Monitoring response to antiangiogenic therapy in non-small cell lung cancer using imaging markers derived from PET and dynamic contrast-enhanced MRI

[15O]H2O PET: Potential or Essential for Molecular Imaging?

Imaging water pathways in the human body provides an excellent way of measuring accurately the blood flow directed to different organs. This makes it a powerful diagnostic tool for a wide range of diseases that are related to perfusion and oxygenation. Although water PET has a long history, its true potential has not made it into regular clinical practice. The article highlights the potential of water PET in molecular imaging and suggests its prospective role in becoming an essential tool for the 21st century precision medicine in different domains ranging from preclinical to clinical research and practice. The recent technical advances in high-sensitivity PET imaging can play a key accelerating role in empowering this technique, though there are still several challenges to overcome.

Whole-body parametric mapping of tumour perfusion in metastatic prostate cancer using long axial field-of-view [15O]H2O PET

PURPOSE

Tumour perfusion is a nutrient-agnostic biomarker for cancer metabolic rate. Use of tumour perfusion for cancer growth assessment has been limited by complicated image acquisition, image analysis and limited field-of-view scanners. Long axial field-of-view (LAFOV) PET scan using [15O]H2O, allows quantitative assessment of whole-body tumour perfusion. We created a tool for automated creation of quantitative parametric whole-body tumour perfusion images in metastatic cancer.

METHODS

Ten metastatic prostate cancer patients underwent dynamic LAFOV [15O]H2O PET (Siemens, Quadra) followed by [18F]PSMA-1007 PET. Perfusion was measured as [15O]H2O K1 (mL/min/mL) with a single-tissue compartment model and an automatically captured cardiac image-derived input function. Parametric perfusion images were automatically calculated using the basis-function method with initial voxel-wise delay estimation and a leading-edge approach. Subsequently, perfusion of volumes-of-interest (VOI) can be directly extracted from the parametric images. We used a [18F]PSMA-1007 SUV 4 fixed threshold for tumour delineation and transferred these VOIs to the perfusion map.

RESULTS

For 8 primary tumours, 64 lymph node metastases, and 85 bone metastases, median tumour perfusion were 0.19 (0.15-0.27) mL/min/mL, 0.16 (0.13-0.27) mL/min/mL, and 0.26 (0.21-0.39), respectively. The correlation between calculated perfusion from time-activity-curves and parametric images was excellent (r = 0.99, p < 0.0001).

CONCLUSION

LAFOV PET imaging using [15O]H2O enables truly quantitative parametric images of whole-body tumour perfusion, a potential biomarker for guiding personalized treatment and monitoring treatment response.

PET Imaging of Metabolism, Perfusion, and Hypoxia: FDG and Beyond

ABSTRACT

Imaging glucose metabolism with [18F]fluorodeoxyglucose positron emission tomography has transformed the diagnostic and treatment algorithms of numerous malignancies in clinical practice. The cancer phenotype, though, extends beyond dysregulation of this single pathway. Reprogramming of other pathways of metabolism, as well as altered perfusion and hypoxia, also typifies malignancy. These features provide other opportunities for imaging that have been developed and advanced into humans. In this review, we discuss imaging metabolism, perfusion, and hypoxia in cancer, focusing on the underlying biology to provide context. We conclude by highlighting the ability to image multiple facets of biology to better characterize cancer and guide targeted treatment.

Molecular and functional imaging in cancer-targeted therapy: current applications and future directions

Targeted anticancer drugs block cancer cell growth by interfering with specific signaling pathways vital to carcinogenesis and tumor growth rather than harming all rapidly dividing cells as in cytotoxic chemotherapy. The Response Evaluation Criteria in Solid Tumor (RECIST) system has been used to assess tumor response to therapy via changes in the size of target lesions as measured by calipers, conventional anatomically based imaging modalities such as computed tomography (CT), and magnetic resonance imaging (MRI), and other imaging methods. However, RECIST is sometimes inaccurate in assessing the efficacy of targeted therapy drugs because of the poor correlation between tumor size and treatment-induced tumor necrosis or shrinkage. This approach might also result in delayed identification of response when the therapy does confer a reduction in tumor size. Innovative molecular imaging techniques have rapidly gained importance in the dawning era of targeted therapy as they can visualize, characterize, and quantify biological processes at the cellular, subcellular, or even molecular level rather than at the anatomical level. This review summarizes different targeted cell signaling pathways, various molecular imaging techniques, and developed probes. Moreover, the application of molecular imaging for evaluating treatment response and related clinical outcome is also systematically outlined. In the future, more attention should be paid to promoting the clinical translation of molecular imaging in evaluating the sensitivity to targeted therapy with biocompatible probes. In particular, multimodal imaging technologies incorporating advanced artificial intelligence should be developed to comprehensively and accurately assess cancer-targeted therapy, in addition to RECIST-based methods.

Characterization of spatially mapped volumetric molecular ultrasound signals for predicting response to anti-vascular therapy

Quantitative three-dimensional molecular ultrasound is a promising technology for longitudinal imaging applications such as therapy monitoring; the risk profile is favorable compared to positron emission tomography and computed tomography. However, clinical translation of quantitative methods for this technology are limited in that they assume that tumor tissues are homogeneous, and often depend on contrast-destruction events that can produce unintended bioeffects. Here, we develop quantitative features (henceforth image features) that capture tumor spatial information, and that are extracted without contrast destruction. We compare these techniques with the contrast-destruction derived differential targeted enhancement parameter (dTE) in predicting response to therapy. We found thirty-three reproducible image features that predict response to antiangiogenic therapy, without the need for a contrast agent disruption pulse. Multiparametric analysis shows that several of these image features can differentiate treated versus control animals with comparable performance to post-destruction measurements, suggesting that these can potentially replace parameters such as the dTE. The highest performing pre-destruction image features showed strong linear correlations with conventional dTE parameters with less overall variance. Thus, our study suggests that image features obtained during the wash in of the molecular agent, pre-destruction, may replace conventional post-destruction image features or the dTE parameter.

Dynamic contrast enhanced MRI of pulmonary adenocarcinomas for early risk stratification: higher contrast uptake associated with response and better prognosis

BACKGROUND

To explore the prognostic value of serial dynamic contrast-enhanced (DCE) MRI in patients with advanced pulmonary adenocarcinoma undergoing first-line therapy with either tyrosine-kinase inhibitors (TKI) or platinum-based chemotherapy (PBC).

METHODS

Patients underwent baseline (day 0, n = 98), and post-therapeutic DCE MRI (PBC: day + 1, n = 52); TKI: day + 7, n = 46) at 1.5T. Perfusion curves were acquired at 10, 40, and 70 s after contrast application and analysed semiquantitatively. Treatment response was evaluated at 6 weeks by CT (RECIST 1.1); progression-free survival (PFS) and overall survival  were analysed with respect to clinical and perfusion parameters. Relative uptake was defined as signal difference between contrast and non-contrast images, divided by the non-contrast signal. Predictors of survival were selected using Cox regression analysis. Median follow-up was 825 days.

RESULTS

In pre-therapeutic and early post-therapeutic MRI, treatment responders (n = 27) showed significantly higher relative contrast uptake within the tumor at 70 s after application as compared to non-responders (n = 71, p ≤ 0.02), response defined as PR by RECIST 1.1 at 6 weeks. There was no significant change of perfusion at early MRI after treatment. In multivariate regression analysis of selected parameters, the strongest association with PFS were relative uptake at 40 s in the early post-treatment MRI and pre-treatment clinical data (presence of liver metastases, ECOG performance status).

CONCLUSION

Higher contrast uptake within the tumor at pre-treatment and early post-treatment MRI was associated with treatment response and better prognosis. DCE MRI of pulmonary adenocarcinoma may provide important prognostic information.

