Prognostic value of volumetric parameters measured by F-18 FDG PET/CT in surgically resected non-small-cell lung cancer

[18F]fluorodeoxyglucose positron emission tomography/computed tomography in combination with clinical data in predicting overall survival in non-small-cell lung cancer patients: A retrospective study

INTRODUCTION

Positron emission tomography/computed tomography (PET/CT) has an established role in evaluating patients with lung cancer. The aim of this work was to assess the predictive capability of [18F]Fluorodeoxyglucose ([18F]FDG) PET/CT parameters on overall survival (OS) in lung cancer patients using an artificial neural network (ANN) in parallel with conventional statistical analysis.

METHODS

Retrospective analysis was performed on a group of 165 lung cancer patients (98M, 67F). PET features associated with the primary tumor: maximum and mean standardized uptake value (SUVmax, SUVmean), total lesion glycolysis (TLG) metabolic tumor volume (MTV) and area under the curve-cumulative SUV histogram (AUC-CSH) and metastatic lesions (SUVmaxtotal, SUVmeantotal, TLGtotal, and MTVtotal) were evaluated. In parallel with conventional statistical analysis (Chi-Square analysis for nominal data, Student's t test for continuous data), the data was evaluated using an ANN. There were 97 input variables in 165 patients using a binary classification of either below, or greater than/equal to median survival post primary diagnosis. Additionally, phantom study was performed to assess the most optimal contouring method.

RESULTS

Males had statistically higher SUVmax (mean: 10.7 vs 8.9; p = 0.020), MTV (mean: 66.5 cm3 vs. 21.5 cm3; p = 0.001), TLG (mean 404.7 vs. 115.0; p = 0.003), TLGtotal (mean: 946.7 vs. 433.3; p = 0.014) and MTVtotal (mean: 242.0 cm3 vs. 103.7 cm3; p = 0.027) than females. The ANN after training and validation was optimised with a final architecture of 4 scaling layer inputs (TLGtotal, SUVmaxtotal, SUVmeantotal and disease stage) and receiving operator characteristic (ROC) analysis demonstrated an AUC of 0.764 (sensitivity of 92.3%, specificity of 57.1%).

CONCLUSION

Conventional statistical analysis and the ANN provided concordant findings in relation to variables that predict decreased survival. The ANN provided a weighted algorithm of the 4 key features to predict decreased survival.

IMPLICATION FOR PRACTICE

Identification of parameters which can predict survival in lung cancer patients might be helpful in choosing the group of patients who require closer look during the follow-up.

Role of dynamic and parametric whole-body FDG PET/CT imaging in molecular characterization of primary breast cancer: a single institution experience

AIM

The aim of this pilot study was to assess the role of dynamic whole-body PET and parametric imaging in the biological characterization of primary breast cancer.

MATERIALS AND METHOD

In total 24 histologically proven primary breast cancer lesions in 21 consecutive patients were retrospectively analyzed. Each patient underwent 18F-fluoro-deoxyglucose whole-body dynamic PET-CT before any treatment. Dynamic PET images were acquired in the list mode for a total duration of 70 min. The reconstructed parametric imaging generated Patlak plot-based 'Slope' and 'Intercept' images, from which parametric indices ki and DV were obtained. The standard uptake value (SUV) metric was also obtained by summing the last few frames of the dynamic study. ki, distribution volume (DV) and SUV were correlated with the histological tumor grade, biomarkers [hormone receptors and human epidermal growth factor receptor 2 (HER-2) neu expression] and molecular subtypes (A, B and C) as well as with tumor size, regional nodal metastases and distant metastases.

RESULTS

The mean ki was found to be significantly higher in grade III than II lesions (P = 0.005), HER-2 neu positive status (P = 0.04) and molecular subtype B (P = 0.04) as well as in greater than T1 lesions(P = 0.0003 and P = 0.04, respectively) and node-positive lesions (P = 0.009). Though mean ki was not found to be significant for the hormone receptors status (P = 0.08), it showed the best correlation compared to the other parameters (P = 0.8 for DV and P = 0.1 for SUV). Spearman's correlation test, area under the curve (AUC) and mismatch percentage also revealed ki to predict tumor grade (AUC, 0.95; r = 0.7; P = 0.0001), HER-2 neu status and molecular subtypes (AUC, 0.81; r = 0.49 and P = 0.01) along with the hormone receptors status (AUC, 0.83; r = 0.32; P = 0.1). The mean DV failed to show any association with any of the biological or anatomical staging parameters. Though ki was found to be comparable to that of SUV in almost all the assessed parameters, it appeared to be better for predicting hormone receptors status even though both parameters were not statistically significant.

CONCLUSION

Our initial observation in a small cohort of breast cancer patients suggests that ki is promising in stratifying primary breast cancer lesions according to the tumor grade and biological characteristics.

The value of the Standardized Uptake Value (SUV) and Metabolic Tumor Volume (MTV) in lung cancer

The diagnosis, staging and therapeutic monitoring of lung cancer were amongst the first applications for which the utility of FDG PET was documented and FDG PET/CT is now a routine diagnostic tool for clinical decision-making. As well as having high sensitivity for detection of disease sites, which provides critical information about stage, the intensity of uptake provides deeper biological characterization, while the burden of disease also has potential clinical significance. These disease characteristics can easily be quantified on delayed whole-body imaging as the maximum standardized uptake value (SUV_max) and metabolic tumor volume (MTV), respectively. There have been significant efforts to harmonize the measurement of these features, particularly within the context of clinical trials. Nevertheless, however calculated, in general, a high SUV_max and large MTV have been shown to have an adverse prognostic significance. Nevertheless, the use of these parameters in the interpretation and reporting of clinical scans remains inconsistent and somewhat controversial. This review details the current status of semi-quantitative FDG PET/CT in the evaluation of lung cancer.

SUVmax to tumor perimeter distance: a robust radiomics prognostic biomarker in resectable non-small cell lung cancer patients

OBJECTIVE

The purpose of this study was to evaluate the prognostic value of novel geometric variables obtained from pre-treatment [¹⁸F]FDG PET/CT with respect to classical ones in patients with non-small cell lung cancer (NSCLC).

METHODS

Retrospective study including stage I-III NSCLC patients with baseline [¹⁸F]FDG PET/CT. Clinical, histopathologic, and metabolic parameters were obtained. After tumor segmentation, SUV and volume-based variables, global texture, sphericity, and two novel parameters, normalized SUVpeak to centroid distance (nSCD) and normalized SUVmax to perimeter distance (nSPD), were obtained. Early recurrence (ER) and short-term mortality (STM) were used as end points. Univariate logistic regression and multivariate logistic regression with respect to ER and STM were performed.

RESULTS

A cohort of 173 patients was selected. ER was detected in 49/104 of patients with recurrent disease. Additionally, 100 patients died and 53 had STM. Age, pathologic lymphovascular invasion, lymph nodal infiltration, TNM stage, nSCD, and nSPD were associated with ER, although only age (aOR = 1.06, p = 0.002), pathologic lymphovascular invasion (aOR = 3.40, p = 0.022), and nSPD (aOR = 0.02, p = 0.018) were significant independent predictors of ER in multivariate analysis. Age, lymph nodal infiltration, TNM stage, nSCD, and nSPD were predictors of STM. Age (aOR = 1.05, p = 0.006), lymph nodal infiltration (aOR = 2.72, p = 0.005), and nSPD (aOR = 0.03, p = 0.022) were significantly associated with STM in multivariate analysis. Coefficient of variation (COV) and SUVmean/SUVmax ratio did not show significant predictive value with respect to ER or STM.

CONCLUSION

The geometric variables, nSCD and nSPD, are robust biomarkers of the poorest outcome prediction of patients with NSCLC with respect to classical PET variables.

KEY POINTS

• In NSCLC patients, it is crucial to find prognostic parameters since TNM system alone cannot explain the variation in lung cancer survival. • Age, lymphovascular invasion, lymph nodal infiltration, and metabolic geometrical parameters were useful as prognostic parameters. • The displacement grade of the highest point of metabolic activity towards the periphery assessed by geometric variables obtained from [¹⁸F]FDG PET/CT was a robust biomarker of the poorest outcome prediction of patients with NSCLC.

Metabolic active tumour volume quantified on [18F]FDG PET/CT further stratifies TNM stage IV non-small cell lung cancer patients

PURPOSE

This study aimed to assess whether the whole body metabolic active tumour volume (MTV_WB), quantified on staging [¹⁸F]FDG PET/CT, could further stratify stage IV non-small cell lung cancer (NSCLC) patients.

METHODS

A group of 160 stage IV NSCLC patients, submitted to staging [¹⁸F]FDG PET/CT between July 2010 and May 2020, were retrospectively evaluated. MTV_WB was quantified. Univariate and multivariate Cox regressions were carried out to assess correlation with overall survival (OS). C-statistic was used to test predictive power. Kaplan-Meier survival curves with Log-Rank tests were performed to compute statistical differences between strata from dichotomized variables and to calculate the estimated mean survival times (EMST). Survival rates at 1 and 5 years were calculated.

