Advantages of Combined PET-CT in Mediastinal Staging in Patients with Non-small Cell Lung Carcinoma

DSG-GAN:A dual-stage-generator-based GAN for cross-modality synthesis from PET to CT

PET/CT devices typically use CT images for PET attenuation correction, leading to additional radiation exposure. Alternatively, in a standalone PET imaging system, attenuation and scatter correction cannot be performed due to the absence of CT images. Therefore, it is necessary to explore methods for generating pseudo-CT images from PET images. However, traditional PET-to-CT synthesis models encounter conflicts in multi-objective optimization, leading to disparities between synthetic and real images in overall structure and texture. To address this issue, we propose a staged image generation model. Firstly, we construct a dual-stage generator, which synthesizes the overall structure and texture details of images by decomposing optimization objectives and employing multiple loss functions constraints. Additionally, in each generator, we employ improved deep perceptual skip connections, which utilize cross-layer information interaction and deep perceptual selection to effectively and selectively leverage multi-level deep information and avoid interference from redundant information. Finally, we construct a context-aware local discriminator, which integrates context information and extracts local features to generate fine local details of images and reasonably maintain the overall coherence of the images. Experimental results demonstrate that our approach outperforms other methods, with SSIM, PSNR, and FID metrics reaching 0.8993, 29.6108, and 29.7489, respectively, achieving the state-of-the-art. Furthermore, we conduct visual experiments on the synthesized pseudo-CT images in terms of image structure and texture. The results indicate that the pseudo-CT images synthesized in this study are more similar to real CT images, providing accurate structure information for clinical disease analysis and lesion localization.

Long-term Survival with 18-Fluorodeoxyglucose Positron Emission Tomography-directed Therapy in Non-small Cell Lung Cancer with Synchronous Solitary Brain Metastasis

AIMS

At diagnosis, <1% of patients with non-small cell lung cancer (NSCLC) have synchronous solitary brain metastasis (SSBM). In prior cohorts without 18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) staging, definitive treatment to intracranial and intrathoracic disease showed a 5-year overall survival (OS) of 11-21%. We investigated the long-term survival outcomes for patients with SSBM NSCLC, diagnosed in the FDG-PET/CT era and treated definitively with local therapies to both intracranial and intrathoracic sites of disease.

MATERIALS AND METHODS

This retrospective study assessed patients staged with FDG-PET/CT who received definitive lung and SSBM treatment from February 1999 to December 2017. A lung-molecular graded prognostic assessment (lung-molGPA) score was assigned for each patient using age, performance status score, and, where carried out, molecular status. Overall survival and progression-free survival (PFS) were calculated using Kaplan-Meier methods. Cox proportional hazard models determined OS and PFS prognostic factors.

RESULTS

Forty-nine patients newly diagnosed with NSCLC and SSBM had a median age of 63 years (range 34-76). The median follow-up of all patients was 3.9 years. Thirty-three patients (67%) had ≥T2 disease, 23 (47%) had ≥N2. At 2 years, 45% of first failures were intracranial only (95% confidence interval 30-59). At 3 and 5 years, OS was 45% (95% confidence interval 32-63) and 30% (95% confidence interval 18-51), respectively. In ≥N1 disease, 5-year OS was 34% (95% confidence interval 18-63). The 3- and 5-year PFS was 8% (95% confidence interval 3-22) and 0%, respectively. Higher lung-molGPA was associated with longer OS (hazard ratio 0.26, 95% confidence interval 0.11-0.61, P = 0.002). Higher lung-molGPA (hazard ratio 0.33, 95% confidence interval 0.15-0.71, P = 0.005) and lower N-stage (hazard ratio 1.56, 95% confidence interval 1.13-2.15, P = 0.007) were associated with longer PFS.

CONCLUSIONS

Definitive treatment of patients with NSCLC and SSBM staged with FDG-PET/CT can result in 5-year survivors, including those with ≥N1 disease.

Surgical approach in oligometastatic non-small cell lung cancer

The vast majority of lung cancer (80%) are non-small cell lung cancer (NSCLC) presenting in huge proportion of patients in a metastatic stage at the time of diagnosis with an overall survival (OS) of only 6 months. Standard treatment at this stage involves systemic platinum based chemotherapy improving the OS for only few months. For the vast majority of patients disease progression occurs and cure cannot achieved. An exception to this general rule is represented by patients with a limited number of metastasis (approximately 7% of patients with metastatic NSCLC): in 1995 Hellman and Weichselbaum introduced the term "oligometastatic" for a selected group of patients with metastatic disease. Several retrospective studies have been published and documented an improved outcome in patients managed surgically. The purpose of this narrative review is to gather all relevant information and present the various clinicopathological and generic aspects of diagnosis, management strategies and prognostic factors in patients with oligometastatic NSCLC. The key for long term survival includes radical treatment of the primary NSCLC, single organ site with either synchronous or metachronous presentation, a disease free interval to be as long as possible and the absence of intrathoracic lymph node spread (N0). A more accurate staging with combination of FDG-PET and CT scan can have on impact on the survival rates due to an increased accuracy in mediastinal staging and in the diagnosis of distant metastasis. No randomized data but only retrospective series are available to date to address this topic: in the future, additional prospective studies will be necessary to provide robust evidence to support the surgical resection as treatment of oligometastatic NSCLC.

