Integrated FDG-PET/CT does not make invasive staging of the intrathoracic lymph nodes in non-small cell lung cancer redundant: a prospective study

Automatic Segmentation of Mediastinal Lymph Nodes and Blood Vessels in Endobronchial Ultrasound (EBUS) Images Using Deep Learning

Endobronchial ultrasound (EBUS) is used in the minimally invasive sampling of thoracic lymph nodes. In lung cancer staging, the accurate assessment of mediastinal structures is essential but challenged by variations in anatomy, image quality, and operator-dependent image interpretation. This study aimed to automatically detect and segment mediastinal lymph nodes and blood vessels employing a novel U-Net architecture-based approach in EBUS images. A total of 1161 EBUS images from 40 patients were annotated. For training and validation, 882 images from 30 patients and 145 images from 5 patients were utilized. A separate set of 134 images was reserved for testing. For lymph node and blood vessel segmentation, the mean ± standard deviation (SD) values of the Dice similarity coefficient were 0.71 ± 0.35 and 0.76 ± 0.38, those of the precision were 0.69 ± 0.36 and 0.82 ± 0.22, those of the sensitivity were 0.71 ± 0.38 and 0.80 ± 0.25, those of the specificity were 0.98 ± 0.02 and 0.99 ± 0.01, and those of the F1 score were 0.85 ± 0.16 and 0.81 ± 0.21, respectively. The average processing and segmentation run-time per image was 55 ± 1 ms (mean ± SD). The new U-Net architecture-based approach (EBUS-AI) could automatically detect and segment mediastinal lymph nodes and blood vessels in EBUS images. The method performed well and was feasible and fast, enabling real-time automatic labeling.

Multidisciplinary approach for locally advanced non-small cell lung cancer (NSCLC): 2023 expert consensus of the Spanish Lung Cancer Group GECP

INTRODUCTION

Recent advances in the treatment of locally advanced NSCLC have led to changes in the standard of care for this disease. For the selection of the best approach strategy for each patient, it is necessary the homogenization of diagnostic and therapeutic interventions, as well as the promotion of the evaluation of patients by a multidisciplinary oncology team.

OBJECTIVE

Development of an expert consensus document with suggestions for the approach and treatment of locally advanced NSCLC leaded by Spanish Lung Cancer Group GECP.

METHODS

Between March and July 2023, a panel of 28 experts was formed. Using a mixed technique (Delphi/nominal group) under the guidance of a coordinating group, consensus was reached in 4 phases: 1. Literature review and definition of discussion topics 2. First round of voting 3. Communicating the results and second round of voting 4. Definition of conclusions in nominal group meeting. Responses were consolidated using medians and interquartile ranges. The threshold for agreement was defined as 85% of the votes.

RESULTS

New and controversial situations regarding the diagnosis and management of locally advanced NSCLC were analyzed and reconciled based on evidence and clinical experience. Discussion issues included: molecular diagnosis and biomarkers, radiologic and surgical diagnosis, mediastinal staging, role of the multidisciplinary thoracic committee, neoadjuvant treatment indications, evaluation of response to neoadjuvant treatment, postoperative evaluation, and follow-up.

CONCLUSIONS

Consensus clinical suggestions were generated on the most relevant scenarios such as diagnosis, staging and treatment of locally advanced lung cancer, which will serve to support decision-making in daily practice.

Prognostic thresholds of fluorine-18 fluorodeoxyglucose-positron emission tomography mean and maximum standardized uptake values for survival and nodal involvement in lung neuroendocrine neoplasms

OBJECTIVES

The mean standardized uptake value (SUVmean) and maximum standardized uptake value (SUVmax) on fluorine-18 fluorodeoxyglucose-positron emission tomography are prognostic biomarkers for survival and nodal involvement in non-small-cell lung cancer but their prognostic value in lung neuroendocrine neoplasms (NENs) remains unexplored. In this study, we aimed to examine whether they are also prognostic biomarkers for survival and nodal involvement in lung NENs.

METHODS

We retrospectively studied patients with typical carcinoid, atypical carcinoid or large cell neuroendocrine carcinoma who had been radically resected at our institution between 2008 and 2020. We measured SUVmean and SUVmax on all primary tumours and lymph nodes that were clinically and/or pathologically involved. We dichotomized the patients into groups of high or low SUVmean and SUVmax of the primary tumour using time-dependent receiver operating characteristic curves and compared their overall survival using Kaplan-Meier curves and Cox models. Lastly, we predicted the patients' pathological nodal status with SUVmean and SUVmax of the lymph nodes using binomial logistic models.

RESULTS

The study included 245 patients. Patients died earlier if their SUVmean of the primary tumour exceeded 3.9 [hazard ratio 1.97, 95% confidence interval (CI) 1.27-3.04, P = 0.002] or SUVmax exceeded 5.3 (hazard ratio 1.85, 95% CI 1.20-2.87, P = 0.006). Likewise, patients had a higher risk of pathological nodal involvement if their SUVmean of the lymph nodes exceeded 3.3 (odds ratio 10.00, 95% CI 2.59-51.01, P = 0.002) or SUVmax exceeded 4.2 (odds ratio 4.00, 95% CI 1.20-14.65, P = 0.028).

CONCLUSIONS

The fluorine-18 fluorodeoxyglucose-positron emission tomography SUVmean and SUVmax are strong prognostic biomarkers for survival and nodal involvement in lung NENs and could be important guides for making treatment decisions.

A machine learning tool to improve prediction of mediastinal lymph node metastases in non-small cell lung cancer using routinely obtainable [18F]FDG-PET/CT parameters

BACKGROUND

In patients with non-small cell lung cancer (NSCLC), accuracy of [18F]FDG-PET/CT for pretherapeutic lymph node (LN) staging is limited by false positive findings. Our aim was to evaluate machine learning with routinely obtainable variables to improve accuracy over standard visual image assessment.

METHODS

Monocentric retrospective analysis of pretherapeutic [18F]FDG-PET/CT in 491 consecutive patients with NSCLC using an analog PET/CT scanner (training + test cohort, n = 385) or digital scanner (validation, n = 106). Forty clinical variables, tumor characteristics, and image variables (e.g., primary tumor and LN SUVmax and size) were collected. Different combinations of machine learning methods for feature selection and classification of N0/1 vs. N2/3 disease were compared. Ten-fold nested cross-validation was used to derive the mean area under the ROC curve of the ten test folds ("test AUC") and AUC in the validation cohort. Reference standard was the final N stage from interdisciplinary consensus (histological results for N2/3 LNs in 96%).

