Advantage of FMISO-PET over FDG-PET for predicting histological response to preoperative chemotherapy in patients with oral squamous cell carcinoma

Molecular imaging of tumor hypoxia: Evolution of nitroimidazole radiopharmaceuticals and insights for future development

Though growing evidence has been collected in support of the concept of dose escalation based on the molecular level images indicating hypoxic tumor sub-volumes that could be radio-resistant, validation of the concept is still a work in progress. Molecular imaging of tumor hypoxia using radiopharmaceuticals is expected to provide the required input to plan dose escalation through Image Guided Radiation Therapy (IGRT) to kill/control the radio-resistant hypoxic tumor cells. The success of the IGRT, therefore, is heavily dependent on the quality of images obtained using the radiopharmaceutical and the extent to which the image represents the true hypoxic status of the tumor in spite of the heterogeneous nature of tumor hypoxia. Available literature on radiopharmaceuticals for imaging hypoxia is highly skewed in favor of nitroimidazole as the pharmacophore given their ability to undergo oxygen dependent reduction in hypoxic cells. In this context, present review on nitroimidazole radiopharmaceuticals would be immensely helpful to the researchers to obtain a birds-eye view on what has been achieved so far and what can be tried differently to obtain a better hypoxia imaging agent. The review also covers various methods of radiolabeling that could be utilized for developing radiotracers for hypoxia targeting applications.

Potential novel imaging targets of inflammation in cardiac sarcoidosis

Cardiac sarcoidosis (CS) is an inflammatory disease with high morbidity and mortality, with a pathognomonic feature of non-caseating granulomatous inflammation. While 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) is a well-established modality to image inflammation and diagnose CS, there are limitations to its specificity and reproducibility. Imaging focused on the molecular processes of inflammation including the receptors and cellular microenvironments present in sarcoid granulomas provides opportunities to improve upon FDG-PET imaging for CS. This review will highlight the current limitations of FDG-PET imaging for CS while discussing emerging new nuclear imaging molecular targets for the imaging of cardiac sarcoidosis.

18F-FMISO PET/CT detects hypoxic lesions of cardiac and extra-cardiac involvement in patients with sarcoidosis

BACKGROUND

18F-fluoromisonidazole (FMISO) is a hypoxia positron emission tomography (PET) tracer. Here, we evaluated cardiac and extra-cardiac sarcoidosis using both FMISO and 18F-fluorodeoxyglucose (FDG) PET/CT in a prospective cohort of patients with sarcoidosis.

METHODS

Ten consecutive sarcoidosis patients with suspected cardiac involvement were prospectively enrolled. Each patient fasted overnight (for ≥ 18 hours) preceded by a low-carbohydrate diet before FDG PET/CT but not given special dietary instructions before the FMISO PET/CT scan. We visually and semiquantitatively assessed the uptakes of FMISO and FDG using the maximal standardized uptake value (SUVmax). The metabolic volume (MV) of FDG was calculated as the volume within the boundary determined by the threshold (mean SUV of blood pool × 1.5).

RESULTS

Nine patients showed focal FDG uptake in the myocardium and were diagnosed with cardiac sarcoidosis. Among the patients with extra-cardiac lesions, FDG uptake was seen in 8 lymph nodes and 3 lung lesions. FMISO uptake was seen in the 7 cardiac (77.8%) and 6 extra-cardiac (54.5%) lesions. None of the patients showed physiological FMISO uptake in the myocardium. The SUVmax values of the lesions with FMISO uptake were higher than those of the lesions without FMISO uptake in both the cardiac (SUVmax: 9.9, IQR: 8.4-10.0 vs 7.3, IQR: 6.3-8.2) and non-cardiac lesions (SUVmax: 17.6, IQR: 14.5-19.3 vs 6.1, IQR: 5.9-6.2; P = 0.006). The MV values of the lesions with FMISO uptake were significantly higher than those of the lesions without FMISO uptake (111.3, IQR: 78.3-135.7 vs 6.4, IQR: 1.9-23.3; P = 0.0009).

