Guidelines for the role of FDG-PET/CT in lung cancer management

Prevalence and Risk Factors for Pathologic N2 Disease in Resected Lung Cancers Assessed as N0 or N1 Disease on Preoperative Imaging

BACKGROUND. For certain patients with lung cancer, guidelines recommend endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) as the primary method to evaluate for metastatic mediastinal lymph nodes defining pN2 disease. EBUS-TBNA has associated costs and complications and possibly limited availability. OBJECTIVE. The purpose of the present study was to investigate the prevalence of and risk factors for pN2 disease in patients undergoing resection of lung cancer who were assessed as having radiologic N0 or N1 disease. METHODS. This retrospective study included 3581 patients (mean age, 63.8 ± 9.4 [SD] years; 1917 men and 1664 women) with lung cancer who underwent chest CT and FDG PET/CT showing radiologic N0 or N1 disease before resection between January 2015 and December 2021. Tumor characteristics were assessed on chest CT. Patients were assessed for the presence of guideline-based indications for EBUS-TBNA as evaluation for imaging-occult N2 disease. Pathologic N categories were determined from surgical specimens. Preoperative risk factors for pN2 disease were identified using logistic regression analyses. RESULTS. A total of 1936 patients had radiologic N0 disease without an EBUS-TBNA indication, 1348 had radiologic N0 disease with an EBUS-TBNA indication, and 297 had radiologic N1 disease. These groups had a prevalence of pN2a disease of 4.1%, 6.5%, and 18.5%, respectively, and a prevalence of pN2b disease of 1.2%, 2.4%, and 14.8%, respectively. In multivariable analyses, independent risk factors for pN2 disease were, in patients with radiologic N0 disease without an EBUS-TBNA indication, female sex (OR = 1.66 [95% CI, 1.08-2.54]), larger size of solid portion of the tumor (OR = 1.05 [95% CI, 1.01-1.10]), pure-solid nodule (OR = 5.53 [95% CI, 3.15-9.72]), and spiculation (OR = 2.66 [95% CI, 1.72-4.11]); in patients with radiologic N0 disease with an EBUS-TBNA indication, they were younger age (OR = 0.97 [95% CI, 0.96-0.99] per year), pure-solid nodule (OR = 1.75 [95% CI, 1.10-2.80]), and lobulation (OR = 1.96 [95% CI, 1.23-3.11]); and in patients with radiologic N1 disease, they were younger age (OR = 0.973 [95% CI, 0.948-0.999] per year), female sex (OR = 2.91 [95% CI, 1.66-5.11]), and spiculation (OR = 2.81 [95% CI, 1.66-4.76]). CONCLUSION. pN2b disease was uncommon in patients with radiologic N0 disease, regardless of indications for EBUS-TBNA, and its prevalence increased in patients with radiologic N1 disease. CLINICAL IMPACT. The identified risk factors can inform patient selection for EBUS-TBNA, to aid in the detection of occult pN2 disease.

Demystifying the Role of Immuno PET-CT in Non-Small Cell Lung Cancer: Clinical Value and Research Trends

The management of Lung cancer, especially non-small cell lung cancer has undergone a paradigm shift recently with the advent of new treatment approaches including focused radiotherapy as well as evolution of a newer class of immunotherapy agents. Treatment efficacy and survival rates have improved and it is now even more important that patients are selected for appropriate interventions on the basis of a comprehensive assessment including a range of imaging as well as in-vitro tests such as immunohistochemistry. A new class of tracers targeting programmed cell death such as PD1 and PDL1 (broadly classed as Immuno PET) are being increasingly used in the molecular characterisation of patients deemed resistant to standard treatment approaches and being considered for additional interventions such as immunotherapy. In this review, we review the latest evidence in the field and propose a summary of clinical usefulness and provide a review of the research trends in this exciting and evolving field.

