The role of new PET tracers for lung cancer

Imaging at the nexus: how state of the art imaging techniques can enhance our understanding of cancer and fibrosis

Both cancer and fibrosis are diseases involving dysregulation of cell signaling pathways resulting in an altered cellular microenvironment which ultimately leads to progression of the condition. The two disease entities share common molecular pathophysiology and recent research has illuminated the how each promotes the other. Multiple imaging techniques have been developed to aid in the early and accurate diagnosis of each disease, and given the commonalities between the pathophysiology of the conditions, advances in imaging one disease have opened new avenues to study the other. Here, we detail the most up-to-date advances in imaging techniques for each disease and how they have crossed over to improve detection and monitoring of the other. We explore techniques in positron emission tomography (PET), magnetic resonance imaging (MRI), second generation harmonic Imaging (SGHI), ultrasound (US), radiomics, and artificial intelligence (AI). A new diagnostic imaging tool in PET/computed tomography (CT) is the use of radiolabeled fibroblast activation protein inhibitor (FAPI). SGHI uses high-frequency sound waves to penetrate deeper into the tissue, providing a more detailed view of the tumor microenvironment. Artificial intelligence with the aid of advanced deep learning (DL) algorithms has been highly effective in training computer systems to diagnose and classify neoplastic lesions in multiple organs. Ultimately, advancing imaging techniques in cancer and fibrosis can lead to significantly more timely and accurate diagnoses of both diseases resulting in better patient outcomes.

Machine Learning in Diagnosis and Prognosis of Lung Cancer by PET-CT

As a disease with high morbidity and high mortality, lung cancer has seriously harmed people's health. Therefore, early diagnosis and treatment are more important. PET/CT is usually used to obtain the early diagnosis, staging, and curative effect evaluation of tumors, especially lung cancer, due to the heterogeneity of tumors and the differences in artificial image interpretation and other reasons, it also fails to entirely reflect the real situation of tumors. Artificial intelligence (AI) has been applied to all aspects of life. Machine learning (ML) is one of the important ways to realize AI. With the help of the ML method used by PET/CT imaging technology, there are many studies in the diagnosis and treatment of lung cancer. This article summarizes the application progress of ML based on PET/CT in lung cancer, in order to better serve the clinical. In this study, we searched PubMed using machine learning, lung cancer, and PET/CT as keywords to find relevant articles in the past 5 years or more. We found that PET/CT-based ML approaches have achieved significant results in the detection, delineation, classification of pathology, molecular subtyping, staging, and response assessment with survival and prognosis of lung cancer, which can provide clinicians a powerful tool to support and assist in critical daily clinical decisions. However, ML has some shortcomings such as slightly poor repeatability and reliability.

Radionuclide-based theranostics - a promising strategy for lung cancer

PURPOSE

This review aims to provide a comprehensive overview of the latest literature on personalized lung cancer management using different ligands and radionuclide-based tumor-targeting agents.

BACKGROUND

Lung cancer is the leading cause of cancer-related deaths worldwide. Due to the heterogeneity of lung cancer, advances in precision medicine may enhance the disease management landscape. More recently, theranostics using the same molecule labeled with two different radionuclides for imaging and treatment has emerged as a promising strategy for systemic cancer management. In radionuclide-based theranostics, the target, ligand, and radionuclide should all be carefully considered to achieve an accurate diagnosis and optimal therapeutic effects for lung cancer.

METHODS

We summarize the latest radiotracers and radioligand therapeutic agents used in diagnosing and treating lung cancer. In addition, we discuss the potential clinical applications and limitations associated with target-dependent radiotracers as well as therapeutic radionuclides. Finally, we provide our views on the perspectives for future development in this field.

CONCLUSIONS

Radionuclide-based theranostics show great potential in tailored medical care. We expect that this review can provide an understanding of the latest advances in radionuclide therapy for lung cancer and promote the application of radioligand theranostics in personalized medicine.

Novel Targets, Novel Treatments: The Changing Landscape of Non-Small Cell Lung Cancer

Treatment of non-small cell lung cancer (NSCLC) has undergone a paradigm shift. Once a disease with limited potential therapies, treatment options for patients have exploded with the availability of molecular testing to direct management and targeted therapies to treat tumors with specific driver mutations. New in vitro diagnostics allow for the early and non-invasive detection of disease, and emerging in vivo imaging techniques allow for better detection and monitoring. The development of checkpoint inhibitor immunotherapy has arguably been the biggest advance in lung cancer treatment, given that the vast majority of NSCLC tumors can be treated with these therapies. Specific targeted therapies, including those against KRAS, EGFR, RTK, and others have also improved the outcomes for those individuals bearing an actionable mutation. New and emerging therapies, such as bispecific antibodies, CAR T cell therapy, and molecular targeted radiotherapy, offer promise to patients for whom none of the existing therapies have proved effective. In this review, we provide the most up-to-date survey to our knowledge regarding emerging diagnostic and therapeutic strategies for lung cancer to provide clinicians with a comprehensive reference of the options for treatment available now and those which are soon to come.

Imaging drug delivery to the lungs: Methods and applications in oncology

Direct delivery to the lung via inhalation is arguably one of the most logical approaches to treat lung cancer using drugs. However, despite significant efforts and investment in this area, this strategy has not progressed in clinical trials. Imaging drug delivery is a powerful tool to understand and develop novel drug delivery strategies. In this review we focus on imaging studies of drug delivery by the inhalation route, to provide a broad overview of the field to date and attempt to better understand the complexities of this route of administration and the significant barriers that it faces, as well as its advantages. We start with a discussion of the specific challenges for drug delivery to the lung via inhalation. We focus on the barriers that have prevented progress of this approach in oncology, as well as the most recent developments in this area. This is followed by a comprehensive overview of the different imaging modalities that are relevant to lung drug delivery, including nuclear imaging, X-ray imaging, magnetic resonance imaging, optical imaging and mass spectrometry imaging. For each of these modalities, examples from the literature where these techniques have been explored are provided. Finally the different applications of these technologies in oncology are discussed, focusing separately on small molecules and nanomedicines. We hope that this comprehensive review will be informative to the field and will guide the future preclinical and clinical development of this promising drug delivery strategy to maximise its therapeutic potential.

