The purpose of this multi-centric work was to investigate the relationship between radiomic features extracted from pre-treatment computed tomography (CT), positron emission tomography (PET) imaging, and clinical outcomes for stereotactic body radiation therapy (SBRT) in early-stage non-small cell lung cancer (NSCLC). One-hundred and seventeen patients who received SBRT for early-stage NSCLC were retrospectively identified from seven Italian centers. The tumor was identified on pre-treatment free-breathing CT and PET images, from which we extracted 3004 quantitative radiomic features. The primary outcome was 24-month progression-free-survival (PFS) based on cancer recurrence (local/non-local) following SBRT. A harmonization technique was proposed for CT features considering lesion and contralateral healthy lung tissues using the LASSO algorithm as a feature selector. Models with harmonized CT features (B models) demonstrated better performances compared to the ones using only original CT features (C models). A linear support vector machine (SVM) with harmonized CT and PET features (A1 model) showed an area under the curve (AUC) of 0.77 (0.63–0.85) for predicting the primary outcome in an external validation cohort. The addition of clinical features did not enhance the model performance. This study provided the basis for validating our novel CT data harmonization strategy, involving delta radiomics. The harmonized radiomic models demonstrated the capability to properly predict patient prognosis.

Background: ¹⁸F-FDG PET/CT imaging allows to study oncological patients and their relative diagnosis through the standardised uptake value (SUV) evaluation. During radiopharmaceutical injection, an extravasation event may occur, making the SUV value less accurate and possibly leading to severe tissue damage. The study aimed to propose a new technique to monitor and manage these events, to provide an early evaluation and correction to the estimated SUV value through a SUV correction coefficient. Methods: A cohort of 70 patients undergoing ¹⁸F- FDG PET/CT examinations was enrolled. Two portable detectors were secured on the patients' arms. The dose-rate (DR) time curves on the injected DRⁱⁿ and contralateral DR^con arm were acquired during the first 10 min of injection. Such data were processed to calculate the parameters Δpⁱⁿ_NOR = (DRⁱⁿ_max- DRⁱⁿ_mean)/DRⁱⁿ_max and ΔR_t = (DRⁱⁿ(t) − DR^con(t)), where DRⁱⁿ_max is the maximum DR value, DRⁱⁿ_mean is the average DR value in the injected arm. OLINDA software allowed dosimetric estimation of the dose in the extravasation region. The estimated residual activity in the extravasation site allowed the evaluation of the SUV's correction value and to define an SUV correction coefficient. Results: Four cases of extravasations were identified for which ΔR_t [(390 ± 26) µSv/h], while ΔR_t [(150 ± 22) µSv/h] for abnormal and ΔR_t [(24 ± 11) µSv/h] for normal cases. The Δpⁱⁿ_NOR showed an average value of (0.44 ± 0.05) for extravasation cases and an average value of (0.91 ± 0.06) and (0.77 ± 0.23) in normal and abnormal classes, respectively. The percentage of SUV reduction (SUV_%CR) ranges between 0.3% and 6%. The calculated self-tissue dose values range from 0.027 to 0.573 Gy, according to the segmentation modality. A similar correlation between the inverse of Δpⁱⁿ_NOR and the normalised ΔR_t with the SUV correction coefficient was found. Conclusions: The proposed metrics allowed to characterised the extravasation events in the first few minutes after the injection, providing an early SUV correction when necessary. We also assume that the characterisation of the DR-time curve of the injection arm is sufficient for the detection of extravasation events. Further validation of these hypotheses and key metrics is recommended in larger cohorts.

Background¹⁸F-FDG PET/CT imaging allows to study oncological patients and their relative diagnosis through the Standardized Uptake Value (SUV) evaluation. During radiopharmaceutical injection, an extravasation event may occur, making the SUV value less accurate and possibly leading to severe tissue damage. The aim of the study was to propose a new technique to monitor and manage these events, in order to evaluate a correction to the calculated SUV value. Methods A cohort of 70 patients undergoing¹⁸F- FDG PET/CT exams was enrolled. Two portable detectors were secured on the patients' arms. The dose-rate (DR) time curves on the injected DRⁱⁿand contralateral DR^conarm were acquired during the first 10 minutes of injection. Such data were processed to calculate the parameters Δpⁱⁿ_NOR= (DRⁱⁿ_max- DRⁱⁿ_mean)/ DRⁱⁿ_maxand ΔR_t= (DRⁱⁿ(t) - DR^con(t)), where DRⁱⁿ_maxis the maximum DR value, DRⁱⁿ_meanis the average DR value in the injected arm. OLINDA software allowed dosimetric estimation of the dose in the extravasation region. The estimated residual activity in the extravasation site allowed the evaluation of the SUV's correction value and to define an SUV correction coefficient. Results Four cases of extravasations were identified for which ΔR_t[(390 ± 26) µSv/h], while ΔR_t[(150 ± 22) µSv/h] for abnormal and ΔR_t[(24 ± 11) µSv/h] for normal cases. The Δpⁱⁿ_NORshowed an average value of 0.44 for extravasation cases and an average value of (0.91 ± 0.06) and (0.77 ± 0.23) in normal and abnormal classes, respectively. The percentage of SUV reduction (SUV_%CR) ranges between 0.3% and 6%. The calculated self-tissue dose values range from 0.027 Gy to 0.573 Gy, according to the segmentation modality. A similar correlation between the inverse of Δpⁱⁿ_NORand the normalised ΔR_twith the SUV correction coefficient was found. Conclusions The proposed metrics allowed to characterised the extravasation events in the first few minutes after the injection, providing an SUV correction when necessary. We also assume that the characterization of the DR-time curve of the injection arm is sufficient for the detection of extravasation events. Further validation of these hypotheses and key metrics is recommended in larger cohorts.