and combined therapies in a single entity is a fast-growing field. These systems are able to improve diagnostic accuracy and therapy success. Multicomponent Nanoparticles (MCNPs), composed of iron oxide and gold, offer new opportunities for Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) diagnosis, as well as combined therapies based on Magnetic Hyperthermia (MH) and Photothermal Therapy (PT). In this work, we describe a new seed-assisted method for the synthesis of Au@Fe Nanoparticles (NPs) with a flower-like structure. For biomedical purposes, Au@Fe NPs were functionalized with a PEGylated ligand, leading to high colloidal stability. Moreover, the as-obtained Au@Fe-PEG NPs exhibited excellent features as both MRI and CT Contrast Agents (CAs), with high r2 relaxivity (60.5 mM−1⋅s−1) and X-ray attenuation properties (8.8 HU mM−1⋅HU). In addition, these nanoflowers presented considerable energy-to-heat conversion under both Alternating Magnetic Fields (AMFs) (∆T ≈ 2.5 °C) and Near-Infrared (NIR) light (∆T ≈ 17 °C). Finally, Au@Fe-PEG NPs exhibited very low cytotoxicity, confirming their potential for theranostics applications.

Mapping the cancer imaging research landscape: which cancers are more and which cancers are less frequently investigated?

OBJECTIVE

To investigate the proportion of published imaging studies relative to incidence and mortality rate per cancer type.

METHODS

From a random sample of 2500 articles published in 2019 by the top 25 imaging-related journals, we included cancer imaging studies. The publication-to-incidence and publication-to-mortality ratios (defined as the publication rate divided by the proportional incidence and mortality rate, respectively) were calculated per cancer type. Ratios >1 indicate a higher publication rate compared to the relative incidence or mortality rate of a specific cancer. Ratios <1 indicate a lower publication rate compared to the relative incidence or mortality rate of a specific cancer.

RESULTS

620 original cancer imaging studies were included. Female breast cancer (20.2%), prostate cancer (13.0%), liver cancer (12.9%), lung cancer (8.8%), and cancers in the central nervous system (8.1%) comprised the top 5 of cancers investigated. Cancers in the central nervous system and liver had publication-to-incidence ratios >2, whereas nonmelanoma of the skin, leukemia, stomach cancer, and laryngeal cancer had publication-to-incidence ratios <0.2. Cancers in the prostate, central nervous system, female breast, and kidney had publication-to-mortality ratios >2, whereas esophageal cancer, stomach cancer, laryngeal cancer, and leukemia had publication-to-mortality ratios <0.2.

CONCLUSION

This overview of published cancer imaging research may be informative and useful to all stakeholders in the field of cancer imaging. The potential causes of disproportionality between the publication rate vs. incidence and mortality rates of some cancer types are multifactorial and need to be further elucidated.

Activity-Based Diagnostics: Recent Advances in the Development of Probes for Use with Diverse Detection Modalities

Abnormal enzyme expression and activity is a hallmark of many diseases. Activity-based diagnostics are a class of chemical probes that aim to leverage this dysregulated metabolic signature to produce a detectable signal specific to diseased tissue. In this Review, we highlight recent methodologies employed in activity-based diagnostics that provide exquisite signal sensitivity and specificity in complex biological systems for multiple disease states. We divide these examples based upon their unique signal readout modalities and highlight those that have advanced into clinical trials.

Advancement and recent trends in seeking less toxic and more active anti-cancer drugs: Insights into thiourea based molecules

The finding of potent anticancer agents with low toxicity and high selectivity has remained valuable for human health. Thiourea derivatives are the most significant organic compounds with integral and typical characteristics of numerous varieties of natural products and pharmaceutical agents. It exhibits various pharmacological properties, and its analogues confer a great deal of structural diversity that was proven to be the most advantageous in the search for novel therapeutic agents. Thiourea derivatives, which show beneficial antitumor activities, are typically considered the central core in various anticancer derivatives. They also have broad-ranging biological activities such as anti-inflammatory, antibacterial, antifungal, antitubercular, antihypertensive, antihistaminic, and antiviral activities. Several FDA-approved drugs of thiourea derivatives and their analogues in the market, currently in progress through various registration statuses or clinical stages, indicating that thiourea derivatives are the most promising drugs. The current review is intended to systematically provide comprehensive evidence in the recent developments of thiourea to treat numerous types of cancer. Furthermore, we hope that this review will be helpful for novel consideration in seeking rational designs of less toxic and more active drugs and more effective diagnostics agents.

Design Principles Governing the Development of Theranostic Anticancer Agents and Their Nanoformulations with Photoacoustic Properties

The unmet need to develop novel approaches for cancer diagnosis and treatment has led to the evolution of theranostic agents, which usually include, in addition to the anticancer drug, an imaging agent based mostly on fluorescent agents. Over the past few years, a non-invasive photoacoustic imaging modality has been effectively integrated into theranostic agents. Herein, we shed light on the design principles governing the development of theranostic agents with photoacoustic properties, which can be formulated into nanocarriers to enhance their potency. Specifically, we provide an extensive analysis of their individual constituents including the imaging dyes, drugs, linkers, targeting moieties, and their formulation into nanocarriers. Along these lines, we present numerous relevant paradigms. Finally, we discuss the clinical relevance of the specific strategy, as also the limitations and future perspectives, and through this review, we envisage paving the way for the development of theranostic agents endowed with photoacoustic properties as effective anticancer medicines.

Advanced Optical Imaging-Guided Nanotheranostics towards Personalized Cancer Drug Delivery

Nanomedicine involves the use of nanotechnology for clinical applications and holds promise to improve treatments. Recent developments offer new hope for cancer detection, prevention and treatment; however, being a heterogenous disorder, cancer calls for a more targeted treatment approach. Personalized Medicine (PM) aims to revolutionize cancer therapy by matching the most effective treatment to individual patients. Nanotheranostics comprise a combination of therapy and diagnostic imaging incorporated in a nanosystem and are developed to fulfill the promise of PM by helping in the selection of treatments, the objective monitoring of response and the planning of follow-up therapy. Although well-established imaging techniques, such as Magnetic Resonance Imaging (MRI), Computed Tomography (CT), Positron Emission Tomography (PET) and Single-Photon Emission Computed Tomography (SPECT), are primarily used in the development of theranostics, Optical Imaging (OI) offers some advantages, such as high sensitivity, spatial and temporal resolution and less invasiveness. Additionally, it allows for multiplexing, using multi-color imaging and DNA barcoding, which further aids in the development of personalized treatments. Recent advances have also given rise to techniques permitting better penetration, opening new doors for OI-guided nanotheranostics. In this review, we describe in detail these recent advances that may be used to design and develop efficient and specific nanotheranostics for personalized cancer drug delivery.

Protein nanoparticles directed cancer imaging and therapy

Cancer has been a serious threat to human health. Among drug delivery carriers, protein nanoparticles are unique because of their mild and environmentally friendly preparation methods. They also inherit desired characteristics from natural proteins, such as biocompatibility and biodegradability. Therefore, they have solved some problems inherent to inorganic nanocarriers such as poor biocompatibility. Also, the surface groups and cavity of protein nanoparticles allow for easy surface modification and drug loading. Besides, protein nanoparticles can be combined with inorganic nanoparticles or contrast agents to form multifunctional theranostic platforms. This review introduces representative protein nanoparticles applicable in cancer theranostics, including virus-like particles, albumin nanoparticles, silk protein nanoparticles, and ferritin nanoparticles. It also describes the common methods for preparing them. It then critically analyzes the use of a variety of protein nanoparticles in improved cancer imaging and therapy.