RESULTS

N2/3 disease was present in 190 patients (39%; training + test, 37%; validation, 46%; p = 0.09). A gradient boosting classifier (GBM) with 10 features was selected as the final model based on test AUC of 0.91 (95% confidence interval, 0.87-0.94). Validation AUC was 0.94 (0.89-0.98). At a target sensitivity of approx. 90%, test/validation accuracy of the GBM was 0.78/0.87. This was significantly higher than the accuracy based on "mediastinal LN uptake > mediastinum" (0.7/0.75; each p < 0.05) or combined PET/CT criteria (PET positive and/or LN short axis diameter > 10 mm; 0.68/0.75; each p < 0.001). Harmonization of PET images between the two scanners affected SUVmax and visual assessment of the LNs but did not diminish the AUC of the GBM.

CONCLUSIONS

A machine learning model based on routinely available variables from [18F]FDG-PET/CT improved accuracy in mediastinal LN staging compared to established visual assessment criteria. A web application implementing this model was made available.

Prospective Evaluation of Quantitative F-18-FDG-PET/CT for Pre-Operative Thoracic Lymph Node Staging in Patients with Lung Cancer as a Target for Computer-Aided Diagnosis

Purpose: Pre-operative assessment of thoracic lymphonodal (LN) involvement in patients with lung cancer (LC) is crucial when choosing the treatment modality. Visual assessment of F-18-FDG-PET/CT (PET/CT) is well established, however, there is still a need for prospective quantitative data to differentiate benign from malignant lesions which would simplify staging and guide the further implementation of computer-aided diagnosis (CAD). Methods: In this prospective study, 37 patients with confirmed lung cancer (m/f = 24/13; age: 70 [52–83] years) were analyzed. All patients underwent PET/CT and quantitative data (standardized uptake values) were obtained. Histological results were available for 101 thoracic lymph nodes. Quantitative data were matched to determine cut-off values for delineation between benign vs. malignant lymph nodes. Furthermore, a scoring system derived from these cut-off values was established. Statistical analyses were performed through ROC analysis. Results: Quantitative analysis revealed the optimal cut-off values (p < 0.01) for the differentiation between benign and malignant thoracic lymph nodes in patients suffering from lung cancer. The respective areas under the curve (AUC) ranged from 0.86 to 0.94. The highest AUC for a ratio of lymph node to healthy lung tissue was 0.94. The resulting accuracy ranged from 78.2% to 89.1%. A dedicated scoring system led to an AUC of 0.93 with a negative predictive value of 95.4%. Conclusion: Quantitative analysis of F-18-FDG-PET/CT data provides reliable results for delineation between benign and malignant thoracic lymph nodes. Thus, quantitative parameters can improve diagnostic accuracy and reliability and can also facilitate the handling of the steadily increasing number of clinical examinations.

Integral mediastinal staging in patients with NON-SMALL cell lung cancer and risk factors for occult N2 disease

BACKGROUND

In patients with non-small cell lung cancer (NSCLC), the presence of abnormal hiliar lymph nodes (clinical N1; cN1), central tumor location and/or tumor size (diameter >3 cm) increases the risk of occult mediastinal metastasis (OMM). This study investigates prospectively the diagnostic value of an integral mediastinal staging (IMS) strategy that combines EndoBronchial Ultrasound-TransBronchial Needle Aspiration (EBUS-TBNA) and Video-Assisted Mediastinoscopy (VAM) in patients with NSCLC at risk of OMM.

METHODS

Patients with NSCLC and radiologically normal mediastinum assessed non-invasively by positron emission tomography and computed tomography of the chest (PET-CT), and OMM risk factors (cN1, central tumor and/or >3 cm) underwent EBUS-TBNA followed by VAM if the former was negative. Those with negative IMS underwent resection surgery of the tumor.

RESULTS

EBUS-TBNA identified OMM in 2 out of the 49 patients evaluated (4%) and VAM in 1 of the 47 patients with negative EBUS (2%). Two patients with a negative IMS had OMM at surgery. Overall, the prevalence of OMM was 10%. EBUS-TBNA has a sensitivity of 40%, a negative predictive value (NPV) of 93.6%, and negative likelihood ratio of 0.60 (95%CI:0.30-1.16). The risk of not diagnosing OMM after EBUS was 6% and after IMS was 4.4%.

CONCLUSION

Integral mediastinal staging in patients with NSCLC and clinical risk factors for OMM, does not seem to provide added diagnostic value to that of EBUS-TBNA, except perhaps in patients with cN1 disease who deserve further research.

Dynamic FDG-PET imaging for differentiating metastatic from non-metastatic lymph nodes of lung cancer

OBJECTIVES

18F-fluorodeoxyglucose (FDG) PET/CT has been widely used in tumor diagnosis, staging, and response evaluation. To determine an optimal therapeutic strategy for lung cancer patients, accurate staging is essential. Semi-quantitative standardized uptake value (SUV) is known to be affected by multiple factors and may fail to differentiate between benign and malignant lesions. Lymph nodes (LNs) in the mediastinal and pulmonary hilar regions with high FDG uptake due to granulomatous lesions such as tuberculosis, which has a high prevalence in China, pose a diagnostic challenge. This study aims to evaluate the diagnostic value of the quantitative metabolic parameters derived from dynamic 18F-FDG PET/CT in differentiating metastatic and non-metastatic LNs in lung cancer.

METHODS

One hundred and eight patients with pulmonary nodules were enrolled to perform 18F-FDG PET/CT dynamic + static imaging with informed consent. One hundred and thirty-five LNs in 29 lung cancer patients were confirmed by pathology. Static image analysis parameters including LN-SUVmax, LN-SUVmax/primary tumor SUVmax (LN-SUVmax/PT-SUVmax), mediastinal blood pool SUVmax (MBP-SUVmax), LN-SUVmax/MBP-SUVmax, and LN-SUVmax/short diameter. Quantitative parameters including K1, k2, k3 and Ki and of each LN were obtained by applying the irreversible two-tissue compartment model using in-house Matlab software. Ki/K1 was computed subsequently as a separate marker. We further divided the LNs into mediastinal LNs (N=82) and pulmonary hilar LNs (N=53). Wilcoxon rank-sum test or Independent-samples T-test and receiver-operating characteristic (ROC) analysis was performed on each parameter to compare the diagnostic efficacy in differentiating lymph node metastases from inflammatory uptake. P<0.05 were considered statistically significant.

RESULTS

Among the 135 FDG-avid LNs confirmed by pathology, 49 LNs were non-metastatic, and 86 LNs were metastatic. LN-SUVmax, MBP-SUVmax, LN-SUVmax/MBP-SUVmax, and LN-SUVmax/short diameter couldn't well differentiate metastatic from non-metastatic LNs (P>0.05). However, LN-SUVmax/PT-SUVmax have good performance in the differential diagnosis of non-metastatic and metastatic LNs (P=0.039). Dynamic metabolic parameters in addition to k3, the parameters including K1, k2, Ki, and Ki/K1, on the other hand, have good performance in the differential diagnosis of metastatic and non-metastatic LNs (P=0.045, P=0.001, P=0.001, P=0.001, respectively). For ROC analysis, the metabolic parameters Ki (AUC of 0.672 [0.579-0.765], sensitivity 0.395, specificity 0.918) and Ki/K1 (AUC of 0.673 [0.580-0.767], sensitivity 0.570, specificity 0.776) have good performance in the differential diagnosis of metastatic from non-metastatic LNs than SUVmax (AUC of 0.596 [0.498-0.696], sensitivity 0.826, specificity 0.388), included the mediastinal region and pulmonary hilar region.