Impact of [18F]FDG PET/CT Radiomics and Artificial Intelligence in Clinical Decision Making in Lung Cancer: Its Current Role

Lung cancer remains one of the most prevalent cancers globally and the leading cause of cancer-related deaths, accounting for nearly one-fifth of all cancer fatalities. Fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography ([18F]FDG PET/CT) plays a vital role in assessing lung cancer and managing disease progression. While traditional PET/CT imaging relies on qualitative analysis and basic quantitative parameters, radiomics offers a more advanced approach to analyzing tumor phenotypes. Recently, radiomics has gained attention for its potential to enhance the prognostic and diagnostic capabilities of [18F]FDG PET/CT in various cancers. This review explores the expanding role of [18F]FDG PET/CT-based radiomics, particularly when integrated with artificial intelligence (AI), in managing lung cancer, especially non-small cell lung cancer (NSCLC). We review how radiomics and AI improve diagnostics, staging, tumor subtype identification, and molecular marker detection, which influence treatment decisions. Additionally, we address challenges in clinical integration, such as imaging protocol standardization, feature reproducibility, and the need for extensive prospective studies. Ultimately, radiomics and AI hold great promise for enabling more personalized and effective lung cancer treatments, potentially transforming disease management.

The Role of [18F]FDG PET/CT in Monitoring of Therapy Response in Lung Cancer

Lung cancer remains a leading cause of cancer deaths worldwide, with an all stage 5-year relative survival rate of less than 30%. Multiple treatment strategies are available and continue to evolve, with therapy primarily tailored to the type and stage of the disease. Accurate monitoring of therapy response is crucial for optimizing treatment outcomes. PET/CT imaging with [18F]FDG has become the standard of care across various phases of lung cancer management due to its ability to assess metabolic activity. This review underscores the pivotal role of [18F]FDG PET/CT in evaluating therapy response in lung cancer, particularly in non-small cell lung cancer (NSCLC). It examines conventional response criteria and their adaptations in the era of immunotherapy, highlighting the value of integrating metabolic imaging with established criteria to improve treatment assessment and guide clinical decisions. The potential of non-[18F]FDG PET tracers targeting diverse biological pathways to provide deeper insights into tumor biology, therapy response and predictive outcomes is also explored. Additionally, the emerging role of radiomics in enhancing treatment efficacy assessment and improving patient management is briefly highlighted. Despite the challenges in the routine clinical application of various metabolic response criteria, [18F]FDG PET/CT remains a crucial tool in monitoring therapy response in lung cancer. Ongoing advancements in therapeutic strategies, radiopharmaceuticals, and imaging techniques continue to drive progress in lung cancer management, promising improved patient outcomes.

Quantitative evaluation of lesion response heterogeneity for superior prognostication of clinical outcome

PURPOSE

Standardized reporting of treatment response in oncology patients has traditionally relied on methods like RECIST, PERCIST and Deauville score. These endpoints assess only a few lesions, potentially overlooking the response heterogeneity of all disease. This study hypothesizes that comprehensive spatial-temporal evaluation of all individual lesions is necessary for superior prognostication of clinical outcome.

METHODS

[18F]FDG PET/CT scans from 241 patients (127 diffuse large B-cell lymphoma (DLBCL) and 114 non-small cell lung cancer (NSCLC)) were retrospectively obtained at baseline and either during chemotherapy or post-chemoradiotherapy. An automated TRAQinform IQ software (AIQ Solutions) analyzed the images, performing quantification of change in regions of interest suspicious of cancer (lesion-ROI). Multivariable Cox proportional hazards (CoxPH) models were trained to predict overall survival (OS) with varied sets of quantitative features and lesion-ROI, compared by bootstrapping with C-index and t-tests. The best-fit model was compared to automated versions of previously established methods like RECIST, PERCIST and Deauville score.