Theoretical study and application of 2-phenyl-1,3,4-thiadiazole derivatives with optical and inhibitory activity against SHP1

Src homology-2 domain-containing protein tyrosine phosphatase 1 (SHP1) is mainly restricted to hematopoietic and epithelial cells and widely accepted as a convergent node for oncogenic cell-signaling cascades. The development of efficient methods for rapidly tracing and inhibiting the SHP1 activity in complex biological systems is of considerable significance for advancing the integration of diagnosis and treatment of the related disease. With this aim, we designed and synthesized five 2-phenyl-1,3,4-thiadiazole derivatives (PT2, PT5, PT8, PT9 and PT10) here based on the reported SHP1 inhibitors (PT1, PT3, PT4, PT6 and PT7). The photophysical properties and inhibitory activities of these 2-phenyl-1,3,4-thiadiazole derivatives (PT1-PT10) against SHP1 were thoroughly studied from the theoretical simulation and experimental application aspects. The representative compound PT10 exhibited a larger quantum yield than the other molecules because of the smaller geometric relaxation and reorganization energy of the excited state, which was consistent with the results from the fluorescence experiments in organic solvents. In addition, PT10 showed a selective fluorescence response for SHP1 activity and low cytotoxicity in HeLa cells. Lastly, it indicated the potential application in two-photon cell fluorescence imaging in the future according to the calculated excellent two-photon absorption properties. In this contribution, firstly, we offered the fluorescent and activated molecule PT10 against SHP1, which achieved the integration of visualization and inhibitory activity of SHP1 preliminarily at the enzyme molecular level.

A literature review on the imaging methods for breast cancer

Breast cancer will be easier and more effective to treat if detected early. Breast cancer is assessed and detected using imaging as a primary approach. The capacity to diagnose breast cancers is continually improving thanks to developments in imaging technologies. However, some of these enhancements have been linked to delays in the initiation of treatment procedures of breast cancer. Overall, cancer management relies heavily on imaging procedures such as screening and symptomatic disease management. Mammography, which is considered the gold standard, and breast ultrasonography are employed as routine imaging modalities. Previous research has shown that, despite recent developments, no single imaging modality can detect and characterizing majority of breast lesions. Various imaging methods and their uses in diagnosing and caring the breast cancer are discussed in this study.

Emerging Technologies for the Detection of Cancer Micrometastasis

The most efficient way to treat tumors is through surgery. However, many cancer patients have a poor prognosis even when they undergo radical excision at an early stage. Micrometastasis is one of the most critical factors that induced this situation. Undetected micrometastasis can lead to the failure of initial treatment. Therefore, preoperative and intraoperative detection of micrometastasis could have a significant clinical influence on the prognosis and optimal therapy for cancer patients. Additionally, to achieve this goal, researchers have aimed to create more effective detection technologies. Herein, we classify the currently reported micrometastasis detection technologies, introduce some representative samples for each technology, including the limitations, and provide future directions to overcome the limitations.

Evaluation of radioiodinated ethopabate as a potential tumor targeting agent

Overexpression of folate synthesis and folate receptor in a wide variety of tumors was reported. As a result, folate derivatives have emerged as a potential candidate for tumor imaging and therapy. Ethopabate is a structural analogue of para-aminobenzoic acid (PABA), a precursor of folic acid. Ethopabate was radiolabeled with radioiodine-131 (¹³¹I) via direct electrophilic substitution reaction. Several factors that might affect the radiolabeling yield were studied. Paper chromatography was utilized for testing and evaluation of [¹³¹I]iodoethopabate, and HPLC was used as a co-chromatographic tool to confirm the radiochemical yield. The biodistribution of [¹³¹I]iodoethopabate in normal and tumor-bearing mice was investigated. The radioiodination of ethopabate resulted in a radiochemical yield of 93.70 ± 0.19%. The biodistribution data revealed that [¹³¹I]iodoethopabate was taken up by tumors with promising target/non-target (T/NT) ratios. Where, the tumor to-blood ratios were 3.30 ± 0.40 and 4.06 ± 0.10 at 1 and 4 h post injection, respectively. As a result of these findings, [¹³¹I]iodoethopabate appears to have excellent tumor uptake and adequate stability to be used for diagnostic purpose in the future.

Review of extremity dosimetry in nuclear medicine

The exposure of the fingers is one of the major radiation protection concerns in nuclear medicine (NM). The purpose of this paper is to provide an overview of the exposure, dosimetry and protection of the extremities in NM. A wide range of reported finger doses were found in the literature. Historically, the highest finger doses are found at the fingertip in the preparation and dispensing of¹⁸F for diagnostic procedures and⁹⁰Y for therapeutic procedures. Doses can be significantly reduced by following recommendations on source shielding, increasing distance and training. Additionally, important trends contributing to a lower dose to the fingers are the use of automated procedures (especially for positron emission tomography (PET)) and the use of prefilled syringes. On the other hand, the workload of PET procedures has substantially increased during the last ten years. In many cases, the accuracy of dose assessment is limited by the location of the dosimeter at the base of the finger and the maximum dose at the fingertip is underestimated (typical dose ratios between 1.4 and 7). It should also be noted that not all dosimeters are sensitive to low-energy beta particles and there is a risk for underestimation of the finger dose when the detector or its filter is too thick. While substantial information has been published on the most common procedures (using^99mTc,¹⁸F and⁹⁰Y), less information is available for more recent applications, such as the use of⁶⁸Ga for PET imaging. Also, there is a need for continuous awareness with respect to contamination of the fingers, as this factor can contribute substantially to the finger dose.

Automatic breast tissue segmentation in MRIs with morphology snake and deep denoiser training via extended Stein's unbiased risk estimator

Accurate segmentation of the breast tissue is a significant challenge in the analysis of breast MR images, especially analysis of breast images with low contrast. Most of the existing methods for breast segmentation are semi-automatic and limited in their ability to achieve accurate results. This is because of difficulties in removing landmarks from noisy magnetic resonance images (MRI). Especially, when tumour is imaged for scanning, how to isolate the tumour region from chest will directly affect the accuracy for tumour to be detected. Due to low intensity levels and the close connection between breast and chest portion in MRIs, this study proposes an innovative, fully automatic and fast segmentation approach which combines histogram with inverse Gaussian gradient for morphology snakes, along with extended Stein's unbiased risk estimator (eSURE) applied for unsupervised learning of deep neural network Gaussian denoisers, aimed at accurate identification of landmarks such as chest and breast.