CONCLUSION

Compared with SUVmax, quantitative parameters such as K1, k2, Ki and Ki/K1 showed promising results for differentiation of metastatic and non-metastatic LNs with high uptake. The Ki and Ki/K1 had a high differential diagnostic value both in the mediastinal region and pulmonary hilar region.

Computational approaches to detect small lesions in 18 F-FDG PET/CT scans

Purpose

When physicians interpret ¹⁸F‐FDG PET/CT scans, they rely on their subjective visual impression of the presence of small lesions, the criteria for which may vary among readers. Our investigation used physical phantom scans to evaluate whether image texture analysis metrics reliably correspond to visual criteria used to identify lesions and accurately differentiate background regions from sub‐centimeter simulated lesions.

Methods

Routinely collected quality assurance test data were processed retrospectively for 65 different ¹⁸F‐FDG PET scans performed of standardized phantoms on eight different PET/CT systems. Phantoms included 8‐, 12‐, 16‐, and 25‐mm diameter cylinders embedded in a cylindrical water bath, prepared with 2.5:1 activity‐to‐background ratio emulating typical whole‐body PET protocols. Voxel values in cylinder regions and background regions were sampled to compute several classes of image metrics. Two experienced physicists, blinded to quantified image metrics and to each other's readings, independently graded cylinder visibility on a 5‐level scale (0 = definitely not visible to 4 = definitely visible).

Results

The three largest cylinders were visible in 100% of cases with a mean visibility score of 3.3 ± 1.2, while the smallest 8‐mm cylinder was visible in 58% of cases with a significantly lower mean visibility score of 1.5±1.1 (P < 0.0001). By ROC analysis, the polynomial‐fit signal‐to‐noise ratio was the most accurate at discriminating 8‐mm cylinders from the background, with accuracy greater than visual detection (93% ± 2% versus 76% ± 4%, P = 0.0001), and better sensitivity (94% versus 58%, P < 0.0001).

Conclusion

Image texture analysis metrics are more sensitive than visual impressions for detecting sub‐centimeter simulated lesions. Therefore, image texture analysis metrics are potentially clinically useful for ¹⁸F‐FDG PET/CT studies.

Quantitative imaging biomarkers in nuclear medicine: from SUV to image mining studies. Highlights from annals of nuclear medicine 2018

OBJECTIVE

Quantification in medical imaging is one of the main goals in research and clinical practice since it allows immediate understanding, objective communication, and comparison. Our aim was to summarize relevant investigations on quantification in nuclear medicine studies published in the volume 32 of Annals of Nuclear Medicine.

METHODS

In this article, we summarized the data of 14 selected papers from international research groups that were published between January and December 2018. This is a descriptive review with an inherently subjective selection of articles.

RESULTS

We discussed the role of parameters ranging from standardized uptake value to ratios, to flow within a region of interest, to volumetric parameters and to texture indices in different clinical scenarios in oncology, cardiology, and neurology.

CONCLUSIONS

In all the medical disciplines in which nuclear medicine examinations play a role, quantification is essential both in research and in clinical practice. Standardization and high-quality protocols are crucial for the success and reliability of imaging biomarkers.

Combined Endosonographic Mediastinal Lymph Node Staging in Positron Emission Tomography and Computed Tomography Node-Negative Non-Small-Cell Lung Cancer in High-Risk Patients

Positron emission tomography (PET) with computed tomography (CT) is routinely utilized to investigate lymph node (LN) metastases in non-small-cell lung cancer. However, it is less sensitive in normal-sized LNs. This study was performed in order to define the prevalence of mediastinal LN metastases discovered on combined endosonography by endobronchial ultrasound (EBUS) and endoscopic ultrasound (EUS) fine needle aspiration in patients with a radiologically normal mediastinum. This study consists of a retrospective, single-institution, tertiary care referral center review of a prospectively maintained database. Patients were identified from a cohort between January 2009 and December 2014. One hundred and sixty-one patients with biopsy-proven, non-small-cell lung cancer were identified in whom both the preendosonography CT and PET-CT were negative for mediastinal LN metastases. Combined endosonography (EBUS + EUS-FNA) was performed in all patients. Z test was used for statistical analysis. A P value of <0.05 was considered statistically significant. A total of 161 consecutive patients were included. Patients were staged if they had central tumor, tumor size >3 cm, N1 lymph node involvement on PET-CT/CT, or if there was low SUV (<2.5) in the primary tumor. A total of 416 lymph nodes were biopsied in the 161 patients using combined endosonography; 147 with EBUS and 269 with EUS. Mean and median number of lymph nodes biopsied per patient using combined EBUS/EUS was 2.5 and 3, respectively (mean and median EBUS: 0.91 and 2.5; mean and median EUS 1.6 and 3). Endosonographic staging upstaged 13% of patients with radiologically normal lymph nodes in the mediastinum, hilum, lobar, and sublobar regions (confidence interval 8.22-19.20). Twenty-one out of 161 patients (13%) with radiologically normal mediastinum were positive on combined EBUS/EUS staging. Out of 21 patients upstaged on endosonography, 15 (71%) had tumor size >3 cm. Six (28%) had occult N1 disease. Thirteen (61%) had occult N2 disease and 2 (9%) had adrenal involvement. None of the upstaged patients had N1 LN involvement on PET-CT or CT scan. Combined endosonographic lymph node staging should be considered in the pretreatment staging of high-risk patients with non-small-cell lung cancer in the presence of radiologically normal mediastinal lymph nodes due to the significant rate of radiologically occult lymph node metastases.

Comparison of 18F-FDG avidity at PET of benign and malignant pure ground-glass opacities: a paradox? Part II: artificial neural network integration of the PET/CT characteristics of ground-glass opacities to predict their likelihood of malignancy

AIM

To assess the ability of artificial neural networks (ANNs) to predict the likelihood of malignancy of pure ground-glass opacities (GGOs), using observations from computed tomography (CT) and 2-[¹⁸F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography (PET) images and relevant clinical information.

MATERIALS AND METHODS

One hundred and twenty-five cases of pure GGOs described in a previous article were used to train and evaluate the performance of an ANN to predict the likelihood of malignancy in each of the GGOs. Eighty-five cases selected randomly were used for training the network and the remaining 40 cases for testing. The ANN was constructed from the image data and basic clinical information. The predictions of the ANN were compared with blinded expert estimates of the likelihood of malignancy.

RESULTS

The ANN showed excellent predictive value in estimating the likelihood of malignancy (AUC = 0.98±0.02). Employing the optimal cut-off point from the receiver operating characteristic (ROC) curve, the ANN correctly identified 11/11 malignant lesions (sensitivity 100%) and 27/29 benign lesions (specificity 93.1%). The expert readers found 23 lesions indeterminate and correctly identified 17 lesions as benign.