Positron emission tomography imaging of lung cancer: An overview of alternative positron emission tomography tracers beyond F18 fluorodeoxyglucose

Lung cancer has been the leading cause of cancer-related mortality in China in recent decades. Positron emission tomography-computer tomography (PET/CT) has been established in the diagnosis of lung cancer. ¹⁸F-FDG is the most widely used PET tracer in foci diagnosis, tumor staging, treatment planning, and prognosis assessment by monitoring abnormally exuberant glucose metabolism in tumors. However, with the increasing knowledge on tumor heterogeneity and biological characteristics in lung cancer, a variety of novel radiotracers beyond ¹⁸F-FDG for PET imaging have been developed. For example, PET tracers that target cellular proliferation, amino acid metabolism and transportation, tumor hypoxia, angiogenesis, pulmonary NETs and other targets, such as tyrosine kinases and cancer-associated fibroblasts, have been reported, evaluated in animal models or under clinical investigations in recent years and play increasing roles in lung cancer diagnosis. Thus, we perform a comprehensive literature review of the radiopharmaceuticals and recent progress in PET tracers for the study of lung cancer biological characteristics beyond glucose metabolism.

Radiopharmaceuticals for PET and SPECT Imaging: A Literature Review over the Last Decade

Positron emission tomography (PET) uses radioactive tracers and enables the functional imaging of several metabolic processes, blood flow measurements, regional chemical composition, and/or chemical absorption. Depending on the targeted processes within the living organism, different tracers are used for various medical conditions, such as cancer, particular brain pathologies, cardiac events, and bone lesions, where the most commonly used tracers are radiolabeled with 18F (e.g., [18F]-FDG and NA [18F]). Oxygen-15 isotope is mostly involved in blood flow measurements, whereas a wide array of 11C-based compounds have also been developed for neuronal disorders according to the affected neuroreceptors, prostate cancer, and lung carcinomas. In contrast, the single-photon emission computed tomography (SPECT) technique uses gamma-emitting radioisotopes and can be used to diagnose strokes, seizures, bone illnesses, and infections by gauging the blood flow and radio distribution within tissues and organs. The radioisotopes typically used in SPECT imaging are iodine-123, technetium-99m, xenon-133, thallium-201, and indium-111. This systematic review article aims to clarify and disseminate the available scientific literature focused on PET/SPECT radiotracers and to provide an overview of the conducted research within the past decade, with an additional focus on the novel radiopharmaceuticals developed for medical imaging.

Predictive Value of 18F-FDG PET/CT Using Machine Learning for Pathological Response to Neoadjuvant Concurrent Chemoradiotherapy in Patients with Stage III Non-Small Cell Lung Cancer

We investigated predictions from 18F-FDG PET/CT using machine learning (ML) to assess the neoadjuvant CCRT response of patients with stage III non-small cell lung cancer (NSCLC) and compared them with predictions from conventional PET parameters and from physicians. A retrospective study was conducted of 430 patients. They underwent 18F-FDG PET/CT before initial treatment and after neoadjuvant CCRT followed by curative surgery. We analyzed texture features from segmented tumors and reviewed the pathologic response. The ML model employed a random forest and was used to classify the binary outcome of the pathological complete response (pCR). The predictive accuracy of the ML model for the pCR was 93.4%. The accuracy of predicting pCR using the conventional PET parameters was up to 70.9%, and the accuracy of the physicians’ assessment was 80.5%. The accuracy of the prediction from the ML model was significantly higher than those derived from conventional PET parameters and provided by physicians (p < 0.05). The ML model is useful for predicting pCR after neoadjuvant CCRT, which showed a higher predictive accuracy than those achieved from conventional PET parameters and from physicians.

Alternative methods for local ablation-interventional pulmonology: a narrative review

OBJECTIVE

To discuss and summarise the background and recent advances in the approach to bronchoscopic ablative therapies for lung cancer, focusing on focal parenchymal lesions.

BACKGROUND

This series focusses on the challenges highlighted by increasing recognition of the prognostically more favourable oligometastatic disease rather than the more frequent, but prognostically poor, high tumour burden metastatic disease. While surgery, stereotactic body radiation therapy (SBRT), and trans-thoracic percutaneous ablative techniques such as microwave (MWA) and radiofrequency ablation (RFA) are well recognised options for selected cases of pulmonary oligometastasis, bronchoscopic approaches to pulmonary tumour ablation are becoming realistic alternatives. An underlying tenet driving research and implementation in this domain is that percutaneous ablative techniques are obliged to traverse the pleura leading to a high rate of pneumothorax, and risks also goes up for peri-vascular lesions. Historically low yield bronchoscopic targeting of isolated peripheral tumors have significantly improved by incorporating multi-modality high resolution imaging and processing, including navigation planning and real-time image guidances (ultrasound, electromagnetic navigation, cone-beam CT). Combining advanced image guidance with ablative technology adaptations for bronchoscopic delivery opens up the options for high dose local ablative therapies that may reduce transthoracic complications and provide palliative to curative options for limited stage primary and oligometastatic diseases.

METHODS

We conduct a narrative review of the literature summarizing the history of bronchoscopic tumor ablation approaches, technical details including biologic rational for their uses, and current evidence for each modality, as well as investigations into future applications. Because of the relative paucity of prospective studies, we have been very inclusive in our inclusion of experiences from the published clinical databases.

CONCLUSIONS

Whilst surgical resection and SBRT remain the current mainstay of curative therapies for peripheral cancers, in the foreseeable future, developments and further research will see bronchoscopic ablative therapies become viable lung sparing alternatives in those deemed suitable. The future is bright.