Systemic PPARγ Antagonism Reduces Metastatic Tumor Progression in Adipocyte-Rich Bone in Excess Weight Male Rodents

Primary tumors are widely associated with an excess in body fat. The role of adipose tissue on tumor cell homing to bone is yet poorly defined. In this study, we aimed to assess whether bone colonization by tumor cells is favored by an adipocyte-rich bone marrow. We delineated the accompanying alterations of the bone microenvironment and established a treatment approach that interferes with high fat diet (HFD)-induced bone metastasis formation. We were able to show that adipocytes affect skeletal tumor growth in a metastatic model of breast cancer in male rats and melanoma in male mice as well as in human breast cancer bone biopsies. Indeed, HFD-induced bone marrow adiposity was accompanied by accelerated tumor progression and increased osteolytic lesions. In human bone metastases, bone marrow adiposity correlated with tumor cell proliferation. By antagonization of the adipocyte differentiation and storage pathway linked to the peroxisome proliferator-activated receptor gamma (PPARγ) with bisphenol-A-diglycidylether (BADGE), we were able to decelerate tumor progression and subsequent osteolytic damage in the bones of two distinct metastatic animal models exposed to HFD. Overall these data show that adipose tissue is a critical factor in bone metastases and cancer-induced bone loss. © 2021 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Bay Leaf Extract-Based Near-Infrared Fluorescent Probe for Tissue and Cellular Imaging

The development of fluorescence dyes for near-infrared (NIR) fluorescence imaging has been a significant interest for deep tissue imaging. Among many imaging fluoroprobes, indocyanine green (ICG) and its analogues have been used in oncology and other medical applications. However, these imaging agents still experience poor imaging capabilities due to low tumor targetability, photostability, and sensitivity in the biological milieu. Thus, developing a biocompatible NIR imaging dye from natural resources holds the potential of facilitating cancer cell/tissue imaging. Chlorophyll (Chl) has been demonstrated to be a potential candidate for imaging purposes due to its natural NIR absorption qualities and its wide availability in plants and green vegetables. Therefore, it was our aim to assess the fluorescence characteristics of twelve dietary leaves as well as the fluorescence of their Chl extractions. Bay leaf extract, a high-fluorescence agent that showed the highest levels of fluorescence, was further evaluated for its tissue contrast and cellular imaging properties. Overall, this study confirms bay-leaf-associated dye as a NIR fluorescence imaging agent that may have important implications for cellular imaging and image-guided cancer surgery.

Role of magnetic resonance spectroscopy in differential diagnosis of solitary pulmonary lesions

PURPOSE

The aim of our study was to evaluate the availability of magnetic resonance spectroscopy (MRS) for the differentiation of benign or malignant pulmonary nodules and masses.

METHODS

A total of 59 patients (45 male, 14 female) with pulmonary nodules and masses were included in this prospective study. MRS was applied to the pulmonary lesions of the patients and choline levels were determined. Afterwards CT-guided percutaneous needle biopsy was performed. According to the biopsy results, pulmonary lesions were benign in 25 patients and malignant in 34 patients.

RESULTS

Choline levels were significantly higher in malignant lesions compared with benign lesions (p < 0.001). When the other conditions were kept constant, the probability of malignancy significantly increased by 17.38-fold (95% CI, 3.78-79.93) in those with choline levels >1.65 µmol/g compared to those with choline levels ≤1.65 µmol/g (p < 0.001).

CONCLUSION

MRS is a noninvasive method that can be used in the differential diagnosis of pulmonary nodules and masses.

Iron Oxide Nanoparticles: Physicochemical Characteristics and Historical Developments to Commercialization for Potential Technological Applications

Iron oxide nanoparticles (IONPs) have gained increasing attention in various biomedical and industrial sectors due to their physicochemical and magnetic properties. In the biomedical field, IONPs are being developed for enzyme/protein immobilization, magnetofection, cell labeling, DNA detection, and tissue engineering. However, in some established areas, such as magnetic resonance imaging (MRI), magnetic drug targeting (MDT), magnetic fluid hyperthermia (MFH), immunomagnetic separation (IMS), and magnetic particle imaging (MPI), IONPs have crossed from the research bench, received clinical approval, and have been commercialized. Additionally, in industrial sectors IONP-based fluids (ferrofluids) have been marketed in electronic and mechanical devices for some time. This review explores the historical evolution of IONPs to their current state in biomedical and industrial applications.

Radiolabeled Silicon-Rhodamines as Bimodal PET/SPECT-NIR Imaging Agents

Radiolabeled fluorescent dyes are decisive for bimodal imaging as well as highly in demand for nuclear- and optical imaging. Silicon-rhodamines (SiRs) show unique near-infrared (NIR) optical properties, large quantum yields and extinction coefficients as well as high photostability. Here, we describe the synthesis, characterization and radiolabeling of novel NIR absorbing and emitting fluorophores from the silicon-rhodamine family for use in optical imaging (OI) combined with positron emission tomography (PET) or single photon emission computed tomography (SPECT), respectively. The presented photostable SiRs were characterized using NMR-, UV-Vis-NIR-spectroscopy and mass spectrometry. Moreover, the radiolabeling conditions using fluorine-18 or iodine-123 were extensively explored. After optimization, the radiofluorinated NIR imaging agents were obtained with radiochemical conversions (RCC) up to 70% and isolated radiochemical yields (RCY) up to 54% at molar activities of g.t. 70 GBq/µmol. Radioiodination delivered RCCs over 92% and allowed to isolate the 123I-labeled product in RCY of 54% at a molar activity of g.t. 7.6 TBq/µmol. The radiofluorinated SiRs exhibit in vitro stabilities g.t. 70% after two hours in human serum. The first described radiolabeled SiRs are a promising step toward their further development as multimodal PET/SPECT-NIR imaging agents for planning and subsequent imaging-guided oncological surgery.

Effect of Peptide Receptor Radionuclide Therapy in Combination with Temozolomide against Tumor Angiogenesis in a Glioblastoma Model

Cell adhesion receptor integrin α_vβ₃ is a promising biomarker for developing tumor-angiogenesis targeted theranostics. In this study, we aimed to examine the therapeutic potential of peptide receptor radionuclide therapy (PRRT) with ¹⁸⁸Re-IDA-D-[c(RGDfK)]₂ (11.1 MBq). The results showed that the tumor volume was significantly decreased by 81% compared with the vehicle-treated group in U87-MG xenografts. The quantitative in vivo anti-angiogenic responses of PRRT were obtained using ^99mTc-IDA-D-[c(RGDfK)]₂ SPECT and corresponded to the measured tumor volume. PRRT combined with temozolomide (TMZ) resulted in a 93% reduction in tumor volume, which was markedly greater than that of each agent used individually. In addition, histopathological characterization showed that PRRT combined with TMZ was superior to PRRT or TMZ alone, even when TMZ was used at half dose. Overall, our results indicated that integrin-targeted PRRT and TMZ combined therapy might be a new medical tool for the effective treatment of glioblastoma.

Effect of testing for cancer on cancer- or venous thromboembolism (VTE)-related mortality and morbidity in people with unprovoked VTE

BACKGROUND

Venous thromboembolism (VTE) is a collective term for two conditions: deep vein thrombosis (DVT) and pulmonary embolism (PE). A proportion of people with VTE have no underlying or immediately predisposing risk factors and the VTE is referred to as unprovoked. Unprovoked VTE can often be the first clinical manifestation of an underlying malignancy. This has raised the question of whether people with an unprovoked VTE should be investigated for an underlying cancer. Treatment for VTE is different in cancer and non-cancer patients and a correct diagnosis would ensure that people received the optimal treatment for VTE to prevent recurrence and further morbidity. Furthermore, an appropriate cancer diagnosis at an earlier stage could avoid the risk of cancer progression and lead to improvements in cancer-related mortality and morbidity. This is the third update of the review first published in 2015.

