Positron Emission Tomography (PET) radiotracers in oncology--utility of 18F-Fluoro-deoxy-glucose (FDG)-PET in the management of patients with non-small-cell lung cancer (NSCLC)

Synthetic 18F labeled biomolecules that are selective and promising for PET imaging: major advances and applications

The concept of positron emission tomography (PET) based imaging was developed more than 40 years ago. It has been a widely adopted technique for detecting and staging numerous diseases in clinical settings, particularly cancer, neuro- and cardio-diseases. Here, we reviewed the evolution of PET and its advantages over other imaging modalities in clinical settings. Primarily, this review discusses recent advances in the synthesis of 18F radiolabeled biomolecules in light of the widely accepted performance for effective PET. The discussion particularly emphasizes the 18F-labeling chemistry of carbohydrates, lipids, amino acids, oligonucleotides, peptides, and protein molecules, which have shown promise for PET imaging in recent decades. In addition, we have deliberated on how 18F-labeled biomolecules enable the detection of metabolic changes at the cellular level and the selective imaging of gross anatomical localization via PET imaging. In the end, the review discusses the future perspective of PET imaging to control disease in clinical settings. We firmly believe that collaborative multidisciplinary research will further widen the comprehensive applications of PET approaches in the clinical management of cancer and other pathological outcomes.

Response Evaluation Criteria in Gastrointestinal and Abdominal Cancers: Which to Use and How to Measure

As the management of gastrointestinal malignancy has evolved, tumor response assessment has expanded from size-based assessments to those that include tumor enhancement, in addition to functional data such as those derived from PET and diffusion-weighted imaging. Accurate interpretation of tumor response therefore requires knowledge of imaging modalities used in gastrointestinal malignancy, anticancer therapies, and tumor biology. Targeted therapies such as immunotherapy pose additional considerations due to unique imaging response patterns and drug toxicity; as a consequence, immunotherapy response criteria have been developed. Some gastrointestinal malignancies require assessment with tumor-specific criteria when assessing response, often to guide clinical management (such as watchful waiting in rectal cancer or suitability for surgery in pancreatic cancer). Moreover, anatomic measurements can underestimate therapeutic response when applied to molecular-targeted therapies or locoregional therapies in hypervascular malignancies such as hepatocellular carcinoma. In these cases, responding tumors may exhibit morphologic changes including cystic degeneration, necrosis, and hemorrhage, often without significant reduction in size. Awareness of pitfalls when interpreting gastrointestinal tumor response is required to correctly interpret response assessment imaging and guide appropriate oncologic management. Data-driven image analyses such as radiomics have been investigated in a variety of gastrointestinal tumors, such as identifying those more likely to respond to therapy or recur, with the aim of delivering precision medicine. Multimedia-enhanced radiology reports can facilitate communication of gastrointestinal tumor response by automatically embedding response categories, key data, and representative images. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

Decoding Diffuse Midline Gliomas: A Comprehensive Review of Pathogenesis, Diagnosis and Treatment

Diffuse midline gliomas (DMGs) are a group of aggressive CNS tumors, primarily affecting children and young adults, which have historically been associated with dismal outcomes. As the name implies, they arise in midline structures in the CNS, primarily in the thalamus, brainstem, and spinal cord. In more recent years, significant advances have been made in our understanding of DMGs, including molecular features, with the identification of potential therapeutic targets. We aim to provide an overview of the most recent updates in the field of DMGs, including classification, molecular subtypes, diagnostic techniques, and emerging therapeutic strategies including a review of the ongoing clinical trials, thus providing the treating multidisciplinary team with a comprehensive understanding of the current landscape and potential therapeutic strategies for this devastating group of tumors.

Utility of PET-CT in Newly Diagnosed HPV-Associated Oropharyngeal Squamous Cell Carcinoma

OBJECTIVE

To compare the utility of positron emission tomography-computed tomography (PET-CT) versus contrasted CT neck combined with routine chest imaging for disease staging and treatment planning in human papillomavirus (HPV) associated oropharyngeal squamous cell carcinoma (OPSCC) with clinically evident sites of primary disease.

METHODS

All adult patients with primary HPV-associated OPSCC at a single quaternary care cancer center from 2018 to 2019 were reviewed, and those with images available for re-review were included. Primary outcomes included concordance in clinical staging between the 2 imaging modalities of interest (PET-CT vs CT), as well as independent agreement of each with pathologic staging. Analysis was performed via ordinal logistic regression. A secondary outcome was treatment selection after diagnostic imaging, analyzed via chi-squared testing.

RESULTS

In total, 100 patients were included for evaluation, of which 89% were male, 91% Caucasian, and mean age was 61.2 years (SD 9.6). Clinical disease staging agreed between imaging modalities in 95% of cases (54 of 57 patients). Pathologic staging agreed with clinical staging from CT neck in 93% of cases (25 of 27 patients; P = .004), and with PET-CT in 82% (14 of 17 patients; P =.003). No differences were observed between the 2 imaging modalities for subsequent treatment selection (P = .39).

CONCLUSION

In uncomplicated HPV-associated OPSCC, CT offers equivalent diagnostic accuracy to that of combined whole-body PET-CT for clinical staging, and has no appreciable impact on treatment selection. A reduced reliance on routine PET-CT during initial workup of HPV-associated OPSCC may be favorable for otherwise healthy patients with clinically evident sites of primary disease.

Generation of Ru(III)-hypochlorite with resemblance to the heme-dependent haloperoxidase enzyme

The reaction of [(Me/BnTPEN)RuII(NCCH3)]2+ (BnTPEN = N1-benzyl-N1,N2,N2-tris(pyridine-2-ylmethyl)ethane-1,2-diamine and MeTPEN = N1-methyl-N1,N2,N2-tris(pyridine-2-ylmethyl)ethane-1,2-diamine) with mCPBA in the presence of chloride ions in CH3CN : H2O generated a novel (Me/BnTPEN)RuIII-OCl species at room temperature. This hypochlorite adduct could also be obtained by the direct reaction of NaOCl and HClO4 with (L)RuII complexes. The current study mimics the synthesis of a metal hypochlorite adduct in a similar fashion as in the heme-dependent haloperoxidase enzyme. As an electrophilic oxidant, the ruthenium hypochlorite adduct catalyzes hydrogen atom abstraction reactions of phenols and their derivatives.

The Role of FDG-PET in the Evaluation of Hidradenitis Suppurativa: A Systematic Review

Hidradenitis suppurativa (HS) is a chronic skin disorder characterized by nodules, comedones, and sinus tracts that often leave prominent scarring. In recent years, non-invasive imaging techniques have been used to assess the inflammatory activity, vascularization, and treatment response of lesions. Specifically, fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scans may aid in identifying systemic inflammation in patients with HS, improving diagnosis. Inflamed hypermetabolic tissues exhibit a greater uptake of FDG due to increased glucose uptake and vascularity. A systematic review was conducted to summarize the utility of nuclear imaging techniques in the diagnosis and treatment follow-up of HS. PubMed, Scopus, and ScienceDirect databases were utilized for relevant articles discussing the utility of PET scans in managing HS. A total of 51 citations were identified in the initial search. Following the review of titles, abstracts, and duplicates, 43 articles were excluded, leaving a total of eight articles for analysis. Data were extracted from each article, encompassing the number of patients, imaging techniques employed, and final results. An analysis of the data demonstrated that FDG-PET showed evidence of identifying subclinical lesions of the disease, improving the visualization of HS, and providing an objective method of assessing severity.