CONCLUSION

ANNs have potential to improve diagnostic certainty in the classification of pure GGOs, based upon their CT appearance, intensity of FDG uptake, and relevant clinical information, and may therefore, be useful to help direct clinical and imaging follow-up.

Intrapulmonary lymph node metastasis is common in clinically staged IA adenocarcinoma of the lung

BACKGROUND

Intrapulmonary lymph nodes (LNs, stations 11-14) are usually omitted in postoperative pathological examination. Some non-small cell lung cancer (NSCLC) patients with intrapulmonary LN metastasis are incorrectly diagnosed as N0 cases. Furthermore, underestimation of intrapulmonary LN involvement in clinically early stage NSCLC may lead to the incorrect choice of surgical procedure: lobectomy or sublobar resection. This study was conducted to determine the status of intrapulmonary LN involvement in clinically staged IA (c-T1N0M0) peripheral adenocarcinoma of the lung.

METHODS

Seventy-five lobectomy specimens of c-T1N0M0 peripheral adenocarcinoma of the lung were carefully dissected to find intrapulmonary LNs. The longest diameter of each intrapulmonary LN was measured and sent for pathological examination, together with hilar and mediastinal LNs, to investigate the relationship between LN metastasis and primary tumor size.

RESULTS

Intrapulmonary LN metastasis was detected in 22.7%(17/75) of patients. Positive LNs were detected in 21.7% (10/46) of T1b patients and 45% (11/24) of T1c patients, while no metastasis (0/5) was observed in T1a patients (P = 0.036). The mean longest diameter of the 17 involved intrapulmonary LNs was only 6.5 ± 2.1 mm, which was not significantly different to the size of negative intrapulmonary LNs (5.2 ± 1.4 mm).

CONCLUSIONS

Intrapulmonary LN metastasis is common in clinically staged IA peripheral adenocarcinoma of the lung. LN metastasis is related to tumor size, and this should be taken into account to determine appropriate surgical procedures and postoperative treatment. Computed tomography is not a reliable method to judge LN metastasis, particularly intrapulmonary LN metastasis.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Impact of Computer-Aided CT and PET Analysis on Non-invasive T Staging in Patients with Lung Cancer and Atelectasis

PURPOSE

Tumor delineation within an atelectasis in lung cancer patients is not always accurate. When T staging is done by integrated 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG)-positron emission tomography (PET)/X-ray computer tomography (CT), tumors of neuroendocrine differentiation and slowly growing tumors can present with reduced FDG uptake, thus aggravating an exact T staging. In order to further exhaust information derived from [¹⁸F]FDG-PET/CT, we evaluated the impact of CT density and maximum standardized uptake value (SUVmax) for the classification of different tumor subtypes within a surrounding atelectasis, as well as possible cutoff values for the differentiation between the primary tumor and atelectatic lung tissue.

PROCEDURES

Seventy-two patients with histologically proven lung cancer and adjacent atelectasis were investigated. Non-contrast-enhanced [¹⁸F]FDG-PET/CT was performed within 2 weeks before surgery/biopsy. Boundaries of the primary within the atelectasis were determined visually on the basis of [¹⁸F]FDG uptake; CT density was quantified manually within each primary and each atelectasis.

RESULTS

CT density of the primary (36.4 Hounsfield units (HU) ± 6.2) was significantly higher compared to that of atelectatic lung (24.3 HU ± 8.3; p < 0.01), irrespective of the histological subtype. The discrimination between different malignant tumors using density analysis failed. SUVmax was increased in squamous cell carcinomas compared to adenocarcinomas. Irrespective of the malignant subtype, a possible cutoff value of 24 HU may help to exclude the presence of a primary in lesions below 24 HU, whereas a density above a threshold of 40 HU can help to exclude atelectatic lung.

CONCLUSION

Density measurements in patients with lung cancer and surrounding atelectasis may help to delineate the primary tumor, irrespective of the specific lung cancer subtype. This could improve T staging and radiation treatment planning (RTP) without additional application of a contrast agent in CT, or an additional magnetic resonance imaging (MRI), even in cases of lung tumors of neuroendocrine differentiation or in slowly growing tumors with less avidity to [¹⁸F]FDG.

Radiomic Analysis using Density Threshold for FDG-PET/CT-Based N-Staging in Lung Cancer Patients

PURPOSE

Mediastinal nodal (N)-staging done by integrated 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) positron emission tomography/x-ray computed tomography (PET/CT) in lung cancer patients is not always accurate. In order to reduce the need for invasive staging procedures, additional surrogate parameters for the detection of malignant lymph node infiltration would be helpful. The purpose of this study was to evaluate if radiomic semi-automated density profiling in mediastinal lymph nodes can improve preclinical N-staging, irrespective of the specific lung cancer entity.

PROCEDURES

This retrospective study was approved by the institutional review board. Two hundred forty-eight histologically proven lymph nodes in 122 lung cancer patients were investigated. In malignantly infiltrated lymph nodes, the specific lung cancer entity was histologically classified; benign lymph nodes were histologically classified as benign. Non-contrast enhanced [¹⁸F]FDG-PET/CT was performed before surgery/biopsy. Lymph node analyses were performed on the basis of FDG uptake and volumetric CT histogram analysis for metric lymph node sampling.

RESULTS

Of the 248 lymph nodes, 118 were benign, 130 malignant. Malignant lymph nodes had a significantly higher median CT density (32.4 Hounsfield units (HU) (min 5.4/max 77.5 HU)) compared to benign lymph nodes (9.3 HU (min -49.5/max 60.4 HU, p < 0.05), irrespective of the histological subtype. The discrimination between different malignant tumour subtypes by means of volumetric density analysis failed. Irrespective of the malignant subtype, a possible cutoff value of 20 HU may help differentiate between benign and malignant lymph nodes.

CONCLUSION

Density measurements in unclear mediastinal and hilar lymph nodes with equivocal FDG uptake in PET might serve as a possible surrogate parameter for N-staging in lung cancer patients, irrespective of the specific lung cancer subtype. This could also help to find possible high yield targets in cases where invasive lymph node staging is necessary.

Comparison of 18F-FDG PET/CT and DWI for detection of mediastinal nodal metastasis in non-small cell lung cancer: A meta-analysis

BACKGROUND

Accurate clinical staging of mediastinal lymph nodes of patients with lung cancer is important in determining therapeutic options and prognoses. We aimed to compare the diagnostic performance of diffusion-weighted magnetic resonance imaging (DWI) and 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in detecting mediastinal nodal metastasis of lung cancer.

METHODS

Relevant studies were systematically searched in the MEDLINE, EMBASE, PUBMED, and Cochrane Library databases. Based on extracted data, the pooled sensitivity, specificity, positive and negative likelihood ratios (PLR and NLR) with individual 95% confidence intervals were calculated. In addition, the publication bias was assessed by Deek's funnel plot of the asymmetry test. The potential heterogeneity was explored by threshold effect analysis and subgroup analyses.