CONCLUSIONS

FMISO showed no physiological myocardial uptake and did not require special preparation. FMISO PET has the potential to detect hypoxic lesions in patients with sarcoidosis.

Imaging of Tumor Hypoxia With Radionuclide-Labeled Tracers for PET

The hypoxic state in a solid tumor refers to the internal hypoxic environment that appears as the tumor volume increases (the maximum radius exceeds 180-200 microns). This state can promote angiogenesis, destroy the balance of the cell’s internal environment, and lead to resistance to radiotherapy and chemotherapy, as well as poor prognostic factors such as metastasis and recurrence. Therefore, accurate quantification, mapping, and monitoring of hypoxia, targeted therapy, and improvement of tumor hypoxia are of great significance for tumor treatment and improving patient survival. Despite many years of development, PET-based hypoxia imaging is still the most widely used evaluation method. This article provides a comprehensive overview of tumor hypoxia imaging using radionuclide-labeled PET tracers. We introduced the mechanism of tumor hypoxia and the reasons leading to the poor prognosis, and more comprehensively included the past, recent and ongoing studies of PET radiotracers for tumor hypoxia imaging. At the same time, the advantages and disadvantages of mainstream methods for detecting tumor hypoxia are summarized.

PET Imaging of Tumor Hypoxia in Head and Neck Cancer: A Primer for Neuroradiologists

Tumor hypoxia is a known independent prognostic factor for adverse patient outcomes in those with head and neck cancer. Areas of tumor hypoxia have been found to be more radiation resistant than areas of tumor with normal oxygenation levels. Hypoxia imaging may serve to help identify the best initial treatment option and to assess intratreatment monitoring of tumor response in case treatment changes can be made. PET imaging is the gold standard method for imaging tumor hypoxia, with 18F-fluoromisonidazole the most extensively studied hypoxic imaging tracer. Newer tracers also show promise.

Targeting Hypoxia Using Evofosfamide and Companion Hypoxia Imaging of FMISO-PET in Advanced Biliary Tract Cancer

Purpose

Hypoxia is widely known as one of the mechanisms of chemoresistance and as an environmental condition which triggers invasion and metastasis of cancer. Evofosfamide is a hypoxia-activated prodrug of the cytotoxin bromo-isophosphoramide mustard conjugated with 2-nitroimidazole. Biliary tract cancer (BTC) is known to contain large hypoxic area. This study evaluated the efficacy and safety of evofosfamide as a second-line treatment of advanced BTC.

Materials and Methods

Patients received evofosfamide at a dose of 340 mg/m² on days 1, 8, and 15 of every 28-day cycle. Primary end-point was progression-free survival (PFS) rate at 4-months (4m-PFSR). Secondary end-points included overall survival (OS), PFS, disease control rate (DCR), metabolic response by ¹⁸F-fluorodeoxyglucose positron emission tomography (PET), hypoxic parameters evaluated by ¹⁸F-fluoromisonidazole (FMISO) PET and toxicity.

Results

Twenty patients were treated with evofosfamide, with 16 response-evaluable patients. There was no objective response; stable disease was observed in nine patients, with a DCR of 56.25%. 4m-PFSR was 40.6%. Median PFS was 3.60 months (95% confidence interval [CI], 1.68 to 5.52). Median OS was 6.37 months (95% CI, 3.94 to 8.79). Reduction of tumor metabolic activity was observed in eight of 15 patients (53.3%). High baseline hypoxic parameters were associated with poor PFS. Change of hypoxic parameters between pretreatment and post-treatment reflected hypoxic-activated drug response. There was no treatment-related death.

Conclusion

Evofosfamide as second-line treatment of advanced BTC showed acceptable safety and comparable efficacy to other agents. Changes in volumetric parameters measured with FMISO PET, showing the degree of tumor hypoxia, reflected the response to evofosfamide based on the mode of action.