Assessing tumor angiogenesis using dynamic contrast-enhanced integrated magnetic resonance-positron emission tomography in patients with non-small-cell lung cancer

Background

Angiogenesis assessment is important for personalized therapeutic intervention in patients with non-small-cell lung cancer (NSCLC). This study investigated whether radiologic parameters obtained by dynamic contrast-enhanced (DCE)-integrated magnetic resonance-positron emission tomography (MR-PET) could be used to quantitatively assess tumor angiogenesis in NSCLC.

Methods

This prospective cohort study included 75 patients with NSCLC who underwent DCE-integrated MR-PET at diagnosis. The following parameters were analyzed: metabolic tumor volume (MTV), maximum standardized uptake value (SUV_max), reverse reflux rate constant (k_ep), volume transfer constant (K^trans), blood plasma volume fraction (v_p), extracellular extravascular volume fraction (v_e), apparent diffusion coefficient (ADC), and initial area under the time-to-signal intensity curve at 60 s post enhancement (iAUC₆₀). Serum biomarkers of tumor angiogenesis, including vascular endothelial growth factor-A (VEGF-A), angiogenin, and angiopoietin-1, were measured by enzyme-linked immunosorbent assays simultaneously.

Results

Serum VEGF-A (p = 0.002), angiogenin (p = 0.023), and Ang-1 (p <  0.001) concentrations were significantly elevated in NSCLC patients compared with healthy individuals. MR-PET parameters, including MTV, K^trans, and k_ep, showed strong linear correlations (p <  0.001) with serum angiogenesis-related biomarkers. Serum VEGF-A concentrations (p = 0.004), MTV values (p <  0.001), and k_ep values (p = 0.029) were significantly higher in patients with advanced-stage disease (stage III or IV) than in those with early-stage disease (stage I or II). Patients with initial higher values of angiogenesis-related MR-PET parameters, including MTV > 30 cm³ (p = 0.046), K^trans > 200 10^− 3/min (p = 0.069), and k_ep > 900 10^− 3/min (p = 0.048), may have benefited from angiogenesis inhibitor therapy, which thus led to significantly longer overall survival.

Conclusions

The present findings suggest that DCE-integrated MR-PET provides a reliable, non-invasive, quantitative assessment of tumor angiogenesis; can guide the use of angiogenesis inhibitors toward longer survival; and will play an important role in the personalized treatment of NSCLC.

Imaging Biomarkers of Tumour Proliferation and Invasion for Personalised Lung Cancer Therapy

Personalised treatment in oncology has seen great developments over the last decade, due to both technological advances and more in-depth knowledge of radiobiological processes occurring in tumours. Lung cancer therapy is no exception, as new molecular targets have been identified to further increase treatment specificity and sensitivity. Yet, tumour resistance to treatment is still one of the main reasons for treatment failure. This is due to a number of factors, among which tumour proliferation, the presence of cancer stem cells and the metastatic potential of the primary tumour are key features that require better controlling to further improve cancer management in general, and lung cancer treatment in particular. Imaging biomarkers play a key role in the identification of biological particularities within tumours and therefore are an important component of treatment personalisation in radiotherapy. Imaging techniques such as PET, SPECT, MRI that employ tumour-specific biomarkers already play a critical role in patient stratification towards individualized treatment. The aim of the current paper is to describe the radiobiological challenges of lung cancer treatment in relation to the latest imaging biomarkers that can aid in the identification of hostile cellular features for further treatment adaptation and tailoring to the individual patient’s needs.

Modern radiopharmaceuticals for lung cancer imaging with positron emission tomography/computed tomography scan: A systematic review

Introduction:

In this study, we evaluated the use and the contribution of radiopharmaceuticals to the field of lung neoplasms imaging using positron emission tomography/computed tomography.

Methods:

We conducted review of the current literature at PubMed/MEDLINE until February 2020. The search language was English.

Results:

The most widely used radiopharmaceuticals are the following:

Experimental/pre-clinical approaches: (18)F-Misonidazole (18F-MISO) under clinical development, D(18)F-Fluoro-Methyl-Tyrosine (18F-FMT), 18F-FAMT (L-[3-18F] (18)F-Fluorothymidine (18F-FLT)), (18)F-Fluoro-Azomycin-Arabinoside (18F-FAZA), (68)Ga-Neomannosylated-Human-Serum-Albumin (68Ga-MSA) (23), (68)Ga-Tetraazacyclododecane (68Ga-DOTA) (as theranostic agent), (11)C-Methionine (11C-MET), 18F-FPDOPA, α_νβ₃ integrin, ⁶⁸Ga-RGD₂, ⁶⁴Cu-DOTA-RGD, ¹⁸F-Alfatide, Folate Radio tracers, and immuno-positron emission tomography radiopharmaceutical agents.

Clinically approved procedures/radiopharmaceuticals agents: (18)F-Fluoro-Deoxy-Glucose (18F-FDG), (18)F-sodium fluoride (18F-NaF) (bone metastases), and (68)Ga-Tetraazacyclododecane (68Ga-DOTA). The quantitative determination and the change in radiopharmaceutical uptake parameters such as standard uptake value, metabolic tumor volume, total lesion glycolysis, FAZA tumor to muscle ratio, standard uptake value tumor to liver ratio, standard uptake value tumor to spleen ratio, standard uptake value maximum ratio, and the degree of hypoxia have prognostic and predictive (concerning the therapeutic outcome) value. They have been associated with the assessment of overall survival and disease free survival. With the positron emission tomography/computed tomography radiopharmaceuticals, the sensitivity and the specificity of the method have increased.

Conclusion:

In terms of lung cancer, positron emission tomography/computed tomography may have clinical application and utility (a) in personalizing treatment, (b) as a biomarker for the estimation of overall survival, disease free survival, and (c) apply a cost-effective patient approach because it reveals focuses of the disease, which are not found with the other imaging methods.