OBJECTIVES

To determine whether testing for undiagnosed cancer in people with a first episode of unprovoked VTE (DVT of the lower limb or PE) is effective in reducing cancer- or VTE-related mortality and morbidity and to determine which tests for cancer are best at identifying treatable cancers early.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 5 May 2021. We also undertook reference checking to identify additional studies.

SELECTION CRITERIA

Randomised and quasi-randomised trials in which people with an unprovoked VTE were allocated to receive specific tests for identifying cancer or clinically indicated tests only were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed risk of bias and extracted data. We assessed the certainty of the evidence using GRADE criteria. We resolved any disagreements by discussion. The main outcomes of interest were all-cause mortality, cancer-related mortality and VTE-related mortality.

MAIN RESULTS

No new studies were identified for this 2021 update. In total, four studies with 1644 participants are included. Two studies assessed the effect of extensive tests including computed tomography (CT) scanning versus tests at the physician's discretion, while the other two studies assessed the effect of standard testing plus positron emission tomography (PET)/CT scanning versus standard testing alone. For extensive tests including CT versus tests at the physician's discretion, the certainty of the evidence, as assessed according to GRADE, was low due to risk of bias (early termination of the studies). When comparing standard testing plus PET/CT scanning versus standard testing alone, the certainty of evidence was moderate due to a risk of detection bias. The certainty of the evidence was downgraded further as detection bias was present in one study with a low number of events. When comparing extensive tests including CT versus tests at the physician's discretion, pooled analysis on two studies showed that testing for cancer was consistent with either benefit or no benefit on cancer-related mortality (odds ratio (OR) 0.49, 95% confidence interval (CI) 0.15 to 1.67; 396 participants; 2 studies; low-certainty evidence). One study (201 participants) showed that, overall, malignancies were less advanced at diagnosis in extensively tested participants than in participants in the control group. In total, 9/13 participants diagnosed with cancer in the extensively tested group had a T1 or T2 stage malignancy compared to 2/10 participants diagnosed with cancer in the control group (OR 5.00, 95% CI 1.05 to 23.76; low-certainty evidence). There was no clear difference in detection of advanced stages between extensive tests versus tests at the physician's discretion: one participant in the extensively tested group had stage T3 compared with four participants in the control group (OR 0.25, 95% CI 0.03 to 2.28; low-certainty evidence). In addition, extensively tested participants were diagnosed earlier than control group (mean: 1 month with extensive tests versus 11.6 months with tests at physician's discretion to cancer diagnosis from the time of diagnosis of VTE). Extensive testing did not increase the frequency of an underlying cancer diagnosis (OR 1.32, 95% CI 0.59 to 2.93; 396 participants; 2 studies; low-certainty evidence). Neither study measured all-cause mortality, VTE-related morbidity and mortality, complications of anticoagulation, adverse effects of cancer tests, participant satisfaction or quality of life. When comparing standard testing plus PET/CT screening versus standard testing alone, standard testing plus PET/CT screening was consistent with either benefit or no benefit on all-cause mortality (OR 1.22, 95% CI 0.49 to 3.04; 1248 participants; 2 studies; moderate-certainty evidence), cancer-related mortality (OR 0.55, 95% CI 0.20 to 1.52; 1248 participants; 2 studies; moderate-certainty evidence) or VTE-related morbidity (OR 1.02, 95% CI 0.48 to 2.17; 854 participants; 1 study; moderate-certainty evidence). Regarding stage of cancer, there was no clear difference for detection of early (OR 1.78, 95% 0.51 to 6.17; 394 participants; 1 study; low-certainty evidence) or advanced (OR 1.00, 95% CI 0.14 to 7.17; 394 participants; 1 study; low-certainty evidence) stages of cancer. There was also no clear difference in the frequency of an underlying cancer diagnosis (OR 1.71, 95% CI 0.91 to 3.20; 1248 participants; 2 studies; moderate-certainty evidence). Time to cancer diagnosis was 4.2 months in the standard testing group and 4.0 months in the standard testing plus PET/CT group (P = 0.88). Neither study measured VTE-related mortality, complications of anticoagulation, adverse effects of cancer tests, participant satisfaction or quality of life.

AUTHORS' CONCLUSIONS

Specific testing for cancer in people with unprovoked VTE may lead to earlier diagnosis of cancer at an earlier stage of the disease. However, there is currently insufficient evidence to draw definitive conclusions concerning the effectiveness of testing for undiagnosed cancer in people with a first episode of unprovoked VTE (DVT or PE) in reducing cancer- or VTE-related morbidity and mortality. The results could be consistent with either benefit or no benefit. Further good-quality large-scale randomised controlled trials are required before firm conclusions can be made.

Shining light on chiral inorganic nanomaterials for biological issues

The rapid development of chiral inorganic nanostructures has greatly expanded from intrinsically chiral nanoparticles to more sophisticated assemblies made by organics, metals, semiconductors, and their hybrids. Among them, lots of studies concerning on hybrid complex of chiral molecules with achiral nanoparticles (NPs) and superstructures with chiral configurations were accordingly conducted due to the great advances such as highly enhanced biocompatibility with low cytotoxicity and enhanced penetration and retention capability, programmable surface functionality with engineerable building blocks, and more importantly tunable chirality in a controlled manner, leading to revolutionary designs of new biomaterials for synergistic cancer therapy, control of enantiomeric enzymatic reactions, integration of metabolism and pathology via bio-to nano or structural chirality. Herein, in this review our objective is to emphasize current research state and clinical applications of chiral nanomaterials in biological systems with special attentions to chiral metal- or semiconductor-based nanostructures in terms of the basic synthesis, related circular dichroism effects at optical frequencies, mechanisms of induced optical chirality and their performances in biomedical applications such as phototherapy, bio-imaging, neurodegenerative diseases, gene editing, cellular activity and sensing of biomarkers so as to provide insights into this fascinating field for peer researchers.

Electrochemical immunoplatform to assist in the diagnosis of oral cancer through the determination of CYFRA 21.1 biomarker in human saliva samples: Preparation of a novel portable biosensor toward non-invasive diagnosis of oral cancer

In this study, a novel, low-cost, and flexible paper-based electrochemical immunosensor was developed for the bioanalysis of Cyfra 21.1 biomarker in human saliva samples by using stabilization of synthesis Ag nano-ink on the surface of paper using pen-on-paper technology. The employed electrochemical techniques for the evaluation of immunoplatform performance were differential pulse voltammetry and chronoamperometry. Also, the prepared immunosensor showed great ability in the determination of Cyfra21.1 in human saliva specimens. Under the optimized conditions, the obtained linear range was from 0.0025 to 10 ng/mL, and the obtained LLOQ was 0.0025 ng/mL. The developed immunosensor is easy to prepare, sensitive, cost-effective, portable, and simple. So proposed immunoplatform can be an accomplished biodevice in clinical laboratories. The proposed paper-based immunosensor could be a hopefully new and cheap tool for the diagnosis of other biomarkers. Also, the prepared immunosensor showed great ability in the determination of Cyfra21.1 biomarker in human saliva specimens.