Radiomics-Based Deep Learning Prediction of Overall Survival in Non-Small-Cell Lung Cancer Using Contrast-Enhanced Computed Tomography

Simple Summary

The five-year survival rate of non-small-cell lung cancer (NSCLC), which accounts for 85% of all lung cancer cases, is only 10–20%. A reliable prediction model of overall survival (OS) that integrates imaging and clinical data is required. Overall, 492 patients with NSCLC from two hospitals were enrolled in this study. The compensation method was applied to reduce the variation of imaging features among different hospitals. We constructed a deep learning prediction model, DeepSurv, based on computed tomography radiomics and key clinical features to generate a personalized survival curve for each patient. The results of DeepSurv showed a good performance in discriminating high and low risk of survival. Furthermore, the generated personalized survival curves could be intuitively applied for individual OS prediction in clinical practice. We concluded that the proposed prediction model could benefit physicians, patients, and caregivers in managing NSCLC and facilitate personalized medicine.

Abstract

Patient outcomes of non-small-cell lung cancer (NSCLC) vary because of tumor heterogeneity and treatment strategies. This study aimed to construct a deep learning model combining both radiomic and clinical features to predict the overall survival of patients with NSCLC. To improve the reliability of the proposed model, radiomic analysis complying with the Image Biomarker Standardization Initiative and the compensation approach to integrate multicenter datasets were performed on contrast-enhanced computed tomography (CECT) images. Pretreatment CECT images and the clinical data of 492 patients with NSCLC from two hospitals were collected. The deep neural network architecture, DeepSurv, with the input of radiomic and clinical features was employed. The performance of survival prediction model was assessed using the C-index and area under the curve (AUC) 8, 12, and 24 months after diagnosis. The performance of survival prediction that combined eight radiomic features and five clinical features outperformed that solely based on radiomic or clinical features. The C-index values of the combined model achieved 0.74, 0.75, and 0.75, respectively, and AUC values of 0.76, 0.74, and 0.73, respectively, 8, 12, and 24 months after diagnosis. In conclusion, combining the traits of pretreatment CECT images, lesion characteristics, and treatment strategies could effectively predict the survival of patients with NSCLC using a deep learning model.

Assessment of Early Response to Lung Cancer Chemotherapy by Semiquantitative Analysis of Dynamic Contrast-Enhanced MRI

Objective

To evaluate the early chemotherapy response in patients with lung cancer using semiquantitative analysis of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI).

Methods

Twenty-two patients with lung cancer treated with chemotherapy were subjected to DCE-MRI at two time points: before starting treatment and after one week of therapy. The image data were collected by DCE-MRI, and the semiquantitative parameters including positive enhancement integral (PEI), signal enhancement ratio (SER), maximum slope of increase (MSI), and time to peak (TTP) were calculated. After chemotherapy, the parameters and relevant variations between the responders and nonresponders were compared with Mann–Whitney U tests. Student's t-test for paired samples was used to evaluate the temporal changes between pre- and posttreatment images.

Results

The patients were categorized as 13 responders and 9 nonresponders based on the tumor response evaluation. After chemotherapy, the PEI, SER, and MSI were significantly increased in responders compared with the pretreatment values (P < 0.05), while no obvious decrease in TTP was observed (P > 0.05). However, 9 nonresponders showed no significant changes in PEI, SER, MSI, and TTP values, as compared with those of pretreatment (P > 0.05). Moreover, the increase of PEI was more dramatically in responders than in nonresponders (P < 0.05), but no significantly differences were observed in SER, MSI, and TTP (P > 0.05).

Conclusion

Semiquantitative analysis of DCE-MRI could provide a reliable noninvasive method for assessing early chemotherapy response in lung cancer patients.

Reproducibility of dynamic contrast enhanced MRI derived transfer coefficient Ktrans in lung cancer

Dynamic contrast enhanced MRI (DCE-MRI) is a useful method to monitor therapy assessment in malignancies but must be reliable and comparable for successful clinical use. The aim of this study was to evaluate the inter- and intrarater reproducibility of DCE-MRI in lung cancer. At this IRB approved single centre study 40 patients with lung cancer underwent up to 5 sequential DCE-MRI examinations. DCE-MRI were performed using a 3.0T system. The volume transfer constant Ktrans was assessed by three readers using the two-compartment Tofts model. Inter- and intrarater reliability and agreement was calculated by wCV, ICC and their 95% confident intervals. DCE-MRI allowed a quantitative measurement of Ktrans in 107 tumors where 91 were primary carcinomas or intrapulmonary metastases and 16 were extrapulmonary metastases. Ktrans showed moderate to good interrater reliability in overall measurements (ICC 0.716-0.841; wCV 30.3-38.4%). Ktrans in pulmonary lesions ≥ 3 cm showed a good to excellent reliability (ICC 0.773-0.907; wCV 23.0-29.4%) compared to pulmonary lesions < 3 cm showing a moderate to good reliability (ICC 0.710-0.889; wCV 31.6-48.7%). Ktrans in intrapulmonary lesions showed a good reliability (ICC 0.761-0.873; wCV 28.9-37.5%) compared to extrapulmonary lesions with a poor to moderate reliability (ICC 0.018-0.680; wCV 28.1-51.8%). The overall intrarater agreement was moderate to good (ICC 0.607-0.795; wCV 24.6-30.4%). With Ktrans, DCE MRI offers a reliable quantitative biomarker for early non-invasive therapy assessment in lung cancer patients, but with a coefficient of variation of up to 48.7% in smaller lung lesions.

Clinical translation of hyperpolarized 13 C pyruvate and urea MRI for simultaneous metabolic and perfusion imaging

Purpose

The combined hyperpolarized (HP) ¹³C pyruvate and urea MRI has provided a simultaneous assessment of glycolytic metabolism and tissue perfusion for improved cancer diagnosis and therapeutic evaluation in preclinical studies. This work aims to translate this dual‐probe HP imaging technique to clinical research.

Methods

A co‐polarization system was developed where [1‐¹³C]pyruvic acid (PA) and [¹³C, ¹⁵N₂]urea in water solution were homogeneously mixed and polarized on a 5T SPINlab system. Physical and chemical characterizations and toxicology studies of the combined probe were performed. Simultaneous metabolic and perfusion imaging was performed on a 3T clinical MR scanner by alternatively applying a multi‐slice 2D spiral sequence for [1‐¹³C]pyruvate and its downstream metabolites and a 3D balanced steady‐state free precession (bSSFP) sequence for [¹³C, ¹⁵N₂]urea.

Results

The combined PA/urea probe has a glass‐formation ability similar to neat PA and can generate nearly 40% liquid‐state ¹³C polarization for both pyruvate and urea in 3‐4 h. A standard operating procedure for routine on‐site production was developed and validated to produce 40 mL injection product of approximately 150 mM pyruvate and 35 mM urea. The toxicology study demonstrated the safety profile of the combined probe. Dynamic metabolite‐specific imaging of [1‐¹³C]pyruvate, [1‐¹³C]lactate, [1‐¹³C]alanine, and [¹³C, ¹⁵N₂]urea was achieved with adequate spatial (2.6 mm × 2.6 mm) and temporal resolution (4.2 s), and urea images showed reduced off‐resonance artifacts due to the J_CN coupling.

Conclusion

The reported technical development and translational studies will lead to the first‐in‐human dual‐agent HP MRI study and mark the clinical translation of the first HP ¹³C MRI probe after pyruvate.

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.

Potential synergy between PSMA uptake and tumour blood flow for prediction of human prostate cancer aggressiveness

BACKGROUND

Both prostate-specific membrane antigen (PSMA) uptake and tumour blood flow (TBF) correlate with International Society of Urological Pathology (ISUP) Grade Group (GG) and hence prostate cancer (PCa) aggressiveness. The aim of the present study was to evaluate the potential synergistic benefit of combining the two physiologic parameters for separating significant PCa from insignificant findings.

