[18F]FDG-PET/CT atypical response patterns to immunotherapy in non-small cell lung cancer patients: long term prognosis assessment and clinical management proposal.

AIM: To determine the long-term prognosis of immune-related response profiles (pseudoprogression and dissociated response), not covered by conventional PERCIST criteria, in patients with non-small-cell lung cancer (NSCLC) treated with immune checkpoint inhibitors (ICPIs). METHODS: 109 patients were prospectively included and underwent [18F]FDG-PET/CT at baseline, after 7 weeks (PETinterim1), and 3 months (PETinterim2) of treatment. On PETinterim1, tumor response was assessed using standard PERCIST criteria. In the event of PERCIST progression at this time-point, the study design provided for continued immunotherapy for 6 more weeks. Additional response patterns were then considered on PETinterim2: pseudo-progression (PsPD, subsequent metabolic response); dissociated response (DR, coexistence of responding and non-responding lesions), and confirmed progressive metabolic disease (cPMD, subsequent homogeneous progression of lesions). Patients were followed up for at least 12 months. RESULTS: Median follow-up was 21 months. At PETinterim1, PERCIST progression was observed in 60% (66/109) of patients and ICPI was continued in 59/66. At the subsequent PETinterim2, 14% of patients showed PsPD, 11% DR, 35% cPMD, and 28% had a sustained metabolic response. Median overall survival (OS) and progression-free-survival (PFS) did not differ between PsPD and DR (27 vs 29 months, p = 1.0; 17 vs 12 months, p = 0.2, respectively). The OS and PFS of PsPD/DR patients were significantly better than those with cPMD (29 vs 9 months, p < 0.02; 16 vs 2 months, p < 0.001), but worse than those with sustained metabolic response (p < 0.001). This 3-group prognostic stratification enabled better identification of true progressors, outperforming the prognostic value of standard PERCIST criteria (p = 0.03). CONCLUSION: [18F]FDG-PET/CT enables early assessment of response to immunotherapy. The new wsPERCIST ("wait and see") PET criteria proposed, comprising immune-related atypical response patterns, can refine conventional prognostic stratification based on PERCIST criteria. TRIAL REGISTRATION: HDH F20230309081206. Registered 20 April 2023. Retrospectively registered.

Performance and Clinical Impact of Radiomics and 3D-CNN Models for the Diagnosis of Neurodegenerative Parkinsonian Syndromes on 18F-FDOPA PET.

PURPOSE: The aim of this study was to compare the performance and added clinical value of a semiautomated radiomics model and an automated 3-dimensinal convolutional neural network (3D-CNN) model for diagnosing neurodegenerative parkinsonian syndromes on 18F-FDOPA PET images. PATIENTS AND METHODS: This 2-center retrospective study included 687 patients with motor symptoms consistent with parkinsonian syndrome. All patients underwent 18F-FDOPA brain PET scans, acquired on 3 PET systems from 2 different hospitals, and classified as pathological or nonpathological (by an expert nuclear physician). Artificial intelligence models were trained to replicate this medical expert's classification using 2 pipelines. The radiomics pipeline was semiautomated and involved manually segmenting the bilateral caudate and putamen nuclei; 43 radiomic features were extracted and combined using the support vector machine method. The deep learning pipeline was fully automatic and used a 3D-CNN model. Both models were trained on 417 patients and tested on an internal (n = 100) and an external (n = 170) test set. The final models' performance was evaluated using balanced accuracy and compared with that of a junior medical expert and nonexpert nuclear physician. RESULTS: On the internal test set, the 3D-CNN model outperformed the radiomic model with a balanced accuracy of 99% (vs 96%). It led to diagnostic performance similar to that of a junior medical expert (only 1 in 100 patients misclassified by both). On the external test set from a less experienced hospital, the 3D-CNN model allowed physicians to correctly reclassify the diagnosis of 10 out 170 patients (6%). CONCLUSIONS: The developed 3D-CNN model can automatically diagnose neurodegenerative parkinsonian syndromes, also reducing diagnostic errors by 6% in less-experienced hospitals.

Review of the PRIODAC project on thyroid protection from radioactive iodine by repeated iodine intake in individuals aged 12.

BACKGROUND: Intake of potassium iodide (KI) reduces the accumulation of radioactive iodine in the thyroid gland in the event of possible contamination by radioactive iodine released from a nuclear facility. The WHO has stated the need for research for optimal timing, appropriate dosing regimen and safety for repetitive iodine thyroid blocking (ITB). The French PRIODAC project, addressed all these issues, involving prolonged or repeated releases of radioactive iodine. Preclinical studies established an effective dose through pharmacokinetic modeling, demonstrating the safety of repetitive KI treatment without toxicity. SUMMARY: Recent preclinical studies have determined an optimal effective dose for repetitive administration, associated with pharmacokinetic modelling. The results show the safety and absence of toxicity of repetitive treatment with KI. Good laboratory practice level preclinical studies corresponding to individuals > 12 years have shown a safety margin established between animal doses without toxic effect. After approval from the French health authorities, the market authorization of the 2 tablets of KI-65mg/day was defined with a new dosing scheme of a daily repetitive intake of the treatment up to 7 days unless otherwise instructed by the competent authorities for all categories of population except pregnant women, and children under the age of 12 years. CONCLUSIONS: This new marketed authorization resulting from scientific-based evidence obtained as part of the PRIODAC project may serve as an example to further harmonize the application of KI for repetitive ITB in situations of prolonged radioactive release at the European and International levels, under the umbrella of the WHO.

Exploración del sistema nervioso central: estado del arte en metodología / Exploring the central nervous system: methodological state of the art

El análisis de la práctica clínica actual demuestra un desfase entre los desarrollos metodológicos publicados y la utilización que de ellos se hace en la práctica clínica. Esta revisión propone una descripción de algunos desarrollos recientes que están próximos a una mayor difusión a propósito de tres indicaciones clásicas: el diagnóstico de la enfermedad de Alzheimer, la evaluación de la neurotransmisión dopaminérgica y el estudio de la epilepsia. En la enfermedad de Alzheimer los métodos de estandarización espacial y la comparación con una base de datos normativa son más útiles en la medida que el observador es menos experimentado y las aproximaciones "orientadas a la rutina" más simples que el SPM parecen prometedoras. La cuantificación es lo esencial del estudio de la neurotransmisión dopaminérgica. La medición de los potenciales de unión está considerablemente sesgado por la penetración septal, la atenuación, la difusión y el efecto de volumen parcial. Es el efecto de volumen parcial que introduce el mayor error. Su corrección es difícil debido a que pasa por un corregisto con imágenes de resonancia magnética. Los resultados de esa corrección son muy sensibles a la precisión de dicho corregistro. El estudio de la epilepsia por sustracción de los SPECT ictal e interictal ha demostrado su valor clínico. Es una operación de fusión de imágenes para la cual los métodos ya están bien definidos.