A systematic review and meta-analysis of predictive and prognostic models for outcome prediction using positron emission tomography radiomics in head and neck squamous cell carcinoma patients

BACKGROUND

Positron emission tomography (PET) images of head and neck squamous cell carcinoma (HNSCC) patients can assess the functional and biochemical processes at cellular levels. Therefore, PET radiomics-based prediction and prognostic models have the potentials to understand tumour heterogeneity and assist clinicians with diagnosis, prognosis and management of the disease. We conducted a systematic review of published modelling information to evaluate the usefulness of PET radiomics in the prediction and prognosis of HNSCC patients.

METHODS

We searched bibliographic databases (MEDLINE, Embase, Web of Science) from 2010 to 2021 and considered 31 studies with pre-defined inclusion criteria. We followed the CHARMS checklist for data extraction and performed quality assessment using the PROBAST tool. We conducted a meta-analysis to estimate the accuracy of the prediction and prognostic models using the diagnostic odds ratio (DOR) and average C-statistic, respectively.

RESULTS

Manual segmentation method followed by 40% of the maximum standardised uptake value (SUVmax ) thresholding is a commonly used approach. The area under the receiver operating curves of externally validated prediction models ranged between 0.60-0.87, 0.65-0.86 and 0.62-0.75 for overall survival, distant metastasis and recurrence, respectively. Most studies highlighted an overall high risk of bias (outcome definition, statistical methodologies and external validation of models) and high unclear concern in terms of applicability. The meta-analysis showed the estimated pooled DOR of 6.75 (95% CI: 4.45, 10.23) for prediction models and the C-statistic of 0.71 (95% CI: 0.67, 0.74) for prognostic models.

CONCLUSIONS

Both prediction and prognostic models using clinical variables and PET radiomics demonstrated reliable accuracy for detecting adverse outcomes in HNSCC, suggesting the prospect of PET radiomics in clinical settings for diagnosis, prognosis and management of HNSCC patients. Future studies of prediction and prognostic models should emphasise the quality of reporting, external model validation, generalisability to real clinical scenarios and enhanced reproducibility of results.

Evaluation of [18F]AlF-EMP-105 for Molecular Imaging of C-Met

C-Met is a receptor tyrosine kinase that is overexpressed in a range of different cancer types, and has been identified as a potential biomarker for cancer imaging and therapy. Previously, a ⁶⁸Ga-labelled peptide, [⁶⁸Ga]Ga-EMP-100, has shown promise for imaging c-Met in renal cell carcinoma in humans. Herein, we report the synthesis and preliminary biological evaluation of an [¹⁸F]AlF-labelled analogue, [¹⁸F]AlF-EMP-105, for c-Met imaging by positron emission tomography. EMP-105 was radiolabelled using the aluminium-[¹⁸F]fluoride method with 46 ± 2% RCY and >95% RCP in 35-40 min. In vitro evaluation showed that [¹⁸F]AlF-EMP-105 has a high specificity for c-Met-expressing cells. Radioactive metabolite analysis at 5 and 30 min post-injection revealed that [¹⁸F]AlF-EMP-105 has good blood stability, but undergoes transformation-transchelation, defluorination or demetallation-in the liver and kidneys. PET imaging in non-tumour-bearing mice showed high radioactive accumulation in the kidneys, bladder and urine, demonstrating that the tracer is cleared predominantly as [¹⁸F]fluoride by the renal system. With its high specificity for c-Met expressing cells, [¹⁸F]AlF-EMP-105 shows promise as a potential diagnostic tool for imaging cancer.

Technological advancements in cancer diagnostics: Improvements and limitations

BACKGROUND

Cancer is characterized by the rampant proliferation, growth, and infiltration of malignantly transformed cancer cells past their normal boundaries into adjacent tissues. It is the leading cause of death worldwide, responsible for approximately 19.3 million new diagnoses and 10 million deaths globally in 2020. In the United States alone, the estimated number of new diagnoses and deaths is 1.9 million and 609 360, respectively. Implementation of currently existing cancer diagnostic techniques such as positron emission tomography (PET), X-ray computed tomography (CT), and magnetic resonance spectroscopy (MRS), and molecular diagnostic techniques, have enabled early detection rates and are instrumental not only for the therapeutic management of cancer patients, but also for early detection of the cancer itself. The effectiveness of these cancer screening programs are heavily dependent on the rate of accurate precursor lesion identification; an increased rate of identification allows for earlier onset treatment, thus decreasing the incidence of invasive cancer in the long-term, and improving the overall prognosis. Although these diagnostic techniques are advantageous due to lack of invasiveness and easier accessibility within the clinical setting, several limitations such as optimal target definition, high signal to background ratio and associated artifacts hinder the accurate diagnosis of specific types of deep-seated tumors, besides associated high cost. In this review we discuss various imaging, molecular, and low-cost diagnostic tools and related technological advancements, to provide a better understanding of cancer diagnostics, unraveling new opportunities for effective management of cancer, particularly in low- and middle-income countries (LMICs).

RECENT FINDINGS

Herein we discuss various technological advancements that are being utilized to construct an assortment of new diagnostic techniques that incorporate hardware, image reconstruction software, imaging devices, biomarkers, and even artificial intelligence algorithms, thereby providing a reliable diagnosis and analysis of the tumor. Also, we provide a brief account of alternative low cost-effective cancer therapy devices (CryoPop®, LumaGEM®, MarginProbe®) and picture archiving and communication systems (PACS), emphasizing the need for multi-disciplinary collaboration among radiologists, pathologists, and other involved specialties for improving cancer diagnostics.

CONCLUSION

Revolutionary technological advancements in cancer imaging and molecular biology techniques are indispensable for the accurate diagnosis and prognosis of cancer.

Skin Cancer Pathobiology at a Glance: A Focus on Imaging Techniques and Their Potential for Improved Diagnosis and Surveillance in Clinical Cohorts

Early diagnosis is essential for completely eradicating skin cancer and maximizing patients' clinical benefits. Emerging optical imaging modalities such as reflectance confocal microscopy (RCM), optical coherence tomography (OCT), magnetic resonance imaging (MRI), near-infrared (NIR) bioimaging, positron emission tomography (PET), and their combinations provide non-invasive imaging data that may help in the early detection of cutaneous tumors and surgical planning. Hence, they seem appropriate for observing dynamic processes such as blood flow, immune cell activation, and tumor energy metabolism, which may be relevant for disease evolution. This review discusses the latest technological and methodological advances in imaging techniques that may be applied for skin cancer detection and monitoring. In the first instance, we will describe the principle and prospective clinical applications of the most commonly used imaging techniques, highlighting the challenges and opportunities of their implementation in the clinical setting. We will also highlight how imaging techniques may complement the molecular and histological approaches in sharpening the non-invasive skin characterization, laying the ground for more personalized approaches in skin cancer patients.