METHODS

From previous studies of [82Rb]Rb positron emission tomography (PET) TBF in PCa, the 43 patients that underwent clinical [68Ga]Ga-PSMA-11 PET were selected for this retrospective study. Tumours were delineated on [68Ga]Ga-PSMA-11 PET or magnetic resonance imaging. ISUP GG was recorded from 52 lesions.

RESULTS

[68Ga]Ga-PSMA-11 maximum standardized uptake value (SUVmax) and [82Rb]Rb SUVmax correlated moderately with ISUP GG (rho = 0.59 and rho = 0.56, both p < 0.001) and with each other (r = 0.65, p < 0.001). A combined model of [68Ga]Ga-PSMA-11 and [82Rb]Rb SUVmax separated ISUP GG > 2 from ISUP GG 1-2 and benign with an area-under-the-curve of 0.85, 96% sensitivity, 74% specificity, and 95% negative predictive value. The combined model performed significantly better than either tracer alone did (p < 0.001), primarily by reducing false negatives from five or six to one (p ≤ 0.025).

CONCLUSION

PSMA uptake and TBF provide complementary information about tumour aggressiveness. We suggest that a combined analysis of PSMA uptake and TBF could significantly improve the negative predictive value and allow non-invasive separation of significant from insignificant PCa.

Radiomics as a personalized medicine tool in lung cancer: Separating the hope from the hype

Radiomics has become a popular image analysis method in the last few years. Its key hypothesis is that medical images harbor biological, prognostic and predictive information that is not revealed upon visual inspection. In contrast to previous work with a priori defined imaging biomarkers, radiomics instead calculates image features at scale and uses statistical methods to identify those most strongly associated to outcome. This builds on years of research into computer aided diagnosis and pattern recognition. While the potential of radiomics to aid personalized medicine is widely recognized, several technical limitations exist which hinder biomarker translation. Aspects of the radiomic workflow lack repeatability or reproducibility under particular circumstances, which is a key requirement for the translation of imaging biomarkers into clinical practice. One of the most commonly studied uses of radiomics is for personalized medicine applications in Non-Small Cell Lung Cancer (NSCLC). In this review, we summarize reported methodological limitations in CT based radiomic analyses together with suggested solutions. We then evaluate the current NSCLC radiomics literature to assess the risk associated with accepting the published conclusions with respect to these limitations. We review different complementary scoring systems and initiatives that can be used to critically appraise data from radiomics studies. Wider awareness should improve the quality of ongoing and future radiomics studies and advance their potential as clinically relevant biomarkers for personalized medicine in patients with NSCLC.

IASLC Multidisciplinary Recommendations for Pathologic Assessment of Lung Cancer Resection Specimens After Neoadjuvant Therapy

Currently, there is no established guidance on how to process and evaluate resected lung cancer specimens after neoadjuvant therapy in the setting of clinical trials and clinical practice. There is also a lack of precise definitions on the degree of pathologic response, including major pathologic response or complete pathologic response. For other cancers such as osteosarcoma and colorectal, breast, and esophageal carcinomas, there have been multiple studies investigating pathologic assessment of the effects of neoadjuvant therapy, including some detailed recommendations on how to handle these specimens. A comprehensive mapping approach to gross and histologic processing of osteosarcomas after induction therapy has been used for over 40 years. The purpose of this article is to outline detailed recommendations on how to process lung cancer resection specimens and to define pathologic response, including major pathologic response or complete pathologic response after neoadjuvant therapy. A standardized approach is recommended to assess the percentages of (1) viable tumor, (2) necrosis, and (3) stroma (including inflammation and fibrosis) with a total adding up to 100%. This is recommended for all systemic therapies, including chemotherapy, chemoradiation, molecular-targeted therapy, immunotherapy, or any future novel therapies yet to be discovered, whether administered alone or in combination. Specific issues may differ for certain therapies such as immunotherapy, but the grossing process should be similar, and the histologic evaluation should contain these basic elements. Standard pathologic response assessment should allow for comparisons between different therapies and correlations with disease-free survival and overall survival in ongoing and future trials. The International Association for the Study of Lung Cancer has an effort to collect such data from existing and future clinical trials. These recommendations are intended as guidance for clinical trials, although it is hoped they can be viewed as suggestion for good clinical practice outside of clinical trials, to improve consistency of pathologic assessment of treatment response.

Repeatability of tumor blood flow quantification with 82Rubidium PET/CT in prostate cancer - a test-retest study

BACKGROUND

Non-invasive tumor blood flow (TBF) quantification is a candidate approach for risk stratification and monitoring of prostate cancer patients. Validation data have recently been published on prostate TBF measurement with the widely used positron emission tomography (PET) flow tracer ⁸²Rubidium (⁸²Rb). However, no test-retest data is available for TBF measurement with ⁸²Rb PET in prostate cancer. Such information is important to determine the potential clinical usefulness of the technique. The aim of the present study was to determine the test-retest repeatability of TBF measurement with both dynamic and static ⁸²Rb PET.

METHODS

We recruited 10 low-to-high-risk prostate cancer patients scheduled for clinical prostate-specific membrane antigen (PSMA) PET/computed tomography (CT) or magnetic resonance imaging. Pelvic and cardiac static and dynamic ⁸²Rb PET/CT were performed at baseline and repeated on a different day within 1 week. In total, 11 primary lesions were analyzed.

RESULTS

For K1, standardized uptake values (SUV)max, SUVmean, and SUVpeak, prostate cancer ⁸²Rb PET TBF has a repeatability of 32%, 51%, 53%, and 58% and an intraclass correlation of 0.98, 0.89, 0.88, and 0.88, respectively.

CONCLUSION

Dynamic ⁸²Rb PET/CT with kinetic modeling measures TBF in prostate cancer with high repeatability, which allows identification of blood flow changes of 32%. Static late-uptake ⁸²Rb PET/CT is inferior, and only intra-individual blood flow changes above 51% can hence be recognized.

Preliminary Results that Assess Metformin Treatment in a Preclinical Model of Pancreatic Cancer Using Simultaneous [18F]FDG PET and acidoCEST MRI

PURPOSE

We sought to determine if the synergy between evaluations of glucose uptake in tumors and extracellular tumor acidosis measured with simultaneous positron emission tomography (PET)/magnetic resonance imaging (MRI) can improve longitudinal evaluations of the response to metformin treatment.

PROCEDURES

A standard 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) PET protocol that evaluates glucose uptake in tumors, and a standard acidoCEST MRI protocol that measures extracellular pH (pHe) in tumors, were simultaneously performed to assess eight vehicle-treated (control) mice and eight metformin-treated mice 1 day before treatment, 1 day after initiating daily treatment with metformin, and 7 days after initiating treatment. Longitudinal changes in SUV_max and extracellular pH (pHe) were evaluated for each treatment group, and differences in SUV_max and pHe between metformin-treated and control groups were also evaluated.

RESULTS

MRI acquisition protocols had little effect on the PET count rate, and the PET instrumentation had little effect on image contrast during acidoCEST MRI, verifying that [¹⁸F]FDG PET and acidoCEST MRI can be performed simultaneously. The average SUV_max of the tumor model had a significant decrease after 7 days of treatment with metformin, as expected. The average tumor pHe decreased after 7 days of metformin treatment, which reflected the inhibition of the consumption of cytosolic lactic acid caused by metformin. However, the average SUV_max of the tumor model was not significantly different between the metformin-treated and control groups after 7 days of treatment, and average pHe was also not significantly different between these groups. For comparison, the combination of average SUV_max and pHe measurements significantly differed between the treatment group and control group on Day 7.