Role of Non-FDG-PET/CT in Head and Neck Cancer

Head and neck cancers are commonly encountered malignancies in the United States, of which the majority are attributed to squamous cell carcinoma. ¹⁸F-FDG-PET/CT has been well established in the evaluation, treatment planning, prognostic implications of these tumors and is routinely applied for the management of patients with these cancers. Many alternative investigational PET radiotracers have been extensively studied in the evaluation of these tumors. Although these radiotracers have not been able to replace ¹⁸F-FDG-PET/CT in routine clinical practice currently, they may provide important additional information about the biological mechanisms of these tumors, such as foci of tumor hypoxia as seen on hypoxia specific PET radiotracers such as ¹⁸F-Fluoromisonidazole (¹⁸F-FMISO), which could be useful in targeting radioresistant hypoxic tumor foci when treatment planning. There are multiple other hypoxia-specific PET radiotracers such as ¹⁸F-Fluoroazomycinarabinoside (FAZA), ¹⁸F-Flortanidazole (HX4), which have been evaluated similarly, of which ¹⁸F-Fluoromisonidazole (¹⁸F-FMISO) has been the most investigated. Other radiotracers frequently studied in the evaluation of these tumors include radiolabeled amino acid PET radiotracers, which show increased uptake in tumor cells with limited uptake in inflammatory tissue, which can be useful especially in differentiating postradiation inflammation from residual and/or recurrent disease. ¹⁸F-Fluorothymidine (FLT) is localized intracellularly by nucleoside transport and undergoes phosphorylation thereby being retained within tumor cells and can serve as an indicator of tumor proliferation. Decrease in radiotracer activity following treatment can be an early indicator of treatment response. This review aims at synthesizing the available literature on the most studied non-FDG-PET/CT in head and neck cancer.

Evaluation of non-Gaussian model-based diffusion-weighted imaging in oral squamous cell carcinoma: comparison with tumour functional information derived from positron-emission tomography

AIM

To evaluate and compare diffusion-weighted imaging (DWI) parameters derived from a non-Gaussian fitting model and positron-emission tomography (PET) parameters derived from ¹⁸F-fluoromisonidazole-PET (FMISO-PET) in patients with oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

Primary sites were evaluated prospectively in 18 patients. DWI was performed using six b-values (0-2,500). Diffusion-related parameters of kurtosis value (K), the kurtosis-corrected diffusion coefficient (D_K), diffusion heterogeneity (α), distributed diffusion coefficient (DDC), the slow diffusion coefficient (D_slow), and the apparent diffusion coefficient (ADC) were calculated from four diffusion-fitting models. Maximal standardised uptake values (SUV_max), mean standardised uptake values (SUV_mean), and the tumour-to-muscle ration (TMR) of the SUV value were calculated for FMISO-PET. Spearman's correlation coefficient was used to evaluate the correlation between each non-Gaussian diffusion model parameters and PET parameter.

RESULTS

There was moderate correlation between FMISO-PET SUV_max and D_slow (ρ=-0.45, p=0.06). In addition, there was good correlation between TMR_max and five non-Gaussian diffusion model parameters (K: ρ=0.65, p=0.004, D_K: ρ=-0.72, p=0.0008, DDC: ρ=-0.75, p=0.0003, ADC: ρ=-0.74, p=0.0005, and D_slow: ρ= -0.65, p=0.003), and between TMR_mean and five non-Gaussian model parameters (K: ρ=0.64, p=0.005, D_K: ρ=-0.61, p=0.007, DDC: ρ=-0.63, p=0.005, ADC: ρ=-0.61, p=0.007, and D_slow: ρ=-0.56, p=0.015).

CONCLUSION

Non-Gaussian diffusion model parameters can be related to tumour hypoxia.