RESULTS

Forty-three studies were finally included. For PET/CT, the pooled sensitivity and specificity were 0.65 (0.63-0.67) and 0.93 (0.93-0.94), respectively. The corresponding values of DWI were 0.72 (0.68-0.76) and 0.97 (0.96-0.98), respectively. The overall PLR and NLR of DWI were 13.15 (5.98-28.89) and 0.32 (0.27-0.39), respectively. For PET/CT, the corresponding values were 8.46 (6.54-10.96) and 0.38 (0.33-0.45), respectively. The Deek's test revealed no significant publication bias. Study design and patient enrollment were potential causes for the heterogeneity of DWI studies and the threshold was a potential source for PET/CT studies.

CONCLUSION

Both modalities are beneficial in detecting lymph nodes metastases in lung cancer without significant differences between them. DWI might be an alternative modality for evaluating nodal status of NSCLC.

The role of endobronchial ultrasound versus mediastinoscopy for non-small cell lung cancer

This review provides an update on the current role of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) and mediastinoscopy (Med) in assessment of patients with non-small cell lung cancer (NSCLC). Invasive mediastinal lymph node (LN) staging is the major application for both of these techniques. Up until recently, Med was the gold standard for invasive mediastinal LN staging in NSCLC. However, EBUS-TBNA has shown to be equivalent, and in some studies better than Med for invasive staging of lung cancer. EBUS-TBNA offers access to N1 LNs and development of the thin convex probe EBUS (TCP-EBUS) will expand EBUS-TBNA access from the paratracheal region and central airways to more distal parabronchial regions allowing for more extensive N1 LN assessment and sampling more distal lung tumors. EBUS-TBNA is more cost-effective than Med and it is currently recommended as the test of first choice for invasive mediastinal LN staging in lung cancer. Confirmatory Med should be performed selectively in patients with high pretest probability of metastatic disease. Addition of esophageal ultrasound fine needle aspiration (EUS-FNA) may increase diagnostic yield of EBUS-TBNA mediastinal staging. Both Med and EBUS-TBNA can be used in primary lung cancer diagnosis, restaging of the mediastinum following neoadjuvant therapy and in diagnosis of lung cancer recurrence. In the future, a combination of EBUS-TBNA with or without EUS-FNA and Med is most likely going to provide the most optimal invasive assessment of the mediastinum in patients with lung cancer. The decision on test choice and sequence should be made on a case-by-case basis and factoring in local resources and expertise.

Increased x-ray attenuation in malignant vs. benign mediastinal nodes in an orthotopic model of lung cancer

PURPOSE

Staging of lung cancer is typically performed with fluorodeoxyglucose-positron emission tomography-computed tomography (FDG-PET/CT); however, false positive PET scans can occur due to inflammatory disease. The CT scan is used for anatomic registration and attenuation correction. Herein, we evaluated x-ray attenuation (XRA) within nodes on CT and correlated this with the presence of malignancy in an orthotopic lung cancer model in rats.

METHODS

1×10⁶ NCI-H460 cells were injected transthoracically in six National Institutes of Health nude rats and six animals served as controls. After two weeks, animals were sacrificed; lymph nodes were extracted and scanned with a micro-CT to determine their XRA prior to histologic analysis.

RESULTS

Median CT density in malignant lymph nodes (n=20) was significantly higher than benign lymph nodes (n=12; P = 0.018). Short-axis diameter of metastatic lymph nodes was significantly different than benign nodes (3.4 mm vs. 2.4 mm; P = 0.025). Area under the curve for malignancy was higher for density-based lymph node analysis compared with size measurements (0.87 vs. 0.7).

CONCLUSION

XRA of metastatic mediastinal lymph nodes is significantly higher than benign nodes in this lung cancer model. This suggests that information on nodal density may be useful when used in combination with the results of FDG-PET in determining the likelihood of malignant adenopathy.

Mediastinal Staging: Endosonographic Ultrasound Lymph Node Biopsy or Mediastinoscopy

Combined endosonographic lymph node biopsy techniques are a minimally invasive alternative to surgical staging in non-small cell lung cancer and may be superior to standard mediastinoscopy and surgical mediastinal staging techniques. Endosonography allows for the biopsy of lymph nodes and metastases unattainable with standard mediastinoscopy. Standard cervical mediastinoscopy is an invasive procedure, which requires general anesthesia and is associated with higher risk, cost, and major complication rates compared with minimally invasive endosonographic biopsy techniques. Combined endosonographic procedures are the new gold standard in staging of non-small cell lung cancer when performed by an experienced operator.

Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration in the Nodal Staging of Stereotactic Ablative Body Radiotherapy Patients

BACKGROUND

Patients with non-small cell lung cancer (NSCLC) being evaluated for stereotactic ablative body radiotherapy (SABR) are typically staged noninvasively with positron emission tomography/computed tomography (PET/CT). Incorporating endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) into the staging workup of these patients has not been evaluated. Our primary objective was to compare the performance of PET/CT with EBUS-TBNA for intrathoracic nodal assessment among SABR-eligible patients.

METHODS

This was a retrospective study consisting of two parts. First, we assessed the concordance for nodal metastasis of PET/CT and EBUS-TBNA. Second, we evaluated clinical outcomes among patients who underwent SABR with and without a prior EBUS-TBNA.

RESULTS

We identified 246 eligible patients. Compared with PET/CT, EBUS-TBNA led to a stage shift in 48 of 246 patients (19%). Of 174 N0 patients by PET/CT, 6 (3.4%) had nodal metastasis on EBUS-TBNA. Among 72 clinical N1 patients, 36 (50%) were downstaged to N0 after EBUS-TBNA, therefore becoming eligible for SABR. Concordance between PET/CT and EBUS-TBNA for nodal metastasis was 83% (κ = 0.53). Clinical outcomes of patients who underwent SABR with or without a prior EBUS-TBNA did not differ significantly.

CONCLUSIONS

Concordance of PET/CT and EBUS-TBNA for nodal disease was only moderate. Incorporating EBUS-TBNA into the staging workup was beneficial in identifying occult nodal metastasis that would otherwise be left untreated with SABR and in expanding the pool of potentially SABR-eligible patients.

Imaging Heterogeneity in Lung Cancer: Techniques, Applications, and Challenges

OBJECTIVE

Texture analysis involves the mathematic processing of medical images to derive sets of numeric quantities that measure heterogeneity. Studies on lung cancer have shown that texture analysis may have a role in characterizing tumors and predicting patient outcome. This article outlines the mathematic basis of and the most recent literature on texture analysis in lung cancer imaging. We also describe the challenges facing the clinical implementation of texture analysis.