CONCLUSIONS

[¹⁸F]FDG PET and acidoCEST MRI studies can be performed simultaneously. The synergistic combination of assessing glucose uptake and tumor acidosis can improve differentiation of a drug-treated group from a control group during drug treatment of a tumor model.

Local control and vertebral compression fractures following stereotactic body radiotherapy for spine metastases

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SBRT provides a satisfying local control rate of 88% in patients with spMets.

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Post-SBRT vertebral compression rate of 4% corresponds to the current literature.

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>6 months of bisphosphonates use is associated with lower fracture-free survival.

Purpose

We aimed to retrospectively assess the incidence of vertebral compression fractures (VCF), examine clinicopathologic factors potentially associated with VCF, and evaluate treatment response in patients who received stereotactic body radiotherapy (SBRT) for spine metastases (spMets).

Methods and Materials

We identified 78 patients with 125 spMets at baseline and subsequent assessments. Patients received SBRT doses of 16 or 18 Gy. Patients with pre-existing VCF and co-existing local progression were excluded. Spine instability neoplastic score (SINS) was used for spMets categorization. Response to SBRT and VCF were assessed according to the Positron Emission tomography Response Criteria In Solid Tumors (PERCIST) and Genant scores, respectively. Kaplan–Meier analyses were used to assess local control of disease and vertebral compression fracture-free survival (FFS).

Results

We treated 103 cases with single spMets and 11 cases involving double spMets with SBRT. Progressive disease was reported in 3.2% and 8.2% of the cases in the first and last PET/CT reports, respectively. The distribution of treatment response in the remaining patients was: complete response in 30.6% of patients, partial response in 47.1% of patients, and stable disease in 22.3% of patients in the first PET/CT; complete response in 62.3% of patients, partial response in 16.7% of patients, and stable disease in 21% of patients at the last monitoring. Local failures were observed in 15 (12%) of cases. Median SINS was 5 (range: 1−13); majority of patients in our cohort (70.4%) were categorized as stable according to SINS, five (4%) patients had Grade 3 VCF at a median time of 16 months after SBRT (range: 2−22 months), and 60% of VCF occurred after an interval of at least 12 months after SBRT. No bisphosphonate usage was significantly associated with VCF (r = −0.204; p = 0.022). Median FFS was 21 months. Univariate analyses indicated that female gender (p < 0.001), bisphosphonate use (p = 0.005), >6 months of bisphosphonates use (p = 0.002), and the lowest vertebral body collapse score (p = 0.023) were associated with higher FFS. Female gender (p = 0.007), >6 months of bisphosphonates usage (p = 0.018), and the lowest vertebral body collapse score (p = 0.044) retained independent significance.

Conclusions

This study demonstrated that spine SBRT with doses of 16–18 Gy promises good local control of disease with acceptable VCF rates. Lowest vertebral body collapse score, female gender, and >6 months of bisphosphonate use were significantly associated with longer FFS.

Predictive value of positron emission tomography for the prognosis of molecularly targeted therapy in solid tumors

Objective

This study aimed at comprehensively exploring the value applying positron emission tomography (PET) to predict the effect of molecularly targeted therapy in solid tumors.

Materials and methods

A systematic search was performed for potentially relevant studies from the time of inception to February 2017. The primary endpoints were progression-free survival (PFS), overall survival (OS), and time to progression (TTP). The results were analyzed by Review Manager version 5.3 (RevMan 5.3) statistical software. Subgroup analyses were implemented based on the type of molecularly targeted agents (monoclonal antibodies arm and small molecular targeted agents arm), mechanism (erlotinib/gefitinib arm and bevacizumab arm), radioactive tracers, type of tumor, and reevaluated PET timing.

Results

Twenty-six studies incorporating 865 individuals were eligible. Compared with PET nonresponse group, PET response group displayed a decrease in maximal standard uptake value (SUVmax), which was associated with a significantly prolonged PFS (HR =0.41, 95% CI [0.29, 0.59]; P<0.00001), OS (HR =0.52, 95% CI [0.40, 0.67]; P<0.00001), and TTP (HR =0.30, 95% CI [0.14, 0.66]; P=0.003). Similar results were obtained in the subgroup analyses of PFS in erlotinib/gefitinib arm and small molecular targeted agents arm; and OS in lung cancer arm, erlotinib/gefitinib arm, bevacizumab arm, small molecular targeted agents arm, monoclonal antibodies arm, 18F-fluorodeoxythymidine (18F-FLT) arm, 18F-fluorodeoxyglucose (18F-FDG) arm, and early PET timing arm.

Conclusion

Our study demonstrated that PET was a favorable approach to predict the prognosis of molecularly targeted therapy for solid tumors. PET assessment within 2 weeks could be useful to predict clinical outcome.

Contrast-enhanced magnetic resonance imaging with a novel nano-size contrast agent for the clinical diagnosis of patients with lung cancer

Recent studies have indicated that magnetic resonance imaging (MRI) efficiently diagnoses lung cancer. However, the efficacy of MRI in diagnosing lung cancer requires improving for patients in the early stage of the disease. In the present study, a novel nano-sized contrast agent of chistosan/Fe₃O₄-enclosed bispecific antibodies (BsAbCENS) was introduced, which targeted carcino-embryonic antigen (CEA) and neuron-specific enolase (NSE) in lung cancer cells. The diagnostic efficacy of contrast-enhanced MRI with BsAbCENS (CEMRI-BsAbCENS) was investigated in a total of 182 patients with suspected lung cancer who had high serum levels of CEA and NSE. BsAbCENS was administered by pulmonary inhalation prior to the MRI scan. The results revealed that CEA and NSE were overexpressed in human lung cancer cell lines. BsAbCENS bound with CEA and NSE on the surface of human lung cancer cells and produced a higher signal intensity than MRI alone for the diagnosis of patients with lung cancer. The diagnostic data revealed that CEMRI-BsAbCENS diagnosed 124/182 lung cancer cases, whereas CEMRI only diagnosed 98/182, which was significantly less (P<0.01). In addition, the survival rate of patients with lung cancer diagnosed by CEMRI-BsAbCENS was significantly higher than the mean 5-year survival rate (P<0.01). Furthermore, the pharmacodynamics demonstrated that BsAbCENS was metabolized within 24 h. The results of the present study indicate that the efficacy and accuracy of lung cancer diagnosis are improved by CEMRI-BsAbCENS. In conclusion, these results provide a potential novel protocol for the diagnosis of tumors in patients with suspected early stage lung cancer.

SEOM-SERAM-SEMNIM guidelines on the use of functional and molecular imaging techniques in advanced non-small-cell lung cancer

Imaging in oncology is an essential tool for patient management but its potential is being profoundly underutilized. Each of the techniques used in the diagnostic process also conveys functional information that can be relevant in treatment decision making. New imaging algorithms and techniques enhance our knowledge about the phenotype of the tumor and its potential response to different therapies. Functional imaging can be defined as the one that provides information beyond the purely morphological data, and include all the techniques that make it possible to measure specific physiological functions of the tumor, whereas molecular imaging would include techniques that allow us to measure metabolic changes. Functional and molecular techniques included in this document are based on multi-detector computed tomography (CT), 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET), magnetic resonance imaging (MRI), and hybrid equipments, integrating PET with CT (PET/CT) or MRI (PET-MRI). Lung cancer is one of the most frequent and deadly tumors although survival is increasing thanks to advances in diagnostic methods and new treatments. This increased survival poises challenges in terms of proper follow-up and definitions of response and progression, as exemplified by immune therapy-related pseudoprogression. In this consensus document, the use of functional and molecular imaging techniques will be addressed to exploit their current potential and explore future applications in the diagnosis, evaluation of response and detection of recurrence of advanced NSCLC.

