Detection of pulmonary nodules by C-arm CT using a phantom lung: comparison with CT

Background: Evaluation of detection of lung nodules by C-arm CT (CACT) is important before this procedure can be used to guide percutaneous lung interventions. Purpose: To compare the efficacy of CACT with CT in the detection of pulmonary nodules using a phantom lung. Material and Methods: A phantom lung containing 12 phantom nodules in four sizes (5 mm/8 mm/10 mm/12 mm) and three CT values (one solid nodule, +100 HU; two ground glass nodules, -630 and -800 HU) was used. Six sessions of CACT (slice thickness 4.5 mm) and CT (slice thickness 5 mm) were performed. In each session, the locations of nodules were arbitrarily changed in the phantom. Three radiologists assessed the detection of a total of 72 nodules. Statistical analysis was performed for the sensitivity and positive predictive value of lung nodules between CACT and CT by the McNemar test and paired t-test (P < 0.05). Results: Sensitivity did not differ between CACT and CT, respectively (reader 1, 82% vs. 88%, P = 0.22; reader 2, 82% vs. 78%, P = 0.37; reader 3, 79% vs. 83%, P = 0.48). For nodules of 8 mm or larger, the sensitivity increased for each reader and showed no significant difference between CACT vs. CT. The positive predictive value did not differ between CACT and CT. Conclusion: In this phantom study, CT and CACT show similar sensitivity for the detection of pulmonary nodules. CACT could be used in percutaneous interventional procedures in the lungs.