CONCLUSION

Texture analysis of lung cancer images has been applied successfully to FDG PET and CT scans. Different texture parameters have been shown to be predictive of the nature of disease and of patient outcome. In general, it appears that more heterogeneous tumors on imaging tend to be more aggressive and to be associated with poorer outcomes and that tumor heterogeneity on imaging decreases with treatment. Despite these promising results, there is a large variation in the reported data and strengths of association.

Endobronchial ultrasound-guided transbronchial needle aspiration of hilar and mediastinal lymph nodes detected on 18F-fluorodeoxyglucose positron emission tomography/computed tomography

Objective

Endobronchial ultrasound-guided transbronchial needle aspiration is of diagnostic value in hilar/mediastinal (N1/N2) lymph node staging. We assessed the utility of endobronchial ultrasound-guided transbronchial needle aspiration in lung cancer patients with N1/N2 lymph nodes detected on ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography.

Methods

Fifty lung cancer patients with N1/N2 disease on ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography underwent endobronchial ultrasound-guided transbronchial needle aspiration for pathological lymph nodes between November 2012 and April 2015. The diagnostic performance of endobronchial ultrasound-guided transbronchial needle aspiration, lymph node site and size, number of needle passes and complications were evaluated retrospectively from patients' medical records. Malignancy was defined as a maximum standardized uptake value (SUV_max) >2.5.

Results

The median longest diameter of the 61 lymph nodes (29 subcarinal, 21 right lower paratracheal, 6 left lower paratracheal, 4 right hilar and 1 upper paratracheal) was 23.4 mm (range: 10.4–45.7); the median number of needle passes was 2 (range: 1–5). There were no severe complications. A definitive diagnosis was made by endobronchial ultrasound-guided transbronchial needle aspiration in 39 patients (31 adenocarcinomas, 3 small-cell carcinomas, 2 squamous-cell carcinomas, 3 large-cell neuroendocrine carcinomas). In the remaining 11 patients, the diagnosis was indefinite: insufficient endobronchial ultrasound-guided transbronchial needle aspiration material was collected in two patients and non-specific lymphadenopathy was confirmed by endobronchial ultrasound-guided transbronchial needle aspiration or thoracotomy in the other nine patients. The mean lymph node SUV_max was 7.09 (range: 2.90–26.9) and was significantly higher in true-positive than in false-positive nodes (P < 0.05, t-test). Non-specific lymphadenopathy was diagnosed by expert visual interpretation of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography images in five of the nine patients.

Conclusion

Endobronchial ultrasound-guided transbronchial needle aspiration accurately diagnoses N1/N2 disease detected on ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography.

An investigation of the relation between tumor-to-liver ratio (TLR) and tumor-to-blood standard uptake ratio (SUR) in oncological FDG PET

Background

The standardized uptake value (SUV) is the nearly exclusive means for quantitative evaluation of clinical [18F-]fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) whole body investigations. However, the SUV methodology has well-known shortcomings. In this context, it has been recognized that at least part of the problems can be eliminated if tumor SUV is normalized to the SUV of a reference region in the liver (tumor-to-liver [TLR] ratio). In recent publications, we have systematically investigated the tumor-to-blood SUV ratio (SUR) for normalization of tumor SUVs which in our view offers principal advantages in comparison to TLR. The aim of this study was a comprehensive comparison of TLR and SUR in terms of quantification of tumor lesions.

Methods

18F-FDG PET/CT was performed in 424 patients (557 scans) with different tumor entities prior to radio(chemo)therapy. In the PET images, SUV_max of the primary tumor was determined. SUV_liver was calculated in the inferior right lobe of the liver. SUV_blood was determined by manually delineating the aorta in the low-dose CT. TLR and SUR were computed and scan time corrected to 60 min p.i. (TLR_tc and SUR_tc). Correlation analysis was performed for SUV_liver vs. SUV_blood, TLR vs. SUR, SUV_liver/SUV_blood vs. SUV_blood,SUR_tc/TLR vs. SUR_tc, and SUR_tc/TLR_tc vs. SUR_tc. Variability of the respective ratios was assessed via histogram analysis. The prognostic value of TLR and TLR_tc for distant metastases-free survival (DM) was investigated with univariate Cox regression in a homogeneous subgroup (N = 130) and compared to previously published results for SUV and SUR_tc.

Results

Correlation analysis revealed a linear correlation of SUV_liver vs. SUV_blood (R ²=0.83) and of TLR vs. SUR_tc (R²=0.92). The SUV_liver/SUV_blood ratio (mean ± s.d.) was 1.47 ± 0.18. For the SUR_tc/TLR ratio, we obtained 1.14 ± 0.21 and for the SUR_tc/TLR_tc ratio 1.38 ± 0.17. Survival analysis revealed TLR and TLR_tc as significant prognostic factors for DM (hazard ratio [HR] = 3.3 and HR = 3, respectively). Both hazard ratios are lower than that of SUR_tc (HR = 4.1) although this reduction does not reach statistical significance for the given limited group size. HRs of TLR and SUR_tc are both significantly higher than HR of SUV (HR = 2.2).

Conclusions

Suitability of the liver as surrogate of arterial tracer supply for SUV normalization via TLR computation is limited. Further studies in sufficiently large patient groups are required to better characterize the relative performance of SUV, TLR, and SUR in different settings.

PET/MRI in Oncological Imaging: State of the Art

Positron emission tomography (PET) combined with magnetic resonance imaging (MRI) is a hybrid technology which has recently gained interest as a potential cancer imaging tool. Compared with CT, MRI is advantageous due to its lack of ionizing radiation, superior soft-tissue contrast resolution, and wider range of acquisition sequences. Several studies have shown PET/MRI to be equivalent to PET/CT in most oncological applications, possibly superior in certain body parts, e.g., head and neck, pelvis, and in certain situations, e.g., cancer recurrence. This review will update the readers on recent advances in PET/MRI technology and review key literature, while highlighting the strengths and weaknesses of PET/MRI in cancer imaging.

Effect of R-CHOP chemotherapy on liver and mediastinal blood pool (18)F-FDG standardized uptake values in patients with non-Hodgkin's lymphoma

AIM

We aimed to investigate the impact of chemotherapy on (18)F-FDG uptake in the liver and mediastinal blood pool (MBP) among patients with non-Hodgkin's lymphoma.

METHODS

Twenty-three patients with NHL underwent baseline, interim, and postchemotherapy (18)F-FDG PET/CT. SUVmax and SUVmean values of the liver and MBP at imaging time were compared statistically.

RESULTS

We did not find any significant differences between the liver and mediastinum SUVmean and SUVmax values (P>.05).

CONCLUSIONS

Our study demonstrates that the (18)F-FDG uptake in the liver and MBP are not significantly affected by R-CHOP chemotherapy in patients with NHL.