Targeted Therapy and Imaging Findings

Non-small cell lung cancer (NSCLC) is usually diagnosed when it is not amenable to curative surgery or radiation. Many of these patients are candidates for systemic therapy. Median survival is only approximately 10 months, and, accordingly, treatment in advanced NSCLC is evolving toward a more personalized approach with the identification of genetic abnormalities based on biomarkers. For example, gene mutations in EGFR (epidermal growth factor receptor) and ALK (anaplastic lymphoma kinase) lead to a cascade of pathways resulting in uncontrolled growth, proliferation, and survival of tumor cells. Targeted therapies are aimed at the products of these mutated genes and include agents such as erlotinib and gefitinib (in EGFR-mutant NSCLC) or crizotinib (in ALK-positive NSCLC). Antiangiogenesis agents such as bevacizumab are another category of targeted therapy that inhibits vascular endothelial growth factors. The imaging characteristics of advanced NSCLC with genetic abnormalities, the evolution of targeted therapies and their imaging manifestations will be discussed.

Validation of [18F]FLT as a perfusion-independent imaging biomarker of tumour response in EGFR-mutated NSCLC patients undergoing treatment with an EGFR tyrosine kinase inhibitor

Background

3′-Deoxy-3′-[¹⁸F]fluorothymidine ([¹⁸F]FLT) was proposed as an imaging biomarker for the assessment of in vivo cellular proliferation with positron emission tomography (PET). The current study aimed to validate [¹⁸F]FLT as a perfusion-independent PET tracer, by gaining insight in the intra-tumoural relationship between [¹⁸F]FLT uptake and perfusion in non-small cell lung cancer (NSCLC) patients undergoing treatment with a tyrosine kinase inhibitor (TKI).

Six patients with metastatic NSCLC, having an activating epidermal growth factor receptor (EGFR) mutation, were included in this study. Patients underwent [¹⁵O]H₂O and [¹⁸F]FLT PET/CT scans at three time points: before treatment and 7 and 28 days after treatment with a TKI (erlotinib or gefitinib). Parametric analyses were performed to generate quantitative 3D images of both perfusion measured with [¹⁵O]H₂O and proliferation measured with [¹⁸F]FLT volume of distribution (V_T). A multiparametric classification was performed by classifying voxels as low and high perfusion and/or low and high [¹⁸F]FLT V_T using a single global threshold for all scans and subjects. By combining these initial classifications, voxels were allocated to four categories (low perfusion-low V_T, low perfusion-high V_T, high perfusion-low V_T and high perfusion-high V_T).

Results

A total of 17 perfusion and 18 [¹⁸F]FLT PET/CT scans were evaluated. The average tumour values across all lesions were 0.53 ± 0.26 mL cm^− 3 min^− 1 and 4.25 ± 1.71 mL cm^− 3 for perfusion and [¹⁸F]FLT V_T, respectively. Multiparametric analysis suggested a shift in voxel distribution, particularly regarding the V_T: from an average of ≥ 77% voxels classified in the “high V_T category” to ≥ 85% voxels classified in the “low V_T category”. The shift was most prominent 7 days after treatment and remained relatively similar afterwards. Changes in perfusion and its spatial distribution were minimal.

Conclusion

The present study suggests that [¹⁸F]FLT might be a perfusion-independent PET tracer for measuring tumour response as parametric changes in [¹⁸F]FLT uptake occurred independent from changes in perfusion.

Trial registration

Nederlands Trial Register (NTR), NTR3557. Registered 2 August 2012

Electronic supplementary material

The online version of this article (10.1186/s13550-018-0376-6) contains supplementary material, which is available to authorized users.

Early assessment of response to chemotherapy in lung cancer using dynamic contrast-enhanced MRI: a proof-of-concept study

AIM

To evaluate the early treatment response to chemotherapy in patients with lung cancer using dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Twenty-two patients with lung cancer underwent DCE-MRI before chemotherapy and 1 week after the start of the first course of chemotherapy. Pharmacokinetic parameters (Ktrans, Kep, and Ve) derived from DCE MRI were generated using the post-processing platform. These parameters and corresponding changes were compared between responders and non-responders after treatment using Student's t or Mann-Whitney U-tests. Diagnostic efficiency of kinetic parameters in differentiating responders from non-responders after 1 week of chemotherapy was also investigated.

RESULTS

Thirteen responders after 1 week of chemotherapy had a significant decrease in Ktrans and Ve compared with the pretreatment value (p<0.05), and had no significant changes in Kep (p>0.05). Nine non-responders had no significant changes in Ktrans, Kep, and Ve compared with the pretreatment value (p>0.05). Changes in Ktrans (ΔKtrans) were significantly larger in responders than that in non-responders (p<0.05). Changes in Ve and Kep (ΔVe andΔKep) were without statistical significance after treatment between responders and non-responders (p>0.05). The cut-off value of ΔKtrans in best predicting tumour's chemotherapeutic response was 0.032/min and the corresponding AUC (area under the curve), sensitivity, specificity, and accuracy were 0.821, 84.62%, 77.78%, and 81.82%, respectively.

CONCLUSION

DCE MRI may be useful for evaluating the early response to chemotherapy in patients with lung cancer, but larger, more definitive studies are needed.

Dynamic contrast-enhanced MRI versus 18F-FDG PET/CT: Which is better in differentiation between malignant and benign solitary pulmonary nodules?

Objective

To prospectively compare the discriminative capacity of dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) with that of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in the differentiation of malignant and benign solitary pulmonary nodules (SPNs).

Methods

Forty-nine patients with SPNs were included in this prospective study. Thirty-two of the patients had malignant SPNs, while the other 17 had benign SPNs. All these patients underwent DCE-MRI and ¹⁸F-FDG PET/CT examinations. The quantitative MRI pharmacokinetic parameters, including the trans-endothelial transfer constant (K^trans), redistribution rate constant (K_ep), and fractional volume (V_e), were calculated using the Extended-Tofts Linear two-compartment model. The ¹⁸F-FDG PET/CT parameter, maximum standardized uptake value (SUV_max), was also measured. Spearman's correlations were calculated between the MRI pharmacokinetic parameters and the SUV_max of each SPN. These parameters were statistically compared between the malignant and benign nodules. Receiver operating characteristic (ROC) analyses were used to compare the diagnostic capability between the DCE-MRI and ¹⁸F-FDG PET/CT indexes.

Results

Positive correlations were found between K^trans and SUV_max, and between K_ep and SUV_max (P<0.05). There were significant differences between the malignant and benign nodules in terms of the K^trans, K_ep and SUV_max values (P<0.05). The areas under the ROC curve (AUC) of K^trans, K_ep and SUV_max between the malignant and benign nodules were 0.909, 0.838 and 0.759, respectively. The sensitivity and specificity in differentiating malignant from benign SPNs were 90.6% and 82.4% for K^trans; 87.5% and 76.5% for K_ep; and 75.0% and 70.6% for SUV_max, respectively. The sensitivity and specificity of K^trans and K_ep were higher than those of SUV_max, but there was no significant difference between them (P>0.05).

Conclusions

DCE-MRI can be used to differentiate between benign and malignant SPNs and has the advantage of being radiation free.

SEOM-SERAM-SEMNIM guidelines on the use of functional and molecular imaging techniques in advanced non-small-cell lung cancer

Imaging in oncology is an essential tool for patient management but its potential is being profoundly underutilized. Each of the techniques used in the diagnostic process also conveys functional information that can be relevant in treatment decision-making. New imaging algorithms and techniques enhance our knowledge about the phenotype of the tumor and its potential response to different therapies. Functional imaging can be defined as the one that provides information beyond the purely morphological data, and include all the techniques that make it possible to measure specific physiological functions of the tumor, whereas molecular imaging would include techniques that allow us to measure metabolic changes. Functional and molecular techniques included in this document are based on multi-detector computed tomography (CT), 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET), magnetic resonance imaging (MRI), and hybrid equipments, integrating PET with CT (PET/CT) or MRI (PET-MRI). Lung cancer is one of the most frequent and deadly tumors although survival is increasing thanks to advances in diagnostic methods and new treatments. This increased survival poises challenges in terms of proper follow-up and definitions of response and progression, as exemplified by immune therapy-related pseudoprogression. In this consensus document, the use of functional and molecular imaging techniques will be addressed to exploit their current potential and explore future applications in the diagnosis, evaluation of response and detection of recurrence of advanced NSCLC.