Recent Advances in Photosensitizers as Multifunctional Theranostic Agents for Imaging-Guided Photodynamic Therapy of Cancer

In recent years tremendous effort has been invested in the field of cancer diagnosis and treatment with an overall goal of improving cancer management, therapeutic outcome, patient survival, and quality of life. Photodynamic Therapy (PDT), which works on the principle of light-induced activation of photosensitizers (PS) leading to Reactive Oxygen Species (ROS) mediated cancer cell killing has received increased attention as a promising alternative to overcome several limitations of conventional cancer therapies. Compared to conventional therapies, PDT offers the advantages of selectivity, minimal invasiveness, localized treatment, and spatio-temporal control which minimizes the overall therapeutic side effects and can be repeated as needed without interfering with other treatments and inducing treatment resistance. Overall PDT efficacy requires proper planning of various parameters like localization and concentration of PS at the tumor site, light dose, oxygen concentration and heterogeneity of the tumor microenvironment, which can be achieved with advanced imaging techniques. Consequently, there has been tremendous interest in the rationale design of PS formulations to exploit their theranostic potential to unleash the imperative contribution of medical imaging in the context of successful PDT outcomes. Further, recent advances in PS formulations as activatable phototheranostic agents have shown promising potential for finely controlled imaging-guided PDT due to their propensity to specifically turning on diagnostic signals simultaneously with photodynamic effects in response to the tumor-specific stimuli. In this review, we have summarized the recent progress in the development of PS-based multifunctional theranostic agents for biomedical applications in multimodal imaging combined with PDT. We also present the role of different imaging modalities; magnetic resonance, optical, nuclear, acoustic, and photoacoustic in improving the pre-and post-PDT effects. We anticipate that the information presented in this review will encourage future development and design of PSs for improved image-guided PDT for cancer treatment.

The Pharmaceutical Technology Approach on Imaging Innovations from Italian Research

Many modern therapeutic approaches are based on precise diagnostic evidence, where imaging procedures play an essential role. To date, in the diagnostic field, a plethora of agents have been investigated to increase the selectivity and sensitivity of diagnosis. However, the most common drawbacks of conventional imaging agents reside in their non-specificity, short imaging time, instability, and toxicity. Moreover, routinely used diagnostic agents have low molecular weights and consequently a rapid clearance and renal excretion, and this represents a limitation if long-lasting imaging analyses are to be conducted. Thus, the development of new agents for in vivo diagnostics requires not only a deep knowledge of the physical principles of the imaging techniques and of the physiopathological aspects of the disease but also of the relative pharmaceutical and biopharmaceutical requirements. In this scenario, skills in pharmaceutical technology have become highly indispensable in order to respond to these needs. This review specifically aims to collect examples of newly developed diagnostic agents connoting the importance of an appropriate formulation study for the realization of effective products. Within the context of pharmaceutical technology research in Italy, several groups have developed and patented promising agents for fluorescence and radioactive imaging, the most relevant of which are described hereafter.

State of Cancer Control in Rwanda: Past, Present, and Future Opportunities

Rwanda is a densely populated low-income country in East Africa. Previously considered a failed state after the genocide against the Tutsi in 1994, Rwanda has seen remarkable growth over the past 2 decades. Health care in Rwanda is predominantly delivered through public hospitals and is emerging in the private sector. More than 80% of patients are covered by community-based health insurance (Mutuelle de Santé). The cancer unit at the Rwanda Biomedical Center (a branch of the Ministry of Health) is responsible for setting and implementing cancer care policy. Rwanda has made progress with human papillomavirus (HPV) and hepatitis B vaccination. Recently, the cancer unit at the Rwanda Biomedical Center launched the country’s 5-year National Cancer Control Plan. Over the past decade, patients with cancer have been able to receive chemotherapy at Butaro Cancer Center, and recently, the Rwanda Cancer Center was launched with 2 linear accelerator radiotherapy machines, which greatly reduced the number of referrals for treatment abroad. Palliative care services are increasing in Rwanda. A cancer registry has now been strengthened, and more clinicians are becoming active in cancer research. Despite these advances, there is still substantial work to be done and there are many outstanding challenges, including the need to build capacity in cancer awareness among the general population (and shift toward earlier diagnosis), cancer care workforce (more in-country training programs are needed), and research.

Rational designed highly sensitive NQO1-activated near-infrared fluorescent probe combined with NQO1 substrates in vivo: An innovative strategy for NQO1-overexpressing cancer theranostics

Since NQO1 is overexpressed in many cancer cells, it can be used as a biomarker for cancer diagnosis and targeted therapy. NQO1 substrates show potent anticancer activity through the redox cycle mediated by NQO1, while the NQO1 probes can monitor NQO1 levels in cancers. High sensitivity of probes is needed for diagnostic imaging in clinic. In this study, based on the analysis of NQO1 catalytic pocket, the naphthoquinone trigger group 13 rationally designed by expanding the aromatic plane of the benzoquinone trigger group 10 shows significantly increased sensitivity to NQO1. The sensitivity of the naphthoquinone trigger group-based probe A was eight times higher than that of benzoquinone trigger group-based probe B in vivo. Probe A was selectively and efficiently sensitive to NQO1 with good safety profile and plasma stability, enabling its combination with NQO1 substrates in vivo for NQO1-overexpressing cancer theranostics for the first time.

Treating colon cancers with a non-conventional yet strategic approach: An overview of various nanoparticulate systems

Regardless of progress in therapy management which are developed for colon cancer (CC), it remains the third most common cause of mortality due to cancers around the world. Conventional medicines pose side effects due to untoward action on non-target cells. Their inability to deliver drugs to the affected regions of the colon locally, in a reproducible manner raises a concern towards the efficacy of therapy. In this regard, nanoparticles emerged as a promising drug delivery system due to their flexibility in designing, drug release modulation and cancer cell targeting. Not only are nanoparticles making their way into colon cancer research in the revolution of conventional onco-therapeutics, but they also offer promising scope in the development of colon cancer vaccines and theranostic tools. However, there are challenges with respect to drug delivery using nanoparticles, which may hamper the delivery of these novel carriers to the colon. The present review addresses recent advents in nanotechnology for colon-specific drug delivery (CDDS) which may help to overcome the existing challenges and intends to recognize futuristic potentials in the treatment of CC with CDDS.