Clinical imaging of hypoxia: Current status and future directions

Tissue hypoxia is a key feature of many important causes of morbidity and mortality. In pathologies such as stroke, peripheral vascular disease and ischaemic heart disease, hypoxia is largely a consequence of low blood flow induced ischaemia, hence perfusion imaging is often used as a surrogate for hypoxia to guide clinical diagnosis and treatment. Importantly, ischaemia and hypoxia are not synonymous conditions as it is not universally true that well perfused tissues are normoxic or that poorly perfused tissues are hypoxic. In pathologies such as cancer, for instance, perfusion imaging and oxygen concentration are less well correlated, and oxygen concentration is independently correlated to radiotherapy response and overall treatment outcomes. In addition, the progression of many diseases is intricately related to maladaptive responses to the hypoxia itself. Thus there is potentially great clinical and scientific utility in direct measurements of tissue oxygenation. Despite this, imaging assessment of hypoxia in patients is rarely performed in clinical settings. This review summarises some of the current methods used to clinically evaluate hypoxia, the barriers to the routine use of these methods and the newer agents and techniques being explored for the assessment of hypoxia in pathological processes.

Integrating quantitative morphological and intratumoural textural characteristics in FDG-PET for the prediction of prognosis in pharynx squamous cell carcinoma patients

AIM

To assess potential prognostic factors in pharynx squamous cell carcinoma (SCC) patients by quantitative morphological and intratumoural characteristics obtained by 2-[¹⁸F]-fluoro-2-deoxy-d-glucose positron-emission tomography/computed tomography (FDG-PET/CT).

MATERIALS AND METHODS

The cases of 54 patients with pharynx SCC who underwent chemoradiation therapy were analysed retrospectively. Using their FDG-PET data, the quantitative morphological and intratumoural characteristics of 14 parameters were calculated. The progression-free survival (PFS) and overall survival (OS) information was obtained from patient medical records. Univariate and multivariate analyses were performed to assess the 14 quantitative parameters as well as the T-stage, N-stage, and tumour location data for their relation to PFS and OS. When an independent predictor was suggested in the multivariate analysis, the parameter was further assessed using the Kaplan-Meier method.

RESULTS

In the assessment of PFS, the univariate and multivariate analyses indicated the following as independent predictors: the texture parameter of homogeneity and the morphological parameter of sphericity. In the Kaplan-Meier analysis, the PFS rate was significantly improved in the patients who had both a higher value of homogeneity (p=0.01) and a higher value of sphericity (p=0.002). With the combined use of homogeneity and sphericity, the patients with different PFS rates could be divided more clearly.

CONCLUSION

The quantitative parameters of homogeneity and sphericity obtained by FDG-PET can be useful for the prediction of the PFS of pharynx SCC patients, especially when used in combination.

Semi-quantitative analysis of pre-treatment morphological and intratumoral characteristics using 18F-fluorodeoxyglucose positron-emission tomography as predictors of treatment outcome in nasal and paranasal squamous cell carcinoma

Background

To investigate the utility of quantitative morphological and intratumoral characteristics obtained by ¹⁸F-fluorodeoxyglucose positron-emission tomography/computed tomography (FDG-PET/CT) for the prediction of treatment outcome in patients with nasal or paranasal cavity squamous cell carcinoma (SCC).

Methods

Twenty-four patients with nasal or paranasal cavity SCC who received curative non-surgical therapy (a combination of super-selective arterial cisplatin infusion and radiotherapy) were retrospectively analyzed. From pre-treatment FDG-PET data, a total of 13 parameters of quantitative morphological characteristics (tumor volume, surface area and sphericity), intratumoral characteristics (the maximum and mean standard uptake value, three intratumoral histogram and four textural parameters) and total lesion glycolysis (TLG) were respectively calculated. Information regarding the treatment outcome was determined from the histological diagnosis or clinical follow-up. Each of the 13 quantitative parameters as well as T- and N-stage was assessed for its relation to treatment outcome of local control or failure.

Results

In univariate analysis, significant differences in surface area and sphericity between the local control and failure groups were observed. The receiver operating characteristic (ROC) curve analysis showed that sphericity had the highest accuracy of 0.88. In the multivariate analysis, sphericity was revealed as an independent predictor of the local control or failure.

Conclusions

The quantitative parameters of sphericity are useful to predict the treatment outcome in patients with nasal or paranasal SCC.