RESULTS

MTV_WB was a statistically significant predictor of OS on univariate (p < 0.0001) and multivariate analyses (p < 0.0001). The multivariate model with MTV_WB (Cindex ± SE = 0.657 ± 0.024) worked significantly better as an OS predictor than the cTNM model (Cindex ± SE = 0.544 ± 0.028) (p = 0.003). An EMST of 29.207 ± 3.627(95% CI 22.099-36.316) months and an EMST of 10.904 ± 1.171(95% CI 8.609-13.199) months (Log-Rank p < 0.0001) were determined for patients with MTV_WB < 104.3 and MTV_WB ≥ 104.3, respectively. In subsamples of stage IVA (cut-off point = 114.5) and IVB patients (cut-off point = 191.1), statistically significant differences between EMST were also reported, with p-values of 0.0001 and 0.0002, respectively. In both substages and in the entire cohort, patients with MTV_WB ≥ cut-off points had lower EMST and survival rates.

CONCLUSION

Baseline MTV_WB, measured on staging [¹⁸F]FDG PET/CT, further stratifies stage IV NSCLC patients. This parameter is an independent predictor of OS and provides valuable prognostic information over the 8th edition of cTNM staging.

Prognostic Value of Metabolic Tumor Parameters in Pretreatment 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography Scan in Advanced Non-Small Cell Lung Cancer

Objective:

This retrospective study aimed to investigate whether metabolic parameters of primary tumour i.e. maximum standardized uptake value (SUVmax), metabolic tumour volume (MTV) and total lesion glycolysis (TLG) predict overall survival (OS) in patients with advanced stage non-small cell lung cancer (NSCLC).

Materials and Methods:

SUVmax, MTV and TLG of the primary tumors were measured in staging ¹⁸F-Fluorodeoxyglucose Positron emission tomography- Computed tomography (¹⁸F-FDG PET/CT) scan of 97 NSCLC patients by gradient based tumour segmentation method. Prognostic ability was assessed for overall survival (OS) of the patients.

Result:

The median follow-up period of the study was 15.84 months (range 1.3 to 47.97 months).The estimated median OS was 11.29 months (range 1.37 to 38.63 months). Total of 40 (41.24%) patients had progressive disease and 21 (21.65%) patients died during the follow up period. Receiver Operating Characteristic (ROC) analysis showed that the area under the curve (AUC) for MTV was significant (area = 0.652 ± 0.065; 95% CI = 0.548 – 0.746; P = 0.020). Kaplan-Meier survival curves showed that the OS differences between the groups of patients who were dichotomized by the median value of MTV (38.76 ml, P = 0.0150) and TLG (301.69 ml, P = 0.0046) were significant. MTV (hazard ratio = 4.524; 95% CI = 1.244 – 16.451; P = 0.022) was found to be an independent prognostic factor for OS in multivariate analysis.

Conclusion:

MTV of the primary tumor is a potential prognostic parameter for OS in our population of advanced NSCLC patients independent of other risk factors.

Differences between TNM classification and 2-[18F]FDG PET parameters of primary tumor in NSCLC patients

Background

The aim of the study was to compare the TNM classification with 2-[¹⁸F]FDG PE T biological parameters of primary tumor in patients with NSCLC.

Materials and methods

Retrospective analysis was performed on a group of 79 newly diagnosed NSCLC patients. PET scans were acquired on Gemini TF PET/CT scanner 60–70 min after injection of 2-[¹⁸F]FDG with the mean activity of 364 ± 75 MBq, with the area being examined from the vertex to mid-thigh. The reconstructed PET images were evaluated using MIM 7.0 Software for SUV_max, MTV and TLG values.

Results

The analysis of the cancer stage according to TNM 8^th edition showed stage IA2 in 8 patients, stage IA3 — 6 patients, stage IB — 4 patients, IIA — 3 patients, 15 patients with stage IIB, stage IIIA — 17 patients, IIIB — 5, IIIC — 5, IVA in 7 patients and stage IVB in 9 patients. The lowest TLG values of primary tumor were observed in stage IA2 (11.31 ± 15.27) and the highest in stage IIIC (1003.20 ± 953.59). The lowest value of primary tumor in SUV_max and MTV were found in stage IA2 (6.8 ± 3.8 and 1.37 ± 0.42, respectively), while the highest SUV_max of primary tumor was found in stage IIA (13.4 ± 11.4) and MTV in stage IIIC (108.15 ± 127.24).

Conclusion

TNM stages are characterized by different primary tumor 2-[¹⁸F]FDG PET parameters, which might complement patient outcome.

Pleomorphic carcinoma of the lung: Prognostic models of semantic, radiomics and combined features from CT and PET/CT in 85 patients

INTRODUCTION

To demonstrate semantic, radiomics, and the combined risk models related to the prognoses of pulmonary pleomorphic carcinomas (PCs).

METHODS

We included 85 patients (M:F = 71:14; age, 35-88 [mean, 63 years]) whose imaging features were divided into training (n = 60) and test (n = 25) sets. Nineteen semantic and 142 radiomics features related to tumors were computed. Semantic risk score (SRS) model was built using the Cox-least absolute shrinkage and selection operator (LASSO) approach. Radiomics risk score (RRS) from CT and PET features and combined risk score (CRS) adopting both semantic and radiomics features were also constructed. Risk groups were stratified by the median of the risk scores of the training set. Survival analysis was conducted with the Kaplan-Meier plots.

RESULTS

Of 85 PCs, adenocarcinoma was the most common epithelial component found in 63 (73 %) tumors. In SRS model, four features were stratified into high- and low-risk groups (HR, 4.119; concordance index ([C-index], 0.664) in the test set. In RRS model, five features helped improve the stratification (HR, 3.716; C-index, 0.591) and in CRS model, three features helped perform the best stratification (HR, 4.795; C-index, 0.617). The two significant features of CRS models were the SUVmax and the histogram feature of energy ([CT Firstorder Energy]).

CONCLUSION

In PCs of the lungs, the combined model leveraging semantic and radiomics features provides a better prognosis compared to using semantic and radiomics features separately. The high SUVmax of solid portion (CT Firstorder Energy) of tumors is associated with poor prognosis in lung PCs.

The Study of Tumor Volume as a Prognostic Factor in T Staging System for Non-Small Cell Lung Cancer: An Exploratory Study

Background:

This study aimed to evaluate T staging system for non-small cell lung cancer (NSCLC) using tumor volume (TV) and other prognostic factors.

Methods:

This study included 1309 cases. The TV and greatest tumor diameter (GTD) were semi-automatically measured. The receiver operating characteristic (ROC) curves of TV and GTD were used to predict survival. The regression analysis was used to describe the correlation between GTD and TV. Overall survival (OS) was analyzed using the Kaplan-Meier method. Cox’s proportional hazards regression model was applied for multivariate analysis.

Results:

Using the OS in pN0M0 patients (997 cases), we obtained 4 optimal cutoff values and divided all cases into 5 TV groups (V1: TV ≤ 2.80 cm³; V2: TV > 2.80–6.40 cm³; V3: TV > 6.40–12.9 cm³; V4: TV > 12.9–55.01 cm³; V5: TV > 55.01 cm³) with significant OS (P < 0.001). Multivariate analysis showed that age, visceral pleural invasion (VPI), and all TV cutoff points were independent factors of OS (P < 0.05). For V3 and V4 groups, the OS in patients without VPI was better than that in patients with VPI. Using the values of TV, VPI, and N stages, we classified all cases into 5 stages from I to V depending on the OS. The OS in I, II, III, IV, and V stages were 71.3%, 65.5%, 59.8%, 47.7%, and 35.1% respectively (P < 0.001).

Conclusions:

We proposed a new T staging system using TV as the main prognostic descriptor in NSCLC patients, which may provide a better comprehensive clinical value than GTD in clinical applications.

A Pilot Study of Texture Analysis of Primary Tumor [18F]FDG Uptake to Predict Recurrence in Surgically Treated Patients with Non-small Cell Lung Cancer

PURPOSE

To examine whether the heterogeneous texture parameters in primary tumor can predict prognosis of patients with non-small cell lung cancer (NSCLC) received surgery after 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) positron emission tomography (PET)/X-ray computed tomography (CT).

PROCEDURE

This retrospective study included 55 patients with NSCLC who underwent [¹⁸F]FDG-PET/CT before surgery from January 2011 and December 2015. SUV-related (SUVmax and SUVmean), volumetric (metabolic tumor volume [SUV ≥ 2.5], and total lesion glycolysis) and texture parameters (local parameters; entropy, homogeneity, and dissimilarity and regional parameters; intensity variability [IV], size-zone variability [SZV], and zone percentage [ZP]) were obtained. Tumor size, TNM stage, SUV-related, volumetric, and texture parameters were compared between the patients with progression and without progression using Mann-Whitney's U or χ² test and progression-free survival (PFS) and prognostic significance were assessed by Kaplan-Meier method and Cox regression analysis, respectively.

RESULTS

Nineteen patients eventually showed progression, and 36 patients were alive without progression during clinical follow-up (median follow-up PFS; 23 months [range, 1-71]). The patients with progression showed significantly larger tumor size (p < 0.001), higher IV (p = 0.010), and higher SZV (p = 0.007) than those without progression. PFS was significantly shorter in patients with large tumor size (p = 0.008), high T stage (p = 0.009), high stage (p = 0.013), high IV (p = 0.012), and high SZV (p = 0.015) at univariate analysis. At multivariate analysis, stage (hazard ratio [HR] 1.62, p = 0.035) and IV (hazard ratio 6.19, p = 0.048) were only remained independent predictors for PFS.

CONCLUSIONS

The regional heterogeneity texture parameters IV and SZV can predict tumor progression, and IV has the potential to predict prognosis of surgically treated NSCLC patients.

