Positron Emission Tomography/Computed Tomography and Whole-Body Magnetic Resonance Imaging in Staging of Advanced Nonsmall Cell Lung Cancer???Initial Results:

Consistency and prognostic value of preoperative staging and postoperative pathological staging using 18F-FDG PET/MRI in patients with non-small cell lung cancer

OBJECTIVE

In recent years, positron emission tomography/magnetic resonance imaging (PET/MRI) has been clinically used as a method to diagnose non-small cell lung cancer (NSCLC). This study aimed to evaluate the concordance of staging and prognostic ability of NSCLC patients using thin-slice computed tomography (CT) and ¹⁸F-fluorodeoxyglucose (FDG) PET/MRI.

METHODS

This retrospective study was performed on consecutive NSCLC patients who underwent both diagnostic CT and ¹⁸F-FDG PET/MRI before surgery between November 2015 and May 2019. The cTNM staging yielded from PET/MRI was compared with CT and pathological staging, and concordance was investigated, defining pathological findings as reference. To assess the prognostic value of disease-free survival (DFS) and overall survival (OS), we dichotomized the typical prognostic factors and TNM classification staging (Stage I vs. Stage II or higher). Kaplan-Meier curves derived by the log-rank test were generated, and univariate and multivariate analyses were performed to identify the factors associated with DFS and OS.

RESULTS

A total of 82 subjects were included; PET/MRI staging was more consistent (59 of 82) with pathological staging than with CT staging. There was a total of 21 cases of CT and 11 cases of PET/MRI that were judged as cStage I, but were actually pStage II or pStage III. CT tended to judge pN1 or pN2 as cN0 compared to PET/MRI. There was a significant difference between NSCLC patients with Stage I and Stage II or higher by PET/MRI staging as well as prognosis prediction of DFS by pathological staging (P < 0.001). In univariate analysis, PET/MRI, CT, and pathological staging (Stage I or lower vs. Stage II or higher) all showed significant differences as prognostic factors of recurrence or metastases. In multivariate analysis, pathological staging was the only independent factor for recurrence (P = 0.009), and preoperative PET/MRI staging was a predictor of patient survival (P = 0.013).

CONCLUSIONS

In NSCLC, pathologic staging was better at predicting recurrence, and preoperative PET/MRI staging was better at predicting survival. Preoperative staging by PET/MRI was superior to CT in diagnosing hilar and mediastinal lymph-node metastases, which contributed to the high concordance with pathologic staging.

Prospective comparison of 18F-FDG PET/MRI and 18F-FDG PET/CT for thoracic staging of non-small cell lung cancer

OBJECTIVES

To compare the diagnostic performance of ¹⁸F-FDG PET/MRI and ¹⁸F-FDG PET/CT for primary and locoregional lymph node staging in non-small cell lung cancer (NSCLC).

METHODS

In this prospective study, a total of 84 patients (51 men, 33 women, mean age 62.5 ± 9.1 years) with histopathologically confirmed NSCLC underwent ¹⁸F-FDG PET/CT followed by ¹⁸F-FDG PET/MRI in a single injection protocol. Two readers independently assessed T and N staging in separate sessions according to the seventh edition of the American Joint Committee on Cancer staging manual for ¹⁸F-FDG PET/CT and ¹⁸F-FDG PET/MRI, respectively. Histopathology as a reference standard was available for N staging in all 84 patients and for T staging in 39 patients. Differences in staging accuracy were assessed by McNemars chi² test. The maximum standardized uptake value (SUV_max) and longitudinal diameters of primary tumors were correlated using Pearson's coefficients.

RESULTS

T stage was categorized concordantly in ¹⁸F-FDG PET/MRI and ¹⁸F-FDG PET/CT in 38 of 39 (97.4%) patients. Herein, ¹⁸F-FDG PET/CT and ¹⁸F-FDG PET/MRI correctly determined the T stage in 92.3 and 89.7% of patients, respectively. N stage was categorized concordantly in 83 of 84 patients (98.8%). ¹⁸F-FDG PET/CT correctly determined the N stage in 78 of 84 patients (92.9%), while ¹⁸F-FDG PET/MRI correctly determined the N stage in 77 of 84 patients (91.7%). Differences between ¹⁸F-FDG PET/CT and ¹⁸F-FDG PET/MRI in T and N staging accuracy were not statistically significant (p > 0.5, each). Tumor size and SUV_max measurements derived from both imaging modalities exhibited excellent correlation (r = 0.963 and r = 0.901, respectively).

CONCLUSION

¹⁸F-FDG PET/MRI and ¹⁸F-FDG PET/CT show an equivalently high diagnostic performance for T and N staging in patients suffering from NSCLC.

Clinical usefulness of 18F-FDG PET/CT for the detection of distant metastases in patients with non-small cell lung cancer at initial staging: a meta-analysis

Background

We undertook a meta-analysis to evaluate the clinical usefulness of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) for the detection of distant metastases in patients with non-small cell lung cancer (NSCLC) at initial staging.