The Role of Positron Emission Tomography and Computed Tomographic (PET/CT) Imaging for Radiation Therapy Planning: A Literature Review

PET/CT is revolutionising radiotherapy treatment planning in many cancer sites. While its utility has been confirmed in some cancer sites, and is used in routine clinical practice, it is still at an experimental stage in many other cancer sites. This review discusses the utility of PET/CT in cancer sites where the role of PET/CT has been established in cases such as head and neck, cervix, brain, and lung cancers, as well as cancer sites where the role of PET/CT is still under investigation such as uterine, ovarian, and prostate cancers. Finally, the review touches on PET/CT utilisation in Africa.

Experimental and Clinical Biomarkers for Progressive Evaluation of Neuropathology and Therapeutic Interventions for Acute and Chronic Neurological Disorders

This article describes commonly used experimental and clinical biomarkers of neuronal injury and neurodegeneration for the evaluation of neuropathology and monitoring of therapeutic interventions. Biomarkers are vital for diagnostics of brain disease and therapeutic monitoring. A biomarker can be objectively measured and evaluated as a proxy indicator for the pathophysiological process or response to therapeutic interventions. There are complex hurdles in understanding the molecular pathophysiology of neurological disorders and the ability to diagnose them at initial stages. Novel biomarkers for neurological diseases may surpass these issues, especially for early identification of disease risk. Validated biomarkers can measure the severity and progression of both acute neuronal injury and chronic neurological diseases such as epilepsy, migraine, Alzheimer's disease, Parkinson's disease, Huntington's disease, traumatic brain injury, amyotrophic lateral sclerosis, multiple sclerosis, and other brain diseases. Biomarkers are deployed to study progression and response to treatment, including noninvasive imaging tools for both acute and chronic brain conditions. Neuronal biomarkers are classified into four core subtypes: blood-based, immunohistochemical-based, neuroimaging-based, and electrophysiological biomarkers. Neuronal conditions have progressive stages, such as acute injury, inflammation, neurodegeneration, and neurogenesis, which can serve as indices of pathological status. Biomarkers are critical for the targeted identification of specific molecules, cells, tissues, or proteins that dramatically alter throughout the progression of brain conditions. There has been tremendous progress with biomarkers in acute conditions and chronic diseases affecting the central nervous system.

Expanding the versatility and scope of the oxime ligation: rapid bioconjugation to disulfide-rich peptides

The oxime ligation is a valuable bioorthogonal conjugation reaction but with limited compatibility with disulfide-rich peptides/proteins and time-sensitive applications. Here we overcome these limitations by introducing a strategy that supports regiospecific control, oxidative folding, production of stable aminooxy-precursors for on-demand modification, and complete ligation within 5 min.

Regiospecific incorporation of a protected aminooxy group into disulfide-rich peptides compatible with oxidative folding. This strategy supports the production of aminooxy precursors for long-term storage and on-demand modifications.

Monitoring the Impact of Spaceflight on the Human Brain

Extended exposure to radiation, microgravity, and isolation during space exploration has significant physiological, structural, and psychosocial effects on astronauts, and particularly their central nervous system. To date, the use of brain monitoring techniques adopted on Earth in pre/post-spaceflight experimental protocols has proven to be valuable for investigating the effects of space travel on the brain. However, future (longer) deep space travel would require some brain function monitoring equipment to be also available for evaluating and monitoring brain health during spaceflight. Here, we describe the impact of spaceflight on the brain, the basic principles behind six brain function analysis technologies, their current use associated with spaceflight, and their potential for utilization during deep space exploration. We suggest that, while the use of magnetic resonance imaging (MRI), positron emission tomography (PET), and computerized tomography (CT) is limited to analog and pre/post-spaceflight studies on Earth, electroencephalography (EEG), functional near-infrared spectroscopy (fNIRS), and ultrasound are good candidates to be adapted for utilization in the context of deep space exploration.

The risk of increasing tumor malignancy after PET diagnosis

This manuscript reviews evidences underlying the estimation of risk of malignancy enhancement of advanced aggressive cancers as a result of the gamma radiation emitted by tracers used in PET diagnostics. We conclude that among many cancers, such a phenomenon likely occurs, particularly in tumor cells with an aggressive biology in the advanced stages of their development, e.g. prostate cancer, melanoma and colorectal cancer. Moreover, we surmise based on gathered evidence that fluorine -18 (18F) labeled pharmaceuticals (18F-deoxyglucose and 18F-choline), commonly used in positron emission tomography (PET) can lead to malignancy enhancement of diagnosed cancer, manifesting as accelerated infiltration of the neighboring tissue, accelerated metastasis and/or radio- and chemotherapy resistance. In this review, some suggestions on future studies verifying this concept are also proposed. If our concerns are justified, it might be appropriate in the future to consider this assumption at the stage of deciding whether to undertake PET monitoring in some patients with advanced aggressive cancer.

Utility of different positron emission tomography/computed tomography tracers in the evaluation of incidentally detected dual malignancies: An experience from a tertiary care center

Multiple primary malignancies in a cancer patient are not a rare occurrence. The most common presentation of multiple primary malignancies is dual malignancies. The usefulness of different positron emission tomography (PET)/computed tomography (CT) tracers in the evaluation of dual synchronous primary malignancies is not well documented. Here, we present a case series, where two patients, referred for PET/CT, after being diagnosed with one primary malignancy were found to be having a second primary malignancy, diagnosed incidentally in PET/CT, further validated by PET/CT with another tracer.

Molecular Imaging and the PD-L1 Pathway: From Bench to Clinic

Programmed death-1 (PD-1) and programmed death ligand 1 (PD-L1) inhibitors target the important molecular interplay between PD-1 and PD-L1, a key pathway contributing to immune evasion in the tumor microenvironment (TME). Long-term clinical benefit has been observed in patients receiving PD-(L)1 inhibitors, alone and in combination with other treatments, across multiple tumor types. PD-L1 expression has been associated with response to immune checkpoint inhibitors, and treatment strategies are often guided by immunohistochemistry-based diagnostic tests assessing expression of PD-L1. However, challenges related to the implementation, interpretation, and clinical utility of PD-L1 diagnostic tests have led to an increasing number of preclinical and clinical studies exploring interrogation of the TME by real-time imaging of PD-(L)1 expression by positron emission tomography (PET). PET imaging utilizes radiolabeled molecules to non-invasively assess PD-(L)1 expression spatially and temporally. Several PD-(L)1 PET tracers have been tested in preclinical and clinical studies, with clinical trials in progress to assess their use in a number of cancer types. This review will showcase the development of PD-(L)1 PET tracers from preclinical studies through to clinical use, and will explore the opportunities in drug development and possible future clinical implementation.

Clinical value of baseline 18F-FDG PET/CT in soft tissue sarcomas

Background

The use of ¹⁸F-FDG Positron emission tomography/Computed tomography (PET/CT) in the initial staging of many cancers is clearly established. Most soft tissue sarcoma (STS) has a high affinity for ¹⁸F-FDG, which is why ¹⁸F-FDG PET/CT has been proposed as a non-invasive method, useful in diagnosis and follow-up. The standardized uptake value values (SUV), the volume-based metabolic parameters MTV (metabolic tumor volume), and TLG (total lesion glycolysis) determine tumor viability and provide its total volume and the total activity of metabolically active tumor cells. The histological grade is the most important predictor of metastases and mortality associated with STS, and a significant relationship between the metabolic parameters of ¹⁸F-FDG PET/CT and the histological grade has been described.