Imaging Assessment of Tumor Response in the Era of Immunotherapy

Assessment of tumor response during treatment is one of the most important purposes of imaging. Before the appearance of immunotherapy, response evaluation criteria in solid tumors (RECIST) and positron emission tomography response criteria in solid tumors (PERCIST) were, respectively, the established morphologic and metabolic response criteria, and cessation of treatment was recommended when progressive disease was detected according to these criteria. However, various types of immunotherapy have been developed over the past 20 years, which show novel false positive findings on images, as well as distinct response patterns from conventional therapies. Antitumor immune response itself causes 18F-fluorodeoxyglucose (FDG) uptake in tumor sites, known as "flare phenomenon", so that positron emission tomography using FDG can no longer accurately identify remaining tumors. Furthermore, tumors often initially increase, followed by stability or decrease resulting from immunotherapy, which is called "pseudoprogression", so that progressive disease cannot be confirmed by computed tomography or magnetic resonance imaging at a single time point. As a result, neither RECIST nor PERCIST can accurately predict the response to immunotherapy, and therefore several new response criteria fixed for immunotherapy have been proposed. However, these criteria are still controversial, and also require months for response confirmation. The establishment of optimal response criteria and the development of new imaging technologies other than FDG are therefore urgently needed. In this review, we summarize the false positive images and the revision of response criteria for each immunotherapy, in order to avoid discontinuation of a truly effective immunotherapy.

Imaging Constructs: The Rise of Iron Oxide Nanoparticles

Over the last decade, an important challenge in nanomedicine imaging has been the work to design multifunctional agents that can be detected by single and/or multimodal techniques. Among the broad spectrum of nanoscale materials being investigated for imaging use, iron oxide nanoparticles have gained significant attention due to their intrinsic magnetic properties, low toxicity, large magnetic moments, superparamagnetic behaviour and large surface area-the latter being a particular advantage in its conjunction with specific moieties, dye molecules, and imaging probes. Tracers-based nanoparticles are promising candidates, since they combine synergistic advantages for non-invasive, highly sensitive, high-resolution, and quantitative imaging on different modalities. This study represents an overview of current advancements in magnetic materials with clinical potential that will hopefully provide an effective system for diagnosis in the near future. Further exploration is still needed to reveal their potential as promising candidates from simple functionalization of metal oxide nanomaterials up to medical imaging.

Zwitterionic Nanogels and Microgels: An Overview on Their Synthesis and Applications

Zwitterionic polymers by virtue of their unique chemical and physical attributes have attracted researchers in recent years. The simultaneous presence of positive and negative charges in the same repeat unit renders them of various interesting properties such as superhydrophilicity, which has significantly broadened their scope for being used in different applications. Among polyzwitterions of different architectures, micro- and/or nano-gels have started receiving attention only until recently. These 3D cross-linked colloidal structures show peculiar characteristics in context to their solution properties, which are attributable either to the comonomers present or the presence of different electrolytes and biological specimens. In this review, a concise yet detailed account is provided of the different synthetic techniques and application domains of zwitterion-based micro- and/or nanogels that have been explored in recent years. Here, the focus is kept solely on the "polybetaines," which have garnered maximum research interest and remain the extensively studied polyzwitterions in literature. While their vast application potential in the biomedical sector is being detailed here, some other areas of scope such as using them as microreactors for the synthesis of metal nanoparticles or making smart membranes for water-treatment are discussed in this minireview as well.

Investigation of Specific Targeting of Triptorelin-Conjugated Dextran-Coated Magnetite Nanoparticles as a Targeted Probe in GnRH+ Cancer Cells in MRI

In recent years, the conjugation of superparamagnetic iron oxide nanoparticles (SPIONs), as tumor-imaging probes for magnetic resonance imaging (MRI), with tumor targeting peptides possesses promising advantages for specific delivery of MRI agents. The objective of the current study was to design a targeted contrast agent for MRI based on Fe₃O₄ nanoparticles conjugated triptorelin (SPION@triptorelin), which has a great affinity to the GnRH receptors. The SPIONs-coated carboxymethyl dextran (SPION@CMD) conjugated triptorelin (SPION@CMD@triptorelin) were synthesized using coprecipitation method and characterized by DLS, TEM, XRD, FTIR, Zeta, and VSM techniques. The relaxivities of synthetized formulations were then calculated using a 1.5 Tesla clinical magnetic field. MRI, quantitative cellular uptake, and cytotoxicity level of them were estimated. The characterization results confirmed that the formation of SPION@CMD@triptorelin has been conjugated with a suitable size. Our results demonstrated the lack of cellular cytotoxicity of SPION@CMD@triptorelin, and it could increase the cellular uptake of SPIONs to MDA-MB-231 cancer cells 6.50-fold greater than to SPION@CMD at the concentration of 75 μM. The relaxivity calculations for SPION@CMD@triptorelin showed a suitable r₂ and r₂/r₁ with values of 31.75 mM⁻¹·s⁻¹ and 10.26, respectively. Our findings confirm that triptorelin-targeted SPIONs could provide a T₂-weighted probe contrast agent that has the great potential for the diagnosis of GnRH-positive cancer in MRI.

Novel cytosensor for accurate detection of circulating tumor cells based on a dual-recognition strategy and BSA@Ag@Ir metallic-organic nanoclusters

Herein, based on a dual-recognition strategy and BSA@Ag@Ir metallic-organic nanoclusters (BSA@Ag@Ir MONs), a highly specific and sensitive cytosensor was developed for detecting circulating tumor cells (CTCs). To amplify current signal, novel BSA@Ag@Ir MONs with outstanding catalytic activity and huge specific surface area were synthesized, and conjugated with hairpin DNA strands as signal probes. Orion carbon black 40 (Ocb40)//AuNPs were firstly used to modify electrode to increase its conductivity and surface area. Moreover, the dual recognition strategy based on DNA proximity effect was designed to improve the specificity of cytosensor. When two capture probes respectively bound to two adjacent membrane markers of target cells, the probes could form the associative toehold through the proximity effect to capture the signal probes. Only CTCs simultaneously expressing two membrane markers could be captured and generate current responses. The developed cytosensor could detect CTCs in the range of 3 - 3 × 10⁶ cells mL^-1 with a detection limit of 1 cell mL^-1. Notably, the cytosensor could accurately identify CTCs even in whole blood. Therefore, this cytosensor has great potential for application in biological science, biomedical engineering and personalized medicine.

Metal-phenolic networks: facile assembled complexes for cancer theranostics

In recent years, metal-phenolic networks (MPNs) have attracted increasing attention for the engineering of multi-functional platforms because of their easy fabrication processes, excellent physicochemical properties, outstanding biocompatibility, and promising theranostic applications. In this review, we summarize recent progress in the design, synthesis, shape-control, biocompatibility evaluation, and potential theranostic applications of MPNs, especially for cancer theranostics. First, we provide an overview of various MPN systems, relevant self-assembly procedures, and shape-controllable preparation. The in vitro and in vivo biocompatibility evaluation of MPNs is also discussed, including co-incubation viability, adhesion, bio-distribution, and inflammation. Finally, we highlight the significant achievements of various MPNs for cancer theranostics, such as tumor imaging, drug delivery, photothermal therapy, radiotherapy, and chemo- and photo-dynamic therapy. This review provides a comprehensive background on the design and controllable synthesis, in vitro and in vivo biocompatibility evaluation, applications of MPNs as cancer theranostic agents, and presents an overview of the most up-to-date achievements in this field.