Materials and methods

All topic-related studies were comprehensively searched in the MEDLINE and Embase databases. We obtained the summary estimates and constructed the summary receiver operating characteristic curve for ¹⁸F-FDG PET/CT using the bivariate regression model.

Results

Across 10 studies (1333 patients), the sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio for ¹⁸F-FDG PET/CT were 0.81 (95% confidence interval [CI] = 0.63–0.92), 0.96 (95% CI = 0.94–0.98), 22.9 (95% CI = 13.3–39.5), and 0.20 (95% CI = 0.09–0.42), respectively. Overall weighted area under the curve was 0.97 (95% CI = 0.96–0.98).

Conclusion

¹⁸F-FDG PET/CT has a good diagnostic performance for distant metastasis staging in patients with NSCLC at initial staging.

Use of Magnetic Resonance Imaging for N-Staging in Patients with Non-Small Cell Lung Cancer. A Systematic Review

INTRODUCTION

The aim of this study is to assess the diagnostic value of the magnetic resonance imaging (MRI) in differentiating metastasic from non-metastatic lymph nodes in NSCLC patients compared with computed tomography (CT) and fluorodeoxyglucose (FDG) - positron emission tomography (PET) or both combined.

METHODS

Twenty-three studies (19 studies and 4 meta-analysis) with sample size ranging between 22 and 250 patients were included in this analysis. MRI, regardless of the sequence obtained, where used for the evaluation of N-staging of NSCLC. Histopathology results and clinical or imaging follow-up were used as the reference standard. Studies were excluded if the sample size was less than 20 cases, if less than 10 lymph nodes assessment were presented or studies where standard reference was not used. Papers not reporting sufficient data were also excluded.

RESULTS

As compared to CT and PET, MRI demonstrated a higher sensitivity, specificity and diagnostic accuracy in the diagnosis of metastatic or non-metastatic lymph nodes in N-staging in NSCLC patients. No study considered MRI inferior than conventional techniques (CT, PET or PET/CT). Other outstanding results of this review are fewer false positives with MRI in comparison with PET, their superiority over PET/CT to detect non-resectable lung cancer, to diagnosing infiltration of adjacent structures or brain metastasis and detecting small nodules.

CONCLUSION

MRI has shown at least similar or better results in diagnostic accuracy to differentiate metastatic from non-metastatic mediastinal lymph nodes. This suggests that MRI could play a significant role in mediastinal NSCLC staging.

Comparison of Gadolinium-enhanced MRI and 18FDG PET/PET-CT for the diagnosis of brain metastases in lung cancer patients: A meta-analysis of 5 prospective studies

Objective

We undertook this meta-analysis to compare the significance of Gadolinium-enhanced MRI and ¹⁸FDG PET/PET-CT for diagnosing brain metastases of lung cancer patients.

Results

Five articles comprising 941 patients were included for analysis. The sensitivities with 95% confidence interval for PET/PET-CT and MRI were 0.21 (0.13 − 0.32) and 0.77 (95% CI = 0.60 − 0.89), specificities were 1.00 (0.99 − 1.00) and 0.99 (0.97 − 1.00), and the areas under curve were 0.98 (0.96 − 0.89) and 0.97 (0.96 − 0.98).

Materials and Methods

A computerized literature search of studies was conducted in the Pubmed and Embase databases. Meta-analysis methods were used to calculate the sensitivities, specificities, likelihood ratios ratios, diagnostic odd ratios, and areas under summary receiver operating characteristic curves for PET/PET-CT and MRI, respectively.

Conclusions

The analysis suggested Gadolinium-enhanced MRI had higher sensitivity than ¹⁸FDG PET/PET-CT for the diagnosis of brain metastases in lung cancer. MRI may provide additional information to PET-CT for diagnosing brain metastatic lesions.

Risk-stratifying capacity of PET/CT metabolic tumor volume in stage IIIA non-small cell lung cancer

OBJECTIVES

Stage IIIA non-small cell lung cancer (NSCLC) is heterogeneous in tumor burden, and its treatment is variable. Whole-body metabolic tumor volume (MTVWB) has been shown to be an independent prognostic index for overall survival (OS). However, the potential of MTVWB to risk-stratify stage IIIA NSCLC has previously been unknown. If we can identify subgroups within the stage exhibiting significant OS differences using MTVWB, MTVWB may lead to adjustments in patients' risk profile evaluations and may, therefore, influence clinical decision making regarding treatment. We estimated the risk-stratifying capacity of MTVWB in stage IIIA by comparing OS of stratified stage IIIA with stage IIB and IIIB NSCLC.

METHODS

We performed a retrospective review of 330 patients with clinical stage IIB, IIIA, and IIIB NSCLC diagnosed between 2004 and 2014. The patients' clinical TNM stage, initial MTVWB, and long-term survival data were collected. Patients with TNM stage IIIA disease were stratified by MTVWB. The optimal MTVWB cutoff value for stage IIIA patients was calculated using sequential log-rank tests. Univariate and multivariate cox regression analyses and Kaplan-Meier OS analysis with log-rank tests were performed.