Methods

A retrospective study was conducted on STS patients, who had histological grade according to the FNCLCC (Fédération Nationale des Centres de Lutte Contre Le Cancer) criteria, as well as a baseline PET/CT. SUV (SUV_max, SUV_mean, and SUV_peak), MTV, and TLG were quantified. A T-student test was performed to establish the relationship between the metabolic biomarkers and the histological grade. Their usefulness as predictors of the histological grade was verified using receiver operator characteristic (ROC) curves. A survival function study was performed using the Kaplan–Meier method. To assess the prognostic utility of the metabolic biomarkers we use the Log-Rank method.

Results

The SUV values were useful to discriminate high-grade STS. We found a significant relationship between the histological grade and the SUV values. SUV_max, SUV_peak, MTV, and TLG were predictors of overall survival (OS). There were no significant differences in the OS for the SUV_mean, or in the disease-free survival (DFS) for SUV_max, SUV_mean, SUV_peak, MTV, and TLG.

Conclusions

The SUV_max, SUV_mean, and SUV_peak values correlate with the HG and are useful to discriminate high-grade from low-grade STS. Patients with high SUV_max, SUV_peak, MTV, and TLG have a significantly lower OS.

Tumor models to assess immune response and tumor-microbiome interactions in colorectal cancer

Despite significant advances over the past 2 decades in preventive screening and therapy aimed at improving patient survival, colorectal cancer (CRC) remains the second most common cause of cancer death in the United States. The average 5-year survival rate of CRC patients with positive regional lymph nodes is only 40%, while less than 5% of patients with distant metastases survive beyond 5 years. There is a critical need to develop novel therapies that can improve overall survival in patients with poor prognoses, particularly since 60% of them are diagnosed at an advanced stage. Pertinently, immune checkpoint blockade therapy has dramatically changed how we treat CRC patients with microsatellite-instable high tumors. Furthermore, accumulating evidence shows that changes in gut microbiota are associated with the regulation of host antitumor immune response and cancer progression. Appropriate animal models are essential to deciphering the complex mechanisms of host antitumor immune response and tumor-gut microbiome metabolic interactions. Here, we discuss various mouse models of colorectal cancer that are developed to address key questions on tumor immune response and tumor-microbiota interactions. These CRC models will also serve as resourceful tools for effective preclinical studies.

The relationship between 18F-FDG-PETCT-derived tumour metabolic activity, nutritional risk, body composition, systemic inflammation and survival in patients with lung cancer

The aim of this study was to examine the relationship between PET-CT derived tumour glucose uptake as measured by maximum standard glucose uptake (SUVmax) and total lesion glycolysis (TLG), nutritional risk as measured by the malnutrition universal screening tool (MUST), CT derived body composition as measured by skeletal muscle index (SMI) and skeletal muscle radiodensity (SMD), the systemic inflammatory response as measured by the modified Glasgow prognostic score (mGPS) and the neutrophil to lymphocyte ratio (NLR) and survival in patients with lung cancer, treated with radiotherapy. In a retrospective cohort study, 119 patients were included in final analyses. The majority of patients were over 65 (86%), female (52%), had a performance status (ECOG-PS) of 0 or 1 (57%), were at nutritional risk (57%), were overweight (53%), had visceral obesity (62%), had a normal SMI (51%), had a low SMD (62%) and were systemically inflammed (mGPS 1/2, 51%). An elevated TLG was associated with sex (p < 0.05), TNM stage (p < 0.001), MUST (p < 0.01) and mGPS (p < 0.01). An elevated mGPS was associated with age (p < 0.05), NLR (p < 0.01), MUST (p < 0.01), and TLG (p < 0.01). On univariate survival analysis, TNM stage (p < 0.01), mGPS (p < 0.05), NLR (p < 0.01), MUST (p ≤ 0.001), Low SMD (p < 0.05), SUVmax (p ≤ 0.001) and TLG (p < 0.001) were associated with overall survival. On multivariate survival analysis MUST (HR: 1.49 95%CI 1.12–01.98 p < 0.01) and TLG (HR: 2.02 95%CI 1.34–3.04 p = 0.001) remained independently associated with survival. In conclusion, elevated tumour metabolic activity was associated with more advanced stage, greater nutritional risk, the systemic inflammatory response and poorer survival but not body composition analysis in patients with lung cancer. These results suggest that detrimental body composition is not directly determined by tumour metabolic activity but rather an ongoing systemic inflammatory response.

Urinary fluorescent metabolite O-aminohippuric acid is a useful biomarker for lung cancer detection

INTRODUCTION

Urine contains diagnostically important metabolites that can act as natural fluorophores. However, whether these fluorescent metabolites can be used in lung cancer diagnosis is unknown.

OBJECTIVES

This study was conducted to determine whether fluorescent urinary metabolites could be useful biomarkers for lung cancer detection.

METHODS

A total of 46 lung cancer patients and 185 volunteers without cancer were evaluated between November 2013 and November 2014. Samples of the first urine of the day were collected from lung cancer patients and diagnosed at the Hamamatsu University School of Medicine and the Hamamatsu Medical Center prior to cancer treatment, and from volunteers without cancer at the Hamamatsu Medical Imaging Center. Fluorescent urinary metabolites were screened by high-performance liquid chromatography and select effective fluorescent substances for distinguishing cancer from non-cancer status.

RESULTS

The fraction of patients at each stage of cancer severity were: 41.3% stage I, 8.7% stage II, 19.6% stage III, and 30.4% stage IV. A robust predictive biomarker for lung cancer was selected by the multivariate logistic analysis of fluorescent metabolites and identified to be O-aminohippuric acid (OAH). The area under the curve (AUC) data for OAH was 0.837 (95% CI 0.769-0.898, P < 0.001).

CONCLUSION

We identified a fluorescent urinary metabolite that can predict lung cancer. OAH exceeds the AUC (0.817) of lung cancer detection by AminoIndex® cancer screening, can be analyzed non-invasively without additional sample processing, and may be a valuable addition to existing lung cancer prediction models.

Use of imaging to assess the activity of hepatic transporters

Introduction: Membrane transporters of the SLC and ABC families are abundantly expressed in the liver, where they control the transfer of drugs/drug metabolites across the sinusoidal and canalicular hepatocyte membranes and play a pivotal role in hepatic drug clearance. Noninvasive imaging methods, such as PET, SPECT or MRI, allow for measuring the activity of hepatic transporters in vivo, provided that suitable transporter imaging probes are available.Areas covered: We give an overview of the working principles of imaging-based assessment of hepatic transporter activity. We discuss different currently available PET/SPECT radiotracers and MRI contrast agents and their applications to measure hepatic transporter activity in health and disease. We cover mathematical modeling approaches to obtain quantitative parameters of transporter activity and provide a critical assessment of methodological limitations and challenges associated with this approach.Expert opinion: PET in combination with pharmacokinetic modeling can be potentially applied in drug development to study the distribution of new drug candidates to the liver and their clearance mechanisms. This approach bears potential to mechanistically assess transporter-mediated drug-drug interactions, to assess the influence of disease on hepatic drug disposition and to validate and refine currently available in vitro-in vivo extrapolation methods to predict hepatic clearance of drugs.