Current Applications for Nuclear Medicine Imaging in Pulmonary Disease

Purpose of Review

The main goal of the article is to familiarize the reader with commonly and uncommonly used nuclear medicine procedures that can significantly contribute to improved patient care. The article presents examples of specific modality utilization in the chest including assessment of lung ventilation and perfusion, imaging options for broad range of infectious and inflammatory processes, and selected aspects of oncologic imaging. In addition, rapidly developing new techniques utilizing molecular imaging are discussed.

Recent Findings

The article describes nuclear medicine imaging modalities including gamma camera, SPECT, PET, and hybrid imaging (SPECT/CT, PET/CT, and PET/MR) in the context of established and emerging clinical applications. Areas of potential future development in nuclear medicine are discussed with emphasis on molecular imaging and implementation of new targeted tracers used in diagnostics and therapeutics (theranostics).

Summary

Nuclear medicine and molecular imaging provide many unique and novel options for the diagnosis and treatment of pulmonary diseases. This article reviews current applications for nuclear medicine and molecular imaging and selected future applications for radiopharmaceuticals and targeted molecular imaging techniques.

Preoperative staging of the mediastinum is an essential and multidisciplinary task

Mediastinal staging is a crucial step in the management of patients with NSCLC. With the recent development of novel techniques, mediastinal staging has evolved from an activity of interest mainly for thoracic surgeons to a joint effort carried out by many specialists. In this regard, the debate of cases in MDT sessions is crucial for optimal management of patients. Current evidence-based clinical guidelines for preoperative NSCLC staging recommend that mediastinal staging should be performed with increasing invasiveness. Image-based techniques are the first approach, although they have limited accuracy and findings must be confirmed by pathology in almost all cases. In this setting, the advent of radiomics is promising. Invasive staging depends on procedural factors rather than diagnostic performance. The choice between endoscopy-based or surgical procedures should depend on the local expertise of each centre. As the extension of mediastinal disease in terms of number of involved lymph nodes and nodal stations affects prognosis and the choice of treatment, systematic samplings are preferred over random targeted samplings. Following this approach, a diagnosis of single mediastinal nodal involvement can be unreliable if all reachable mediastinal nodal stations have not been assessed. The performance of confirmatory mediastinoscopy after a negative endoscopy-based procedure is controversial but currently recommended. Current indications of invasive staging in patients with radiologically normal mediastinum have to be re-evaluated, especially for central tumour location.

Robust, independent and relevant prognostic 18F-fluorodeoxyglucose positron emission tomography radiomics features in non-small cell lung cancer: Are there any?

In locally advanced lung cancer, established baseline clinical variables show limited prognostic accuracy and ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET) radiomics features may increase accuracy for optimal treatment selection. Their robustness and added value relative to current clinical factors are unknown. Hence, we identify robust and independent PET radiomics features that may have complementary value in predicting survival endpoints. A 4D PET dataset (n = 70) was used for assessing the repeatability (Bland-Altman analysis) and independence of PET radiomics features (Spearman rank: |ρ|<0.5). Two 3D PET datasets combined (n = 252) were used for training and validation of an elastic net regularized generalized logistic regression model (GLM) based on a selection of clinical and robust independent PET radiomics features (GLM_all). The fitted model performance was externally validated (n = 40). The performance of GLM_all (measured with area under the receiver operating characteristic curve, AUC) was highest in predicting 2-year overall survival (0.66±0.07). No significant improvement was observed for GLM_all compared to a model containing only PET radiomics features or only clinical variables for any clinical endpoint. External validation of GLM_all led to AUC values no higher than 0.55 for any clinical endpoint. In this study, robust independent FDG PET radiomics features did not have complementary value in predicting survival endpoints in lung cancer patients. Improving risk stratification and clinical decision making based on clinical variables and PET radiomics features has still been proven difficult in locally advanced lung cancer patients.

Early Response Assessment to Targeted Therapy Using 3'-deoxy-3'[(18)F]-Fluorothymidine (18F-FLT) PET/CT in Lung Cancer

Although 2-deoxy-2-[18F]-fluoro-D-glucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) is a sensitive nuclear medicine modality, specificity for characterizing lung cancer is limited. Tumor proliferation and early response to molecularly targeted therapy could be visualized using 3′-deoxy-3′[(18)F]-fluorothymidine (¹⁸F-FLT) PET/CT. The superiority of ¹⁸F-FLT PET/CT over ¹⁸F-FDG PET/CT in early therapeutic monitoring has been well described in patients after chemotherapy, radiotherapy, and/or chemo/radiotherapy. In thispilot study, we explorethe use of ¹⁸F-FLT PET/CT as an early response evaluation modality in patients with lung cancerand provide specific case studies of patients with small cell lung cancer and non-small cell lung cancer who received novel targeted therapies. Early response for c-MET inhibitor was observed in four weeks and for MDM2 inhibitor in nine days.

Alternative and New Radiopharmaceutical Agents for Lung Cancer

BACKGROUND

FDG PET/CT imaging has an established role in lung cancer (LC) management. Whilst it is a sensitive technique, FDG PET/CT has a limited specificity in the differentiation between LC and benign conditions and is not capable of defining LC heterogeneity since FDG uptake varies between histotypes.

OBJECTIVE

To get an overview of new radiopharmaceuticals for the study of cancer biology features beyond glucose metabolism in LC.

METHODS

A comprehensive literature review of PubMed/Medline was performed using a combination of the following keywords: "positron emission tomography", "lung neoplasms", "non-FDG", "radiopharmaceuticals", "tracers".