RESULTS

The optimal MTVWB cut-point was 29.2 mL for the risk-stratification of stage IIIA. We identified statistically significant differences in OS between stage IIB and IIIA patients (p < 0.01), between IIIA and IIIB patients (p < 0.01), and between the stage IIIA patients with low MTVWB (below 29.2 mL) and the stage IIIA patients with high MTVWB (above 29.2 mL) (p < 0.01). There was no OS difference between the low MTVWB stage IIIA and the cohort of stage IIB patients (p = 0.485), or between the high MTVWB stage IIIA patients and the cohort of stage IIIB patients (p = 0.459). Similar risk-stratification capacity of MTVWB was observed in a large range of cutoff values from 15 to 55 mL in stage IIIA patients.

CONCLUSIONS

Using MTVWB cutoff points ranging from 15 to 55 mL with an optimal value of 29.2 mL, stage IIIA NSCLC may be effectively stratified into subgroups with no significant survival difference from stages IIB or IIIB NSCLC. This may result in more accurate survival estimation and more appropriate risk adapted treatment selection in stage IIIA NSCLC.

A CBR framework with gradient boosting based feature selection for lung cancer subtype classification

Molecular subtype classification represents a challenging field in lung cancer diagnosis. Although different methods have been proposed for biomarker selection, efficient discrimination between adenocarcinoma and squamous cell carcinoma in clinical practice presents several difficulties, especially when the latter is poorly differentiated. This is an area of growing importance, since certain treatments and other medical decisions are based on molecular and histological features. An urgent need exists for a system and a set of biomarkers that provide an accurate diagnosis. In this paper, a novel Case Based Reasoning framework with gradient boosting based feature selection is proposed and applied to the task of squamous cell carcinoma and adenocarcinoma discrimination, aiming to provide accurate diagnosis with a reduced set of genes. The proposed method was trained and evaluated on two independent datasets to validate its generalization capability. Furthermore, it achieved accuracy rates greater than those of traditional microarray analysis techniques, incorporating the advantages inherent to the Case Based Reasoning methodology (e.g. learning over time, adaptability, interpretability of solutions, etc.).

Quantification of metabolic tumor activity and burden in patients with non-small-cell lung cancer: Is manual adjustment of semiautomatic gradient-based measurements necessary?

PURPOSE

Metabolic tumor burden (MTB) measurements including metabolic tumor volume and total lesion glycolysis have been shown to have prognostic value in non-small-cell lung cancer (NSCLC). The calculation of MTB typically utilizes software to semiautomatically draw volumes of interest around the tumor, which are subsequently manually adjusted by the radiologist to include the entire tumor. The manual adjustment step can be time-consuming and observer-dependent. We compared the agreement of MTB values obtained using the semiautomatic method with and without manual adjustment in NSCLC patients.

METHODS

This IRB-approved prospective study included 134 patients with histologically proven NSCLC who underwent fluorine-18 fluorodeoxyglucose PET/computed tomography. The MTB of the primary tumor was measured with a semiautomatic gradient-based method without manual adjustment (the semiautomatic gradient method) and with manual adjustment (the manually adjusted semiautomatic gradient method) by two radiologists using the MIM PETedge tool. The paired t-test, Wilcoxon signed-rank test, and concordance correlation coefficient (CCC) were calculated to evaluate the agreement between MTB measures obtained with these two methods, as well as agreement between the two radiologists for each method.

RESULTS

Maximum standardized uptake value was identical between the two methods. No statistically significant difference was present for peak standardized uptake value, metabolic tumor volume, and total lesion glycolysis values between the two methods (P=0.23, 0.45, and 0.37, respectively). Excellent agreement between the two methods was found in terms of CCC (CCC>0.98 for all measures). Interobserver reliability was excellent for all measures (CCC>0.90).

CONCLUSION

The semiautomatic gradient-based tumor-segmentation method can be used without the additional manual adjustment step for MTB quantification of primary NSCLC tumors.

Conspicuity of FDG-Avid Osseous Lesions on PET/MRI Versus PET/CT: a Quantitative and Visual Analysis

BACKGROUND

Because standard MRI-based attenuation correction (AC) does not account for the attenuation of photons by cortical bone, PET/MRI may have reduced sensitivity for FDG-avid focal bone lesions (FFBLs). This study evaluates whether MRI-based AC compromises detection of FFBLs, by comparing their conspicuity both quantitatively and qualitatively on PET/MRI versus PET/CT.

METHODS

One hundred ninety general oncology patients underwent whole-body PET/CT followed by whole-body PET/MRI, utilizing the same FDG dose. Thirteen patients with a total of 50 FFBLs were identified. Using automated contouring software, a volumetric contour was generated for each FFBL. Adjacent regions of normal background bone (BB) were selected manually. For each contour, SUV-max and SUV-mean were determined. Lesion-to-background SUV ratios served as quantitative metrics of conspicuity. Additionally, two blinded readers evaluated the relative conspicuity of FFBLs on PET images derived from MRI-based AC versus CT-based AC. Visibility of an anatomic correlate for FFBLs on the corresponding CT and MR images was also assessed.