Prediction of Therapeutic Effect of Chemotherapy for NSCLC Using Dual-Input Perfusion CT Analysis: Comparison among Bevacizumab Treatment, Two-Agent Platinum-based Therapy without Bevacizumab, and Other Non-Bevacizumab Treatment Groups

Purpose To determine whether dual-input perfusion computed tomography (CT) can predict therapeutic response and prognosis in patients who underwent chemotherapy for non-small cell lung cancer (NSCLC). Materials and Methods The institutional review board approved this study and informed consent was obtained. Sixty-six patients with stage III or IV NSCLC (42 men, 24 women; mean age, 63.4 years) who underwent chemotherapy were enrolled. Patients were separated into three groups: those who received chemotherapy with bevacizumab (BV) (n = 20), those who received two-agent platinum-based therapy without BV (n = 25), and those who received other non-BV treatment (n = 21). Before treatment, pulmonary artery perfusion (PAP) and bronchial artery perfusion (BAP) of the tumors were calculated. Predictors of tumor reduction after two courses of chemotherapy and prognosis were identified by using univariate and multivariate analyses. Covariates included were age, sex, patient's performance status, baseline maximum diameter of the tumor, clinical stage, pretreatment PAP, and pretreatment BAP. For multivariate analyses, multiple linear regression analysis for tumor reduction rate and Cox proportional hazards model for prognosis were performed, respectively. Results Pretreatment BAP was independently correlated with tumor reduction rate after two courses of chemotherapy in the BV treatment group (P = .006). Pretreatment BAP was significantly associated with a highly cumulative risk of death (P = .006) and disease progression after chemotherapy (P = .015) in the BV treatment group. Pretreatment PAP and clinical parameters were not significant predictors of therapeutic effect or prognosis in three treatment groups. Conclusion Pretreatment BAP derived from dual-input perfusion CT seems to be a promising tool to help predict responses to chemotherapy with BV in patients with NSCLC. ^© RSNA, 2017.

[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。

Prognostic value of early response assessment using (18F)FDG-PET in patients with advanced non-small cell lung cancer treated with tyrosine-kinase inhibitors

The purpose of this meta-analysis was to determine the prognostic value of early response assessment using (18F)fluorodeoxyglucose (FDG)-positron emission thermography (PET) in patients with advanced non-small cell lung cancer (NSCLC) treated with tyrosine-kinase inhibitors (TKIs). MEDLINE, PubMed, Cochrane, EMBASE, and Google Scholar databases were searched until August 1, 2016 using the keywords non-small cell lung carcinoma, positron-emission tomography, fluorodeoxyglucose, prognosis, disease progression, survival, erlotinib, gefitinib, and afatinib. Inclusion criteria were studies of patients with stage III or IV NSCLC treated with a TKI and had response assessed by FDG-PET. Outcome measures were overall survival (OS) and progression-free survival (PFS). Of the 167 articles identified, 10 studies including 302 patients were included in the analysis. In 8 studies, patients were treated with erlotinib, and in 2 they were treated with gefitinib. The overall analysis revealed that early metabolic response was statistically associated with improved OS (HR=0.54; 95% CI 0.46 to 0.63; p<0.001), and with longer PFS (HR=0.23; 95% CI 0.17 to 0.33; p<0.001). Early response of patients with NSCLC treated with TKIs identified on FDG-PET is associated with improved OS and PFS.

The Value of FDG PET/CT in Treatment Response Assessment, Follow-Up, and Surveillance of Lung Cancer

OBJECTIVE

The purpose of this article is to summarize the evidence regarding the role of FDG PET/CT in treatment response assessment and surveillance of lung cancer and to provide suggested best practices.

CONCLUSION

FDG PET/CT is a valuable imaging tool for assessing treatment response for patients with lung cancer, though evidence for its comparative effectiveness with chest CT is still evolving. FDG PET/CT is most useful when there is clinical suspicion or other evidence for disease recurrence or metastases. The sequencing, cost analysis, and comparative effectiveness of FDG PET/CT and conventional imaging modalities in the follow-up setting need to be investigated.

One Coin, No Need to Flip: Shared PET Targets in Cancer and Coronary Artery Disease

OBJECTIVE

The purposes of this article are to review the common biologic features of cancer and coronary artery disease assessed with PET tracers, focusing on those already used in the clinic and those with translational potential, and to discuss the current value and expected contribution of PET in diagnosis, risk stratification, and treatment monitoring.

CONCLUSION

PET using a wide variety of radiotracers enhances understanding of pathophysiologic changes shared by cancer and coronary artery disease, helps establish an accurate diagnosis, and aids in prognostic assessment and management decisions. It is likely that with the evolution of therapeutic strategies for blocking the development and progression of both diseases and with the introduction of novel, specific ligands in clinical practice, PET will play an ever stronger role in diagnosis, risk stratification, and monitoring of therapy.

DCE-MRI Perfusion and Permeability Parameters as predictors of tumor response to CCRT in Patients with locally advanced NSCLC

In this prospective study, 36 patients with stage III non-small cell lung cancers (NSCLC), who underwent dynamic contrast-enhanced MRI (DCE-MRI) before concurrent chemo-radiotherapy (CCRT) were enrolled. Pharmacokinetic analysis was carried out after non-rigid motion registration. The perfusion parameters [including Blood Flow (BF), Blood Volume (BV), Mean Transit Time (MTT)] and permeability parameters [including endothelial transfer constant (K^trans), reflux rate (K_ep), fractional extravascular extracellular space volume (V_e), fractional plasma volume (V_p)] were calculated, and their relationship with tumor regression was evaluated. The value of these parameters on predicting responders were calculated by receiver operating characteristic (ROC) curve. Multivariate logistic regression analysis was conducted to find the independent variables. Tumor regression rate is negatively correlated with V_e and its standard variation V_e_SD and positively correlated with K^trans and K_ep. Significant differences between responders and non-responders existed in K^trans, K_ep, V_e, V_e_SD, MTT, BV_SD and MTT_SD (P < 0.05). ROC indicated that V_e < 0.24 gave the largest area under curve of 0.865 to predict responders. Multivariate logistic regression analysis also showed V_e was a significant predictor. Baseline perfusion and permeability parameters calculated from DCE-MRI were seen to be a viable tool for predicting the early treatment response after CCRT of NSCLC.

TLG-S criteria are superior to both EORTC and PERCIST for predicting outcomes in patients with metastatic lung adenocarcinoma treated with erlotinib

PURPOSE

In this retrospective review of prospectively collected data, we sought to investigate whether early FDG-PET assessment of treatment response based on total lesion glycolysis measured using a systemic approach (TLG-S) would be superior to either local assessment with EORTC (European Organization for Research and Treatment of Cancer) criteria or single-lesion assessment with PERCIST (PET Response Criteria in Solid Tumors) for predicting clinical outcomes in patients with metastatic lung adenocarcinoma treated with erlotinib. We also examined the effect of bone flares on tumor response evaluation by single-lesion assessment with PERCIST in patients with metastatic bone lesions.

