Automatic Scan Range Delimitation in Chest CT Using Deep Learning

Purpose: To develop and evaluate fully automatic scan range delimitation for chest CT by using deep learning. Materials and Methods: For this retrospective study, scan ranges were annotated by two expert radiologists in consensus in 1149 (mean age, +/- 5 years +/- 16 [standard deviation]; 595 male patients) chest CT topograms acquired between March 2002 and February 2019 (350 with pleural effusion, 376 with atelectasis, 409 with neither, 14 with both). A conditional generative adversarial neural network was trained on 1000 randomly selected topograms to generate virtual scan range delimitations. On the remaining 149 topograms the software-based scan delimitations, scan lengths, and estimated radiation exposure were compared with those from clinical routine. For statistical analysis an equivalence test (two one-sided t tests) was used, with equivalence limits of 10 mm. Results: The software-based scan ranges were similar to the radiologists' annotations, with a mean Dice score coefficient of 0.99 +/- 0.01 and an absolute difference of 1.8 mm +/- 1.9 and 3.3 mm +/- 5.6 at the upper and lower boundary, respectively. An equivalence test indicated that both scan range delimitations were similar (P < .001). The software-based scan delimitation led to shorter scan ranges compared with those used in clinical routine (298.2 mm +/- 32.7 vs 327.0 mm +/- 42.0; P,.001), resulting in a lower simulated total radiation exposure (3.9 mSv +/- 3.0 vs 4.2 mSv +/- 3.3; P < .001). Conclusion: A conditional generative adversarial neural network was capable of automating scan range delimitation with high accuracy, potentially leading to shorter scan times and reduced radiation exposure. (C)RSNA, 2021