Measurement Variability in Treatment Response Determination for Non-Small Cell Lung Cancer: Improvements Using Radiomics

Multimodality imaging measurements of treatment response are critical for clinical practice, oncology trials, and the evaluation of new treatment modalities. The current standard for determining treatment response in non-small cell lung cancer (NSCLC) is based on tumor size using the RECIST criteria. Molecular targeted agents and immunotherapies often cause morphological change without reduction of tumor size. Therefore, it is difficult to evaluate therapeutic response by conventional methods. Radiomics is the study of cancer imaging features that are extracted using machine learning and other semantic features. This method can provide comprehensive information on tumor phenotypes and can be used to assess therapeutic response in this new age of immunotherapy. Delta radiomics, which evaluates the longitudinal changes in radiomics features, shows potential in gauging treatment response in NSCLC. It is well known that quantitative measurement methods may be subject to substantial variability due to differences in technical factors and require standardization. In this review, we describe measurement variability in the evaluation of NSCLC and the emerging role of radiomics.

Validation of Independent Prognostic Value of Asphericity of 18F-Fluorodeoxyglucose Uptake in Non-Small-Cell Lung Cancer Patients Undergoing Treatment With Curative Intent

BACKGROUND

In patients with non-small-cell lung cancer (NSCLC), asphericity (ASP) of the primary tumor's metabolic tumor volume (MTV) has shown prognostic significance. This study aimed at validation in an independent and sufficiently large cohort.

PATIENTS AND METHODS

A retrospective study was performed of 311 NSCLC patients undergoing ¹⁸F-fluorodeoxyglucose positron emission tomography / computed tomography (¹⁸F-FDG PET/CT) before curatively intended treatment (always including surgery). A total of 140 patients had International Union Against Cancer (UICC) stage I disease, 78 had stage II disease, and 93 had stage III disease (adenocarcinoma, n = 153; squamous-cell carcinoma, n = 141). Primary tumor MTV was delineated with semiautomated background-adapted threshold relative to the standardized maximum uptake value (SUV_max). Cox regression (progression-free survival [PFS] and overall survival [OS]) analysis for positron emission tomography (MTV, ASP, SUV_max) as well as for clinical (T/N descriptor, UICC stages), histologic, and treatment variables (Rx/1 vs. R0 resection, chemotherapy/radiotherapy yes/no) were performed.

RESULTS

Events (progression and relapse) occurred in 167 of 311 patients; 137 died (median survivor follow-up, 37 months). In multivariable Cox regression for OS, ASP > 33.3% (hazard ratio, 1.58 [1.04-2.39]), male sex (1.84), age (1.04 per year), Eastern Cooperative Oncology Group performance status ≥ 2 versus 0/1 (2.68), stage II versus I (1.96), and Rx/1 versus R0 resection (2.1) were significant. Among separate UICC stages, ASP only predicted OS in stage II (optimal, > 19.5%; median OS, 33 vs. 59 months). Regarding PFS, ASP > 21.2%, male sex, Eastern Cooperative Oncology Group performance status ≥ 2, stage II versus I disease, and Rx/1 resection were prognostic. ASP remained prognostic for stage II disease (optimal, > 19.5%; PFS, 12 vs. 47 months). Log-rank test for ASP was significant at any cutoff ≥ 18% (OS) or from 9% to 59% (PFS).

CONCLUSION

ASP was validated as prognostic factor for PFS and OS in patients with NSCLC and curative treatment intent, especially stage II. High ASP in stage II could imply intensified treatment or intensified follow-up.

Prognostic Significance of Metabolic Parameters and Textural Features on 18F-FDG PET/CT in Invasive Ductal Carcinoma of Breast

To investigate the prognostic significance of metabolic parameters and texture analysis on ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) in patients with breast invasive ductal carcinoma (IDC), from August 2005 to May 2015, IDC patients who had undergone pre-treatment FDG PET/CT were enrolled. The metabolic parameters, including maximal standardized uptake value of breast tumor (SUVbt) and ipsilateral axillary lymph node (SUVln), metabolic tumor volume (MTVbt) and total lesion glycolysis (TLGbt) of breast tumor, whole-body MTV (MTVwb) and whole-body TLG (TLGwb) were recorded. Nine textural features of tumor (four co-occurrence matrices and five SUV-based statistics) were measured. The prognostic significance of above parameters and clinical factors was assessed by univariate and multivariate analyses. Thirty-five patients were enrolled. Patients with low and high MTVwb had 5-year progression-free survival (PFS) of 81.0 and 14.3% (p < 0.0001). The 5-year overall survival for low and high MTVwb was 88.5% and 43.6% (p = 0.0005). Multivariate analyses showed MTVwb was an independent prognostic factor for PFS (HR: 8.29, 95% CI: 2.17–31.64, p = 0.0020). The SUV, TLG and textural features were not independently predictive. Elevated MTVwb was an independent predictor for shorter PFS in patients with breast IDC.

Predictive Value of Preoperative Volume-Based 18F-2-Fluoro-2-Deoxy-d-Glucose Positron Emission Tomography/Computed Tomography Parameters in Patients with Resectable Lung Adenocarcinoma

Purpose

This study aimed to investigate the prognostic value of metabolic tumor volume (MTV) and total lesion glycolysis (TLG), which are volume-based PET parameters, using ¹⁸F-2-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in patients with surgically resectable lung adenocarcinoma.

Methods

We retrospectively evaluated 149 patients with lung adenocarcinoma who underwent ¹⁸F-FDG PET/CT before surgical resection. Maximum standardized uptake value (SUVmax), MTV, and TLG of the primary tumor with threshold value of SUVmax 30, 40, and 50% were calculated, respectively. To compare the predictive performance of volume-based PET parameters, recurrence-free survival was assessed using the Kaplan-Meier method.

Results

The study included 70 males and 79 females with an average age of 65.8 years. The median follow-up time was 45.4 months. Recurrence was observed in 53 patients (35.6%). The mean ± SD SUVmax, MTV_30%, and TLG_30% of the entire cohort were 4.79 ± 2.94, 19.45 ± 24.85, and 56.43 ± 101.88, respectively. The cut-off values of MTV_30% and TLG_30% for recurrence were 11.07 ad 30.56, respectively. The 1-year recurrence-free survival (RFS) rate was 96.5% in low-MTV_30% patients compared with 86.2% in high-MTV_30% patients (p = 0.018) and 96.0% in low-TLG_30% patients compared with 88.5% in high-TLG_30% patients (p < 0.001). On univariate and multivariate analysis, TLG_30% (HR, 2.828, p < 0.001; HR, 2.738, p < 0.001, respectively) was an independent prognostic factor for predicting recurrence-free survival (RFS).

Conclusion

TLG_30% value was observed to be a significant prognostic factor for RFS in patients with lung adenocarcinoma treated by surgical resection.

Prognostic significance of fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography-derived metabolic parameters in surgically resected clinical-N0 nonsmall cell lung cancer

OBJECTIVE

Our aim was to assess the significance of metabolic positron emission tomography (PET) parameters for the prediction of occult mediastinal lymph node metastasis (OLM) and recurrence in patients with clinical-N0 nonsmall cell lung cancer (NSCLC) after surgical resection and lymph node dissection.

MATERIALS AND METHODS

We evaluated 98 patients with NSCLC [52 adenocarcinoma (ADC), 46 squamous cell carcinoma (SQCC)] who had undergone initial/preoperative fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT). Eligibility criteria for participation were clinically staged as N0 and no FDG uptake in mediastinal lymph nodes on preoperative PET/CT. Clinicopathological characteristics and the diagnosis of recurrence were obtained by reviewing the hospital records. Metabolic parameters [maximum standardized uptake value, mean standardized uptake value, metabolic tumor volume (MTV), total lesion glycolysis] were determined on F-FDG PET/CT images. The association of metabolic parameters with OLM and recurrence was assessed.

RESULTS

OLM was found in 26 (26.53%) patients. T-stage, central location, and lymphovascular invasion were associated with OLM (respectively, P=0.007, 0.011, <0.001). None of the metabolic parameters was associated with OLM. Metabolic parameters of the tumor were significantly higher in patients with recurrence when the cohort was evaluated as a whole (P=0.002, 0.005, 0.016, and 0.004, respectively). In particular, there was a significant association between recurrence and tumor size, grade, stage, MTV (P<0.001), and TLG (P<0.001) in ADC. This association was not found in SQCC. Multivariate analysis showed that MTV was an independent prognostic factor for recurrence and associated with disease-free survival.

CONCLUSION

Metabolic parameters of the primary tumor on preoperative F-FDG PET/CT could not predict OLM in patients with clinical-N0 NSCLC. MTV was an independent risk factor for recurrence in ADC, but not in SQCC.

Metabolic positron emission tomography parameters predict failure patterns in early non-small-cell lung cancer treated with stereotactic body radiation therapy: a single institution experience

Objective

The prognostic value of metabolic parameters using 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) has not been established for early non-small cell lung cancer (NSCLC). Accordingly, the authors investigated the prognostic value of metabolic parameters in terms of failure patterns in patients with early NSCLC who underwent stereotactic body radiation therapy (SBRT).

Methods

Data from 35 patients with Stage I NSCLC who underwent SBRT using CyberKnife and received pretreatment FDG PET/CT between 2008 and 2016 were retrospectively reviewed. Maximum standardized uptake value (SUVmax), metabolic tumor volume, and total lesion glycolysis were measured. The significance of these parameters with regard to failure patterns was assessed.