METHODS

We performed a retrospective review of prospectively collected data from 23 patients with metastatic lung adenocarcinoma treated with erlotinib. All participants underwent FDG-PET imaging at baseline and on days 14 and 56 after completion of erlotinib treatment. In addition, diagnostic CT scans were performed at baseline and on day 56. FDG-PET response was assessed with TLG-S, EORTC, and PERCIST criteria. Response assessment based on RECIST 1.1 (Response Evaluation Criteria in Solid Tumors) from diagnostic CT imaging was used as the reference standard. Two-year progression-free survival (PFS) and overall survival (OS) served as the main outcome measures.

RESULTS

We identified 13 patients with bone metastases. Of these, four (31 %) with persistent bone uptake due to bone flares on day 14 were erroneously classified as non-responders according to the PERCIST criteria, but they were correctly classified as responders according to both the EORTC and TLG-S criteria. Patients who were classified as responders on day 14 based on TLG-S criteria had higher rates of 2-year PFS (26.7 % vs. 0 %, P = 0.007) and OS (40.0 % vs. 7.7 %, P = 0.018). Similar rates were observed in patients who showed a response on day 56 based on CT imaging according to the RECIST criteria. Patients classified as responders on day 14 according to the EORTC criteria on FDG-PET imaging had better rates of 2-year OS than did non-responders (36.4 % vs. 8.3 %, P = 0.015).

CONCLUSIONS

TLG-S criteria may be of greater help in predicting survival outcomes than other forms of assessment. Bone flares, which can interfere with the interpretation of treatment response based on PERCIST criteria, are not uncommon in patients with metastatic lung adenocarcinoma treated with erlotinib.

βIII-Tubulin alters glucose metabolism and stress response signaling to promote cell survival and proliferation in glucose-starved non-small cell lung cancer cells

Non-small cell lung cancer (NSCLC) survival rates are dismal and high βIII-tubulin expression is associated with chemotherapy drug resistance and tumor aggressiveness in this disease. Mounting evidence supports a role for βIII-tubulin in promoting cell survival in the harsh tumor microenvironment, which is characterized by poor nutrient supply. This study aimed to investigate the role of βIII-tubulin in glucose stress response signaling and the survival and proliferation of NSCLC cells. This study revealed that βIII-tubulin regulates cellular metabolism and glucose stress response signaling in NSCLC cells to promote cell survival and proliferation in glucose starvation. βIII-Tubulin decreases the reliance of cells on glycolytic metabolism, priming them to cope with variable nutrient supply present within the tumor microenvironment. βIII-Tubulin protects cells from endoplasmic reticulum (ER) stress and reduces both basal and glucose starvation-induced autophagy to maintain cell survival and proliferation. βIII-Tubulin enables rapid Akt activation in response to glucose starvation and co-immunoprecipitates with the master regulator of the ER stress response GRP78. Furthermore, suppression of βIII-tubulin delays the association of GRP78 with Akt in response to glucose starvation with the potential to influence Akt activation and ER homeostasis under these conditions. Together these results identify that βIII-tubulin regulates glucose metabolism and alters glucose starvation stress signaling to promote cell proliferation and survival in NSCLC cells. This elucidates a hitherto unknown role for this microtubule protein and provides insight into correlations between high βIII-tubulin expression and poor patient outcome in this disease.

Mechanism and non-mechanism based imaging biomarkers for assessing biological response to treatment in non-small cell lung cancer

Therapeutic options in locally advanced non-small cell lung cancer (NSCLC) have expanded in the past decade to include a palate of targeted interventions such as high dose targeted thermal ablations, radiotherapy and growing platform of antibody and small molecule therapies and immunotherapies. Although these therapies have varied mechanisms of action, they often induce changes in tumour architecture and microenvironment such that response is not always accompanied by early reduction in tumour mass, and evaluation by criteria other than size is needed to report more effectively on response. Functional imaging techniques, which probe the tumour and its microenvironment through novel positron emission tomography and magnetic resonance imaging techniques, offer more detailed insights into and quantitation of tumour response than is available on anatomical imaging alone. Use of these biomarkers, or other rational combinations as readouts of pathological response in NSCLC have potential to provide more accurate predictors of treatment outcomes. In this article, the robustness of the more commonly available positron emission tomography and magnetic resonance imaging biomarker indices is examined and the evidence for their application in NSCLC is reviewed.

Inter-reader reproducibility of dynamic contrast-enhanced magnetic resonance imaging in patients with non-small cell lung cancer treated with bevacizumab and erlotinib

Objectives When evaluating anti-tumor treatment response by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) it is necessary to assure its validity and reproducibility. This has not been well addressed in lung tumors. Therefore we have evaluated the inter-reader reproducibility of response classification by DCE-MRI in patients with non-small cell lung cancer (NSCLC) treated with bevacizumab and erlotinib enrolled in a multicenter trial.

MATERIALS AND METHODS

Twenty-one patients were scanned before and 3 weeks after start of treatment with DCE-MRI in a multicenter trial. The scans were evaluated by two independent readers. The primary lung tumor was used for response assessment. Responses were assessed in terms of relative changes in tumor mean trans endothelial transfer rate (K(trans)) and its heterogeneity in terms of the spatial standard deviation. Reproducibility was expressed by the inter-reader variability, intra-class correlation coefficient (ICC) and dichotomous response classification.

RESULTS

The inter-reader variability and ICC for the relative K(trans) were 5.8% and 0.930, respectively. For tumor heterogeneity the inter-reader variability and ICC were 0.017 and 0.656, respectively. For the two readers the response classification for relative K(trans) was concordant in 20 of 21 patients (k=0.90, p<0.0001) and for tumor heterogeneity in 19 of 21 patients (k=0.80, p<0.0001).

CONCLUSIONS

Strong agreement was seen with regard to the inter-reader variability and reproducibility of response classification by the two readers of lung cancer DCE-MRI scans.

Comparison of CT volumetric measurement with RECIST response in patients with lung cancer

PURPOSE

To examine the correlations between uni-dimensional RECIST and volumetric measurements in patients with lung adenocarcinoma and to assess their association with overall survival (OS) and progression-free survival (PFS).

MATERIALS AND METHODS

In this study of patients receiving chemotherapy for lung cancer in the setting of a clinical trial, response was prospectively evaluated using RECIST 1.0. Retrospectively, volumetric measurements were recorded and response was assessed by two different volumetric methods at each followup CT scan using a semi-automated segmentation algorithm. We subsequently evaluated the correlation between the uni-dimensional RECIST measurements and the volumetric measurements and performed landmark analyses for OS and PFS at the completion of the first and second follow-ups. Kaplan-Meier curves together with log-rank tests were used to evaluate the association between the different response criteria and patient outcome.

RESULTS

Forty-two patients had CT scans at baseline, after the first follow up scan and second followup scan, and then every 8 weeks. The uni-dimensional RECIST measurements and volumetric measurements were strongly correlated, with a Spearman correlation coefficient (ρ) of 0.853 at baseline, ρ=0.861 at the first followup, ρ=0.843 at the 2nd followup, and ρ=0.887 overall between-subject. On first follow-up CT, partial responders and non responders as assessed by an "ellipsoid" volumetric criteria showed a significant difference in OS (p=0.008, 1-year OS of 70% for partial responders and 46% for non responders). There was no difference between the groups when assessed by RECIST criteria on first follow-up CT (p=0.841, 1-year OS rate of 64% for partial responders and 64% for non responders).

CONCLUSION

Volumetric response on first follow-up CT may better predict OS than RECIST response.

CLINICAL RELEVANCE STATEMENT

Assessment of tumor size and response is of utmost importance in clinical trials. Volumetric measurements may help to better predict OS than uni-dimensional RECIST criteria.