RESULTS

Evidences suggest that proliferation markers, such as 18F-Fluorothymidine and 11CMethionine, improve LC staging and are useful in evaluating treatment response and progression free survival. 68Ga-DOTA-peptides are already routinely used in pulmonary neuroendocrine neoplasms (NENs) management and should be firstly performed in suspected NENs. 18F-Fluoromisonidazole and other radiopharmaceuticals show a promising impact on staging, prognosis assessment and therapy response in LC patients, by visualizing hypoxia and perfusion. Radiolabeled RGD-peptides, targeting angiogenesis, may have a role in LC staging, treatment outcome and therapy. PET radiopharmaceuticals tracing a specific oncogene/signal pathway, such as EGFR or ALK, are gaining interest especially for therapeutic implications. Other PET tracers, like 68Ga-PSMA-peptides or radiolabeled FAPIs, need more development in LC, though, they are promising for therapy purposes.

CONCLUSION

To date, the employment of most of the described tracers is limited to the experimental field, however, research development may offer innovative opportunities to improve LC staging, characterization, stratification and response assessment in an era of increased personalized therapy.

Correlations between the metabolic profile and 18F-FDG-Positron Emission Tomography-Computed Tomography parameters reveal the complexity of the metabolic reprogramming within lung cancer patients

Several studies have demonstrated that the metabolite composition of plasma may indicate the presence of lung cancer. The metabolism of cancer is characterized by an enhanced glucose uptake and glycolysis which is exploited by ¹⁸F-FDG positron emission tomography (PET) in the work-up and management of cancer. This study aims to explore relationships between ¹H-NMR spectroscopy derived plasma metabolite concentrations and the uptake of labeled glucose (¹⁸F-FDG) in lung cancer tissue. PET parameters of interest are standard maximal uptake values (SUV_max), total body metabolic active tumor volumes (MATV_WTB) and total body total lesion glycolysis (TLG_WTB) values. Patients with high values of these parameters have higher plasma concentrations of N-acetylated glycoproteins which suggest an upregulation of the hexosamines biosynthesis. High MATV_WTB and TLG_WTB values are associated with higher concentrations of glucose, glycerol, N-acetylated glycoproteins, threonine, aspartate and valine and lower levels of sphingomyelins and phosphatidylcholines appearing at the surface of lipoproteins. These higher concentrations of glucose and non-carbohydrate glucose precursors such as amino acids and glycerol suggests involvement of the gluconeogenesis pathway. The lower plasma concentration of those phospholipids points to a higher need for membrane synthesis. Our results indicate that the metabolic reprogramming in cancer is more complex than the initially described Warburg effect.

Does the ATSM-Cu(II) Biomarker Integrate into the Human Cellular Copper Cycle?

Hypoxia is commonly encountered in the tumor microenvironment and drives proliferation, angiogenesis, and resistance to therapy. Imaging of hypoxia is important in many disease states in oncology, cardiology, and neurology. Finding clinically approved imaging biomarkers for hypoxia has proved challenging. Candidate biomarkers have shown low uptake into tumors and low signal to background ratios that adversely affect imaging quality. Copper complexes have been identified as potential biomarkers for hypoxia owing to their redox ability. Active uptake of copper complexes into cells could ensure selectivity and high sensitivity. We explored the reactivity and selectivity of the ATSM-Cu(II) biomarker to proteins that are involved in the copper cycle using electron paramagnetic resonance (EPR) spectroscopy and UV-vis measurements. We show that the affinity of the ATSM-Cu(II) complex to proteins in the copper cycle is low and the cell probably does not actively uptake ATSM-Cu(II).

The plasma glutamate concentration as a complementary tool to differentiate benign PET-positive lung lesions from lung cancer

Background

Pulmonary imaging often identifies suspicious abnormalities resulting in supplementary diagnostic procedures. This study aims to investigate whether the metabolic fingerprint of plasma allows to discriminate between patients with lung inflammation and patients with lung cancer.

Methods

Metabolic profiles of plasma from 347 controls, 269 cancer patients and 108 patients with inflammation were obtained by ¹H-NMR spectroscopy. Models to discriminate between groups were trained by PLS-LDA. A test set was used for independent validation. A ROC curve was built to evaluate the diagnostic performance of potential biomarkers.

Results

Sensitivity, specificity, PPV and NPV of PET-CT to diagnose cancer are 96, 23, 76 and 71%. Metabolic profiles differentiate between cancer and inflammation with a sensitivity of 89%, a specificity of 87% and a MCE of 12%. Removal of the glutamate metabolite results in an increase of MCE (38%) and a decrease of both sensitivity and specificity (62%), demonstrating the importance of glutamate for discrimination. At the cut-off point 0.31 on the ROC curve, the relative glutamate concentration discriminates between cancer and inflammation with a sensitivity of 85%, a specificity of 81%, and an AUC of 0.88. PPV and NPV are 92 and 69%. In PET-positive patients with a relative glutamate level ≤ 0.31 the sensitivity to diagnose cancer reaches 100% with a PPV of 94%. In PET-negative patients, a relative glutamate level > 0.31 increases the specificity of PET from 23% to 58% and results in a high NPV of 100%. In case of discrepancy between SUV_max and the glutamate concentration, lung cancer is missed in 19% of the cases.

Conclusion

This study indicates that the ¹H-NMR-derived relative plasma concentration of glutamate allows discrimination between lung cancer and lung inflammation. A glutamate level ≤ 0.31 in PET-positive patients corresponds to the diagnosis of lung cancer with a higher specificity and PPV than PET-CT. Glutamate levels > 0.31 in patients with PET negative lung lesions is likely to correspond with inflammation. Caution is needed for patients with conflicting SUV_max values and glutamate concentrations. Confirmation is needed in a prospective study with external validation and by another analytical technique such as HPLC-MS.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4755-1) contains supplementary material, which is available to authorized users.