Results

The median follow-up was 23 months for all patients and 34 months for living patients. Ten patients experienced recurrence: three local failures, five regional failures (RF), and eight distant failures (DF). Three-year local, regional and distant control rates were 96.7%, 86.4% and 71.1%, respectively. High SUVmax (<9 vs. ≥9) was an independent predictive factor associated with increased RF (P = 0.027) and DF (P = 0.008). Furthermore, SUVmax was indicative of both progression-free (P = 0.015) and overall (P = 0.034) survival.

Conclusions

High SUVmax was a significant metabolic parameter associated with increased RF and DF in patients with early NSCLC who received SBRT, having a high propensity for dissemination. These results suggest that adjuvant treatment in conjunction with SBRT may be considered in patients with early NSCLC and high SUVmax.

Prognostic significance of metabolic tumor volume and total lesion glycolysis in patients with advanced cervical carcinoma

AIM

18-Fluoro-2-deoxy-d-glucose positron emission tomography (¹⁸F-FDG PET/CT) is considered to be the most accurate image method of detection of node or distant metastases in cervical cancer. Metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of ¹⁸F-FDG PET/CT are volumetric measurements of tumor cells with increased ¹⁸F-FDG uptake. The prognostic value of MTV and TLG in patients with advanced cervical cancer (ACC) were evaluated.

METHODS

38 patients with ACC from one tertiary university hospital underwent ¹⁸F-FDG PET/CT between June 2009 and December 2015. Clinicopathologic factors and various PET parameters were analyzed to evaluate their relationship with recurrence-free survival (RFS) and overall survival (OS). These parameters were: maximum standardized uptake value (SUVmax), mean standardized uptake value (SUV mean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of the primary tumor, of the pelvic nodes, of the paraaortic nodes and the metabolic volume of the metastases if any.

RESULTS

A total of 38 patients with ACC fulfilled the inclusion criteria. All of them underwent a ¹⁸F-FDG PET/CT before definitive chemoradiotherapy. In the univariate analyses higher tumor size, pelvic lymph node metastasis and both MTV and TLG showed a significant association with OS and with RFS (MTV HR=1.55, p=0.011 and TLG HR=1.43, p=0.017 for RFS and MTV HR=1.82, p=0.006 and TLG HR=1.67, p=0.007 for OS).

CONCLUSION

Pretreatment TLG sum and MTV sum seem to be independent prognostic factors for OS and RFS in patients with advanced cervical cancer treated with definitive chemoradiotherapy and they are better than the classic measurement of SUVmax.

Quantitative 18F-FDG PET analysis in survival rate prediction of patients with non-small cell lung cancer

The aim of the present study was to investigate the prognostic value of quantitative [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) parameters for patients with non-small cell lung cancer (NSCLC). The present study conducted a retrospective review of the medical records of 203 patients with NSCLC, of which 193 patients underwent baseline 18F-FDG PET/CT prior to initial therapy. Multivariate analyses using Cox's proportional hazards regression were performed for the assessment of the association between initial PET/CT measurements and overall survival (OS). The multivariate models were adjusted for sex, age, smoking status, disease stage, standardized uptake value (SUV), standardized uptake value corrected for lean body mass (SUL), metabolic tumor volume (MTV), total lesion glycolysis (TLG) and standard deviation of SUV (SD). Kaplan-Meier (K-M) estimator curves were constructed following the formation of three approximately equal-sized groups using tertiles for each PET/CT measurement (n=65, 64 and 64). OS curves were plotted using K-M estimator curves. Results demonstrated significant associations between OS and MTVPET volume computerized assisted reporting (PETVCAR), MTV2.5, MTV25%, MTV42% and TLGPETVCAR; however, no significant associations were identified between OS and MTV50%, MTV75%, TLG2.5, all SUV and SUL. Subgroup analyses according to pathology demonstrated that there were statistically significant associations between OS and stage (P<0.001), MTV50% (P=0.002) and MTV42% (P=0.004) in the adenocarcinoma group, and SULmean (P=0.010), MTV25% (P=0.005) and MTV42% (P=0.001) in the squamous cell carcinoma group; however, no significant differences were identified between any other group. Furthermore, there was a significant association between OS and MTV42% (P=0.02) and MTV50% (P=0.04) in the early-stage group; however, no significant differences were identified in the advanced-stage group. K-M estimator curve analyses demonstrated that the pathology (P=0.01), stage (P<0.001) and all PET metabolic parameters with the exception of SD were significantly associated with OS (P<0.05). No significant associations were demonstrated between SD and OS. In conclusion, 18F-FDG PET/CT MTVPETVCAR, MTV2.5, MTV25%, MTV42% and TLGPETVCAR exhibit prognostic values with regard to OS. Overall, selection of appropriate metabolic parameters may predict NSCLC prognosis.

The value of different 18F-FDG PET/CT baseline parameters in risk stratification of stage I surgical NSCLC patients

OBJECTIVE

Administration of postoperative chemotherapy to patients with completely resected stage I NSCLC is still a matter of debate. The aim of the present study was to evaluate the value of different baseline ¹⁸F-FDG PET parameters in identifying surgical stage I NSCLC patients who are at high risk of recurrence, and thus are indicated for further postoperative treatment.

METHODS

This is a retrospective study, which included 49 patients (28 males, 21 females) with the median age of 69 years (range 28-84), who had pathologically proven stage I NSCLC. All patients underwent ¹⁸F-FDG PET/CT at baseline followed by complete surgical resection of the tumor (R0). Baseline SUV_max, MTV and TLG were measured. Patients' follow-up records were retrospectively reviewed, and DFS (disease-free survival) was assessed. For each parameter, the most accurate cut-off value for the prediction of recurrence was calculated using the ROC curve analysis and the Youden index. DFS was evaluated for patients above and below the calculated cut-off value using the Kaplan-Meier method and the difference in survival between the two groups was estimated using the log-rank test.

RESULTS

Median observation time of the patients after surgery was 28.7 months (range 3.5-58.8 months). 9 patients developed recurrence. The calculated cut-off values for SUV_max, MTV and TLG were 6, 6.6 and 33.6, respectively. Using these cut-offs, the observed sensitivity for SUV_max, MTV and TLG for prediction of recurrence was 100%, 89% and 89%, respectively, while the observed specificity was 43%, 73% and 65%, respectively. The difference in survival between patients below and above the cut-off value was statistically significant in all three studied parameters. The highest AUC was observed for MTV (AUC = 0.825, p = 0.003), followed by TLG (AUC = 0.789, p = 0.007), and lastly SUV_max (AUC = 0.719, p = 0.041). ROC curve analysis showed that volumetric parameters had better predictive performance than SUV_max as regards recurrence.

CONCLUSION

PET-derived parameters at baseline were predictive of recurrence in stage I surgical NSCLC patients. Moreover, the metabolic volume of the tumor was the most significant parameter for this purpose among the studied indices.

The assessment of correlation and prognosis among 18F-FDG uptake parameters, Glut1, pStat1 and pStat3 in surgically resected non-small cell lung cancer patients

Introduction

To assess the correlation among ¹⁸F-FDG uptake, Glut1, pStat1 and pStat3, and to investigate the relationship between the prognosis and ¹⁸F-FDG uptake and these molecular markers in surgically resected non-small cell lung cancer (NSCLC) patients.

Results

Knockdown of Glut1 led to a significant increase in pStat1 expression. Glut1 expression positively correlated with the SUVmax, SUVmean, and TLG significantly (P<0.001). pStat3 expression negatively correlated with all PET parameters significantly (P<0.001). pStat1 had positive weak correlations with the SUVmax and SUVmean. All PET parameters and Glut1 were significantly associated with DFS (P<0.05). TLG, MTV, Glut1 and pStat1 were significantly associated with OS (P<0.05).

Conclusion

pStat3 and Glut1 may be associated with ¹⁸F-FDG uptake mechanism. TLG, MTV, and Glut1 may be independent prognostic factors.

Methods

The SUVmax, SUVmean, MTV and TLG of primary lesions were calculated in 140 patients. The expressions of Glut1 and Stat pathway proteins in NSCLC cell lines were examined by immune blots. Excised tumor tissue was analyzed by immunohistochemistry. OS and DFS were evaluated by the Kaplan-Meier method. The difference in survival between subgroups was analyzed by log-rank test. The prognostic significance of clinicopathological, molecular and PET parameters was assessed by Cox proportional hazard regression analysis.

Dual-Energy Computed Tomography-Based Iodine Quantitation for Response Evaluation of Lung Cancers to Chemoradiotherapy/Radiotherapy: A Comparison With Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography-Based Positron Emission Tomography/Computed Tomography Response Evaluation Criterion in Solid Tumors

OBJECTIVE

The objective of this study was to investigate the correlation between dual-energy computed tomography (DECT)-based iodine quantitation and fluorine-18 fluorodeoxyglucose (F-FDG) positron emission tomography (PET)/computed tomography (CT) imaging for response evaluation of lung cancers to treatment.

METHODS

In this prospective study, a total of 32 pairs of DECT and F-FDG PET/CT imaging acquired consecutively from 13 patients with primary or metastatic lung cancers receiving either radiotherapy alone or chemoradiotherapy were analyzed. Imaging examinations were performed before, immediately, and no later than 6 months after treatment for response evaluation. Iodine-related parameters including the total iodine uptake (TIU) and vital volume (VIV) from DECT and metabolic metrics such as the standardized uptake value normalized to lean body mass (SULpeak), metabolic tumor volume (MTV), and the total lesion glycolysis (TLG) from F-FDG-PET/CT were generated and measured by semiautomatic approaches. Dual-energy CT and PET/CT metrics were calculated and followed up with comparison with response evaluation criteria in solid tumors (RECIST).