RESULTS

SUV-mean was lower on PET/MRI for both FFBLs (-6.5 %, p = 0.009) and BB (-20.5 %, p < 0.001). SUV-max was lower on PET/MRI for BB (-14.2 %, p = 0.002) but not for FFBLs (-6.2 %, p = 0.068). The ratio of FFBL SUV-mean to BB SUV-mean was higher for PET/MRI (+29.5 %, p < 0.001). Forty of 50 lesions (80 %) were visually deemed to be of equal or greater conspicuity on PET images derived from PET/MRI. Thirty-five of 50 FFBLs (70 %) had CT correlates, while 40/50 FFBLs (80 %) had a correlate on at least one MRI sequence. The mean interval from tracer administration to imaging was longer (p < 0.001) for PET/MRI (127 v. 62 min).

CONCLUSIONS

Both FFBLs and BB had lower mean SUVs on PET/MRI than PET/CT. This finding was likely in part due to differences in the handling of cortical bone by MRI-based AC versus CT-based AC. Despite this systematic bias, FFBLs had greater conspicuity on PET/MRI, both qualitatively and quantitatively. This difference was likely due to the longer tracer uptake times for PET/MRI, which allowed for more tracer accumulation by FFBLs and more tracer washout from BB. Our results suggest that whole-body PET/MRI and PET/CT provide comparable sensitivity for detection of FDG-avid focal bone lesions.

PET/MRI: Emerging Clinical Applications in Oncology

Positron emission tomography (PET), commonly performed in conjunction with computed tomography (CT), has revolutionized oncologic imaging. PET/CT has become the standard of care for the initial staging and assessment of treatment response for many different malignancies. Despite this success, PET/CT is often supplemented by magnetic resonance imaging (MRI), which offers superior soft-tissue contrast and a means of assessing cellular density with diffusion-weighted imaging. Consequently, PET/MRI, the newest clinical hybrid imaging modality, has the potential to provide added value over PET/CT or MRI alone. The purpose of this article is to provide a comprehensive review of the current body of literature pertaining to the clinical performance of PET/MRI, with the aim of summarizing current evidence and identifying gaps in knowledge to direct clinical expansion and future research. Multiple example cases are also provided to illustrate the central findings of these publications.

Clinical applications of PET/MRI: current status and future perspectives

Fully integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) scanners have been available for a few years. Since then, the number of scanner installations and published studies have been growing. While feasibility of integrated PET/MRI has been demonstrated for many clinical and preclinical imaging applications, now those applications where PET/MRI provides a clear benefit in comparison to the established reference standards need to be identified. The current data show that those particular applications demanding multiparametric imaging capabilities, high soft tissue contrast and/or lower radiation dose seem to benefit from this novel hybrid modality. Promising results have been obtained in whole-body cancer staging in non-small cell lung cancer and multiparametric tumor imaging. Furthermore, integrated PET/MRI appears to have added value in oncologic applications requiring high soft tissue contrast such as assessment of liver metastases of neuroendocrine tumors or prostate cancer imaging. Potential benefit of integrated PET/MRI has also been demonstrated for cardiac (i.e., myocardial viability, cardiac sarcoidosis) and brain (i.e., glioma grading, Alzheimer's disease) imaging, where MRI is the predominant modality. The lower radiation dose compared to PET/computed tomography will be particularly valuable in the imaging of young patients with potentially curable diseases.However, further clinical studies and technical innovation on scanner hard- and software are needed. Also, agreements on adequate refunding of PET/MRI examinations need to be reached. Finally, the translation of new PET tracers from preclinical evaluation into clinical applications is expected to foster the entire field of hybrid PET imaging, including PET/MRI.

Magnetic resonance imaging for N staging in non-small cell lung cancer: A systematic review and meta-analysis

Background

Lymph node staging in non-small cell lung cancer (NSCLC) is essential for deciding appropriate treatment. This study systematically reviews the literature regarding the diagnostic performance of magnetic resonance imaging (MRI) in lymph node staging of patients with NSCLC, and determines its pooled sensitivity and specificity.

Methods

PubMed and Embase databases and the Cochrane library were used to search for relevant studies. Two reviewers independently identified the methodological quality of each study. A meta-analysis of the reported sensitivity and specificity of each study was performed.

Results

Nine studies were included. These studies had moderate to good methodological quality. Pooled sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR−) and diagnosis odds ratio (DOR) for per-patient based analyses (7 studies) were 74%, 90%, 7.5, 0.26, and 36.7, respectively, and those for per-lymph node based analyses (5 studies) were 77%, 98%, 42.24, 0.21, and 212.35, respectively. For meta-analyses of quantitative short time inversion recovery imaging (STIR) and diffusion-weighted imaging (DWI), pooled sensitivity and specificity were 84% and 91%, and 69% and 93%, respectively. Pooled LR+ and pooled LR− were 8.44 and 0.18, and 8.36 and 0.36, respectively. The DOR was 56.29 and 27.2 respectively.