Emerging Role of MRI for Radiation Treatment Planning in Lung Cancer

Magnetic resonance imaging (MRI) provides excellent soft-tissue contrast and allows for specific scanning sequences to optimize differentiation between various tissue types and properties. Moreover, it offers the potential for real-time motion imaging. This makes magnetic resonance imaging an ideal candidate imaging modality for radiation treatment planning in lung cancer. Although the number of clinical research protocols for the application of magnetic resonance imaging for lung cancer treatment is increasing (www.clinicaltrials.gov) and the magnetic resonance imaging sequences are becoming faster, there are still some technical challenges. This review describes the opportunities and challenges of magnetic resonance imaging for radiation treatment planning in lung cancer.

Monitoring hypoxia and vasculature during bevacizumab treatment in a murine colorectal cancer model

The purpose of this study was to assess the effect of bevacizumab on vasculature and hypoxia in a colorectal tumor model. Nude mice with subcutaneous LS174T tumors were treated with bevacizumab or saline. To assess tumor properties, separate groups of mice were imaged using (18) F-Fluoromisonidazole (FMISO) and (18) F-Fluorodeoxyglucose (FDG) positron emission tomography or magnetic resonance imaging before and 2, 6 and 10 days after the start of treatment. Tumors were harvested after imaging to determine hypoxia and vascular density immunohistochemically. The T2 * time increased significantly less in the bevacizumab group. FMISO uptake increased more over time in the control group. Vessel density significantly decreased in the bevacizumab-treated group. The Carbonic anhydrase 9 (CAIX) and glucose uptake transporter 1 (GLUT1) fractions were higher in bevacizumab-treated tumors. However, the hypoxic fraction showed no significant difference. Bevacizumab led to shorter T2 * times and higher GLUT1 and CAIX expression, suggesting an increase in hypoxia and a higher glycolytic rate. This could be a mechanism of resistance to bevacizumab. The increase in hypoxia, however, could not be demonstrated by pimonidazole/FMISO, possibly because distribution of these tracers is hampered by bevacizumab-induced effects on vascular permeability and perfusion.

Acute vascular response to cediranib treatment in human non-small-cell lung cancer xenografts with different tumour stromal architecture

•

We studied cediranib, a VEGFR tyrosine kinase inhibitor in lung cancer xenografts.

•

Gadolinium-enhanced DCE-MRI was used to study acute vascular responses.

•

Acute vascular response was associated with tumour stromal architecture.

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Tumour growth inhibition by cediranib was linked to acute vascular response.

•

Acute vascular changes are a potential predictive marker of response to cediranib.

Objectives

Tumours can be categorised based on their stromal architecture into tumour vessel and stromal vessel phenotypes, and the phenotypes have been suggested to define tumour response to chronic treatment with a VEGFR2 antibody. However, it is unclear whether the vascular phenotypes of tumours associate with acute vascular response to VEGFR tyrosine kinase inhibitors (TKI), or whether the early changes in vascular function are associated with subsequent changes in tumour size. This study was sought to address these questions by using xenograft models of human non-small cell lung cancer (NSCLC) representing stromal vessel phenotype (Calu-3) and tumour vessel phenotype (Calu-6), respectively.

Methods

For dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), nude mice bearing established Calu-3 or Calu-6 xenografts were treated with a potent pan-VEGFR TKI, cediranib (6 mg/kg), at 0 h and 22 h. DCE-MRI was performed 2 h before the first dose and 2 h after the second dose of cediranib to examine acute changes in tumour vessel perfusion. Tumours were harvested for hypoxia detection by CA9 immunohistochemistry. For tumour growth study, mice carrying established Calu-3 or Calu-6 tumours were treated with cediranib once daily for 5 days.

Results

Twenty-four hours after cediranib administration, the perfusion of Calu-3 tumours was markedly reduced, with a significant increase in hypoxia. In contrast, neither perfusion nor hypoxia was significantly affected in Calu-6 tumours. Tumour regressions were induced in Calu-3 xenografts, but not in Calu-6 xenografts, although there was a trend towards tumour growth inhibition after 5 days of cediranib treatment.

Conclusion

These findings suggest that tumour stromal architecture may associate with acute tumour vascular response to VEGFR TKI, and this acute tumour vascular response may be a promising early predictive marker of response to VEGFR TKI in NSCLC.

Future of thoracic PET scanning

The advances in PET scanning for thoracic diseases that are deemed most likely to have clinical impact in the near-term future are highlighted in this article. We predict that the current practice of medicine will continue to embrace the power of molecular imaging and specifically PET scanning. 18F-fluorodeoxyglucose-PET scanning will continue to evolve and will expand into imaging of inflammatory disorders. New clinically available PET scan radiotracers, such as PET scan versions of octreotide and amyloid imaging agents, will expand PET imaging into different disease processes. Major improvements in thoracic PET/CT imaging technology will become available, including fully digital silicone photomultipliers and Bayesian penalized likelihood image reconstruction. These will result in significant improvements in image quality, improving the evaluation of smaller lung nodules and metastases and allowing better prediction of prognosis. The birth of clinical PET/MRI scan will add new imaging opportunities, such as better PET imaging of pleural diseases currently obscured by complex patient motion.

Positron emission tomography to assess hypoxia and perfusion in lung cancer

In lung cancer, tumor hypoxia is a characteristic feature, which is associated with a poor prognosis and resistance to both radiation therapy and chemotherapy. As the development of tumor hypoxia is associated with decreased perfusion, perfusion measurements provide more insight into the relation between hypoxia and perfusion in malignant tumors. Positron emission tomography (PET) is a highly sensitive nuclear imaging technique that is suited for non-invasive in vivo monitoring of dynamic processes including hypoxia and its associated parameter perfusion. The PET technique enables quantitative assessment of hypoxia and perfusion in tumors. To this end, consecutive PET scans can be performed in one scan session. Using different hypoxia tracers, PET imaging may provide insight into the prognostic significance of hypoxia and perfusion in lung cancer. In addition, PET studies may play an important role in various stages of personalized medicine, as these may help to select patients for specific treatments including radiation therapy, hypoxia modifying therapies, and antiangiogenic strategies. In addition, specific PET tracers can be applied for monitoring therapy. The present review provides an overview of the clinical applications of PET to measure hypoxia and perfusion in lung cancer. Available PET tracers and their characteristics as well as the applications of combined hypoxia and perfusion PET imaging are discussed.

Quantification of heterogeneity as a biomarker in tumor imaging: a systematic review

BACKGROUND

Many techniques are proposed for the quantification of tumor heterogeneity as an imaging biomarker for differentiation between tumor types, tumor grading, response monitoring and outcome prediction. However, in clinical practice these methods are barely used. This study evaluates the reported performance of the described methods and identifies barriers to their implementation in clinical practice.

METHODOLOGY

The Ovid, Embase, and Cochrane Central databases were searched up to 20 September 2013. Heterogeneity analysis methods were classified into four categories, i.e., non-spatial methods (NSM), spatial grey level methods (SGLM), fractal analysis (FA) methods, and filters and transforms (F&T). The performance of the different methods was compared.

PRINCIPAL FINDINGS

Of the 7351 potentially relevant publications, 209 were included. Of these studies, 58% reported the use of NSM, 49% SGLM, 10% FA, and 28% F&T. Differentiation between tumor types, tumor grading and/or outcome prediction was the goal in 87% of the studies. Overall, the reported area under the curve (AUC) ranged from 0.5 to 1 (median 0.87). No relation was found between the performance and the quantification methods used, or between the performance and the imaging modality. A negative correlation was found between the tumor-feature ratio and the AUC, which is presumably caused by overfitting in small datasets. Cross-validation was reported in 63% of the classification studies. Retrospective analyses were conducted in 57% of the studies without a clear description.

CONCLUSIONS

In a research setting, heterogeneity quantification methods can differentiate between tumor types, grade tumors, and predict outcome and monitor treatment effects. To translate these methods to clinical practice, more prospective studies are required that use external datasets for validation: these datasets should be made available to the community to facilitate the development of new and improved methods.