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

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

Molecular mechanisms of hypoxia in cancer

PURPOSE

Hypoxia is a condition of insufficient oxygen to support metabolism which occurs when the vascular supply is interrupted, or when a tumour outgrows its vascular supply. It is a negative prognostic factor due to its association with an aggressive tumour phenotype and therapeutic resistance. This review provides an overview of hypoxia imaging with Positron emission tomography (PET), with an emphasis on the biological relevance, mechanism of action, highlighting advantages, and limitations of the currently available hypoxia radiotracers.

METHODS

A comprehensive PubMed literature search was performed, identifying articles relating to biological significance and measurement of hypoxia, MRI methods, and PET imaging of hypoxia in preclinical and clinical settings, up to December 2016.

RESULTS

A variety of approaches have been explored over the years for detecting and monitoring changes in tumour hypoxia, including regional measurements with oxygen electrodes placed under CT guidance, MRI methods that measure either oxygenation or lactate production consequent to hypoxia, different nuclear medicine approaches that utilise imaging agents the accumulation of which is inversely related to oxygen tension, and optical methods. The advantages and disadvantages of these approaches are reviewed, along with individual strategies for validating different imaging methods. PET is the preferred method for imaging tumour hypoxia due to its high specificity and sensitivity to probe physiological processes in vivo, as well as the ability to provide information about intracellular oxygenation levels.

CONCLUSION

Even though hypoxia could have significant prognostic and predictive value in the clinic, the best method for hypoxia assessment has in our opinion not been realised.

Glucose Metabolism and Its Complicated Relationship with Tumor Growth and Perfusion in Head and Neck Squamous Cell Carcinoma

Objective

To determine the relationship between tumor glucose metabolism and tumor blood flow (TBF) in head and neck squamous cell carcinoma (HNSCC).

Methods

We retrospectively analyzed 57 HNSCC patients. Tumor glucose metabolism was assessed by maximum and mean standardized uptake values (SUVmax and SUVmean) obtained by ¹⁸F-fluorodeoxyglucose positron-emission tomography. TBF values were obtained by arterial spin labeling with 3-tesla MRI. The correlations between both SUVs and TBF were assessed in the total series and among patients divided by T-stage (T1–T3 and T4 groups) and tumor location (pharynx/oral cavity and sinonasal cavity groups). Pearson’s correlation coefficients were calculated for significant correlations.

Results

Significant correlations were detected: a negative correlation in the advanced T-stage group (TBF and SUV max: r, −0.61, SUVmean: r, −0.62), a positive correlation in the non-advanced T-stage pharynx/oral cavity group (TBF and SUVmax: r, 0.70, SUVmean: r, 0.73), a negative correlation in the advanced T-stage pharynx/oral cavity group (TBF and SUVmax: r, −0.62, SUVmean: r, −0.65), and a negative correlation in the advanced T-stage sinonasal cavity group (TBF and SUVmax: r, −0.61, SUVmean: r, −0.65).

Conclusion

Significant correlations between glucose uptake and TBF in HNSCC were revealed by the division of T-stage and tumor location.

Molecular Imaging and Precision Medicine in Head and Neck Cancer

The concept of using tumor genomic profiling information has revolutionized personalized cancer treatment. Head and neck (HN) cancer management is being influenced by recent discoveries of activating mutations in epidermal growth factor receptor and related targeted therapies with tyrosine kinase inhibitors, targeted therapies for Kristen Rat Sarcoma, and MET proto-oncogenes. Molecular imaging using PET plays an important role in assessing the biologic behavior of HN cancer with the goal of delivering individualized cancer treatment. This review summarizes recent genomic discoveries in HN cancer and their implications for functional PET imaging in assessing response to targeted therapies, and drug resistance mechanisms.

Prognostic value of PET/CT with (18)F-fluoroazomycin arabinoside for patients with head and neck squamous cell carcinomas receiving chemoradiotherapy

OBJECTIVE

The prognostic value of positron emission tomography/computed tomography (PET/CT) with (18)F-fluoroazomycin arabinoside (FAZA) was evaluated in patients with head and neck squamous cell carcinoma (HNSCC) who underwent chemoradiotherapy (CRT).