RESULTS

Multivariable CoxPH models demonstrated superior prognostic power when trained with features quantifying response heterogeneity in all individual lesion-ROI in DLBCL (C-index = 0.84, p < 0.001) and NSCLC (C-index = 0.71, p < 0.001). Prognostic power significantly deteriorated (p < 0.001) when using subsets of lesion-ROI (C-index = 0.78 and 0.67 for DLBCL and NSCLC, respectively) or excluding response heterogeneity (C-index = 0.67 and 0.70). RECIST, PERCIST, and Deauville score could not significantly associate with OS (C-index < 0.65 and p > 0.1), performing significantly worse than the multivariable models (p < 0.001).

CONCLUSIONS

Quantitative evaluation of response heterogeneity of all individual lesions is necessary for the superior prognostication of clinical outcome.

[68Ga]Ga-Pentixafor PET/CT imaging for in vivo CXCR4 receptor mapping in different lung cancer histologic sub-types: correlation with quantitative receptors' density by immunochemistry techniques

PURPOSE

In vivo CXCR4 receptor quantification in different lung cancer (LC) sub-types using [⁶⁸Ga]Ga-Pentixafor PET/CT and to study correlation with quantitative CXCR4 receptors' tissue density by immunochemistry analyses.

METHODS

[⁶⁸Ga]Ga-Pentixafor PET/CT imaging was performed prospectively in 94 (77 M: 17F, mean age 60.1 ± 10.1 years) LC patients. CXCR4 receptors' expression on lung mass in all the patients was estimated by immunohistochemistry (IHC) and fluorescence-activated cell sorting (FACS) analyses. SUV_max on PET, intensity score on IHC, and mean fluorescence index (MFI) on FACS analyses were measured.

RESULTS

A total of 75/94 (79.8%) cases had non-small cell lung cancer (NSCLC), 14 (14.9%) had small cell lung cancer (SCLC), and 5 (5.3%) had lung neuroendocrine neoplasm (NEN). All LC types showed increased CXCR4 expression on PET (SUV_max) and FACS (MFI). However, both these parameters (mean SUV_max = 10.3 ± 5.0; mean MFI = 349.0 ± 99.0) were significantly (p = 0.005) higher in SCLC as compared to those in NSCLC and lung NEN. The mean SUV_max in adenocarcinoma (n = 16) was 8.0 ± 1.9 which was significantly (p = 0.003) higher than in squamous cell carcinoma (n = 54; 6.2 ± 2.1) and in not-otherwise specified (NOS) sub-types (n = 5; 5.8 ± 1.5) of NSCLC. A significant correlation (r = 0.697; p = 001) was seen between SUV_max and MFI values in squamous cell NSCLC as well as in NSCLC adenocarcinoma (r = 0.538, p = 0.031) which supports the specific in vivo uptake of [⁶⁸Ga]Ga-Pentixafor by CXCR4 receptors. However, this correlation was not significant in SCLC (r = 0.435, p = 0.121) and NEN (r = 0.747, p = 0.147) which may be due to the small sample size. [⁶⁸Ga]Ga-Pentixafor PET/CT provided good sensitivity (85.7%) and specificity (78.1%) for differentiating SCLC from NSCLC (ROC cutoff SUV_max = 7.2). This technique presented similar sensitivity (87.5%) and specificity (71.4%) (ROC cutoff SUV_max = 6.7) for differentiating adenocarcinoma and squamous cell variants of NSCLC.

CONCLUSION

The high sensitivity and specificity of [⁶⁸Ga]Ga-Pentixafor PET/CT for in vivo targeting of CXCR4 receptors in lung cancer can thus be used effectively for the response assessment and development of CXCR4-based radioligand therapies in LC.