RESULTS

Analysis of pretreatment imaging data revealed a strong correlation between DECT metrics (RECIST, TIU, and VIV) and F-FDG PET/CT metrics (MTV, TLG) with coefficients of R ranging from 0.86 to 0.90 (P < 0.01). With the delivery of treatment, all measured DECT and PET/CT metrics significantly decreased whereas the descending amplitude in RECIST was significantly smaller than that of the remaining parameters (P < 0.05). During follow-up examinations, both metrics followed a similar changing pattern. Overall, strong consistency was found between RECIST, TIU, VIV and SULpeak, MTV, TLG (R covers 0.78-0.96, P < 0.05).

CONCLUSIONS

Semiautomatic iodine-related quantitation in DECT correlated well with metabolism-based measurements in F-FDG PET/CT, suggesting that DECT-based iodine quantitation might be a feasible substitute for assessment of lung cancer response to chemoradiotherapy/radiotherapy with comparison with F-FDG PET/CT.

Developing and validating a novel metabolic tumor volume risk stratification system for supplementing non-small cell lung cancer staging

PURPOSE

We hypothesized that whole-body metabolic tumor volume (MTVwb) could be used to supplement non-small cell lung cancer (NSCLC) staging due to its independent prognostic value. The goal of this study was to develop and validate a novel MTVwb risk stratification system to supplement NSCLC staging.

METHODS

We performed an IRB-approved retrospective review of 935 patients with NSCLC and FDG-avid tumor divided into modeling and validation cohorts based on the type of PET/CT scanner used for imaging. In addition, sensitivity analysis was conducted by dividing the patient population into two randomized cohorts. Cox regression and Kaplan-Meier survival analyses were performed to determine the prognostic value of the MTVwb risk stratification system.

RESULTS

The cut-off values (10.0, 53.4 and 155.0 mL) between the MTVwb quartiles of the modeling cohort were applied to both the modeling and validation cohorts to determine each patient's MTVwb risk stratum. The survival analyses showed that a lower MTVwb risk stratum was associated with better overall survival (all p < 0.01), independent of TNM stage together with other clinical prognostic factors, and the discriminatory power of the MTVwb risk stratification system, as measured by Gönen and Heller's concordance index, was not significantly different from that of TNM stage in both cohorts. Also, the prognostic value of the MTVwb risk stratum was robust in the two randomized cohorts. The discordance rate between the MTVwb risk stratum and TNM stage or substage was 45.1% in the modeling cohort and 50.3% in the validation cohort.

CONCLUSION

This study developed and validated a novel MTVwb risk stratification system, which has prognostic value independent of the TNM stage and other clinical prognostic factors in NSCLC, suggesting that it could be used for further NSCLC pretreatment assessment and for refining treatment decisions in individual patients.

A Novel Framework for Automated Segmentation and Labeling of Homogeneous Versus Heterogeneous Lung Tumors in [18F]FDG-PET Imaging

PURPOSE

Determination of intra-tumor high-uptake area using 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) positron emission tomography (PET) imaging is an important consideration for dose painting in radiation treatment applications. The aim of our study was to develop a framework towards automated segmentation and labeling of homogeneous vs. heterogeneous tumors in clinical lung [¹⁸F]FDG-PET with the capability of intra-tumor high-uptake region delineation.

PROCEDURES

We utilized and extended a fuzzy random walk PET tumor segmentation algorithm to delineate intra-tumor high-uptake areas. Tumor textural feature (TF) analysis was used to find a relationship between tumor type and TF values. Segmentation accuracy was evaluated quantitatively utilizing 70 clinical [¹⁸F]FDG-PET lung images of patients with a total of 150 solid tumors. For volumetric analysis, the Dice similarity coefficient (DSC) and Hausdorff distance (HD) measures were extracted with respect to gold-standard manual segmentation. A multi-linear regression model was also proposed for automated tumor labeling based on TFs, including cross-validation analysis.

RESULTS

Two-tailed t test analysis of TFs between homogeneous and heterogeneous tumors revealed significant statistical difference for size-zone variability (SZV), intensity variability (IV), zone percentage (ZP), proposed parameters II and III, entropy and tumor volume (p < 0.001), dissimilarity, high intensity emphasis (HIE), and SUV_min (p < 0.01). Lower statistical differences were observed for proposed parameter I (p = 0.02), and no significant differences were observed for SUV_max and SUV_mean. Furthermore, the Spearman rank analysis between visual tumor labeling and TF analysis depicted a significant correlation for SZV, IV, entropy, parameters II and III, and tumor volume (0.68 ≤ ρ ≤ 0.84) and moderate correlation for ZP, HIE, homogeneity, dissimilarity, parameter I, and SUV_min (0.22 ≤ ρ ≤ 0.52), while no correlations were observed for SUV_max and SUV_mean (ρ < 0.08). The multi-linear regression model for automated tumor labeling process resulted in R ² and RMSE values of 0.93 and 0.14, respectively (p < 0.001), and generated tumor labeling sensitivity and specificity of 0.93 and 0.89. With respect to baseline random walk segmentation, the results showed significant (p < 0.001) mean DSC, HD, and SUV_mean error improvements of 21.4 ± 11.5 %, 1.4 ± 0.8 mm, and 16.8 ± 8.1 % in homogeneous tumors and 7.4 ± 4.4 %, 1.5 ± 0.6 mm, and 7.9 ± 2.7 % in heterogeneous lesions. In addition, significant (p < 0.001) mean DSC, HD, and SUV_mean error improvements were observed for tumor sub-volume delineations, namely 5 ± 2 %, 1.5 ± 0.6 mm, and 7 ± 3 % for the proposed Fuzzy RW method compared to RW segmentation.

CONCLUSION

We proposed and demonstrated an automatic framework for significantly improved segmentation and labeling of homogeneous vs. heterogeneous tumors in lung [¹⁸F]FDG-PET images.

Prognostic value of metabolic parameters determined by preoperative ¹⁸F-FDG PET/CT in patients with uterine carcinosarcoma

Objective

To evaluate the prognostic value of metabolic parameters measured by preoperative ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) in patients with uterine carcinosarcoma (UCS).

Methods

Data of 55 eligible patients with UCS who underwent preoperative ¹⁸F-FDG PET/CT and surgical staging were analyzed retrospectively. Maximum standardized uptake value (SUV_max), metabolic tumor volume (MTV_2.5), and total lesion glycolysis (TLG_2.5) of the primary tumors were measured using a SUV threshold of 2.5. The optimal cutoff value of each parameter was determined by time-dependent receiver operating characteristic curve, and its impact on progression-free survival and overall survival was evaluated by Cox proportional hazards model.

Results

During a median follow-up period of 29 (range, 1.5–109.4) months, 47.3% (26/55) of the patients experienced disease progression, and the disease-associated mortality rate was 43.6% (24/55). Univariate analysis determined that hazard ratios (HRs) for disease progression for SUV_max (≥8.33), MTV_2.5 (≥63.92 mL), and TLG_2.5 (≥396.16) were 1.930 (95% confidence interval [CI]=0.793–4.701), 3.264 (95% CI=1.466–7.268), and 2.692 (95% CI=1.224–5.924), respectively. And, HRs for death were 1.979 (95% CI=0.774–5.060), 2.764 (95% CI=1.217–6.274), and 2.721 (95% CI=1.198–6.182), respectively. While peritoneal cytology, histology, and tumor diameter were independent prognostic factors in multivariate analysis, MTV and TLG were not.

Conclusion

Though MTV and TLG of primary UCS were not independent predictors compared to surgically obtained data, MTV and TLG of primary UCS may provide useful information on prognosis especially in patients who are not able to undergo surgical staging.

Whole body metabolic tumor volume is a prognostic marker in patients with newly diagnosed stage 3B non-small cell lung cancer, confirmed with external validation

Purpose

TNM Stage 3B encompasses a wide range of primary tumor and nodal metastatic tumor burden. This study aimed to evaluate the prognostic value of quantitative FDG PET/CT parameters in patients with newly diagnosed Stage 3B Non-Small Cell Lung Cancer (NSCLC).

Materials and Methods

Institutional review board approved retrospective study identified patients diagnosed with Stage 3B NSCLC (8^th edition TNM classification) on baseline FDG PET/CT at two medical centers (Medical centers A and B), between Feb 2004 and Dec 2014. Patients were excluded if they had prior NSCLC treatment or recent diagnosis of a second primary cancer. Quantitative FDG PET/CT parameters including whole body metabolic tumor volume (MTVwb), total lesion glycolysis (TLGwb), and maximum standardized uptake value (SUVmaxwb) were measured from baseline PET/CT using Edge method with Mimvista software. The primary endpoint was overall survival (OS). Cox proportional hazard regression and Kaplan-Meier overall survival analyses were used to test for an association between OS and quantitative FDG PET/CT parameters. The distributions of MTVwb, TLGwb, SUVmaxwb were skewed, so a natural logarithm transformation was applied and the transformed variables [(ln(MTVwb), ln(TLGwb), and ln(SUVmaxwb)] were used in the analysis.