METHODS

Twenty-nine patients with head and neck cancer underwent FAZA PET/CT before treatment. Data acquisition started 2 h after FAZA administration. In 26 patients with squamous cell carcinoma, FAZA uptakes by the primary lesions (tumor-muscle ratio in primary lesion: Pr T/M) and by the lymph node metastases (tumor-muscle ratio in lymph node metastasis) were compared with various clinical parameters. For the HNSCC patients who completed CRT protocol (n = 23), those who experienced disease progression were compared with those who did not experience disease progression with respect to the clinical and PET parameters. The prognostic values of the clinical and PET parameters were then evaluated with regard to progression-free survival (PFS).

RESULTS

Pr T/M positively correlated with the lesion's maximum diameter, and it was significantly higher in stage IV lesions compared with stage I-III lesions. No significant differences were observed between the patients who experienced disease progression and those who did not, with respect to the clinical parameters. The average Pr T/M tended to be higher in patients with disease progression, although the differences were not statistically significant (p = 0.086). Kaplan-Meier analysis with log-rank tests indicated that Pr T/M was an only significant predictor of PFS among PET and clinical parameters evaluated (p = 0.010).

CONCLUSIONS

FAZA uptake by the primary lesion was a significant prognostic indicator in HNSCC patients undergoing CRT. Hence, FAZA PET/CT may provide useful information in the management of HNSCC patients treated with CRT. Registration number of clinical trial's registry: UMIN000003440.

F-18 fluoromisonidazole for imaging tumor hypoxia: imaging the microenvironment for personalized cancer therapy

Hypoxia in solid tumors is one of the seminal mechanisms for developing aggressive trait and treatment resistance in solid tumors. This evolutionarily conserved biological mechanism along with derepression of cellular functions in cancer, although resulting in many challenges, provide us with opportunities to use these adversities to our advantage. Our ability to use molecular imaging to characterize therapeutic targets such as hypoxia and apply this information for therapeutic interventions is growing rapidly. Evaluation of hypoxia and its biological ramifications to effectively plan appropriate therapy that can overcome the cure-limiting effects of hypoxia provides an objective means for treatment selection and planning. Fluoromisonidazole (FMISO) continues to be the lead radiopharmaceutical in PET imaging for the evaluation, prognostication, and quantification of tumor hypoxia, one of the key elements of the tumor microenvironment. FMISO is less confounded by blood flow, and although the images have less contrast than FDG-PET, its uptake after 2 hours is an accurate reflection of inadequate regional oxygen partial pressure at the time of radiopharmaceutical administration. By virtue of extensive clinical utilization, FMISO remains the lead candidate for imaging and quantifying hypoxia. The past decade has seen significant technological advances in investigating hypoxia imaging in radiation treatment planning and in providing us with the ability to individualize radiation delivery and target volume coverage. The presence of widespread hypoxia in the tumor can be effectively targeted with a systemic hypoxic cell cytotoxin or other agents that are more effective with diminished oxygen partial pressure, either alone or in combination. Molecular imaging in general and hypoxia imaging in particular will likely become an important in vivo imaging biomarker of the future, complementing the traditional direct tissue sampling methods by providing a snap shot of a primary tumor and metastatic disease and in following treatment response and will serve as adjuncts to personalized therapy.

Prognostic significance of hypoxic PET using (18)F-FAZA and (62)Cu-ATSM in non-small-cell lung cancer

OBJECTIVES

Tumor hypoxia is believed to have a strong correlation with the resistance to chemoradiotherapy. Noninvasive evaluation of hypoxic status in tumors using molecular imaging has the potential to characterize the tumor aggressiveness. We evaluated the clinical usefulness of newly-developed tumor hypoxic positron emission tomography (PET) tracers in localized non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Forty-seven patients with localized NSCLC received either or both hypoxic PETs using the tracers: (18)F-fluoroazomycin arabinoside ((18)F-FAZA) (n=45) and/or (62)Cu-diacetyl-bis (N4)-methylsemithiocarbazone ((62)Cu-ATSM) (n=22). All received (18)F-fluorodeoxyglucose ((18)F-FDG) PET tracer (n=47). We examined the correlation between uptake of three PET tracers and clinicopathological factors, and evaluated their impacts on survival after treatment retrospectively.