Glycolytic Plasticity of Metastatic Lung Cancer Captured by Noninvasive 18F-FDG PET/CT and Serum 1H-NMR Analysis: An Orthotopic Murine Model Study

We aim to establish a noninvasive diagnostic platform to capture early phenotypic transformation for metastasis using 18F-FDG PET and 1H-NMR-based serum metabolomics. Mice with implantation of NCI-H460 cells grew only primary lung tumors in the localized group and had both primary and metastatic lung tumors in the metastatic group. The serum metabolites were analyzed using 1H-NMR at the time of PET/CT scan. The glycolysis status and cell proliferation were validated by Western blotting and staining. A receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic accuracy of SUVmean and serum metabolites in metastasis. In the metastatic mice, the SUVmean of metastatic tumors was significantly higher than that of primary lung tumors in PET images, which was supported by elevated glycolytic protein expression of HK2 and PKM2. The serum pyruvate level in the metastatic group was significantly lower than that in the localized group, corresponding to increased pyruvate-catalyzed enzyme and proliferation rates in metastatic tumors. In diagnosing localized or metastatic tumors, the areas under the ROC curves of SUVmean and pyruvate were 0.92 and 0.91, respectively, with p < 0.05. In conclusion, the combination of 18F-FDG PET and 1H-NMR-based serum metabolomics demonstrated the feasibility of a glycolytic platform for diagnosing metastatic lung cancers.

Current investigative modalities for detecting and staging lung cancers: a comprehensive summary

This narrative review compares the advantages and drawbacks of imaging and other investigation modalities which currently assist with lung cancer diagnosis and staging, as well as those which are not routinely indicated for this. We examine plain film radiography, computed tomography (CT) (alone, as well as in conjunction with positron emission tomography (PET)), magnetic resonance imaging (MRI), ultrasound, and newer techniques such as image-guided bronchoscopy (IGB) and robotic bronchoscopy (RB). While a chest X-ray is the first-line imaging investigation in patients presenting with symptoms suggestive of lung cancer, it has a high positive predictive value (PPV) even after negative X-ray findings, which calls into question its value as part of a potential national screening programme. CT lowers the mortality for high-risk patients when compared to X-ray and certain scoring systems, such as the Brock model can guide the need for further imaging, like PET-CT, which has high sensitivity and specificity for diagnosing solitary pulmonary nodules as malignant, as well as for assessing small cell lung cancer spread. In practice, PET-CT is offered to everyone whose lung cancer is to be treated with a curative intent. In contrast, MRI is only recommended for isolated distant metastases. Similarly, ultrasound imaging is not used for diagnosis of lung cancer but can be useful when there is suspicion of intrathoracic lymph node involvement. Ultrasound imaging in the form of endobronchial ultrasonography (EBUS) is often used to aid tissue sampling, yet the diagnostic value of this technique varies widely between studies. RB is another novel technique that offers an alternative way to biopsy lesions, but further research on it is necessary. Lastly, thoracic surgical biopsies, particularly minimally invasive video-assisted techniques, have been used increasingly to aid in diagnosis and staging.

Clinical value of 3'-deoxy-3'-[18F]fluorothymidine-positron emission tomography for diagnosis, staging and assessing therapy response in lung cancer

Lung cancer has the highest mortality rate of any tumour type. The main driver of lung tumour growth and development is uncontrolled cellular proliferation. Poor patient outcomes are partly the result of the limited range of effective anti-cancer therapies available and partly due to the limited accuracy of biomarkers to report on cell proliferation rates in patients. Accordingly, accurate methods of diagnosing, staging and assessing response to therapy are crucial to improve patient outcomes. One effective way of assessing cell proliferation is to employ non-invasive evaluation using 3'-deoxy-3'-[¹⁸F]fluorothymidine ([¹⁸F]FLT) positron emission tomography [¹⁸F]FLT-PET. [¹⁸F]FLT, unlike the most commonly used PET tracer [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG), can specifically report on cell proliferation and does not accumulate in inflammatory cells. Therefore, this radiotracer could exhibit higher specificity in diagnosis and staging, along with more accurate monitoring of therapy response at early stages in the treatment cycle. This review summarises and evaluates published studies on the clinical use of [¹⁸F]FLT to diagnose, stage and assess response to therapy in lung cancer.