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

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

A pilot study of 4'-[methyl-11C]-thiothymidine PET/CT for detection of regional lymph node metastasis in non-small cell lung cancer

Background

4′-[methyl-¹¹C]-thiothymidine (4DST) is a novel positron emission tomography (PET) tracer to assess proliferation of malignancy. The diagnostic abilities of 4DST and 2-deoxy-2-¹⁸ F-fluoro-d-glucose (FDG) for detecting regional lymph node (LN) metastases of non-small cell lung cancer (NSCLC) were prospectively compared. In addition, the relationship between the PET result and the patient's prognosis was evaluated.

Methods

A total of 31 patients with NSCLC underwent 4DST PET/computed tomography (CT) and FDG PET/CT. The PET/CT images were evaluated qualitatively and quantitatively for focal uptake of each PET tracer, according to the staging system of the American Joint Committee on Cancer. Surgical and histological results provided the reference standards. Patients were followed for up to two years to assess disease-free survival.

Results

On a per-lesion basis, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for LN staging were 82%, 72%, 32%, 96%, and 73%, respectively, for 4DST, and 29%, 86%, 25%, 88%, and 78%, respectively, for FDG. The sensitivity of 4DST was significantly higher than that of FDG (P < 0.001). The disease-free survival rate with positive 4DST uptake in nodal lesions was 0.35, which was considerably lower than the rate of 0.83 with negative findings (P = 0.04). Among the factors tested, nodal staging by 4DST was the most influential prognostic factor (P = 0.05) in predicting the presence of a previously existing spread lesion or of a recurrence over the course of 2 years.

Conclusion

4DST PET/CT is sensitive for detecting mediastinal lymph node metastasis in NSCLC, but its low specificity is a limitation. However, it may be helpful in predicting the prognosis of NSCLC.

Advances in the diagnosis and treatment of non-small cell lung cancer

The diagnostic and therapeutic landscape of non-small cell lung cancer (NSCLC) has changed dramatically in the past 50 years since the Surgeon General's report on smoking and lung cancer. Early detection is now a reality for lung cancer. The use of low-dose computed tomography scans for early detection decreases mortality and is beginning to be used in routine clinical practice. Technological advances such as positron emission tomography and endobronchial ultrasound have improved the accuracy of NSCLC staging. The cure rate for early-stage NSCLC has improved as a result of multimodality treatment approaches. The role of systemic therapy has also expanded to earlier stages of the disease. In recent years, the initial steps toward personalized medicine by utilization of targeted treatments based on tumor genotype have been undertaken. Emerging technological advances and greater insights into tumor biology are poised to greatly reduce the burden of lung cancer in the years to come.

Radiographic evaluation of the patient with lung cancer: surgical implications of imaging

Lung cancer is the leading cause of cancer deaths in the United States. Despite many advances in treatment, surgery remains the preferred treatment modality for patients presenting with early stage disease. Imaging is critical in the preoperative evaluation of these patients being considered for a curative resection. Advanced imaging techniques provide valuable information, including primary diagnostics, staging, and intraoperative localization for suspected lung cancer. Knowledge of surgical implications of imaging findings can aid both radiologists and surgeons in delivering safe and effective care.

Integrated positron emission tomography and computed tomography in preoperative lymph node staging of non-small cell lung cancer

BACKGROUND

Integrated positron emission tomography and computed tomography (PET/CT) is increasingly used for the preoperative nodal staging of non-small cell lung cancer (NSCLC). The aim of this study was to evaluate the accuracy of PET/CT in comparison with CT in detection of nodal metastasis and preoperative nodal staging in patients with NSCLC, and to analyze the causes of the PET/CT false-negative and false-positive results.

METHODS

Consecutive patients with pathologically proven NSCLC who underwent staging using PET/CT from July 2008 to February 2012 were evaluated retrospectively. Nodal staging was pathologically confirmed on tissue specimens obtained at thoracotomy. The accuracy of PET/CT and CT in the assessment of intrathoracic nodal involvement was determined using histological results as the reference standard. Logistic regression was used to define the causes of the false-negative and false-positive results.

RESULTS

A total of 528 lymph node stations were evaluated in 101 patients. Lymph nodes were positive for malignancy in 43 out of 101 patients (42.6%), and 101 out of 528 nodal stations (19.2%). PET/CT was significantly more accurate for nodal staging than CT. The sensitivity, specificity, positive and negative predictive values, and accuracy of PET/CT for detecting nodal metastasis were 51.5%, 95.8%, 74.3%, 89.3%, and 87.3% and the corresponding data by CT were 45.5%, 87.1%, 45.5%, 87.1%, and 79.2%, respectively. PET/CT confers significantly higher specificity, positive predictive value, and accuracy than CT in detecting nodal metastasis. False-negative results by PET/CT are significantly associated with smaller lymph node size, whereas false-positive results are related to a combination of inflammatory disorders and larger lymph node size.

CONCLUSION

PET/CT confers significantly higher accuracy than CT in nodal staging, and is more specific and accurate than CT in detecting nodal metastasis but has a low sensitivity and high false-negative rate.

Impact of 18F-FDG PET/CT in the treatment of patients with non-small cell lung cancer

INTRODUCTION

Disease stage is the most important prognostic factor in lung cancer, and optimal staging is important to determine the best therapeutic option. FDG-PET/CT has demonstrated its value in early stage non-small cell lung cancer (NSCLC) but there is still insufficient data to define its role in other stages.

HYPOTHESIS

Information provided by FDG-PET/CT has an impact on the therapeutic management of patients with NSCLC.

METHODS

A retrospective review was made of patients who underwent FDG-PET/CT between January 2008 and December 2010 for the diagnosis of NSCLC. Clinical stage before and after FDG-PET/CT and information about any change in therapeutic decision due to information provided by FDG-PET/CT were collected. Using pathologic evaluation as the gold standard, sensitivity, specificity, and positive and negative predictive values for CT and FDG-PET/CT were calculated.

RESULTS

Of the 522 patients diagnosed of NSCLC, FDG-PET/CT was performed in 246 (47.1%). In 85 cases (34.6%) FDG-PET/CT led to stage migration. Treatment was modified in 60 patients (24.4% of all FDG-PET/CT performed), avoiding a futile thoracotomy in 13 cases (5.2%), and allowing treatment with curative intent in 26 (10.5%). Out of 90 patients (36.5%) evaluated as stage iii by CT staging, FDG-PET/CT modified the therapeutic approach in 36 (40%). For the 133 cases (54%) with pathological assessment of the mediastinal lymph nodes, sensitivity, specificity, positive predictive value and negative predictive value were 0.57, 0.64, 0.48 and 0.72 for CT, and 0.68, 0.86, 0.75 and 0.81 for FDG-PET/CT.

DISCUSSION

Our data support previous reports that FDG-PET/CT is essential in the staging process not only for patients with potentially operable NSCLC but also for stage iii patients, as demonstrated by our data.

Characteristics of Metastatic Mediastinal Lymph Nodes of Non-Small Cell Lung Cancer on Preoperative F-18 FDG PET/CT

PURPOSE

The aim of this study was to evaluate the characteristics of PET and CT features of mediastinal metastatic lymph nodes on F-18 FDG PET/CT and to determine the diagnostic criteria in nodal staging of non-small cell lung cancer.