Neurovascular Uncoupling in Schizophrenia: A Bimodal Meta-Analysis of Brain Perfusion and Glucose Metabolism

The use of modern neuroimaging approaches has demonstrated resting-state regional cerebral blood flow (rCBF) to be tightly coupled to resting cerebral glucose metabolism (rCMRglu) in healthy brains. In schizophrenia, several lines of evidence point toward aberrant neurovascular coupling, especially in the prefrontal regions. To investigate this, we used Signed Differential Mapping to undertake a voxel-based bimodal meta-analysis examining the relationship between rCBF and rCMRglu in schizophrenia, as measured by arterial spin labeling (ASL) and ¹⁸Flurodeoxyglucose positron emission tomography (FDG-PET) respectively. We used 19 studies comprised of data from 557 patients and 584 controls. Our results suggest that several key regions implicated in the pathophysiology of schizophrenia such as the frontoinsular cortex, dorsal ACC, putamen, and temporal pole show conjoint metabolic and perfusion abnormalities in patients. In contrast, discordance between metabolism and perfusion were seen in superior frontal gyrus and cerebellum, indicating that factors contributing to neurovascular uncoupling (e.g. inflammation, mitochondrial dysfunction, oxidative stress) are likely operates at these loci. Studies enrolling patients on high doses of antipsychotics had showed larger rCBF/rCMRglu effects in patients in the left dorsal striatum. Hybrid ASL-PET studies focusing on these regions could confirm our proposition regarding neurovascular uncoupling at superior frontal gyrus in schizophrenia.

A Gas Phase Route to [18F]fluoroform with Limited Molar Activity Dilution

Positron emission tomography (PET) is an important imaging modality for biomedical research and drug development. PET requires biochemically selective radiotracers to realize full potential. Fluorine-18 (t1/2 = 109.8 min) is a major radionuclide for labeling such radiotracers but is only readily available in high activities from cyclotrons as [18F]fluoride ion. [18F]fluoroform has emerged for labeling tracers in trifluoromethyl groups. Prior methods of [18F]fluoroform synthesis used difluoro precursors in solution and led to high dilution with carrier and low molar activity (Am). We explored a new approach for the synthesis of [18F]fluoroform based on the radiosynthesis of [18F]fluoromethane from [18F]fluoride ion and then cobaltIII fluoride mediated gas phase fluorination. We estimate that carrier dilution in this process is limited to about 3-fold and find that moderate to high Am values can be achieved. We show that [18F]fluoroform so produced is highly versatile for rapidly and efficiently labeling various chemotypes that carry trifluoromethyl groups, thereby expanding prospects for developing new PET radiotracers.

Preclinical Molecular Imaging for Precision Medicine in Breast Cancer Mouse Models

Precision and personalized medicine is gaining importance in modern clinical medicine, as it aims to improve diagnostic precision and to reduce consequent therapeutic failures. In this regard, prior to use in human trials, animal models can help evaluate novel imaging approaches and therapeutic strategies and can help discover new biomarkers. Breast cancer is the most common malignancy in women worldwide, accounting for 25% of cases of all cancers and is responsible for approximately 500,000 deaths per year. Thus, it is important to identify accurate biomarkers for precise stratification of affected patients and for early detection of responsiveness to the selected therapeutic protocol. This review aims to summarize the latest advancements in preclinical molecular imaging in breast cancer mouse models. Positron emission tomography (PET) imaging remains one of the most common preclinical techniques used to evaluate biomarker expression in vivo, whereas magnetic resonance imaging (MRI), particularly diffusion-weighted (DW) sequences, has been demonstrated as capable of distinguishing responders from nonresponders for both conventional and innovative chemo- and immune-therapies with high sensitivity and in a noninvasive manner. The ability to customize therapies is desirable, as this will enable early detection of diseases and tailoring of treatments to individual patient profiles. Animal models remain irreplaceable in the effort to understand the molecular mechanisms and patterns of oncologic diseases.

Targeting Cellular Metabolism Modulates Head and Neck Oncogenesis

Considering the great energy and biomass demand for cell survival, cancer cells exhibit unique metabolic signatures compared to normal cells. Head and neck squamous cell carcinoma (HNSCC) is one of the most prevalent neoplasms worldwide. Recent findings have shown that environmental challenges, as well as intrinsic metabolic manipulations, could modulate HNSCC experimentally and serve as clinic prognostic indicators, suggesting that a better understanding of dynamic metabolic changes during HNSCC development could be of great benefit for developing adjuvant anti-cancer schemes other than conventional therapies. However, the following questions are still poorly understood: (i) how does metabolic reprogramming occur during HNSCC development? (ii) how does the tumorous milieu contribute to HNSCC tumourigenesis? and (iii) at the molecular level, how do various metabolic cues interact with each other to control the oncogenicity and therapeutic sensitivity of HNSCC? In this review article, the regulatory roles of different metabolic pathways in HNSCC and its microenvironment in controlling the malignancy are therefore discussed in the hope of providing a systemic overview regarding what we knew and how cancer metabolism could be translated for the development of anti-cancer therapeutic reagents.

Anti-PSMA 124I-scFvD2B as a new immuno-PET tool for prostate cancer: preclinical proof of principle

Background

Prostate cancer (PCa) is the second leading cause of cancer-related death in the Western population. The use in oncology of positron emission tomography/computed tomography (PET/CT) with emerging radiopharmaceuticals promises accurate staging of primary disease, restaging of recurrent disease and detection of metastatic lesions. Prostate-specific membrane antigen (PSMA) expression, directly related to androgen-independence, metastasis and progression, renders this tumour associate antigen a good target for the development of new radiopharmaceuticals for PET. Aim of this study was to demonstrate in a preclinical in vivo model (PSMA-positive versus PSMA-negative tumours) the targeting specificity and sensitivity of the anti-PSMA single-chain variable fragment (scFv) labelled with ¹²⁴I.

Methods

The ¹²⁴I-labeling conditions of the antibody fragment scFvD2B were optimized and assessed for purity and immunoreactivity. The specificity of ¹²⁴I-scFvD2B was tested in mice bearing PSMA-positive and PSMA-negative tumours to assess both ex-vivo biodistribution and immune-PET.

Results

The uptake fraction of ¹²⁴I-scFvD2B was very high on PSMA positive cells (range 75–91%) and highly specific and immuno-PET at the optimal time point, defined between 15 h and 24 h, provides a specific localization of lesions bearing the target antigen of interest (PSMA positive vs PSMA negative tumors %ID/g: p = 0.0198 and p = 0.0176 respectively) yielding a median target/background ratio around 30–40.

Conclusions

Preclinical in vivo results of our immuno-PET reagent are highly promising. The target to background ratio is improved notably using PET compared to SPECT previously performed.

These data suggest that, upon clinical confirmation of sensitivity and specificity, our anti-PSMA ¹²⁴I-scFvD2B may be superior to other diagnostic modalities for PCa. The possibility to combine in patients our ¹²⁴I-scFvD2B in multi-modal systems, such as PET/CT, PET/MR and PET/SPECT/CT, will provide quantitative 3D tomographic images improving the knowledge of cancer biology and treatment.