Results

The training set included 110 patients from center A with Stage 3B NSCLC. 78.2% of patients expired during follow-up. Median OS was 14 months. 1-year, 2-year, and 5-year OS was 56.5%, 34.6% and 13.9%, respectively. Univariate Cox regression analysis showed no significant difference in OS on the basis of age, gender, histology, ln(TLGwb), or ln(SUVmaxwb). ln(MTVwb) was positively associated with OS [hazard ratio (HR) of 1.23, p = 0.037]. This association persisted on multivariate Cox regression analysis (HR 1.28, p = 0.043), with adjustments for age, gender, treatment and tumor histology. External validation with 44 patients from center B confirmed increasing MTVwb was associated significantly worse OS. An MTVwb cut-off point of 85.6 mL significantly stratified Stage 3B NSCLC patient prognosis.

Conclusion

MTVwb is a prognostic marker for OS in patients with Stage 3B NSCLC, independent of age, gender, treatment, and tumor histology.

Prognostic Value of 18F-Fluorodeoxyglucose PET/Computed Tomography in Non-Small-Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is a leading cause of cancer-related death with a poor prognosis. Numerous factors contribute to treatment outcome. 18F-fluorodeoxyglucose (FDG) uptake reflects tumor metabolic activity and is an important prognosticator in patients with NSCLC. Volume-based FDG-PET parameters reflect the metabolic status of a malignancy more accurately than maximum standardized uptake value and thus are better prognostic markers in lung cancer. FDG-avid tumor burden parameters may help clinicians to predict treatment outcomes before and during therapy so that treatment can be adjusted to achieve the best possible outcomes while avoiding side effects.

Current Methods to Define Metabolic Tumor Volume in Positron Emission Tomography: Which One is Better?

Numerous methods to segment tumors using ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG PET) have been introduced. Metabolic tumor volume (MTV) refers to the metabolically active volume of the tumor segmented using FDG PET, and has been shown to be useful in predicting patient outcome and in assessing treatment response. Also, tumor segmentation using FDG PET has useful applications in radiotherapy treatment planning. Despite extensive research on MTV showing promising results, MTV is not used in standard clinical practice yet, mainly because there is no consensus on the optimal method to segment tumors in FDG PET images. In this review, we discuss currently available methods to measure MTV using FDG PET, and assess the advantages and disadvantages of the methods.

18F-FDG PET/CT in lung cancer. The added value of quantification

OBJECTIVE

To test a software application for the quantification of metabolic heterogeneity and to evaluate its superiority in relation to visual interpretation. To investigate if a quantitative analysis adds information to the interpretation of ¹⁸F-FDG-PET/CT.

MATERIAL AND METHODS

The study analyzed 215 patients with a ¹⁸F-FDG-PET/CT done for the initial staging of lung cancer between March 2011 and December 2015. The study included 57 (26.5%) women and 158 (73.5%) men, with ages ranging from 34 to 88 years (mean±SD: 67.23±10.04). There were 82 surgical stages (I, II, IIIA), and 133 non-surgical stages (IIIB, IV). The primary tumour was analyzed quantitatively by obtaining the following parameters: SUVmax, metabolic active tumour volume (MATV), total lesion glycolysis (TLG), and the entropy heterogeneity index (ET). Heterogeneity was assessed visually. Death dates and/or the follow-up time were registered, ranging from 0.70 to 67.60 months (mean±SD: 23.20±17.68).

RESULTS

In multivariate analysis, ET emerged as a better predictor of survival than visual analysis of heterogeneity that was not statistically significant. The C-index determination demonstrated that all quantitative parameters were statistically-significant predictors of survival. Cut-offs were obtained in order to compare survival times. A multivariate analysis was performed. In the total population, the best predictor was the TNM stage, but MATV, ET, and male gender were statistically significant and independent predictors of survival. In stages without surgical indication, the best predictor was the TNM stage, but the MATV and male gender were statistically significant and independent predictors of survival. In the surgical stages, ET was the only statistically significant and independent predictor of survival.

CONCLUSIONS

Quantification adds prognostic information to the visual analysis of ¹⁸F-FDG-PET/CT.

Prognostic value of pretreatment standardized uptake value of F-18-fluorodeoxyglucose PET in patients with gastric cancer: a meta-analysis

Background

F-18- fluorodeoxyglucose Positron emission tomography (¹⁸FDG-PET) has been widely used in clinical practice. However, the prognostic value of the pretreatment standardized uptake value (SUV) for patients with gastric cancer remains controversial.

Methods

Major databases were systematically searched. The quality of the included studies was assessed using the Newcastle–Ottawa scale; the PET protocols were also evaluated. The pooled hazard ratio (HR) for overall survival (OS) and recurrence-free survival (RFS) were used to estimate the effect size. Data from the included studies were analyzed using Review Manager Software version 5.2.

Results

Eight studies with 1080 patients were included. The pooled HR for OS of six studies including 672 patients was 1.72 (95% CI [1.28–2.3], p = 0.0004, I² = 0%), indicating that patients with high SUVs may have poor prognosis. The pooled HR for RFS was 1.70 (95% CI [1.20–2.39], p = 0.003, I² = 0%). Subgroup analysis based on the cutoff values determining method indicated that the receiver operating characteristic (ROC) method could better define the cutoff value. Subgroup analysis based on the therapeutic strategies used subsequently indicated the significant prognostic value of SUV.

Conclusion

In conclusion, our meta-analysis indicated that pretreatment SUV in primary lesions can be an important prognostic factor for overall survival and recurrence-free survival in patients with gastric cancer. High SUVs may indicate poor prognosis.

The role of PET/CT as a prognosticator and outcome predictor in lung cancer

Positron emission tomography/computed tomography (PET/CT) is an important imaging tool for management of lung cancer and can be utilized in diagnosis, staging, restaging, treatment planning and evaluating treatment response. In the past decade PET/CT has proven to be beneficial for the prediction of prognosis and outcome. PET findings before and after treatment, the quantitative PET parameters such as standardized uptake value (SUV), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) as well as delayed PET/CT imaging can be used to determine patient prognosis and outcome. Other tracers such as hypoxia and proliferation marker tracers may be used for prognostication. The prognostic factors derived from PET/CT imaging help early development of risk-adapted treatment strategies, which provides cost-effective treatment and leads to improved patient management. Here, we discuss findings of studies related to application of PET/CT in lung cancer as well as some technical updates on quantitative PET/CT in lung cancer.

Prognostic Value of Tumor-to-Blood Standardized Uptake Ratio in Patients with Resectable Non-Small-Cell Lung Cancer

OBJECTIVES

Previously published studies showed that the standard tumor-to-blood standardized uptake value (SUV) ratio (SUR) was a more accurate prognostic method than tumor maximum standardized uptake value (SUV_max). This study evaluated and compared prognostic value of positron emission tomography (PET) parameters and normalized value of PET parameters by blood pool SUV in non-small-cell lung cancer (NSCLC) patients who received curative surgery.

METHODS

Seventy-seven patients who underwent curative resection for NSCLC between January 2010 to December 2013 were enrolled in this study. ¹⁸Fluorine-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) was performed before surgery. The mean standardized uptake value (SUV_mean), SUV_max, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of each lesion was measured, on the workstation. SUR_mean, SUR_max, and TLGSUR were calculated by dividing each of them by descending aorta SUV_mean. Cox proportional hazards regression was used to analyze the effect of age, sex, pathological parameters, and PET parameters on recurrence and death.

RESULTS

In Cox regression analysis, N stage predicted for both recurrence (p < 0.0001) and death (p < 0.0001). SUR_max predicted recurrence (p = 0.0014), not death. Area under the receiver operating characteristic curve of SUR_max was 0.759 with cutoff value 4.004. However, SUV_max, SUV_mean, MTV, TLG, SUR_mean, and TLGSUR predicted neither recurrence nor death.

CONCLUSIONS

Among PET parameters, SUR_max was the independent predictor of recurrence in NSCLC patients who received curative surgery. N stage was the independent prognostic factor for both recurrence and death. Both parameters could be used to stratify the risk of NSCLC patients.

Molecular image-directed biopsies: improving clinical biopsy selection in patients with multiple tumors

Site selection for image-guided biopsies in patients with multiple lesions is typically based on clinical feasibility and physician preference. This study outlines the development of a selection algorithm that, in addition to clinical requirements, incorporates quantitative imaging data for automatic identification of candidate lesions for biopsy. The algorithm is designed to rank potential targets by maximizing a lesion-specific score, incorporating various criteria separated into two categories: (1) physician-feasibility category including physician-preferred lesion location and absolute volume scores, and (2) imaging-based category including various modality and application-specific metrics. This platform was benchmarked in two clinical scenarios, a pre-treatment setting and response-based setting using imaging from metastatic prostate cancer patients with high disease burden (multiple lesions) undergoing conventional treatment and receiving whole-body [¹⁸F]NaF PET/CT scans pre- and mid-treatment. Targeting of metastatic lesions was robust to different weighting ratios and candidacy for biopsy was physician confirmed. Lesion ranked as top targets for biopsy remained so for all patients in pre-treatment and post-treatment biopsy selection after sensitivity testing was completed for physician-biased or imaging-biased scenarios. After identifying candidates, biopsy feasibility was evaluated by a physician and confirmed for 90% (32/36) of high-ranking lesions, of which all top choices were confirmed. The remaining cases represented lesions with high anatomical difficulty for targeting, such as proximity to sciatic nerve. This newly developed selection method was successfully used to quantitatively identify candidate lesions for biopsies in patients with multiple lesions. In a prospective study, we were able to successfully plan, develop, and implement this technique for the selection of a pre-treatment biopsy location.

