Dual-layer spectral detector CT electron density imaging: impressive technology for imaging characteristics of ground-glass nodules.

Background: Pulmonary ground-glass nodules (GGNs) are increasingly being detected as manifestations of early lung cancer. However, conventional computed tomography (CT) images may fail to clearly show small lesion details, particularly in the case of small, low-density GGNs, which are often difficult to observe. Limited evidence suggests that dual-layer spectral detector CT (SDCT) electron density imaging (EDI) improves the visualization of ground-glass opacities (GGOs) and increases the detection rate of mixed GGNs (mGGNs). This study aimed to evaluate the clinical value of SDCT EDI reconstruction images in detecting pulmonary GGNs by comparing them with conventional CT images of different reconstruction slice thicknesses.

Methods: The SDCT data of 27 patients with GGNs, including pure GGNs (pGGNs) and mGGNs, were included in both the EDI and conventional CT groups. The images were reconstructed using thin 1 mm, 3 mm minimum intensity projection (MinIP), and 5 mm maximum intensity projection (MIP). Two radiologists, each with over 10 years of experience, subjectively assessed the morphological signs and image quality of the lesions. Additionally, the clinical value of the images was evaluated by another 20 thoracic surgeons and radiologists through a six-item questionnaire.

Results: The results showed that lobulation (P<0.001), spiculation (P=0.029), tumor-lung interface (P<0.001), and solid components (P=0.003) was significantly more prominent in electron density (ED) images. Conversely, the vacuole sign (P=0.016) was more apparent in conventional CT images. Neither the pleural indentation sign (P=0.429) nor the vessel crossing sign (P=0.227) showed statistically significant differences between the groups. The subjective image quality of lung structures study found that image noise suppression and artifact reduction were significantly greater in ED images (P<0.001). Conventional CT images demonstrated sharper visual reproduction of lung parenchyma, lung vessels and fissures, lung-thorax wall, and the pleuro-mediastinal border (P<0.001). In clinical evaluations of the value of conventional CT and ED reconstruction images, ED images showed significant advantages in defining the tumor-lung boundary, confirming solid components, measuring the size and solid portions, making a definitive diagnosis, choosing treatment options, increasing confidence in treatment decisions, facilitating multidisciplinary consultations, and reducing time (P<0.001).

Conclusions: SDCT EDI is an effective method for the differential diagnosis of benign and malignant GGNs. It provides clearer image features, particularly in terms of the lobulation and the tumor-lung interface and solid components, helping radiologists and thoracic surgeons to make more accurate diagnostic and treatment decisions.