Intracellular Delivery of Biologically-Active Fungal Metabolite Gliotoxin Using Magnetic Nanoparticles

Gliotoxin (GT), a secondary metabolite produced by Aspergillus molds, has been proposed as a potential anti-tumor agent. Here we have developed a nanoparticle approach to enhance delivery of GT in tumor cells and establish a basis for its potential use as therapeutical drug. GT bound to magnetic nanoparticles (MNPs) retained a high anti-tumor activity, correlating with efficient intracellular delivery, which was increased in the presence of glucose. Our results show that the attachment of GT to MNPs by covalent bonding enhances intracellular GT delivery without affecting its biological activity. This finding represents the first step to use this potent anti-tumor agent in the treatment of cancer.

Nanotechnology in the diagnosis and treatment of lung cancer

Lung cancer is an umbrella term for a subset of heterogeneous diseases that are collectively responsible for the most cancer-related deaths worldwide. Despite the tremendous progress made in understanding lung tumour biology, advances in early diagnosis, multimodal therapy and deciphering molecular mechanisms of drug resistance, overall curative outcomes remain low, especially in metastatic disease. Nanotechnology, in particular nanoparticles (NPs), continue to progressively impact the way by which tumours are diagnosed and treated. The unique physicochemical properties of materials at the nanoscale grant access to a diverse molecular toolkit that can be manipulated for use in respiratory oncology. This realisation has resulted in several clinically approved NP formulations and many more in clinical trials. However, NPs are not a panacea and have yet to be utilised to maximal effect in lung cancer, and medicine in a wider context. This review serves to: describe the complexity of lung cancer, the current diagnostic and therapeutic environment, and highlight the recent advancements of nanotechnology based approaches in diagnosis and treatment of respiratory malignancies. Finally, a brief outlook on the future directions of nanomedicine is provided; presently the full potential of the field is yet to be realised. By gleaning lessons and integrating advancements from neighbouring disciplines, nanomedicine can be elevated to a position where the current barriers that stymie full clinical impact are lifted.

The Relationship Between Tumor Glucose Metabolism and Host Systemic Inflammatory Responses in Patients with Cancer: A Systematic Review

One of the most important and long recognized characteristics of tumor cells is their dysregulated cellular energetics with anaerobic driven glucose uptake. In patients with cancer, the prognostic value of the systemic inflammatory response has been well established, and the recent combination of PET and CT scanning combines the assessment of tumor physiologic activity with detailed anatomic localization. The aim of this study was to perform a systematic review of the assessment of the relationship between both the tumor and the host inflammatory responses using PET/CT. Methods: An extensive literature review using targeted subject headings was performed in the U.S. National Library of Medicine, the Excerpta Medica database, and the Cochrane Database of Systematic Reviews on March 31, 2018. On completion of the online search, the title and abstracts of each identified study were examined for relevance. Studies with duplicate datasets, not available in English, and that did not have full text availability were excluded. Full texts of relevant articles were obtained and were then examined to identify any further relevant articles. Results: Twelve studies containing 2,588 patients were included in the final analysis. All of the included studies used the ¹⁸F-FDG tracer in PET/CT imaging and had biochemical assessment of the systemic inflammatory response. Most studies showed a direct relationship between the tumor and bone marrow glucose uptake and host systemic inflammatory responses as measured by C-reactive protein (n = 2), albumin (n = 2), white cell count (n = 3), neutrophils (n = 2), and platelets (n = 2). Most of the studies (n = 8) also showed a direct relationship between tumor and bone marrow glucose uptake and poor outcomes. Conclusion: This review suggests a direct relationship between the tumor and bone marrow glucose uptake and host systemic inflammation. This may suggest new approaches for more optimal therapeutic targeting and monitoring strategies in patients with cancer.

Current Status of Hybrid PET/MRI in Oncologic Imaging

OBJECTIVE

This review article explores recent advancements in PET/MRI for clinical oncologic imaging.

CONCLUSION

Radiologists should understand the technical considerations that have made PET/MRI feasible within clinical workflows, the role of PET tracers for imaging various molecular targets in oncology, and advantages of hybrid PET/MRI compared with PET/CT. To facilitate this understanding, we discuss clinical examples (including gliomas, breast cancer, bone metastases, prostate cancer, bladder cancer, gynecologic malignancy, and lymphoma) as well as future directions, challenges, and areas for continued technical optimization for PET/MRI.

Optimal Scan Time of 18F-FDG PET in Identifying Therapeutic Efficacy Secondary to Radiofrequency Ablation of Lung Cancer: Case Report

Positron emission tomography (PET)/computed tomography (CT)-guided radiofrequency ablation (RFA) has become a major treatment approach for small tumors. Identifying this quantitative dynamic 18F-2-fluoro-2-deoxy-d-glucose (18F-FDG) activity at the primary lesion can minimize misdiagnosis and allow an opportunity to reintervene. Here, we report 3 patients with nonsmall cell lung cancer (NSCLC) who underwent the ablative therapy with split-dose 18F-FDG fused PET/CT scans for early identification of residual tumors and follow-up evaluation of treatment. Our results indicate that reliable post-RFA imaging follow-up is critical in fast and efficient assessment of complete tumor resection in patients experienced the ablation procedure.

A review on segmentation of positron emission tomography images

Positron Emission Tomography (PET), a non-invasive functional imaging method at the molecular level, images the distribution of biologically targeted radiotracers with high sensitivity. PET imaging provides detailed quantitative information about many diseases and is often used to evaluate inflammation, infection, and cancer by detecting emitted photons from a radiotracer localized to abnormal cells. In order to differentiate abnormal tissue from surrounding areas in PET images, image segmentation methods play a vital role; therefore, accurate image segmentation is often necessary for proper disease detection, diagnosis, treatment planning, and follow-ups. In this review paper, we present state-of-the-art PET image segmentation methods, as well as the recent advances in image segmentation techniques. In order to make this manuscript self-contained, we also briefly explain the fundamentals of PET imaging, the challenges of diagnostic PET image analysis, and the effects of these challenges on the segmentation results.

Recent advances in nanoparticle-based nuclear imaging of cancers

Nuclear imaging techniques that include positron emission tomography (PET) and single-photon computed tomography have found great success in the clinic because of their inherent high sensitivity. Radionuclide imaging is the most popular form of imaging to be used for molecular imaging in oncology. While many types of molecules have been used for radionuclide-based molecular imaging, there has been a great interest in developing newer nanomaterials for use in clinic, especially for cancer diagnosis and treatment. Nanomaterials have unique physical properties which allow them to be used as imaging probes to locate and identify cancerous lesions. Over the past decade, a great number of nanoparticles have been developed for radionuclide imaging of cancer. This chapter reviews the different kinds of nanomaterials, both organic and inorganic, which are currently being researched for as potential agents for nuclear imaging of variety of cancers. Several radiolabeled multifunctional nanocarriers have been extremely successful for the detection of cancer in preclinical models. So far, significant progress has been achieved in nanoparticle structure design, in vitro/in vivo trafficking, and in vivo fate mapping by using PET. There is a great need for the development of newer nanoparticles, which improve active targeting and quantify new biomarkers for early disease detection and possible prevention of cancer.