METHODS

One hundred four non-small cell lung cancer patients who had preoperative F-18 FDG PET/CT were included. For quantitative analysis, the maximum SUV of the primary tumor, maximum SUV of the lymph nodes (SUVmax), size of the lymph nodes, and average Hounsfield units (aHUs) and maximum Hounsfield units (mHUs) of the lymph nodes were measured. The SUVmax, SUV ratio of the lymph node to blood pool (LN SUV/blood pool SUV), SUV ratio of the lymph node to primary tumor (LN SUV/primary tumor SUV), size, aHU, and mHU were compared between the benign and malignant lymph nodes.

RESULTS

Among 372 dissected lymph node stations that were pathologically diagnosed after surgery, 49 node stations were malignant and 323 node stations benign. SUVmax, LN SUV/blood pool SUV, and size were significantly different between the malignant and benign lymph node stations (P < 0.0001). However, there was no significant difference in LN SUV/primary tumor SUV (P = 0.18), mHU (P = 0.42), and aHU (P = 0.98). Using receiver-operating characteristic curve analyses, there was no significant difference among these three variables (SUVmax, LN SUV/blood pool SUV, and size). The optimal cutoff values were 2.9 for SUVmax, 1.4 for LN SUV/blood pool SUV, and 5 mm for size. When the cutoff value of SUVmax ≥2.9 and size ≥5 mm were used in combination, the positive predictive value was 44.2 %, and the negative predictive value was 90.9 %. When we evaluated the results based on the histology of the primary tumor, the negative predictive value was 92.3 % in adenocarcinoma (cutoff values of SUVmax ≥2.3 and size ≥5 mm) and 97.2 % in squamous cell carcinoma (cutoff values of SUVmax ≥3.6 and size ≥8 mm), separately.

CONCLUSIONS

In the lymph node staging of non-small cell lung cancer, SUVmax, LN SUV/blood pool SUV, and size show statistically significant differences between malignant and benign lymph nodes. These variables can be used to differentiate malignant from benign lymph nodes. The combination of the SUVmax and size of lymph node might have a good negative predictive value.

FDG PET/CT for the preoperative nodal staging of non-small cell lung cancer in a tuberculosis-endemic country: Are maximum standardized uptake values useful?

BACKGROUND

The aim of this study was to determine an optimum standardized uptake value threshold for identifying nodal metastasis in non-small cell lung cancer (NSCLC) patients using Fluorine-18 2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) in Taiwan, a tuberculosis-endemic country. The variation in standardized uptake values of nodal metastasis among different NSCLC histological subtypes was also evaluated.

METHODS

We retrospectively reviewed 75 NSCLC patients who had received FDG PET/CT before surgery. The diagnostic accuracy of FDG PET/CT for the preoperative nodal staging was evaluated by histopathologic findings.

RESULTS

A total of 316 nodal stations were evaluated. The sensitivity and specificity of FDG PET/CT for nodal staging were 58.6% and 81.8%, respectively, using an SUV cut-off of 2.6. With regard to the levels of mean SUVmax in true-positive and false-positive groups, there was no significant difference among different histological subtypes.

CONCLUSION

The present study demonstrated that FDG PET/CT for pre-operative nodal staging using SUVmax > 2.6 is a useful tool (with a higher specificity and a higher negative predictive value) to rule out the possibility of metastatic lymphadenopathy in operable patients with NSCLC.

Measurement of primary tumor volume by PET-CT to evaluate risk of mediastinal nodal involvement in NSCLC patients with clinically negative N2 lymph nodes

AIM

The study aimed to determine a prognostic value of primary tumor volume measured on the basis of integrated positron emission tomography-computerized tomography (PET-CT) in terms of mediastinal nodal metastases (N2) prediction in non-small-cell lung cancer (NSCLC) patients with PET-CT N2 negative lymph nodes.

METHODS

The records of 70 potentially operable NSCLC patients treated with surgical resection were analyzed. All patients underwent diagnostic, preoperative PET-CT, which was the basis for tumor volume calculations as well as the evaluation of N2 nodes status. The logistic regression analysis was employed to determine correlation between mediastinal nodal involvement and volume of primary tumor (izoSUV2.5 volume), that is the volume of primary tumor inside SUV 2.5 line, tumor histology, location (peripheral vs. central), hilar node status.

RESULTS

A statistically significant correlation between mediastinal node involvement and izoSUV2.5 volume, tumor histology, locations peripheral vs. central and hilar node status was found. The risk of mediastinal lymph node metastasis is 24% for tumor volume of 100 cm(3) and increases up to 40% for tumor volume of 360 cm(3). An increase of tumor volume by 1 cm(3) increases the risk of lymph node disease by 0.3%. Tumor histology adenocarcinoma vs. squamous cell carcinoma increases the risk of mediastinal lymph node involvement by 195%, location central vs. peripheral by 68% and hilar node involvement by 166%.

CONCLUSIONS

The study demonstrates that izoSUV2.5 volume of primary tumor may be considered as a prognostic factor in NSCLC patients, since it strongly correlates with mediastinal lymph node pathological status. This correlation is modified by primary tumor location, histology and hilar node involvement.

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

Fluoro-2-deoxy-d-glucose (FDG)-positron emission tomography (PET) and PET/computed tomography (FDG-PET/CT) is regarded as a standard of care in the management of non-small-cell lung carcinoma (NSCLC) and is a useful adjunct in the characterization of indeterminate solitary lung nodules (SLN), and pre-treatment staging of NSCLC, notably mediastinal nodal staging and detection of remote metastases. FDG-PET/CT has the ability to assess locoregional lymph node spread more precisely than CT, to detect metastatic lesions that would have been missed on conventional imaging or are located in difficult areas, and to help in the differentiation of lesions that are equivocal after conventional imaging. Increasingly FDG-PET/CT is employed in radiotherapy planning, prediction of prognosis in terms of tumor response to neo-adjuvant, radiation and chemotherapy treatment. Evidence is accumulating of usefulness of PET/CT in small cell lung cancer.

Virtual 18F-FDG PET/CT bronchoscopy for lymph node staging in non-small-cell lung cancer patients: present and future applications

Virtual (18)F-fluorodeoxyglucose (FDG) PET/computed tomography (CT) bronchoscopies provide virtually realistic, 3D endoscopic views of the airways combining anatomical and functional data at a high resolution. Today, even very small airways can be imaged by virtual bronchoscopy. (18)F-FDG PET/CT bronchoscopy images are generated from standard whole-body (18)F-FDG PET/CT scan source data without any additional radiation exposure. The purpose of this review was to give an overview over the studies that are currently available, to provide the technical background of (18)F-FDG PET/CT bronchoscopy and to explain the diagnostic accuracy of (18)F-FDG PET/CT bronchoscopy. Moreover, this manuscript highlights potential future applications of this promising new imaging technique.