Applications of Topological Data Analysis in Oncology

The emergence of the information age in the last few decades brought with it an explosion of biomedical data. But with great power comes great responsibility: there is now a pressing need for new data analysis algorithms to be developed to make sense of the data and transform this information into knowledge which can be directly translated into the clinic. Topological data analysis (TDA) provides a promising path forward: using tools from the mathematical field of algebraic topology, TDA provides a framework to extract insights into the often high-dimensional, incomplete, and noisy nature of biomedical data. Nowhere is this more evident than in the field of oncology, where patient-specific data is routinely presented to clinicians in a variety of forms, from imaging to single cell genomic sequencing. In this review, we focus on applications involving persistent homology, one of the main tools of TDA. We describe some recent successes of TDA in oncology, specifically in predicting treatment responses and prognosis, tumor segmentation and computer-aided diagnosis, disease classification, and cellular architecture determination. We also provide suggestions on avenues for future research including utilizing TDA to analyze cancer time-series data such as gene expression changes during pathogenesis, investigation of the relation between angiogenic vessel structure and treatment efficacy from imaging data, and experimental confirmation that geometric and topological connectivity implies functional connectivity in the context of cancer.

The P.I.N.K. Study Approach for Supporting Personalized Risk Assessment and Early Diagnosis of Breast Cancer

Breast cancer is a clear example of excellent survival when it is detected and properly treated in the early stage. Currently, screening of this cancer relies on mammography, which may be integrated by new imaging techniques for more exhaustive evaluation. The Personalized, Integrated, Network, Knowledge (P.I.N.K.) study is a longitudinal multicentric study involving several diagnostic centres across Italy, co-ordinated by the Italian National Research Council and co-funded by the Umberto Veronesi Foundation. Aim of the study is to evaluate the increased diagnostic accuracy in detecting cancers obtained with different combinations of imaging technologies, and find the most effective diagnostic pathway matching the characteristics of an individual patient. The study foresees the enrolment of 50,000 women over the age of 40 years presenting for breast examination and providing informed consent to data handling. So far, the 15 participating centres across Italy have recruited a total of 22,848 patients. Based on the analyses of the first 175 histopathological-proven breast cancers, mammographic sensitivity was estimated to be 61.7% (n = 108 cancers), whereas diagnostic accuracy increased by 35.5% (n = 44 cancers) when mammography was integrated with other imaging modalities (ultrasound and/or digital breast tomosynthesis). Increase was mainly determined by ultrasound alone. Given the ongoing data collection and recruitment, the number of cancers detected is too low to allow any further in-depth analysis to explore links to patient characteristics. Past studies show that the uniform approach of population screening guidelines should be revised in favour of more personalised regimens, where known standards are integrated by imaging techniques most suitable for the individual's characteristics. With the ultimate goal of identifying early breast cancer detection strategies, our preliminary results suggest that integrated diagnostic approach could lead to a paradigm shift from an age-based regimen toward more specific and effective risk-based personalised screening regimens, in order to reduce mortality from breast cancer.

Tunable blood oxygenation in the vascular anatomy of a semi-anthropomorphic photoacoustic breast phantom

SIGNIFICANCE

Recovering accurate oxygenation estimations in the breast with quantitative photoacoustic tomography (QPAT) is not straightforward. Accurate light fluence models are required, but the unknown ground truth of the breast makes it difficult to validate them. Phantoms are often used for the validation, but most reported phantoms have a simple architecture. Fluence models developed in these simplistic objects are not accurate for application on the complex tissues of the breast.

AIM

We present a sophisticated breast phantom platform for photoacoustic (PA) and ultrasound (US) imaging in general, and specifically for QPAT. The breast phantom is semi-anthropomorphic in distribution of optical and acoustic properties and contains wall-less channels with blood.

APPROACH

3D printing approaches are used to develop the solid 3D breast phantom from custom polyvinyl chloride plastisol formulations and additives for replicating the tissue optical and acoustic properties. A flow circuit was developed to flush the channels with bovine blood with a controlled oxygen saturation level. To showcase the phantom's functionality, PA measurements were performed on the phantom with two oxygenation levels. Image reconstructions with and without fluence compensation from Monte Carlo simulations were analyzed for the accuracy of oxygen saturation estimations.

RESULTS

We present design aspects of the phantom, demonstrate how it is developed, and present its breast-like appearance in PA and US imaging. The oxygen saturations were estimated in two regions of interest with and without using the fluence models. The fluence compensation positively influenced the SO2 estimations in all cases and confirmed that highly accurate fluence models are required to minimize estimation errors.

CONCLUSIONS

This phantom allows studies to be performed in PA in carefully controlled laboratory settings to validate approaches to recover both qualitative and quantitative features sought after in in-vivo studies. We believe that testing with phantoms of this complexity can streamline the transition of new PA technologies from the laboratory to studies in the clinic.

Internally Responsive Nanomaterials for Activatable Multimodal Imaging of Cancer

Advances in technology and nanomedicine have led to the development of nanoparticles that can be activated for multimodal imaging of cancer, where a stimulus induces a material modification that enhances image contrast. Multimodal imaging using nanomaterials with this capability can combine the advantages and overcome the limitations of any single imaging modality. When designed with stimuli-responsive abilities, the target-to-background ratio of multimodal imaging nanoprobes increases because specific stimuli in the tumor enhance the signal. Several aspects of the tumor microenvironment can be exploited as an internal stimulus response for multimodal imaging applications, such as the pH gradient, redox processes, overproduction of various enzymes, or combinations of these. In this review, design strategies are discussed and an overview of the recent developments of internally responsive multimodal nanomaterials is provided. Properly implementing this approach improves noninvasive cancer diagnosis and staging as well as provides a method to monitor drug delivery and treatment response.

Radiomics in immuno-oncology

With the ongoing advances in imaging techniques, increasing volumes of anatomical and functional data are being generated as part of the routine clinical workflow. This surge of available imaging data coincides with increasing research in quantitative imaging, particularly in the domain of imaging features. An important and novel approach is radiomics, where high-dimensional image properties are extracted from routine medical images. The fundamental principle of radiomics is the hypothesis that biomedical images contain predictive information, not discernible to the human eye, that can be mined through quantitative image analysis. In this review, a general outline of radiomics and artificial intelligence (AI) will be provided, along with prominent use cases in immunotherapy (e.g. response and adverse event prediction) and targeted therapy (i.e. radiogenomics). While the increased use and development of radiomics and AI in immuno-oncology is highly promising, the technology is still in its early stages, and different challenges still need to be overcome. Nevertheless, novel AI algorithms are being constructed with an ever-increasing scope of applications.

Radiogenomics in Colorectal Cancer

Simple Summary

Colorectal carcinoma is characterized by intratumoral heterogeneity that can be assessed by radiogenomics. Radiomics, high-throughput quantitative data extracted from medical imaging, combined with molecular analysis, through genomic and transcriptomic data, is expected to lead to significant advances in personalized medicine. However, a radiogenomics approach in colorectal cancer is still in its early stages and many problems remain to be solved. Here we review the progress and challenges in this field at its current stage, as well as future developments.

Abstract

The steady improvement of high-throughput technologies greatly facilitates the implementation of personalized precision medicine. Characterization of tumor heterogeneity through image-derived features—radiomics and genetic profile modifications—genomics, is a rapidly evolving field known as radiogenomics. Various radiogenomics studies have been dedicated to colorectal cancer so far, highlighting the potential of these approaches to enhance clinical decision-making. In this review, a general outline of colorectal radiogenomics literature is provided, discussing the current limitations and suggested further developments.