Consistency of metabolic tumor volume of non-small-cell lung cancer primary tumor measured using 18F-FDG PET/CT at two different tracer uptake times

OBJECTIVES

The objective of this study was to test the hypothesis that the metabolic tumor volume (MTV) of primary non-small-cell lung cancer is not sensitive to differences in F-fluorodeoxyglucose (F-FDG) uptake time, and to compare this consistency of MTV measurements with that of standardized uptake value (SUV) and total lesion glycolysis (TLG).

METHODS

Under Institutional Review Board approval, 134 consecutive patients with histologically proven non-small-cell lung cancer underwent F-FDG PET/computed tomography scanning at about 1 h (early) and 2 h (delayed) after intravenous injection of F-FDG. MTV, SUV, and TLG of the primary tumor were all measured. Student's t-test and Wilcoxon's signed-rank test for paired data were used to compare MTV, SUV, and TLG between the two scans. The intraclass correlation coefficient (ICC) was used to assess agreement in PET parameters between the two scans and between the measurements made by two observers.

RESULTS

MTV was not significantly different (P=0.17) between the two scans. However, SUVmax, SUVmean, SUVpeak, and TLG increased significantly from the early to the delayed scans (P<0.0001 for all). The median percentage change between the two scans in MTV (1.65%) was smaller than in SUVmax (11.76%), SUVmean(10.57%), SUVpeak(13.51%), and TLG (14.34%); the ICC of MTV (0.996) was greater than that of SUVmax (0.933), SUVmean (0.952), SUVpeak (0.928), and TLG (0.982). Interobserver agreement between the two radiologists was excellent for MTV, SUV, and TLG on both scans (ICC: 0.934-0.999).

CONCLUSION

MTV is not sensitive to common clinical variations in F-FDG uptake time, its consistency is greater than that of SUVmax, SUVmean, SUVpeak, and TLG, and it has excellent interobserver agreement.

Application of novel quantitative techniques for fluorodeoxyglucose positron emission tomography/computed tomography in patients with non-small-cell lung cancer

AIM

Flurodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is routinely used in non-small-cell lung cancer. This study aims to assess the prognostic value of quantitative FDG-PET/CT parameters including standard uptake value (SUV), metabolic tumor volume (MTV) and total lesional glycolysis (TLG) in non-small-cell lung cancer.

METHODS

A retrospective review of 92 nonsurgical patients with pathologically confirmed stage I-III non-small-cell lung cancers treated with radical dose radiotherapy (≥50 Gy) was conducted. Metabolically active tumor regions on FDG-PET/CT scans were contoured manually. SUV, MTV and TLG were calculated for primary, nodal and whole-body disease. Univariate and multivariate (adjusting for age, sex, disease stage and primary tumor size in centimeters) Cox regression modeling were performed to assess the association between these parameters and both overall and progression-free survival (PFS).

RESULTS

On univariate analysis, overall survival (OS) was significantly associated with primary MTV (P = 0.03), whole-body MTV (P = 0.02), whole-body maximum SUV (P = 0.05) and whole-body TLG (P = 0.03). PFS was significantly associated with primary MTV (P = 0.01), primary TLG (P = 0.04), whole-body MTV (P < 0.01) and whole-body TLG (P = 0.01). On multivariate analysis, OS was significantly associated with whole-body MTV (P = 0.05). PFS was significantly associated with whole-body MTV (P = 0.02) and whole-body TLG (P = 0.05).

CONCLUSIONS

Whole-body MTV was significantly associated with overall and PFS, and whole-body TLG was significantly associated with PFS on multivariate analysis. These two parameters may be significant prognostic factors independent of other factors such as stage. SUV was not significantly associated with survival on multivariate analysis.

Quantification of Intratumoral Metabolic Macroheterogeneity on 18F-FDG PET/CT and Its Prognostic Significance in Pathologic N0 Squamous Cell Lung Carcinoma

PURPOSE

This study aimed to develop a novel quantification method for intratumoral metabolic macroheterogeneity (IMMH) on F-FDG PET/CT and evaluate its prognostic significance in pathologic N0 (pN0) squamous cell lung carcinoma (SQCLC) patients.

PATIENTS AND METHODS

A total of 83 patients who underwent pretreatment F-FDG PET/CT and were diagnosed with pN0 SQCLC after curative surgery were examined. Patients with tumor measuring greater than 2 cm were included. Metabolic parameters (SUVmax, metabolic tumor volume, and total lesion glycolysis) for the primary lesions were calculated on the F-FDG PET/CT, and IMMH was quantified as the macroheterogeneity factor (MHF), defined as surface/spherical surface area having volume of the primary tumor multiplied by the sphericity. Heterogeneity of the primary tumor was also visually assessed (visual heterogeneity score) and compared with MHF. Univariate and multivariate analyses for recurrence were performed using the Cox proportional hazards regression.

RESULTS

Recurrence was observed in 27 (32.5%) of 83 patients during follow-up period (37.6 ± 25.5 months). Significant correlations were observed between the visual heterogeneity score and the MHF (R = 0.534, P < 0.001). Macroheterogeneity factor was significantly higher in patients who experienced recurrence (median, 1.073 vs 1.016; P = 0.004). Univariate analysis showed that MHF was only significant prognostic factor for recurrence (P = 0.019), and multivariate analysis after adjusting for age, sex, tumor size, histologic grade, and pathologic T stage, high MHF exhibited an association with increased risk of recurrence.

CONCLUSIONS

New quantification method for IMMH on F-FDG PET/CT was developed, and the heterogeneity parameter MHF was well correlated with visual heterogeneity. Macroheterogeneity factor on pretreatment F-FDG PET/CT was the sole prognostic factor predicting recurrence in pN0 SQCLC patients.

Prognostic value of early response assessment using 18F-FDG PET/CT in chemotherapy-treated patients with non-small-cell lung cancer

OBJECTIVE

We aimed to evaluate the prognostic value of early response assessment using a volumetric fluorine-18-fluorodeoxyglucose (F-FDG) PET analysis in chemotherapy-treated patients with non-small-cell lung cancer (NSCLC).

MATERIALS AND METHODS

We retrospectively reviewed 33 patients with NSCLC who received first-line chemotherapy and performed F-FDG PET/computed tomography before (baseline PET) and after two cycles of chemotherapy (interim PET). The maximum standardized uptake value (SUVmax) and metabolic tumor volume (MTV) of the total malignant lesion were measured in baseline (SUV1 and MTV1) and interim (SUV2 and MTV2) PET images, and percentage changes in SUVmax (ΔSUV) and MTV (ΔMTV) were calculated between the two images. We compared PET parameters and clinicopathologic variables in terms of the 2-year overall survival (OS).

RESULTS

The median follow-up period was 14.3 months and the 2-year OS was 31%. In PET images, the mean SUV1, MTV1, SUV2, MTV2, ΔSUV, and ΔMTV were 13.1±4.5, 307.9±340.0 cm, 9.5±5.1, 180.4±29.6 cm, 27±28%, and 42±65%, respectively. In univariable analysis, M stage, TNM stage, and all six PET parameters associated significantly with OS. Both the MTV1 and the ΔMTV were tested against OS controlling for M stage, one at time, and the effect remained significant in multivariable analyses.

CONCLUSION

A smaller baseline MTV and greater decrease in MTV between baseline and interim PET images are associated with a significantly prolonged OS. A volume-based F-FDG PET analysis would facilitate prediction of clinical outcome and identification of treatment-resistant patients early during chemotherapy and could thus be used in personalized treatment approaches for patients with NSCLC.

Total 18F-FDG PET/CT Metabolic Tumor Volume Is Associated With Postoperative Biochemical Response in Patients With Metastatic Pheochromocytomas and Paragangliomas

OBJECTIVE

The aim of this pilot study was to determine if metabolic tumor volume (MTV) and total lesion glycolysis (TLG) could serve as predictors of biochemical remission and pharmacotherapy-free interval in patients with metastatic pheochromocytomas (PCCs) and paragangliomas (PGLs).

BACKGROUND

Patients with metastatic PCCs/PGLs have a high rate of biochemical recurrence, which can be associated with increased cardiovascular morbidity. Predictors of biochemical response are needed to guide and select patients who may benefit from therapy.

METHODS

Whole body MTV and TLG was calculated from preoperative 18F-FDG PET/CT scans and analyzed as marker of biochemical response and pharmacotherapy-free interval.

RESULTS

Seventeen patients underwent a total of 19 procedures, with a median follow-up time of 26.4 months. Whole body MTV of patients with biochemical recurrence (n = 13, mean 73.8  mL) was higher than those who had a biochemical response (n = 6, mean 14.7  mL, P = 0.05). Patients with low MTV (<37.2  mL) had an improved durable partial biochemical response (P < 0.05), and a statistical trend for complete biochemical remission (P = 0.07) and pharmacotherapy-free interval (P = 0.06). In 8 patients with metastatic disease outside the abdomen, 4 patients had less than 35% of their disease burden outside the abdomen and these patients had a more durable partial biochemical response compared to patients with greater than 35% of their disease burden outside the abdomen (P < 0.05).

CONCLUSIONS

Whole body MTV and TLG represents novel and valuable predictors of biochemical response for patients with metastatic PCCs and PGLs. A larger prospective study should be performed to validate these findings.