Improving accuracy of 18F-fluorodeoxyglucose PET computed tomography to diagnose nodal involvement in non-small cell lung cancer: utility of using various predictive models

PURPOSE

To determine predictive models (PM) that could improve the accuracy for identifying metastatic regional nodes in non-small cell lung cancer based on both PET and CT findings seen on 18F-FDG PET CT.

METHODS

Three hundred thirty-nine biopsy-proven NSCLC patients who underwent surgical resection and had a staging 18F-FDG PET CT were enrolled. PET parameters obtained were (1) presence of visual PET positive nodes, (2) SUVmax of nodes (NSUV), (3) ratio of node to aorta SUVmax (N/A ratio) and (4) ratio of node to primary tumour SUVmax (N/T ratio). CT parameters obtained were (1) short-axis diameter and (2) Hounsfield units (HU) of PET-positive nodes. PET and CT parameters were correlated with nodal histopathology to find out the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and overall accuracy. Different PM combining these parameters were devised and the incremental improvement in accuracy was determined.

RESULTS

Visual PET positivity showed sensitivity, specificity, PPV, NPV and accuracy of 72.4, 76.1, 30.1, 95.1 and 75.6, respectively. PM2 which combined visual PET positivity, NSUV and HU appears more clinically relevant and showed sensitivity, specificity, PPV, NPV and accuracy of 53.5, 96.5, 68.9, 93.6 and 91.2, respectively. PM6 which combined visual PET positivity, NSUV, N/A ratio and HU showed the maximum PPV (80.0%), specificity (98.3%) and accuracy of (91.9%).

CONCLUSION

PM combining parameters like nodal SUVmax, N/A ratio, N/T ratio and HU values have shown to improve the PPV, specificity and overall accuracy of 18FDG PET CT in the preoperative diagnosis of nodal metastases.

A Systematic Review of PET Textural Analysis and Radiomics in Cancer

Background: Although many works have supported the utility of PET radiomics, several authors have raised concerns over the robustness and replicability of the results. This study aimed to perform a systematic review on the topic of PET radiomics and the used methodologies. Methods: PubMed was searched up to 15 October 2020. Original research articles based on human data specifying at least one tumor type and PET image were included, excluding those that apply only first-order statistics and those including fewer than 20 patients. Each publication, cancer type, objective and several methodological parameters (number of patients and features, validation approach, among other things) were extracted. Results: A total of 290 studies were included. Lung (28%) and head and neck (24%) were the most studied cancers. The most common objective was prognosis/treatment response (46%), followed by diagnosis/staging (21%), tumor characterization (18%) and technical evaluations (15%). The average number of patients included was 114 (median = 71; range 20–1419), and the average number of high-order features calculated per study was 31 (median = 26, range 1–286). Conclusions: PET radiomics is a promising field, but the number of patients in most publications is insufficient, and very few papers perform in-depth validations. The role of standardization initiatives will be crucial in the upcoming years.

Is invasive mediastinal staging necessary in intermediate risk patients with negative PET/CT?

Background

Tumor involvement of mediastinal lymph nodes is of high importance in non-small cell lung cancer (NSCLC). Invasive mediastinal staging is recommended in selected patients without evidence of mediastinal involvement on staging by imaging. In the present study we aimed to evaluate the effectiveness of invasive mediastinal staging in reducing pN2, its impact on survival and the risk factors for occult pN2.

Methods

Patients with NSCLC tumors larger than 3 cm, central tumors or cN1 cases treated in our institution between 2013 and 2018 were prospectively included in the study. Incidence of pN2 and overall survival was compared among invasively staged (IS) and non-invasively staged groups (NIS). Multivariate analysis was performed to identify risk factors of pN2.

Results

A total of 201 patients were included in the study, 79 (39.3%) of whom were not invasively staged (NIS group) and 122 (60.7%) were invasively staged (IS group). Incidence of cN1 and mean PET/CT uptake was different among both groups. Prevalence of pN2 was similar in both groups (7.6% in NIS vs. 12.6% in IS; P>0.05). Median survival in IS-pN2 patients was 11 months longer than in NIS-pN2 group (33.6 vs. 22.5 months; P=0.245). cN1 emerged as the only a risk factor for pN2.

