Rapid Contour-based Segmentation for 18F-FDG PET Imaging of Lung Tumors by Using ITK-SNAP: Comparison to Expert-based Segmentation.

Purpose To assess the performance of the ITK-SNAP software for fluorodeoxyglucose (FDG) positron emission tomography (PET) segmentation of complex-shaped lung tumors compared with an optimized, expert-based manual reference standard. Materials and Methods Seventy-six FDG PET images of thoracic lesions were retrospectively segmented by using ITK-SNAP software. Each tumor was manually segmented by six raters to generate an optimized reference standard by using the simultaneous truth and performance level estimate algorithm. Four raters segmented 76 FDG PET images of lung tumors twice by using ITK-SNAP active contour algorithm. Accuracy of ITK-SNAP procedure was assessed by using Dice coefficient and Hausdorff metric. Interrater and intrarater reliability were estimated by using intraclass correlation coefficients of output volumes. Finally, the ITK-SNAP procedure was compared with currently recommended PET tumor delineation methods on the basis of thresholding at 41% volume of interest (VOI; VOI41) and 50% VOI (VOI50) of the tumor's maximal metabolism intensity. Results Accuracy estimates for the ITK-SNAP procedure indicated a Dice coefficient of 0.83 (95% confidence interval: 0.77, 0.89) and a Hausdorff distance of 12.6 mm (95% confidence interval: 9.82, 15.32). Interrater reliability was an intraclass correlation coefficient of 0.94 (95% confidence interval: 0.91, 0.96). The intrarater reliabilities were intraclass correlation coefficients above 0.97. Finally, VOI41 and VOI50 accuracy metrics were as follows: Dice coefficient, 0.48 (95% confidence interval: 0.44, 0.51) and 0.34 (95% confidence interval: 0.30, 0.38), respectively, and Hausdorff distance, 25.6 mm (95% confidence interval: 21.7, 31.4) and 31.3 mm (95% confidence interval: 26.8, 38.4), respectively. Conclusion ITK-SNAP is accurate and reliable for active-contour-based segmentation of heterogeneous thoracic PET tumors. ITK-SNAP surpassed the recommended PET methods compared with ground truth manual segmentation.

A Patient-Centered Model of Fast-Track Lung Cancer Diagnosis.

INTRODUCTION: Despite the increasing importance of digital resources in modern life over the past decades, little is known about the impact of internet-based solutions on patient's health. We aimed to study the potential benefit of a digital platform helping patients to deal with abnormal chest CT scan revealing possible lung cancer. METHODS: We set up a fast-track lung cancer diagnosis pathway through a secure online platform. Patient-generated information combined with online review of their imaging enables preplanning of further investigations ahead of clinical assessment. We compared outcomes of "self-referred" patients (patient group), who directly fill out the online questionnaire, to general practitioner-driven patients (GP group), who were referred by their GP. RESULTS: From June 2021 to June 2022, we included 125 patients (61% males, median age 67 years, IQR 56.9-72.5): 41% in the patient group and 59% in the GP group. No difference was found between groups in terms of time from contact to first appointment (median 5 days in both groups, P = .6), percentage of pathways including prebooked tests (94% vs. 92%, P = .6), number of scheduled invasive procedures (median 1, IQR 1-2 vs. 2, IQR 1-2, P = .4) and in final cancer diagnosis (76% vs. 78%, P = .4). CONCLUSION: A lung cancer diagnosis pathway directly accessible by patients through a secure online platform was feasible and as efficient as the usual general practitioner pathway. It demonstrated the benefit of leaning on new digital tools in order to answer to the new challenges of a patient-centered health care system.

Prognostic value of early 18F-FDG PET scanning evaluation in immunocompetent primary CNS lymphoma patients.

Primary central nervous system lymphoma (PCNSL) is a rare topographic variant of diffuse large B-cell lymphoma (DLBCL). While prognostic scales are useful in clinical trials, no dynamic prognostic marker is available in this disease. We report here the prognostic value of early metabolic response by 18F-FDG PET scanner (PET) in 25 newly diagnosed immunocompetent PCNSL patients. Induction treatment consisted of four cycles of Rituximab, Methotrexate and Temozolamide (RMT). Based on patient's general condition, consolidation by high-dose Etoposide and Aracytine was given to responding patients. Brain MRI and PET were performed at diagnosis, after two and four cycles of RMT, and after treatment completion. Two-year progression-free (PFS) and overall survival (OS) were 62% and 74%, respectively for the whole cohort. Best responses after RMT induction were 18 (72%) complete response (CR)/CR undetermined (CRu), 4 (16%) partial response, 1 (4%) progressive disease and 2 (8%) stable disease. Response evaluation was concordant between MRI and PET at the end of induction therapy. Nineteen patients (76%) had a negative PET2. Predictive positive and negative values of PET2 on end-of-treatment (ETR) CR were 66.67% and 94.74%, respectively. We observed a significant association between PET2 negativity and ETR (p = 0.001) and longer PFS (p = 0.02), while having no impact on OS (p = 0.32). Two years PFS was 72% and 33% for PET2- and PET2+ patients, respectively (p < 0.02). PET2 evaluation may help to early define a subgroup of CR PCNSL patients with a favorable outcome.

Persistent foreign body reaction around inguinal mesh prostheses: a potential pitfall of FDG PET.

OBJECTIVE: FDG PET has been recognized as an efficient imaging technique for the treatment of oncology patients. However, false-positive results can occur. The purpose of this study is to describe three oncology patients with persistent FDG up-take around inguinal mesh prostheses that occurred up to 10 years after the surgical repair of inguinal hernias and led to false-positive results. CONCLUSION: Remote mesh prostheses can induce FDG uptake because of persistent foreign body reaction. Consequently, each time an unexpected pelvic focus is noticed on FDG PET, the medical history of patients should be carefully reviewed to avoid false-positive results.