Calculation Accuracy of Gross Tumor Volume at the Diaphragm Boundary Evaluated Using Respiratory-gated PET/CT

OBJECTIVE

The present study aimed to clarify gross tumor volume (GTV) contouring accuracy at the diaphragm boundary using respiratory-gated PET/CT.

METHODS

The lung/diaphragm boundary was simulated using a phantom containing ¹⁸F solution (10.6 kBq/mL). Tumors were simulated using spheres (diameter, 11-38 mm) containing ¹⁸F and located at the positions of the lungs and liver. The tumor background ratios (TBR) were 2, 4, and 8. The phantom was moved from the superior to inferior direction with a 20-mm motion displacement at 3.6 s intervals. The recovery coefficient (RC), volume RC (VRC), and standardized uptake value (SUV) threshold were calculated using stationary, non-gated (3D), and gated (4D) PET/CT.

RESULTS

In lung cancer simulation, RC and VRC in 3D PET images were, respectively, underestimated and overestimated in smaller tumors, whereas both improved in 4D PET images regardless of tumor size and TBR. The optimal SUV threshold was about 30% in 4D PET images. In liver cancer simulation, RC and VRC were, respectively, underestimated and overestimated in smaller tumors, and when the TBR was lower, but both improved in 4D PET images when tumors were >17 mm and the TBR was >4. The optimal SUV threshold tended to depend on the TBR.

CONCLUSIONS

The contouring accuracy of GTV was improved by considering TBR and using an optimal SUV threshold acquired from 4D PET images.

Surgical management of oligometastatic non-small cell lung cancer

The oligometastatic stage IV non-small cell lung cancer (NSCLC) offers a new surgical opportunity. New reported data is showing that surgery can offer a reasonable benefit, in terms of long-term survival, to some patients. The advantages of surgical treatment rely on a more adequate patient selection and a better understanding of the biology of these tumors. Currently, mediastinal involvement of the primary tumor can be identified as the most important prognostic variable after curative-intent of synchronous or metachronous metastasis. It seems clear that the routine use of combined FDG-PET and CT will help to detect the more favorable cohort of oligometastatic patients. As expected, pathological T staging of the primary tumor and the completeness of its resection are also crucial factors influencing final results. The real benefit of the local treatment over synchronous or metachronous metastasis is controversial with series showing better outcomes for metachronous lesions than for synchronous and others offering equal results. Also non conclusive results appear when analyzing different sites of metastasis. Retrospective series tend to show different outcomes depending on the affected organ while usually no differences are found in prospective ones. Most of the current evidence is based on retrospective studies on patients collected along extended periods of time. That represents a great limitation to the knowledge on this topic. Some prospective analyses have added some insight, but still the quality of the evidence is too low to allow drawing robust conclusions. As frequently concluded, prospective well designed investigation is requested to ascertain the value of surgery in this specific population of patients with extended NSCLC.

Value of Positron Emission Tomography/Computed Tomography (PET-CT) in Suspected Non-small Cell Lung Cancer Recurrence and Impact on Patient Management

INTRODUCTION

Positron emission tomography/computed tomography (PET-CT) is very sensitive for diagnosis of recurrent NSCLC and has a significant impact on change of management. Preliminary data suggest superiority of PET-CT comparing to CT alone for lung cancer restaging.

MATERIALS AND METHODS

This is a retrospective study which aim is to validate usage of PET-CT in suspected non-small cell lung carcinoma recurrence and its impact on further patient management. Total number of 31 patients with non-small cell lung carcinoma and uncertain diagnosis of recurrent disease or its extent after routine clinical and CT work-up were enrolled in this study.

DISCUSSION

We found in our study that PET-CT diagnosed recurrent disease in 65% of patients who were previously presented with an indeterminante CT. In 85% of patients there were change in further management.

CONCLUSION

We suggest that PET should be performed on patients who have suspected relapse after potentially curative treatment, particularly if active treatment is being considered. PET-CT improved the diagnosis of recurrent NSCLC and this resulted in a significant impact and change in further patient management.