Conclusion

MRI showed high specificity in the lymph node staging of NSCLC. Quantitative STIR has greater DOR than quantitative DWI. Large, direct, and prospective studies are needed to compare the diagnostic power of STIR versus DWI; consistent diagnostic criteria should be established.

PET-CT for assessing mediastinal lymph node involvement in patients with suspected resectable non-small cell lung cancer

BACKGROUND

A major determinant of treatment offered to patients with non-small cell lung cancer (NSCLC) is their intrathoracic (mediastinal) nodal status. If the disease has not spread to the ipsilateral mediastinal nodes, subcarinal (N2) nodes, or both, and the patient is otherwise considered fit for surgery, resection is often the treatment of choice. Planning the optimal treatment is therefore critically dependent on accurate staging of the disease. PET-CT (positron emission tomography-computed tomography) is a non-invasive staging method of the mediastinum, which is increasingly available and used by lung cancer multidisciplinary teams. Although the non-invasive nature of PET-CT constitutes one of its major advantages, PET-CT may be suboptimal in detecting malignancy in normal-sized lymph nodes and in ruling out malignancy in patients with coexisting inflammatory or infectious diseases.

OBJECTIVES

To determine the diagnostic accuracy of integrated PET-CT for mediastinal staging of patients with suspected or confirmed NSCLC that is potentially suitable for treatment with curative intent.

SEARCH METHODS

We searched the following databases up to 30 April 2013: The Cochrane Library, MEDLINE via OvidSP (from 1946), Embase via OvidSP (from 1974), PreMEDLINE via OvidSP, OpenGrey, ProQuest Dissertations & Theses, and the trials register www.clinicaltrials.gov. There were no language or publication status restrictions on the search. We also contacted researchers in the field, checked reference lists, and conducted citation searches (with an end-date of 9 July 2013) of relevant studies.

SELECTION CRITERIA

Prospective or retrospective cross-sectional studies that assessed the diagnostic accuracy of integrated PET-CT for diagnosing N2 disease in patients with suspected resectable NSCLC. The studies must have used pathology as the reference standard and reported participants as the unit of analysis.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data pertaining to the study characteristics and the number of true and false positives and true and false negatives for the index test, and they independently assessed the quality of the included studies using QUADAS-2. We calculated sensitivity and specificity with 95% confidence intervals (CI) for each study and performed two main analyses based on the criteria for test positivity employed: Activity > background or SUVmax ≥ 2.5 (SUVmax = maximum standardised uptake value), where we fitted a summary receiver operating characteristic (ROC) curve using a hierarchical summary ROC (HSROC) model for each subset of studies. We identified the average operating point on the SROC curve and computed the average sensitivities and specificities. We checked for heterogeneity and examined the robustness of the meta-analyses through sensitivity analyses.

MAIN RESULTS

We included 45 studies, and based on the criteria for PET-CT positivity, we categorised the included studies into three groups: Activity > background (18 studies, N = 2823, prevalence of N2 and N3 nodes = 679/2328), SUVmax ≥ 2.5 (12 studies, N = 1656, prevalence of N2 and N3 nodes = 465/1656), and Other/mixed (15 studies, N = 1616, prevalence of N2 to N3 nodes = 400/1616). None of the studies reported (any) adverse events. Under-reporting generally hampered the quality assessment of the studies, and in 30/45 studies, the applicability of the study populations was of high or unclear concern.The summary sensitivity and specificity estimates for the 'Activity > background PET-CT positivity criterion were 77.4% (95% CI 65.3 to 86.1) and 90.1% (95% CI 85.3 to 93.5), respectively, but the accuracy estimates of these studies in ROC space showed a wide prediction region. This indicated high between-study heterogeneity and a relatively large 95% confidence region around the summary value of sensitivity and specificity, denoting a lack of precision. Sensitivity analyses suggested that the overall estimate of sensitivity was especially susceptible to selection bias; reference standard bias; clear definition of test positivity; and to a lesser extent, index test bias and commercial funding bias, with lower combined estimates of sensitivity observed for all the low 'Risk of bias' studies compared with the full analysis.The summary sensitivity and specificity estimates for the SUVmax ≥ 2.5 PET-CT positivity criterion were 81.3% (95% CI 70.2 to 88.9) and 79.4% (95% CI 70 to 86.5), respectively.In this group, the accuracy estimates of these studies in ROC space also showed a very wide prediction region. This indicated very high between-study heterogeneity, and there was a relatively large 95% confidence region around the summary value of sensitivity and specificity, denoting a clear lack of precision. Sensitivity analyses suggested that both overall accuracy estimates were marginally sensitive to flow and timing bias and commercial funding bias, which both lead to slightly lower estimates of sensitivity and specificity.Heterogeneity analyses showed that the accuracy estimates were significantly influenced by country of study origin, percentage of participants with adenocarcinoma, (¹⁸F)-2-fluoro-deoxy-D-glucose (FDG) dose, type of PET-CT scanner, and study size, but not by study design, consecutive recruitment, attenuation correction, year of publication, or tuberculosis incidence rate per 100,000 population.