Joint segmentation of anatomical and functional images: applications in quantification of lesions from PET, PET-CT, MRI-PET, and MRI-PET-CT images

We present a novel method for the joint segmentation of anatomical and functional images. Our proposed methodology unifies the domains of anatomical and functional images, represents them in a product lattice, and performs simultaneous delineation of regions based on random walk image segmentation. Furthermore, we also propose a simple yet effective object/background seed localization method to make the proposed segmentation process fully automatic. Our study uses PET, PET-CT, MRI-PET, and fused MRI-PET-CT scans (77 studies in all) from 56 patients who had various lesions in different body regions. We validated the effectiveness of the proposed method on different PET phantoms as well as on clinical images with respect to the ground truth segmentation provided by clinicians. Experimental results indicate that the presented method is superior to threshold and Bayesian methods commonly used in PET image segmentation, is more accurate and robust compared to the other PET-CT segmentation methods recently published in the literature, and also it is general in the sense of simultaneously segmenting multiple scans in real-time with high accuracy needed in routine clinical use.

Quantitative receptor-based imaging of tumor proliferation with the sigma-2 ligand [(18)F]ISO-1

The sigma-2 receptor is expressed in higher density in proliferating (P) tumor cells versus quiescent (Q) tumor cells, thus providing an attractive target for imaging the proliferative status (i.e., P:Q ratio) of solid tumors. Here we evaluate the utility of the sigma-2 receptor ligand 2-(2-[(18)F]fluoroethoxy)-N-(4-(3,4-dihydro-6,7-dimethoxyisoquinolin-2(1H)-yl)butyl)-5-methyl-benzamide, [(18)F]ISO-1, in two different rodent models of breast cancer. In the first study, small animal Positron Emission Tomography (PET) imaging studies were conducted with [(18)F]ISO-1 and (18)FDG in xenografts of mouse mammary tumor 66 and tracer uptake was correlated with the in vivo P:Q ratio determined by flow cytometric measures of BrdU-labeled tumor cells. The second model utilized a chemically-induced (N-methyl-N-nitrosourea [MNU]) model of rat mammary carcinoma to correlate measures of [(18)F]ISO-1 and FDG uptake with MR-based volumetric measures of tumor growth. In addition, [(18)F]ISO-1 and FDG were used to assess the response of MNU-induced tumors to bexarotene and Vorozole therapy. In the mouse mammary 66 tumors, a strong linear correlation was observed between the [(18)F]ISO-1 tumor: background ratio and the proliferative status (P:Q ratio) of the tumor (R = 0.87). Similarly, measures of [(18)F]ISO-1 uptake in MNU-induced tumors significantly correlated (R = 0.68, P<0.003) with changes in tumor volume between consecutive MR imaging sessions. Our data suggest that PET studies of [(18)F]ISO-1 provide a measure of both the proliferative status and tumor growth rate, which would be valuable in designing an appropriate treatment strategy.

Liposome imaging agents in personalized medicine

In recent years the importance of molecular and diagnostic imaging has increased dramatically in the treatment planning of many diseases and in particular in cancer therapy. Within nanomedicine there are particularly interesting possibilities for combining imaging and therapy. Engineered liposomes that selectively localize in tumor tissue can transport both drugs and imaging agents, which allows for a theranostic approach with great potential in personalized medicine. Radiolabeling of liposomes have for many years been used in preclinical studies for evaluating liposome in vivo performance and has been an important tool in the development of liposomal drugs. However, advanced imaging systems now provide new possibilities for non-invasive monitoring of liposome biodistribution in humans. Thus, advances in imaging and developments in liposome radiolabeling techniques allow us to enter a new arena where we start to consider how to use imaging for patient selection and treatment monitoring in connection to nanocarrier based medicines. Nanocarrier imaging agents could furthermore have interesting properties for disease diagnostics and staging. Here, we review the major advances in the development of radiolabeled liposomes for imaging as a tool in personalized medicine.

A tomografia por emissão de pósitrons com 2-[18F]-fluoro-2-desoxi-D-glicose é custo-efetiva em pacientes com câncer de pulmão não pequenas células no Brasil

OBJETIVO: Comparar a acurácia e a custo-efetividade do estadiamento metabólico (EM) com o FDG-PET em relação ao estadiamento convencional (EC) no estadiamento inicial de pacientes com câncer de pulmão não pequenas células (CPNPC). MATERIAIS E MÉTODOS: Noventa e cinco pacientes com diagnóstico inicial de CPNPC foram estadiados antes do início do tratamento. Os resultados do EC e EM foram comparados quanto a definição do tratamento e incidência de toracotomia fútil em cada estratégia. RESULTADOS: O EM com FDG-PET classificou 48,4% dos pacientes como estádio mais avançado e 5,3% como menos avançado. O resultado do EM modificaria o tratamento em 41% dos pacientes. A toracotomia foi considerada fútil em 47% dos pacientes com EC e em 19% dos casos com EM. O custo das toracotomias fúteis em oito pacientes no EM foi de R$ 79.720, enquanto em 31 pacientes no EC seria de R$ 308.915. Apenas esta economia seria mais que suficiente para cobrir os custos de todos os exames de FDG-PET nos 95 pacientes (R$ 126.350) ou de FDG-PET/CT (R$ 193.515). CONCLUSÃO: O EM com FDG-PET tem maior acurácia que o EC em pacientes com CPNPC. A FDG-PET e FDG-PET/CT são custo-efetivas e sua utilização se justifica economicamente na saúde pública no Brasil.

Therapeutic implications of an enriched cancer stem-like cell population in a human osteosarcoma cell line

BACKGROUND

Osteosarcoma is a bone-forming tumor of mesenchymal origin that presents a clinical pattern that is consistent with the cancer stem cell model. Cells with stem-like properties (CSCs) have been identified in several tumors and hypothesized as the responsible for the relative resistance to therapy and tumor relapses. In this study, we aimed to identify and characterize CSCs populations in a human osteosarcoma cell line and to explore their role in the responsiveness to conventional therapies.

METHODS

CSCs were isolated from the human MNNG/HOS cell line using the sphere formation assay and characterized in terms of self-renewal, mesenchymal stem cell properties, expression of pluripotency markers and ABC transporters, metabolic activity and tumorigenicity. Cell's sensitivity to conventional chemotherapeutic agents and to irradiation was analyzed and related with cell cycle-induced alterations and apoptosis.

RESULTS

The isolated CSCs were found to possess self-renewal and multipotential differentiation capabilities, express markers of pluripotent embryonic stem cells Oct4 and Nanog and the ABC transporters P-glycoprotein and BCRP, exhibit low metabolic activity and induce tumors in athymic mice. Compared with parental MNNG/HOS cells, CSCs were relatively more resistant to both chemotherapy and irradiation. None of the treatments have induced significant cell-cycle alterations and apoptosis in CSCs.

CONCLUSIONS

MNNG/HOS osteosarcoma cells contain a stem-like cell population relatively resistant to conventional chemotherapeutic agents and irradiation. This resistant phenotype appears to be related with some stem features, namely the high expression of the drug efflux transporters P-glycoprotein and BCRP and their quiescent nature, which may provide a biological basis for resistance to therapy and recurrence commonly observed in osteosarcoma.

Meta-analysis: comparison of F-18 fluorodeoxyglucose-positron emission tomography and bone scintigraphy in the detection of bone metastasis in patients with lung cancer

RATIONALE AND OBJECTIVES

The aim of this review was to evaluate the diagnostic properties of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) or PET/computed tomography (CT) and bone scintigraphy in the detection of osseous metastases in patients with lung cancer.