Conclusions

Invasive staging does not reduce the incidence of pN2. However, this finding could be biased because in our series cN1 patients were more often staged and cN1 has been detected as a risk factor for pN2. In addition patient better selection after invasive staging might have an impact on overall survival. To conclude, invasive mediastinal staging in intermediate risk patients for positive mediastinal nodes is justified.

[Lung cancer and elective nodal irradiation: A solved issue?]

Lung cancer treatment is a heavy workload for radiation oncologist and that field showed many evolutions over the last two decades. The issue about target volume was raised when treatment delivery became more precise with the development of three-dimensional conformal radiotherapy. Initially based upon surgical series, numerous retrospective and prospective studies aimed to evaluate the risk of elective nodal failure of involved-field radiotherapy compared to standard large field elective nodal irradiation. In every setting, locally advanced non-small cell lung cancer, localized non-small cell lung cancer, localized small cell lung cancer, exclusive chemoradiation or postoperative radiotherapy, most of the studies showed no significant difference between involved-field radiotherapy or elective nodal irradiation with elective nodal failure rate under 5% at 2 years, provided staging had been done with modern imaging and diagnostic techniques (positron emission tomography scan, endoscopy, etc.). Moreover, if reducing irradiated volumes are safe regarding recurrences, involved-field radiotherapy allowed dose escalation while reducing acute and late oesophageal, cardiac and pulmonary toxicities. Consequently, major clinical trials involving radiotherapy initiated in the last two decades and international clinical guidelines recommended omission of elective nodal irradiation in favour of in-field radiotherapy.

Performance Comparison Between 18F-FDG PET/CT Plus Brain MRI and Conventional Staging Plus Brain MRI in Staging of Small Cell Lung Carcinoma

OBJECTIVE

The purpose of this study was to prospectively compare the capabilities of integrated FDG PET/CT and conventional staging for identification of TNM factors, evaluation of the TNM and Veterans Administration Lung Study Group (VALSG) stages, and selection of patients with stage I small cell lung carcinoma (SCLC).

SUBJECTS AND METHODS

Fifty-nine patients (mean age, 69.6 ± 7.8 [SD] years; range, 40-84 years) with pathologically diagnosed SCLC underwent integrated ¹⁸F-FDG PET/CT and conventional staging with enhanced brain MRI. TNM and VALSG stages were evaluated by two different reader groups. Kappa statistics and chi-square test result were determined for evaluations of interobserver agreement of all factors and for each clinical stage for both methods. Diagnostic accuracy of identification of each factor and clinical stage was statistically compared by McNemar test.

RESULTS

Interobserver agreements for all factors and each clinical stage were assessed as almost perfect for PET/CT (0.83 ≤ κ ≤ 0.93; p < 0.001) and substantial and almost perfect (0.63 ≤ κ ≤ 0.96; p < 0.001) for conventional staging plus enhanced brain MRI. The diagnostic accuracy of PET/CT for N factor and TNM stage (N, 89.8% [53/59]; TNM stage, 88.1% [52/59]) was significantly higher than that of conventional staging plus enhanced brain MRI (N, 67.8% [40/59], p = 0.0002; TNM stage, 72.9% [43/59], p = 0.004).

CONCLUSION

Integrated FDG PET/CT with contrast-enhanced brain MRI is potentially equal to or more effective than conventional staging plus enhanced brain MRI for T, N, and M assessment and TNM and VALSG staging of SCLC.

