Performance of Lung Nodule Computer-Aided Detection Systems on Standard-Dose and Low-Dose Pediatric CT Scans: An Intraindividual Comparison

BACKGROUND. When lung nodule computer-aided detection (CAD) systems are applied for pediatric CT, performance may be degraded on low-dose scans due to increased image noise. OBJECTIVE. The purpose of this study was to conduct an intraindividual comparison of the performance for lung nodule detection of two CAD systems trained using adult data between low-dose and standard-dose pediatric chest CT scans. METHODS. This retrospective study included 73 patients (32 female participants, 41 male participants; mean age, 14.7 years; age range, 4-20 years) who underwent both clinical standard-dose and investigational low-dose chest CT examinations during the same encounter from November 30, 2018, to August 31, 2020, as part of an earlier prospective study. Fellowship-trained pediatric radiologists annotated lung nodules to serve as the reference standard. Both CT scans were processed using two publicly available lung nodule CAD systems previously trained using adult data: FlyerScan (github.com/rhardie1/FlyerScanCT) and Medical Open Network for Artificial Intelligence (MONAI; github.com/Project-MONAI/model-zoo/releases). The sensitivities of the two CAD systems for nodules measuring 3-30 mm (n = 247) were calculated when operating at a fixed frequency of two false-positives per scan. RESULTS. FlyerScan exhibited detection sensitivities of 76.9% (190/247; 95% CI, 73.3-80.8%) on standard-dose scans and 66.8% (165/247; 95% CI, 62.6-71.5%) on low-dose scans. MONAI exhibited detection sensitivities of 67.6% (167/247; 95% CI, 61.5-72.1%) on standard-dose scans and 62.3% (154/247; 95% CI, 56.1-66.5%) on low-dose scans. The number of detected nodules for standard-dose versus low-dose scans for 3-mm nodules was 33 versus 24 (FlyerScan) and 16 versus 13 (MONAI), 4-mm nodules was 46 versus 42 (FlyerScan) and 39 versus 30 (MONAI), 5-mm nodules was 38 versus 33 (FlyerScan) and 32 versus 31 (MONAI), and 6-mm nodules was 27 versus 20 (FlyerScan) and 24 versus 24 (MONAI). For nodules measuring 7 mm or larger, detection did not show a consistent pattern between standard-dose and low-dose scans for either system. CONCLUSION. Two lung nodule CAD systems showed decreased sensitivity on low-dose versus standard-dose pediatric CT scans obtained in the same patients. The reduced detection at low dose was overall more pronounced for nodules measuring less than 5 mm. CLINICAL IMPACT. Caution is needed when using low-dose CT protocols in combination with CAD systems to help detect small lung nodules in pediatric patients.