The developing role of FDG PET imaging for prognostication and radiotherapy target volume delineation in non-small cell lung cancer

Advancements in functional imaging technology have allowed new possibilities in contouring of target volumes, monitoring therapy, and predicting treatment outcome in non-small cell lung cancer (NSCLC). Consequently, the role of ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET) has expanded in the last decades from a stand-alone diagnostic tool to a versatile instrument integrated with computed tomography (CT), with a prominent role in lung cancer radiotherapy. This review outlines the most recent literature on developments in FDG PET imaging for prognostication and radiotherapy target volume delineation (TVD) in NSCLC. We also describe the challenges facing the clinical implementation of these developments and present new ideas for future research.

18F-Flortanidazole Hypoxia PET Holds Promise as a Prognostic and Predictive Imaging Biomarker in a Lung Cancer Xenograft Model Treated with Metformin and Radiotherapy

Metformin may improve tumor oxygenation and thus radiotherapy response, but imaging biomarkers for selection of suitable patients are still under investigation. First, we assessed the effect of acute metformin administration on non-small cell lung cancer xenograft tumor hypoxia using PET imaging with the hypoxia tracer ¹⁸F-flortanidazole. Second, we verified the effect of a single dose of metformin before radiotherapy on long-term treatment outcome. Third, we examined the potential of baseline ¹⁸F-flortanidazole as a prognostic or predictive biomarker for treatment response. Methods: A549 tumor-bearing mice underwent a ¹⁸F-flortanidazole PET/CT scan to determine baseline tumor hypoxia. The next day, mice received a 100 mg/kg intravenous injection of metformin. ¹⁸F-flortanidazole was administered intravenously 30 min later, and a second PET/CT scan was performed to assess changes in tumor hypoxia. Two days later, the mice were divided into 3 therapy groups: controls (group 1), radiotherapy (group 2), and metformin + radiotherapy (group 3). Animals received saline (groups 1-2) or metformin (100 mg/kg; group 3) intravenously, followed by a single radiotherapy dose of 10 Gy (groups 2-3) or sham irradiation (group 1) 30 min later. Tumor growth was monitored triweekly by caliper measurement, and tumor volume relative to baseline was calculated. The tumor doubling time (TDT), that is, the time to reach twice the preirradiation tumor volume, was defined as the endpoint. Results: Thirty minutes after metformin treatment, ¹⁸F-flortanidazole demonstrated a significant change in tumor hypoxia, with a mean intratumoral reduction in ¹⁸F-flortanidazole tumor-to-background ratio (TBR) from 3.21 ± 0.13 to 2.87 ± 0.13 (P = 0.0001). Overall, relative tumor volume over time differed across treatment groups (P < 0.0001). Similarly, the median TDT was 19, 34, and 52 d in controls, the radiotherapy group, and the metformin + radiotherapy group, respectively (log-rank P < 0.0001). Both baseline ¹⁸F-flortanidazole TBR (hazard ratio, 2.0; P = 0.0004) and change from baseline TBR (hazard ratio, 0.39; P = 0.04) were prognostic biomarkers for TDT irrespective of treatment, and baseline TBR predicted metformin-specific treatment effects that were dependent on baseline tumor hypoxia. Conclusion: Using ¹⁸F-flortanidazole PET imaging in a non-small cell lung cancer xenograft model, we showed that metformin may act as a radiosensitizer by increasing tumor oxygenation and that baseline ¹⁸F-flortanidazole shows promise as an imaging biomarker.

Lung cancer staging: a concise update

Diagnosis and clinical staging of lung cancer are fundamental to planning therapy. The techniques for clinical staging, i.e anatomic and metabolic imaging, endoscopies and minimally invasive surgical procedures, should be performed sequentially and with an increasing degree of invasiveness. Intraoperative staging, assessing the magnitude of the primary tumour, the involved structures, and the loco-regional lymphatic spread by means of systematic nodal dissection, is essential in order to achieve a complete resection. In resected tumours, pathological staging, with the systematic study of the resected specimens, is the strongest prognostic indicator and is essential to make further decisions on therapy. In the present decade, the guidelines on lung cancer staging of the American College of Chest Physicians and the European Society of Thoracic Surgeons are based on the best available evidence and are widely followed. Recent advances in the classification of the adenocarcinoma of the lung, with the definition of adenocarcinoma in situ, minimally invasive adenocarcinoma and lepidic predominant adenocarcinoma, and the publication of the eighth edition of the tumour, node and metastasis classification of lung cancer, have to be integrated into the staging process. The present review complements the latest guidelines on lung cancer staging by providing an update of all these issues.

Imaging of Tumor Characteristics and Molecular Pathways With PET: Developments Over the Last Decade Toward Personalized Cancer Therapy

PURPOSE

Improvements in personalized therapy are made possible by the advances in molecular biology that led to developments in molecular imaging, allowing highly specific in vivo imaging of biological processes. Positron emission tomography (PET) is the most specific and sensitive imaging technique for in vivo molecular targets and pathways, offering quantification and evaluation of functional properties of the targeted anatomy.

MATERIALS AND METHODS

This work is an integrative research review that summarizes and evaluates the accumulated current status of knowledge of recent advances in PET imaging for cancer diagnosis and treatment, concentrating on novel radiotracers and evaluating their advantages and disadvantages in cancer characterization. Medline search was conducted, limited to English publications from 2007 onward. Identified manuscripts were evaluated for most recent developments in PET imaging of cancer hypoxia, angiogenesis, proliferation, and clonogenic cancer stem cells (CSC).

RESULTS

There is an expansion observed from purely metabolic-based PET imaging toward antibody-based PET to achieve more information on cancer characteristics to identify hypoxia, proangiogenic factors, CSC, and others. ⁶⁴Cu-ATSM, for example, can be used both as a hypoxia and a CSC marker.

CONCLUSIONS

Progress in the field of functional imaging will possibly lead to more specific tumor targeting and personalized treatment, increasing tumor control and improving quality of life.