AUTHORS' CONCLUSIONS

This review has shown that accuracy of PET-CT is insufficient to allow management based on PET-CT alone. The findings therefore support National Institute for Health and Care (formally 'clinical') Excellence (NICE) guidance on this topic, where PET-CT is used to guide clinicians in the next step: either a biopsy or where negative and nodes are small, directly to surgery. The apparent difference between the two main makes of PET-CT scanner is important and may influence the treatment decision in some circumstances. The differences in PET-CT accuracy estimates between scanner makes, NSCLC subtypes, FDG dose, and country of study origin, along with the general variability of results, suggest that all large centres should actively monitor their accuracy. This is so that they can make reliable decisions based on their own results and identify the populations in which PET-CT is of most use or potentially little value.

Multimodality molecular imaging of the lung

Lung diseases cause significant morbidity and mortality and lead to high healthcare utilization. However, few lung disease-specific biomarkers are available to accurately monitor disease activity for the purposes of clinical management or drug development. Advances in cross-modal imaging technologies, such as combined positron emission tomography (PET) and magnetic resonance (MR) imaging scanners and PET or single-photon emission computed tomography (SPECT) combined with computed tomography (CT), may aid in the development of noninvasive, molecular-based biomarkers for lung disease. However, the lungs pose particular challenges in obtaining accurate quantification of imaging data due to the low density of the organ and breathing motion. This review covers the basic physics underlying PET, SPECT, CT, and MR lung imaging and presents technical considerations for multimodal imaging with regard to PET and SPECT quantification. It also includes a brief review of the current and potential clinical applications for these hybrid imaging technologies.

Prognostic value of metabolic tumor burden in lung cancer

Accurate prognosis in patients with lung cancer is important for clinical decision making and treatment selection. The TNM staging system is currently the main method for establishing prognosis. Using this system, patients are grouped into one of four stages based on primary tumor extent, nodal disease, and distant metastases. However, each stage represents a range of disease extent and may not on its own be the best reflection of individual patient prognosis. (18)F-fluorodeoxyglucose-positron emission tomography ((18)F-FDG-PET) can be used to evaluate the metabolic tumor burden affecting the whole body with measures such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG). MTV and TLG have been shown to be significant prognostic factors in patients with lung cancer, independent of TNM stage. These metabolic tumor burden measures have the potential to make lung cancer staging and prognostication more accurate and quantitative, with the goal of optimizing treatment choices and outcome predictions.

Fluorodeoxyglucose positron emission tomography/magnetic resonance imaging: current status, future aspects

Simultaneous positron emission tomography (PET)/magnetic resonance (MR) imaging is a promising novel technology for oncology diagnosis and staging and neurologic and cardiac applications. Our institution's current research protocol results in a total imaging time of approximately 45 to 70 minutes with simultaneous PET/MR imaging, making this a feasible total body imaging protocol. Further development of MR-based attenuation correction will improve PET quantification. Quantitatively accurate multiparametric PET/MR data sets will likely improve diagnosis of disease and help guide and monitor the therapies for individualized patient care.

Methods for staging non-small cell lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

Correctly staging lung cancer is important because the treatment options and prognosis differ significantly by stage. Several noninvasive imaging studies and invasive tests are available. Understanding the accuracy, advantages, and disadvantages of the available methods for staging non-small cell lung cancer is critical to decision-making.

METHODS

Test accuracies for the available staging studies were updated from the second iteration of the American College of Chest Physicians Lung Cancer Guidelines. Systematic searches of the MEDLINE database were performed up to June 2012 with the inclusion of selected meta-analyses, practice guidelines, and reviews. Study designs and results are summarized in evidence tables.

RESULTS

The sensitivity and specificity of CT scanning for identifying mediastinal lymph node metastasis were approximately 55% and 81%, respectively, confirming that CT scanning has limited ability either to rule in or exclude mediastinal metastasis. For PET scanning, estimates of sensitivity and specificity for identifying mediastinal metastasis were approximately 77% and 86%, respectively. These findings demonstrate that PET scanning is more accurate than CT scanning, but tissue biopsy is still required to confirm PET scan findings. The needle techniques endobronchial ultrasound-needle aspiration, endoscopic ultrasound-needle aspiration, and combined endobronchial ultrasound/endoscopic ultrasound-needle aspiration have sensitivities of approximately 89%, 89%, and 91%, respectively. In direct comparison with surgical staging, needle techniques have emerged as the best first diagnostic tools to obtain tissue. Based on randomized controlled trials, PET or PET-CT scanning is recommended for staging and to detect unsuspected metastatic disease and avoid noncurative resections.