RESULTS

A couple of commonly-identified unfavorable factors such as presence of vascular invasion and pleural invasion was significantly correlated with higher uptake of these hypoxic agents as well as that of (18)F-FDG. Larger tumor diameter, high neutrophil-to-lymphocyte ratio and advanced pathological stage were also associated with accumulation of hypoxic PETs ((18)F-FAZA, p<0.01; (62)Cu-ATSM, p<0.04), but not with that of (18)F-FDG. The patients with a higher accumulation had significantly poorer overall survival [(18)F-FAZA, HR (hazard ratio), 9.50, p<0.01; (62)Cu-ATSM, HR, 4.06, p<0.05] and progression free survival ((18)F-FAZA, HR, 5.28, p<0.01, (62)Cu-ATSM, HR, 2.72, p<0.05).

CONCLUSION

Both (18)F-FAZA and (62)Cu-ATSM PET provide useful information regarding tumor aggressiveness and prediction of survival among NSCLC patients. We believe these hypoxic PETs could contribute to the establishment of the optimally individualized treatment of NSCLC.

Integration of imaging into clinical practice to assess the delivery and performance of macromolecular and nanotechnology-based oncology therapies

Functional and molecular imaging has become increasingly used to evaluate interpatient and intrapatient tumor heterogeneity. Imaging allows for assessment of microenvironment parameters including tumor hypoxia, perfusion and proliferation, as well as tumor metabolism and the intratumoral distribution of specific molecular markers. Imaging information may be used to stratify patients for targeted therapies, and to define patient populations that may benefit from alternative therapeutic approaches. It also provides a method for non-invasive monitoring of treatment response at earlier time-points than traditional cues, such as tumor shrinkage. Further, companion diagnostic imaging techniques are becoming progressively more important for development and clinical implementation of targeted therapies. Imaging-based companion diagnostics are likely to be essential for the validation and FDA approval of targeted nanotherapies and macromolecular medicines. This review describes recent clinical advances in the use of functional and molecular imaging to evaluate the tumor microenvironment. Additionally, this article focuses on image-based assessment of distribution and anti-tumor effect of nano- and macromolecular systems.

Feasibility and repeatability of PET with the hypoxia tracer [(18)F]HX4 in oesophageal and pancreatic cancer

BACKGROUND AND PURPOSE

To investigate the feasibility and to determine the repeatability of recurrent [(18)F]HX4 PET scans in patients with oesophageal (EC) and pancreatic (PC) cancer.

MATERIALS AND METHODS

32 patients were scanned in total; seven patients (4 EC/3 PC) were scanned 2, 3 and 4h post injection (PI) of [(18)F]HX4 and 25 patients (15 EC/10 PC) were scanned twice 3.5h PI, on two separate days (median 4, range 1-9days). Maximum tumour to background ratio (TBRmax) and the tumour hypoxic volume (HV) (TBR>1.0) were calculated. Repeatability was assessed using Bland-Altman analysis. Agreement in localization was calculated as the distance between the centres of mass in the HVs.

RESULTS

For EC, the TBRmax in the tumour (mean±SD) was 1.87±0.46 with a coefficient of repeatability (CoR) of 0.53 (28% of mean). The HV ranged from 3.4 to 98.8ml with a CoR of 5.1ml. For PC, the TBRmax was 1.72±0.23 with a CoR of 0.27 (16% of mean). The HV ranged from 4.6 to 104.0ml with a CoR of 7.8ml. The distance between the centres of mass in the HV was 2.2±1.3mm for EC and 2.1±1.5mm for PC.

CONCLUSIONS

PET scanning with [(18)F]HX4 was feasible in both EC and PC patients. Amount and location of elevated [(18)F]HX4 uptake showed good repeatability, suggesting [(18)F]HX4 PET could be a promising tool for radiation therapy planning and treatment response monitoring in EC and PC patients.