An assessment of 18 F-FDG PET/CT for thoracic screening and risk stratification of pulmonary nodules in multiple endocrine neoplasia type 1

CONTEXT

Bronchopulmonary neuroendocrine tumours (bpNETs) and thymic carcinoid (ThC) are features of multiple endocrine neoplasia type 1 (MEN 1), and surveillance guidelines recommend periodic thoracic imaging. The optimal thoracic imaging modality and screening frequency remain uncertain as does the prognosis of small lung nodules when identified.

OBJECTIVES

To evaluate fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸ F-FDG PET/CT) for identification and prognostic assessment of thoracic lesions in MEN 1.

DESIGN

Retrospective observational study.

SETTING AND PARTICIPANTS

Fifty consecutive MEN 1 patients undergoing screening with ¹⁸ F-FDG PET/CT at a tertiary referral hospital between July 2011 and December 2016.

INTERVENTIONS

¹⁸ F-FDG PET/CT.

OUTCOME MEASURES

Pulmonary and thymic lesion prevalence, size, functional characteristics and behaviour.

RESULTS

Thirteen patients (26.0%) exhibited pulmonary nodules with multiple nodules identified in nine (18.0%). An asymptomatic 31 mm FDG-avid ThC was identified in one patient (2%). Of the 13 patients with pulmonary nodules, four (8.0%) exhibited 13 FDG-avid nodules (mean size 10.1 ± 9.1 mm), and nine (18.0%) demonstrated 26 FDG nonavid nodules (mean size 6.9 ± 5.8 mm). All FDG-avid lesions increased in size vs 11 (42.3%) FDG nonavid lesions (P = .0004). For FDG-avid and nonavid nodules, the median doubling time was 24.2 months (IQR 11.4-40.7) and 48.6 months (IQR 37.0-72.2), respectively. Nodule resection was undertaken in two patients, typical bronchial carcinoid diagnosed in one (FDG nonavid) and metastatic renal cell carcinoma in the second (FDG avid).

CONCLUSION

Thoracic imaging with ¹⁸ F-FDG PET/CT effectively identifies pulmonary nodules and ThC. FDG-avid pulmonary lesions are significantly more likely to progress than nonavid lesions.

Positron emission tomography/magnetic resonance imaging (PET/MRI): An update and initial experience at HC-FMUSP

The new technology of PET/MRI is a prototype of hybrid imaging, allowing for the combination of molecular data from PET scanning and morphofunctional information derived from MRI scanning. Recent advances regarding the technical aspects of this device, especially after the development of MRI-compatible silicon photomultipliers of PET, permitted an increase in the diagnostic performance of PET/MRI translated into dose reduction and higher imaging quality. Among several clinical applications, PET/MRI gains ground initially in oncology, where MRI per se plays an essential role in the assessment of primary tumors (which is limited in the case of PET/CT), including prostate, rectal and gynecological tumors. On the other hand, the evaluation of the lungs remains an enigma although new MRI sequences are being designed to overcome this. More clinical indications of PET/MRI are seen in the fields of neurology, cardiology and inflammatory processes, and the use of PET/MRI also opens perspectives for pediatric populations as it involves very low radiation exposure. Our review aimed to highlight the current indications of PET/MRI and discuss the challenges and perspectives of PET/MRI at HC-FMUSP.

The role of positron emission tomography in the diagnosis, staging and response assessment of non-small cell lung cancer

Lung cancer is a common disease and the leading cause of cancer-related mortality, with non-small cell lung cancer (NSCLC) accounting for the majority of cases. Following diagnosis of lung cancer, accurate staging is essential to guide clinical management and inform prognosis. Positron emission tomography (PET) in conjunction with computed tomography (CT)-as PET-CT has developed as an important tool in the multi-disciplinary management of lung cancer. This article will review the current evidence for the role of ¹⁸F-fluorodeoxyglucose (FDG) PET-CT in NSCLC diagnosis, staging, response assessment and follow up.

Non-Small-Cell Lung Cancer PET Imaging Beyond F18 Fluorodeoxyglucose

F18 Flurodeoxyglucose (FDG) is a nonspecific PET tracer representing tumor energy metabolism, with common false-positive and false-negative findings in clinical practice. Non-small cell lung cancer is highly heterogeneous histologically, biologically, and molecularly. Novel PET tracers designed to characterize a specific aspect of tumor biology or a pathway-specific molecular target have the potential to provide noninvasive key information in tumor heterogeneity for patient stratification and in the assessment of treatment response. Non-FDG PET tracers, including ⁶⁸Ga-somatostatin analogs, and some PET tracers targeting tumor proliferation, hypoxia, angiogenesis, and pathway-specific targets are briefly reviewed in this article.

ImmunoPET Imaging of CD146 in Murine Models of Intrapulmonary Metastasis of Non-Small Cell Lung Cancer

CD146 has been identified as an excellent biomarker for lung cancer as its overexpression in solid tumors has been linked to disease progression, invasion, and metastasis. Previously, our group described a positive correlation between ⁶⁴Cu-labeled YY146 uptake and increased expression of CD146 in six human lung cancer cell lines using subcutaneous tumor models. In this study, we investigate a monoclonal antibody called YY146 for immunoPET imaging of CD146 in two intrapulmonary metastasis models of non-small cell lung cancer (NSCLC). The binding and immunoreactivity of the tracer were assessed by in vitro assays. Radiolabeling of YY146 with positron emitting Cu-64 (⁶⁴Cu-NOTA-YY146) enabled PET imaging of intrapulmonary metastasis. Mice were intravenously injected with two million tumor cells, and CT imaging was used to verify the presence of lung metastases. ⁶⁴Cu-NOTA-YY146 was injected into tumor-bearing mice, and animals were subjected to PET/CT imaging at 4, 24, and 48 h postinjection. Both the average and maximum lung PET signal intensities were quantified and compared between high and low CD146-expressing metastases. Further validation was accomplished through immunofluorescence imaging of resected tissues with CD31 and CD146. In flow cytometry, YY146 revealed strong binding to CD146 in H460 cells due to its high expression with minimal binding to CD146-low expressing H358 cells. Both YY146 and NOTA-YY146 showed similar binding, suggesting that NOTA conjugation did not elicit any negative effects on its binding affinity. Imaging of ⁶⁴Cu-NOTA-YY146 in H460 tumor-bearing mice revealed rapid, persistent, and highly specific tracer accumulation. Uptake of ⁶⁴Cu-NOTA-YY146 in the whole lung was calculated for H460 and H358 as 7.43 ± 0.38 and 3.95 ± 0.47% ID/g at 48 h postinjection (n = 4, p < 0.05), and the maximum lung signals were determined to be 13.85 ± 1.07 (H460) and 6.08 ± 0.73% ID/g (H358) at equivalent time points (n = 4, p < 0.05). To ensure the specificity of the tracer, a nonspecific antibody was injected into H460 tumor-bearing mice. Ex vivo biodistribution and immunofluorescence imaging validated the PET findings. In summary, ⁶⁴Cu-NOTA-YY146 allowed for successful imaging of CD146-expressing intrapulmonary metastases of NSCLC in mice. This preliminary study provides evidence supporting the future clinical utilization of ⁶⁴Cu-NOTA-YY146 for possible treatment monitoring of CD146-targeted therapy or improving patient stratification.