CONCLUSIONS

Since the last iteration of the staging guidelines, PET scanning has assumed a more prominent role both in its use prior to surgery and when evaluating for metastatic disease. Minimally invasive needle techniques to stage the mediastinum have become increasingly accepted and are the tests of first choice to confirm mediastinal disease in accessible lymph node stations. If negative, these needle techniques should be followed by surgical biopsy. All abnormal scans should be confirmed by tissue biopsy (by whatever method is available) to ensure accurate staging. Evidence suggests that more complete staging improves patient outcomes.

Comparison between whole-body MRI and Fluorine-18-Fluorodeoxyglucose PET or PET/CT in oncology: a systematic review

BACKGROUND

The aim of the article is to systematically review published data about the comparison between positron emission tomography (PET) or PET/computed tomography (PET/CT) using Fluorine-18-Fluorodeoxyglucose (FDG) and whole-body magnetic resonance imaging (WB-MRI) in patients with different tumours.

METHODS

A comprehensive literature search of studies published in PubMed/MEDLINE, Scopus and Embase databases through April 2012 and regarding the comparison between FDG-PET or PET/CT and WB-MRI in patients with various tumours was carried out.

RESULTS

Forty-four articles comprising 2287 patients were retrieved in full-text version, included and discussed in this systematic review. Several articles evaluated mixed tumours with both diagnostic methods. Concerning the specific tumour types, more evidence exists for lymphomas, bone tumours, head and neck tumours and lung tumours, whereas there is less evidence for other tumour types.

CONCLUSIONS

Overall, based on the literature findings, WB-MRI seems to be a valid alternative method compared to PET/CT in oncology. Further larger prospective studies and in particular cost-effectiveness analysis comparing these two whole-body imaging techniques are needed to better assess the role of WB-MRI compared to FDG-PET or PET/CT in specific tumour types.

Performance of whole-body PET/CT for the detection of distant malignancies in various cancers: a systematic review and meta-analysis

At present, there is no ideal imaging modality for the diagnosis of distant metastases and second primary cancers in cancer patients. We aimed to assess the accuracy of whole-body PET/CT for the overall assessment of distant malignancies in patients with various cancers.

METHODS

Studies about whole-body PET/CT for the detection of distant malignancies in cancer patients were systematically searched in MEDLINE and EMBASE. We determined sensitivities and specificities across studies, calculated positive and negative likelihood ratios, and constructed summary receiver operating characteristic curves using hierarchical regression models for whole-body PET/CT.

RESULTS

Across 41 studies (4,305 patients), the sensitivity and specificity of whole-body PET/CT were 0.93 (95% confidence interval [CI], 0.88-0.96) and 0.96 (95% CI, 0.95-0.96), respectively. Subgroup analysis showed that the sensitivity and specificity of whole-body PET/CT for various cancers, respectively, were as follows: head and neck cancer, 0.90 (95% CI, 0.83-0.95) and 0.95 (95% CI, 0.94-0.96); lung cancer, 0.91 (95% CI, 0.76-0.97) and 0.96 (95% CI, 0.94-0.98); breast cancer, 0.97 (95% CI, 0.93-0.99) and 0.95 (95% CI, 0.90-0.97); and cancer of digestive system, 0.92 (95% CI, 0.68-0.98) and 0.97 (95% CI, 0.91-0.99).

CONCLUSION

Whole-body PET/CT has excellent diagnostic performance for the overall assessment of distant malignancies in patients with various cancers, especially head and neck cancer, breast cancer, and lung cancer.

Pulmonary lesion assessment: comparison of whole-body hybrid MR/PET and PET/CT imaging--pilot study

PURPOSE

To compare the performance of magnetic resonance (MR)/positron emission tomography (PET) imaging in the staging of lung cancer with that of PET/computed tomography (CT) as the reference standard and to compare the quantification accuracy of a new whole-body MR/PET system with corresponding PET/CT data sets.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained. Ten patients in whom bronchial carcinoma was proven or clinically suspected underwent clinically indicated fluorine 18 fluorodeoxyglucose (FDG) PET/CT and, immediately thereafter, whole-body MR/PET imaging with a new hybrid whole-body system (3.0-T MR imager with integrated PET system). Attenuation correction of MR/PET images was segmentation based with fat-water separation. Tumor-to-liver ratios were calculated and compared between PET/CT and MR/PET imaging. Tumor staging on the basis of the PET/CT and MR/PET studies was performed by two readers. Spearman rank correlation was used for comparison of data.

RESULTS

MR/PET imaging provided diagnostic image quality in all patients, with good tumor delineation. Most lesions (nine of 10) showed pronounced FDG uptake. One lesion was morphologically suspicious for malignancy at CT and MR imaging but showed no FDG uptake. MR/PET imaging had higher mean tumor-to-liver ratios than did PET/CT (4.4 ± 2.0 [standard deviation] for PET/CT vs 8.0 ± 3.9 for MR/PET imaging). Significant correlation regarding the tumor-to-liver ratio was found between both imaging units (ρ = 0.93; P < .001). Identical TNM scores based on MR/PET and PET/CT data were found in seven of 10 patients. Differences in T and/or N staging occurred mainly owing to modality-inherent differences in lesion size measurement.