MATERIALS AND METHODS

MEDLINE was searched for relevant original articles published between January 1995 and August 2010. Inclusion criteria were as follows: FDG-PET or PET/CT and bone scintigraphy was carried out to detect bone metastases in patients with lung cancer, sufficient data were presented to construct a 2 × 2 contingency table, and histopathologic analysis and/or close clinical and imaging follow-up and/or radiographic confirmation by multiple imaging modalities was used as the reference standard. Two reviewers independently extracted data related to research design, sample size, imaging techniques, technical characteristics, reference standards, methods of imaging interpretation, and totals of true-positives, false-positives, true-negatives, and false-negatives. Stata was used to obtain per patient and per lesion pooled estimates of sensitivity, specificity, and positive and negative likelihood ratios, and areas under summary receiver-operating characteristic curves (AUCs) were calculated.

RESULTS

The pooled patient-based sensitivity of FDG-PET or PET/CT was 0.93 (95% confidence interval [CI], 0.88-0.96), specificity was 0.95 (95% CI, 0.91-0.98), and the AUC was 0.94. The pooled sensitivity of bone scans was 0.87 (95% CI, 0.79-0.93), specificity was 0.82 (95% CI, 0.62-0.92), and the AUC was 0.91. The pooled lesion-based sensitivity of FDG-PET or PET/CT was 0.93 (95% CI, 0.84-0.97), specificity was 0.91 (95% CI, 0.80-0.96), and the AUC was 0.97. The pooled sensitivity of bone scans was 0.92 (95% CI, 0.87-0.95), specificity was 0.57 (95% CI, 0.09-0.95), and the AUC was 0.92.

CONCLUSIONS

Although FDG-PET or PET/CT has higher sensitivity and specificity than bone scintigraphy, further research with a less biased design is needed to determine the most efficacious imaging modality for the detection of metastatic lung cancer.

Novel positron emission tomography tracer distinguishes normal from cancerous cells

Development of tumor-specific probes for imaging by positron emission tomography has broad implications in clinical oncology, such as diagnosis, staging, and monitoring therapeutic responses in patients, as well as in biomedical research. Thymidylate synthase (TSase)-based de novo biosynthesis of DNA is an important target for drug development. Increased DNA replication in proliferating cancerous cells requires TSase activity, which catalyzes the reductive methylation of dUMP to dTMP using (R)-N(5),N(10)-methylene-5,6,7,8-tetrahydrofolate (MTHF) as a cofactor. In principle, radiolabeled MTHF can be used as a substrate for this reaction to identify rapidly dividing cells. In this proof-of-principle study, actively growing (log phase) breast cancer (MCF7, MDA-MB-231, and hTERT-HME1), normal breast (human mammary epithelial and MCF10A), colon cancer (HT-29), and normal colon (FHC) cells were incubated with [(14)C]MTHF in culture medium from 30 min to 2 h, and uptake of radiotracer was measured. Cancerous cell lines incorporated significantly more radioactivity than their normal counterparts. The uptake of radioactively labeled MTHF depended upon a combination of cell doubling time, folate receptor status, S phase percentage, and TSase expression in the cells. These findings suggest that the recently synthesized [(11)C]MTHF may serve as a new positron emission tomography tracer for cancer imaging.

18F-FDG PET/CT imaging in oncology

Accurate diagnosis and staging are essential for the optimal management of cancer patients. Positron emission tomography with 2-deoxy-2-[fluorine-18]fluoro-D-glucose integrated with computed tomography (18F-FDG PET/CT) has emerged as a powerful imaging tool for the detection of various cancers. The combined acquisition of PET and CT has synergistic advantages over PET or CT alone and minimizes their individual limitations. It is a valuable tool for staging and restaging of some tumors and has an important role in the detection of recurrence in asymptomatic patients with rising tumor marker levels and patients with negative or equivocal findings on conventional imaging techniques. It also allows for monitoring response to therapy and permitting timely modification of therapeutic regimens. In about 27% of the patients, the course of management is changed. This review provides guidance for oncologists/radiotherapists and clinical and surgical specialists on the use of 18F-FDG PET/CT in oncology.

Impact of 18-fluorodeoxyglucose positron emission tomography on the management of pancreatic cancer

BACKGROUND

We compared the usefulness of positron emission tomography with the glucose analogue 2-deoxy-2-[18F]-fluoro-D-glucose (FDG-PET) and multidetector-row computed tomography (MD-CT) in diagnosing pancreatic cancer and in determining the patients' suitability for surgery.

METHODS

We reviewed the clinical FDG-PET data of 103 consecutive pancreatic cancer patients between July 2004 and March 2009.

RESULTS

The detection rates of pancreatic cancer by MD-CT (89%) and FDG-PET (91%) were similar. From the MD-CT findings, 38 patients were judged as operable, and 65, inoperable. Among the inoperable patients, noncurative factors (metastasis to the liver, peritoneum, remote lymph nodes, bones, and other organs and major arterial invasion) were detected by MD-CT and/or FDG-PET. Detection rates of liver metastasis and arterial invasion by FDG-PET were significantly inferior to those of MD-CT (neither was detected by FDG-PET alone). Remote lymph nodes and bone metastasis were detected in 20 lesions by FDG-PET alone; however, MD-CT indicated other noncurative factors in these patients. All 65 patients could be diagnosed as inoperable without FDG-PET.

CONCLUSIONS

FDG-PET is not a suitable imaging modality for either diagnosis or preoperative treatment in pancreatic cancer patients. Since it is expensive, FDG-PET as a routine diagnostic tool in pancreatic cancer patients must be used with caution.

Molecular imaging of pulmonary cancer and inflammation

Molecular imaging (MI) may be defined as imaging in vivo using molecules that report on biologic function. This review will focus on the clinical use of radioactive tracers (nonpharmacologic amounts of compounds labeled with a radioactive substance) that permit external imaging using single photon emission computed tomography (planar, SPECT) or positron emission tomography (PET) imaging. Imaging of lung cancer has been revolutionized with the use of fluorine-18-labeled fluorodeoxyglucose (18F-FDG), an analog of glucose that can be imaged using PET. The ability to carry out whole body imaging after intravenous injection of 18F-FDG allows accurate staging of disease, helping to determine regional and distant nodal and other parenchymal involvement. Glycolysis is increased in nonmalignant conditions, including inflammation (e.g., sarcoidosis), and 18F-FDG PET is a sensitive method for evaluation of active inflammatory disease. Inflammatory disease has been imaged, even before the advent of PET, with planar and SPECT imaging using gallium-67, a radiometal that binds to transferrin. Metabolic alteration in pulmonary pathology is currently being studied, largely in lung cancer, primarily with PET, with a variety of other radiotracers. Prominent among these is thymidine; fluorine-18-labeled thymidine PET is being increasingly used to evaluate proliferation rate in lung and other cancers. This overview will focus on the clinical utility of 18F-FDG PET in the staging and therapy evaluation of lung cancer as well as in imaging of nonmalignant pulmonary conditions. PET and SPECT imaging with other radiotracers of interest will also be reviewed. Future directions in PET imaging of pulmonary pathophysiology will also be explored.