A Systematic Review of PET Textural Analysis and Radiomics in Cancer

Background: Although many works have supported the utility of PET radiomics, several authors have raised concerns over the robustness and replicability of the results. This study aimed to perform a systematic review on the topic of PET radiomics and the used methodologies. Methods: PubMed was searched up to 15 October 2020. Original research articles based on human data specifying at least one tumor type and PET image were included, excluding those that apply only first-order statistics and those including fewer than 20 patients. Each publication, cancer type, objective and several methodological parameters (number of patients and features, validation approach, among other things) were extracted. Results: A total of 290 studies were included. Lung (28%) and head and neck (24%) were the most studied cancers. The most common objective was prognosis/treatment response (46%), followed by diagnosis/staging (21%), tumor characterization (18%) and technical evaluations (15%). The average number of patients included was 114 (median = 71; range 20–1419), and the average number of high-order features calculated per study was 31 (median = 26, range 1–286). Conclusions: PET radiomics is a promising field, but the number of patients in most publications is insufficient, and very few papers perform in-depth validations. The role of standardization initiatives will be crucial in the upcoming years.

Worm-Based Microfluidic Biosensor for Real-Time Assessment of the Metastatic Status

Simple Summary

We proposed a high-throughput screening and low-cost worm-based (WB) microfluidic biosensor to monitor biochemical cues related to metastasis. Caenorhabditis elegans placed in the WB biosensor chambers and exposed to samples conditioned with cancer cell clusters reflect differences in the chemotactic preference of worms. We observed a higher distribution of worms associated with samples of higher metastatic potential (p < 0.005). A chemotaxis index (CI) was defined to standardize the quantitative assessment from the WB biosensor, where increased metastatic potential was associated with higher CI levels (6.5 ± 1.37). We found that the secreted metabolite glutamate was a chemorepellent, and lower glutamate levels were associated with samples derived from more metastatic cancer cell clusters. In conclusion, WB biosensors could evaluate patient status in real time, thereby facilitating early detection of metastases and routine management.

Abstract

Background: Metastasis is a complex process that affects patient treatment and survival. To routinely monitor cancer plasticity and guide treatment strategies, it is highly desired to provide information about metastatic status in real-time. Here, we proposed a worm-based (WB) microfluidic biosensor to rapidly monitor biochemical cues related to metastasis in a well-defined environment. Compared to conventional biomarker-based methods, the WB biosensor allowed high throughput screening under low cost, requiring only visual quantification of outputs; Methods: Caenorhabditis elegans were placed in the WB biosensor and exposed to samples conditioned with cancer cell clusters. The chemotactic preference of these worms was observed under discontinuous imaging to minimize the impact on physiological activity; Results: A chemotaxis index (CI) was defined to standardize the quantitative assessment from the WB biosensor, where moderate (3.24–6.5) and high (>6.5) CI levels reflected increased metastasis risk and presence of metastasis, respectively. We demonstrated that the secreted metabolite glutamate was a chemorepellent, and larger clusters associated with increased metastatic potential also enhanced CI levels; Conclusions: Overall, this study provided a proof of concept for the WB biosensors in assessing metastasis status, with the potential to evaluate patient-derived cancer clusters for routine management.

Polytetrafluoroethylene-like Nanoparticles as a Promising Contrast Agent for Dual Modal Ultrasound and X-ray Bioimaging

Various noninvasive imaging techniques are used to produce deep-tissue and high-resolution images for biomedical research and clinical purposes. Organic and inorganic bioimaging agents have been developed to enhance the resolution and contrast intensity. This paper describes the synthesis of polytetrafluoroethylene-like nanoparticles (PTFE≈ NPs), their characterization, biological activity, and bioimaging properties. Transmission electron microscopy (TEM) images showed the shape and the size of the as-obtained small and ultrasmall PTFE≈ NPs. Fourier transform infrared spectroscopy (FTIR) confirmed the PTFE-like character of the samples. X-ray diffraction (XRD) enabled the determination of the crystallization system, cell lattice, and index of crystallinity of the material in addition to the presence of titania (TiO₂) as the contamination. These findings were corroborated by X-ray photoelectron spectroscopy (XPS) that identifies the chemical states of the elements present in the samples along with their atomic percentages allowing the determination of both the purity index of the sample and the nature of the impurities. Additionally, diffuse reflectance ultraviolet-visible spectroscopy (UV-vis) was used to further assess the optical properties of the materials. Importantly, PTFE≈ NPs showed significant in vitro and in vivo biocompatibility. Lastly, PTFE≈ NPs were tested for their ultrasound and X-ray contrast properties. Our encouraging preliminary results open new avenues for PTFE-like nanomaterials as a suitable multifunctional contrast agent for biomedical imaging applications. Combined with suitable surface chemistry and morphology design, these findings shed light to new opportunities offered by PTFE nanoparticles in the ever-booming biomedical field.

Deep Learning-Based Annotation Transfer between Molecular Imaging Modalities: An Automated Workflow for Multimodal Data Integration

An ever-increasing array of imaging technologies are being used in the study of complex biological samples, each of which provides complementary, occasionally overlapping information at different length scales and spatial resolutions. It is important to understand the information provided by one technique in the context of the other to achieve a more holistic overview of such complex samples. One way to achieve this is to use annotations from one modality to investigate additional modalities. For microscopy-based techniques, these annotations could be manually generated using digital pathology software or automatically generated by machine learning (including deep learning) methods. Here, we present a generic method for using annotations from one microscopy modality to extract information from complementary modalities. We also present a fast, general, multimodal registration workflow [evaluated on multiple mass spectrometry imaging (MSI) modalities, matrix-assisted laser desorption/ionization, desorption electrospray ionization, and rapid evaporative ionization mass spectrometry] for automatic alignment of complex data sets, demonstrating an order of magnitude speed-up compared to previously published work. To demonstrate the power of the annotation transfer and multimodal registration workflows, we combine MSI, histological staining (such as hematoxylin and eosin), and deep learning (automatic annotation of histology images) to investigate a pancreatic cancer mouse model. Neoplastic pancreatic tissue regions, which were histologically indistinguishable from one another, were observed to be metabolically different. We demonstrate the use of the proposed methods to better understand tumor heterogeneity and the tumor microenvironment by transferring machine learning results freely between the two modalities.

Bioconjugated technetium carbonyls by transmetalation reaction with zinc derivatives

The transmetalation reaction between zinc dithiocarbamates functionalized with organic groups and the cation fac-[^99mTc(H₂O)₃(CO)₃]⁺ has been studied as a new strategy to bind biomolecules to this radionuclide for preparing radiopharmaceuticals with high molar activity. All complexes were obtained in high yields by heating at moderate temperatures and without subsequent purification. The chemical identity was ascertained by HPLC comparison with the homologous rhenium complexes. Stability studies in cysteine solution and serum have shown a good stability of the coordination set fac-[^99mTc(CO)₃(SS)(P)]. Preliminary biological studies of the radiocomplex functionalized with D-(+)-glucosamine with carcinoma cells have been performed.