CONCLUSION

MR/PET imaging of the lung is feasible and provides diagnostic image quality in the assessment of pulmonary masses. Similar lesion characterization and tumor stage were found in comparing PET/CT and MR/PET images in most patients.

(18)FDG-PET/CT for detection of mediastinal nodal metastasis in non-small cell lung cancer: a meta-analysis

BACKGROUND

We performed a meta-analysis to evaluate the role of (18)F-fluorodeoxyglucos -e positron emission tomography/computed tomography ((18)FDG-PET/CT) in detecting mediastinal nodal metastasis in patients with non-small cell lung cancer (NSCLC).

METHODS

Studies about (18)FDG-PET/CT for detecting mediastinal nodal metastasis in patient with NSCLC were systematically searched in the MEDLINE, EMBASE, and EBM Review databases from January 1, 2000 to July 26, 2011. A software called "Meta-Disc" was used to obtain pooled estimates of sensitivity, specificity, positive likelihood ratio (PLR), and negative likelihood ratio (NLR), respectively. We also calculated summary receiver operating characteristic (SROC) curves, and the Q* index.

RESULTS

20 articles fulfilled all inclusion criteria (3028 eligible patients). The pooled sensitivity, and specificity with 95% confidence interval for PET/CT on a per-patient analysis were 0.719 (0.683-0.753), and 0.898 (0.882-0.912). Corresponding values for PET/CT on a per-nodal-station analysis were 0.610 (0.582-0.636), 0.924 (0.918-0.930). The Q* index estimates under SROC were 0.8464 and 0.8067, respectively.

CONCLUSIONS

(18)FDG-PET/CT had more specificity but less sensitivity for mediastinal nodal metastasis in patients with NSCLC.

Review of Physiologic and Pathophysiologic Sources of Fluorodeoxyglucose Uptake in the Chest Wall on PET

The chest wall can be defined as the osseous and soft tissue structures that form the outer framework of the thorax and move during breathing. Topics discussed in this article include physiologic uptake of fluorodeoxyglucose, benign diseases of the chest wall, and malignant tumors of the chest wall.

Whole-body MRI using a sliding table and repositioning surface coil approach

Objective

To introduce and assess a new way of performing whole-body magnetic resonance imaging (MRI) using a non-integrated surface coil approach as available on most clinical MRI systems worldwide.

Methods

Ten consecutive asymptomatic subjects prospectively underwent whole-body MRI for health screening. Whole-body MRI included T1-, T2- and diffusion-weighted sequences, and was performed using a non-integrated surface coil to image four different stations without patient repositioning. The four separately acquired stations were merged, creating seamless coronal whole-body T1-, T2- and diffusion-weighted images. Anatomical alignment, image quality at the boundaries of adjacent stations, and overall image quality of all stations were qualitatively assessed.

Results

The average time (±SD) taken to change the surface coil from one station to the next station was 53.8 (±7.1) s. The average total extra examination time ± SD was 2 min 41.4 s (±15.3 s). Anatomical alignment, image quality at the boundaries of adjacent stations, and overall image quality of all stations of T1-, T2- and diffusion-weighted whole-body MRI were overall graded as “good” to “excellent”.

Conclusion

This study shows that a time-efficient and high-quality whole-body MRI examination can easily be performed by using a non-integrated sliding surface coil approach.

Electronic supplementary material

The online version of this article (doi:10.1007/s00330-009-1674-1) contains supplementary material, which is available to authorized users.

PET, CT, and MR Imaging for Assessment of Thoracic Malignancy: Structure Meets Function

Imaging of patients with thoracic malignancy usually requires a multimodality approach. Each of these modalities has its own strengths and weaknesses. CT remains central to the staging and restaging of thoracic malignancies, but has recently been complemented with [18F]-2-fluoro-2-deoxy-D-glucose(FDG)-positron emission tomography (PET) imaging to maximize its potential. Furthermore, because FDG-PET/CT is useful at all stages of the workup and treatment of these patients, this modality has taken hold in the clinical realm for evaluation of patients with thoracic malignancy and is rapidly replacing PET-only imaging. MR imaging is also occasionally used in some patients with thoracic malignancies to improve disease staging or lesion characterization. PET/MR imaging may come to be used to evaluate patients with thoracic malignancies as well.

Advances in magnetic resonance (2008)

Current advances in magnetic resonance, as a diagnostic modality, are discussed in the context of publications from Investigative Radiology during 2007 and 2008. The articles relating to this topic, published during the past 2 years, are reviewed by anatomic region. The discussion concludes with a consideration of magnetic resonance contrast media, focusing on studies published in the journal, and examining in particular the potential impact of nephrogenic systemic fibrosis.