Role of interim 18F-FDG-PET/CT for the early prediction of clinical outcomes of Non-Small Cell Lung Cancer (NSCLC) during radiotherapy or chemo-radiotherapy. A systematic review

BACKGROUND

Non-Small Cell Lung Cancer (NSCLC) is characterized by aggressiveness and includes the majority of thorax malignancies. The possibility of early stratification of patients as responsive and non-responsive to radiotherapy with a non-invasive method is extremely appealing. The distribution of the Fluorodeoxyglucose (¹⁸F-FDG) in tumours, provided by Positron-Emission-Tomography (PET) images, has been proved to be useful to assess the initial staging of the disease, recurrence, and response to chemotherapy and chemo-radiotherapy (CRT).

OBJECTIVES

In the last years, particular efforts have been focused on the possibility of using ad interim ¹⁸F-FDG PET (FDG_int) to evaluate response already in the course of radiotherapy. However, controversial findings have been reported for various malignancies, although several results would support the use of FDG_int for individual therapeutic decisions, at least in some pathologies. The objective of the present review is to assemble comprehensively the literature concerning NSCLC, to evaluate where and whether FDG_int may offer predictive potential.

METHODS

Several searches were completed on Medline and the Embase database, combining different keywords. Original papers published in the English language from 2005 to 2016 with studies involving FDG_int in patients affected by NSCLC and treated with radiation therapy or chemo-radiotherapy only were chosen.

RESULTS

Twenty-one studies out of 970 in Pubmed and 1256 in Embase were selected, reporting on 627 patients.

CONCLUSION

Certainly, the lack of univocal PET parameters was identified as a major drawback, while standardization would be required for best practice. In any case, all these papers denoted FDG_int as promising and a challenging examination for early assessment of outcomes during CRT, sustaining its predictivity in lung cancer.

[Quantitative Imaging Assessment of Tumor Response to Chemoradiation in Lung Cancer]

精准医疗的实施要求及时准确地对治疗疗效进行评估，以便于治疗方案的调整和优化，从而进一步提高疗效，改善预后。以定量评估为基础的影像组学以其无创、直观和可重复的特点在临床疗效评估方面具有不可替代的作用。本文将综述定量影像学在肺癌放化疗疗效评估中的应用现状及其相关进展。

Comparison of Positron Emission Tomography Using 2-[18F]-fluoro-2-deoxy-D-glucose and 3-deoxy-3-[18F]-fluorothymidine in Lung Cancer Imaging

Background:

The detection of solitary pulmonary nodules (SPNs) that may potentially develop into a malignant lesion is essential for early clinical interventions. However, grading classification based on computed tomography (CT) imaging results remains a significant challenge. The 2-[¹⁸F]-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) positron emission tomography (PET)/CT imaging produces both false-positive and false-negative findings for the diagnosis of SPNs. In this study, we compared ¹⁸F-FDG and 3-deoxy-3-[¹⁸F]-fluorothymidine (¹⁸F-FLT) in lung cancer PET/CT imaging.

Methods:

The binding ratios of the two tracers to A549 lung cancer cells were calculated. The mouse lung cancer model was established (n = 12), and micro-PET/CT analysis using the two tracers was performed. Images using the two tracers were collected from 55 lung cancer patients with SPNs. The correlation among the cell-tracer binding ratios, standardized uptake values (SUVs), and Ki-67 proliferation marker expression were investigated.

Results:

The cell-tracer binding ratio for the A549 cells using the ¹⁸F-FDG was greater than the ratio using ¹⁸F-FLT (P < 0.05). The Ki-67 expression showed a significant positive correlation with the ¹⁸F-FLT binding ratio (r = 0.824, P < 0.01). The tumor-to-nontumor uptake ratio of ¹⁸F-FDG imaging in xenografts was higher than that of ¹⁸F-FLT imaging. The diagnostic sensitivity, specificity, and the accuracy of ¹⁸F-FDG for lung cancer were 89%, 67%, and 73%, respectively. Moreover, the diagnostic sensitivity, specificity, and the accuracy of ¹⁸F-FLT for lung cancer were 71%, 79%, and 76%, respectively. There was an obvious positive correlation between the lung cancer Ki-67 expression and the mean maximum SUV of ¹⁸F-FDG and ¹⁸F-FLT (r = 0.658, P < 0.05 and r = 0.724, P < 0.01, respectively).

Conclusions:

The ¹⁸F-FDG uptake ratio is higher than that of ¹⁸F-FLT in A549 cells at the cellular level. ¹⁸F-FLT imaging might be superior for the quantitative diagnosis of lung tumor tissue and could distinguish lung cancer nodules from other SPNs.