Implementation of diffusion-weighted magnetic resonance imaging in target delineation of central lung cancer accompanied with atelectasis in precision radiotherapy

Radiotherapy, particularly the target delineation of cancer based on scanned images, plays a key role in the planning of cancer treatment. Recently, diffusion-weighted magnetic resonance imaging (DW-MRI) has emerged as a prospective superior procedure compared with intensified computed tomography (CT) and positron emission tomography (PET) in the target delineation of cancer. However, the implication of DW-MRI in lung cancer, the leading cause of cancer-associated mortality worldwide, has not been extensively evaluated. In the present study, the gross target volumes of lung cancer masses delineated using the DW-MRI, CT and PET procedures were compared in a pairwise manner in a group of 27 lung cancer patients accompanied with atelectasis of various levels. The data showed that compared with CT and PET procedures, DW-MRI has a more precise delineation of lung cancer while exhibiting higher reproducibility. Together with the fact that it is non-invasive and cost-effective, these data demonstrate the great application potential of the DW-MRI procedure in cancer precision radiotherapy.

Stage III Non-Small Cell Lung Cancer: Prognostic Value of FDG PET Quantitative Imaging Features Combined with Clinical Prognostic Factors

PURPOSE

To determine whether quantitative imaging features from pretreatment positron emission tomography (PET) can enhance patient overall survival risk stratification beyond what can be achieved with conventional prognostic factors in patients with stage III non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

The institutional review board approved this retrospective chart review study and waived the requirement to obtain informed consent. The authors retrospectively identified 195 patients with stage III NSCLC treated definitively with radiation therapy between January 2008 and January 2013. All patients underwent pretreatment PET/computed tomography before treatment. Conventional PET metrics, along with histogram, shape and volume, and co-occurrence matrix features, were extracted. Linear predictors of overall survival were developed from leave-one-out cross-validation. Predictive Kaplan-Meier curves were used to compare the linear predictors with both quantitative imaging features and conventional prognostic factors to those generated with conventional prognostic factors alone. The Harrell concordance index was used to quantify the discriminatory power of the linear predictors for survival differences of at least 0, 6, 12, 18, and 24 months. Models were generated with features present in more than 50% of the cross-validation folds.

RESULTS

Linear predictors of overall survival generated with both quantitative imaging features and conventional prognostic factors demonstrated improved risk stratification compared with those generated with conventional prognostic factors alone in terms of log-rank statistic (P = .18 vs P = .0001, respectively) and concordance index (0.62 vs 0.58, respectively). The use of quantitative imaging features selected during cross-validation improved the model using conventional prognostic factors alone (P = .007). Disease solidity and primary tumor energy from the co-occurrence matrix were found to be selected in all folds of cross-validation.

CONCLUSION

Pretreatment PET features were associated with overall survival when adjusting for conventional prognostic factors in patients with stage III NSCLC.

Adenocarcinoma with BAC features presented as the nonsolid nodule is prone to be false-negative on 18F-FDG PET/CT

Purpose. The present study investigated which type of adenocarcinoma with BAC features was prone to be false-negative on 18F-FDG PET/CT. Materials and Methods. A retrospective study was performed on 51 consecutive patients with localized adenocarcinoma with BAC features. CT and PET were assessed for lesion size, GGO percentage, and SUVmax. Lesions with FDG uptake the same as or more than mediastinal blood-pool activity were considered as PET-positive. Results. Of the 51 cases, 19.6% presented as pure GGO nodules, 31.4% as mixed nodules, and 49.0% as solid nodules. None of the pure GGO nodules was 18F-FDG avid, compared with 37.5% of mixed nodules and 96.0% of solid nodules (χ² = 31.55, P = 0.000). In the mixed nodule group, SUVmax was negatively correlated with GGO percentage (r = −0.588; P = 0.021). The positive detection rate of 18F-FDG PET/CT was 50.0%, 55.6%, and 100% in tumors 1.1–2.0 cm, 2.1–3.0 cm, and >3.0 cm in diameter, respectively (χ² = 5.815, P = 0.055). General linear model factor analysis showed that the GGO was an important factor contributing to false-negative PET/CT results (F = 23.992, P = 0.000), but lesion size was not (F = 0.602, P = 0.866). Conclusions. The present study indicated that the adenocarcinoma with BAC features presented as nonsolid nodule is prone to be false negative on 18F-FDG PET/CT.