The Advantage of Digital Tomosynthesis for Pulmonary Nodule Detection concerning Influence of Nodule Location and Size: Phantom Study

Abstract

Purpose: To investigate the advantage of DT over chest radiography (CXR) and dual-energy subtraction radiography (DES) for pulmonary nodule detection according to the location and size of simulated pulmonary nodule (SPN)

Material and Methods: Four different sizes (5, 8, 10 and 12 mm in a diameter) of SPNs (1~4 nodules/1 exam) were inserted into 8 different area of lung phantom classified as danger or non-danger zone. All 96 cases in which SPNs were inserted underwent examinations of 3 modalities at the same time. Additional 96 examinations were done to serve as a normal control using the same thoracic phantom. Finally, a total of 192 examinations were prepared for each set of modality. Three sets of image data were randomly arranged and three observers independently reviewed all images in a random order. Three observers were asked to identify nodule and score confidence with 4 scales. Also asked to record interpretation time. The jackknife alternative free-response receiver operating characteristic (JAFROC) was used to analyze overall diagnostic performance for each modality. The lesion localization fraction (LLF) and non-lesion localization fraction (NLF) were determined and compared among three modalities classified by size and location of nodule.

Result: JAFROC analyses revealed DT was superior to CXR and DES for the detection of SPN regardless of location and size of nodule (p<0.01). The observer-averaged figure of merit was 0.78, 0.77 and 0.95 for CXR, DES, and DT, respectively. The LLFs of all modalities were higher in non-danger zone than those of danger zone for the detection of SPNs. In case of 10 and 12 mm nodules, CXR and DES showed no significant difference of performance with DT for detection in non-danger zone. However, DT was superior to CXR and DES for detection of those nodules in danger zone. In the task for detection of 5 and 8 mm nodules, DT showed significant superior performance than CXR and DES regardless of nodule locations.

Conclusion: DT significantly improved the diagnostic performance to detect SPN compared with CXR and DES, especially boosts its ability for larger nodules (10, 12 mm) located in danger zone and smaller nodules (5, 8 mm) in any location.