The Volume-metabolic Combined Parameters from (18)F-FDG PET/CT May Help Predict the Outcomes of Cervical Carcinoma

RATIONALE AND OBJECTIVES

The aim of this study was to evaluate the prognostic value of 18-fluoro-2-deoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) volume-metabolic combined parameters in patients with cervical carcinoma.

MATERIALS AND METHODS

We retrospectively reviewed 91 consecutive patients' whole-body FDG-PET/CT images, and further measured and calculated FDG PET/CT volume-metabolic parameters, including cervical metabolic tumor volume (CMTV), cervical total lesion glycolysis (CTLG), whole-body metabolic tumor volume (WB-MTV), whole-body total lesions glycolysis (WB-TLG). The prognostic value of these tumor volume-metabolic measures was assessed by Cox Proportional Hazard Regression Analysis.

RESULTS

The overall survival (OS) was 88.8% for patients with low CMTV (≤53.75 mL) and 45.5% for those with high CMTV (>53.75 mL), respectively (P < 0.01, 95% confidence interval). Univariate analysis showed that CMTV and CTLG were significant prognostic factors for OS, in addition to International Federation of Gynecology and Obstetrics (FIGO) stage, age, lymphadenopathy, and maximum standardized uptake value (SUVmax) (P < 0.05 for all). On multivariate analysis, CMTV remained significant for OS, in addition to FIGO stage (P < 0.05 for all). CMTV remains as prognostic factor for OS regardless of patients' FIGO stages (P < 0.05). In patients in the metastatic diseases group, univariate and multivariate analyses demonstrated that CMTV, WB-MTV, and WB-TLG were independent prognostic factors for OS (P < 0.05 for all).

CONCLUSION

CMTV, WB-MTV, and WB-TLG are reliable prognostic factors for patients with cervical carcinoma and should be included in FDG-PET/CT reports to guide referral clinicians for risk-adapted therapies.

Prognostic Significance of Intratumoral Metabolic Heterogeneity on 18F-FDG PET/CT in Pathological N0 Non-Small Cell Lung Cancer

PURPOSE

The aim of the study was to evaluate the prognostic significance of intratumoral metabolic heterogeneity on pretreatment F-FDG PET/CT in patients with lung cancer who were pathologically N0 (pN0) after curative surgical resection.

METHODS

We examined 119 patients (M/F = 79/40; mean age, 64.6 ± 9.0 years) who had undergone pretreatment F-FDG PET/CT and were diagnosed as pN0 after curative surgery for adenocarcinoma (ADC; n = 67) or squamous cell carcinoma (SQCC; n = 52). Heterogeneity factor (HF) and other metabolic parameters (SUVmax, metabolic tumor volume [MTV] and total lesion glycolysis [TLG]) for the primary lesions were measured, and the results were analyzed for recurrence. The HF, defined as the derivative of the volume-threshold function from 20% to 80%, was computed for primary lesions. Univariate and multivariate analyses for recurrence were performed using the Kaplan-Meier method and using the Cox proportional hazards model.

RESULTS

SUVmax, MTV, TLG, and HF were statistically different between patients with ADC and SQCC. Forty-one (34.5%) of 119 patients experienced recurrence (ADC, 25/67 = 37.3% vs. SQCC, 16/52 = 30.8%). Results of univariate analysis indicate that SUVmax, MTV, TLG, and HF in ADC and TLG and HF in SQCC were predictors for recurrence. After adjusting for sex, age, and histological grade in multivariate analysis, high SUVmax, MTV, TLG, and HF in ADC exhibited an association with increased risk of recurrence.

CONCLUSIONS

Metabolic parameters and heterogeneity of primary tumor on pretreatment F-FDG PET/CT can predict recurrence in pN0 NSCLC patients of ADC type who have undergone curative surgery but not in patients of SQCC type.

Prognostic Value of 18F-FDG PET/CT in Surgical Non-Small Cell Lung Cancer: A Meta-Analysis

Background

The identification of surgical non-small cell lung cancer (NSCLC) patients with poor prognosis is a priority in clinical oncology because of their high 5-year mortality. This meta-analysis explored the prognostic value of maximal standardized uptake value (SUV_max), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) on disease-free survival (DFS) and overall survival (OS) in surgical NSCLC patients.

Materials and Methods

MEDLINE, EMBASE and Cochrane Libraries were systematically searched until August 1, 2015. Prospective or retrospective studies that evaluated the prognostic roles of preoperative 18F-FDG PET/CT with complete DFS and OS data in surgical NSCLC patients were included. The impact of SUV_max, MTV or TLG on survival was measured using hazard ratios (HR). Sub-group analyses were performed based on disease stage, pathological classification, surgery only and cut-off values.

Results

Thirty-six studies comprised of 5807 patients were included. The combined HRs for DFS were 2.74 (95%CI 2.33–3.24, unadjusted) and 2.43 (95%CI: 1.76–3.36, adjusted) for SUV_max, 2.27 (95%CI 1.77–2.90, unadjusted) and 2.49 (95%CI 1.23–5.04, adjusted) for MTV, and 2.46 (95%CI 1.91–3.17, unadjusted) and 2.97 (95%CI 1.68–5.28, adjusted) for TLG. The pooled HRs for OS were 2.54 (95%CI 1.86–3.49, unadjusted) and 1.52 (95%CI 1.16–2.00, adjusted) for SUV_max, 2.07 (95%CI 1.16–3.69, unadjusted) and 1.91 (95%CI 1.13–3.22, adjusted) for MTV, and 2.47 (95%CI 1.38–4.43, unadjusted) and 1.94 (95%CI 1.12–3.33, adjusted) for TLG. Begg’s test detected publication bias, the trim and fill procedure was performed, and similar HRs were obtained. The prognostic role of SUV_max, MTV and TLG remained similar in the sub-group analyses.

Conclusions

High values of SUV_max, MTV and TLG predicted a higher risk of recurrence or death in patients with surgical NSCLC. We suggest the use of FDG PET/CT to select patients who are at high risk of disease recurrence or death and may benefit from aggressive treatments.

Prognostic significance of volume-based 18F-FDG PET/CT parameter in patients with surgically resected non-small cell lung cancer. Comparison with immunohistochemical biomarkers

AIM

We investigated the prognostic value of volume-based 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) parameters compared with other factors including several immunohistochemical biomarkers in patients with surgically resected non-small cell lung cancer (NSCLC).

PATIENTS, METHODS

STUDY PARTICIPANTS

290 patients with surgically resected and histopathologically confirmed NSCLC. The maxmum standardized uptake value (SUVmax) and metabolic tumour volume (MTV) of the primary tumour were obtained on 18F-FDG PET/ computed tomography (CT) for initial staging and Ki-67 labeling index (LI), p16, CD31 and cyclin E were evaluated in the primary tumours by immunohistochemical staining. Survival analyses for variables including PET parameters, immunohistochemical biomarker and other clinical factors were performed using the Kaplan-Meier method and Cox proportional hazards regression analysis.

RESULTS

In univariate analyses, tumour stage, tumour size, and MTV were significant prognostic factors for decreased overall survival (OS) and disease-free survival (DFS). Multivariate analyses showed MTV and tumour stage were significant predictors of poor OS (MTV, hazard ratio (HR) = 1.135, p = 0.015; stage, HR = 0.644, p = 0.025) and DFS (MTV, HR = 1.128, p = 0.043; stage, HR = 0.541, p = 0.009).

CONCLUSION

The MTV of primary tumours is a significant prognostic factor for survival along with tumour stage in patients with surgically resected NSCLC. The MTV can predict OS and DFS better than immunohistochemical biomarkers.

A new PET/CT volumetric prognostic index for non-small cell lung cancer

OBJECTIVES

Whole-body metabolic tumor volume (MTVWB) has been shown of prognostic value for non-small cell lung cancer (NSCLC) beyond that of TNM stage, age, gender, performance status, and treatment selection. The current TNM staging system does not incorporate tumor volumetric information. We propose a new PET/CT volumetric prognostic (PVP) index that combines the prognostic value of MTVWB and TNM stage.

MATERIALS AND METHODS

Based on 328 consecutive NSCLC patients with a baseline PET/CT scan before treatment, from which MTVWB was measured semi-automatically, we estimated hazard ratios (HRs) for ln(MTVWB) and TNM stage from a Cox proportional hazard regression model that consisted of only ln(MTVWB) and TNM stage as prognostic variables of overall survival. We used the regression coefficients, which gave rise to the HRs, as weights to formulate the PET/CT volumetric prognostic (PVP) index. We also compared the prognostic value of the PVP index against that of TNM stage alone and ln(MTVWB) alone with univariate and multivariate survival analyses and C-statistics.

RESULTS

Univariate analysis C-statistic for the PVP index (C=0.71) was statistically significantly greater than those for TNM stage alone (C=0.67, p<0.01) and for ln(MTVWB) alone (C=0.69, p=0.033). Multivariate analyses showed that the PVP index yielded significantly greater discriminatory power (C=0.74) than similar models based on either TNM stage (C=0.72, p<0.01) or ln(MTVWB) (C=0.73, p<0.01). Lower values of the PVP index were associated with significantly better overall survival (adjusted HR=2.70, 95%CI [2.16, 3.37]).

CONCLUSION

The PVP index provides a practical means for clinicians to combine the prognostic value of MTVWB and TNM stage and offers significantly better prognostic accuracy for overall survival of NSCLC patients than the current TNM staging system or metabolic tumor burden alone.