Assessing the Blood Supply Status of the Focal Ground-Glass Opacity in Lungs Using Spectral Computed Tomography

Objective: To exploit material decomposition analysis in dual-energy spectral computed tomography (CT) to assess the blood supply status of the ground-glass opacity (GGO) in lungs. Materials and Methods: This retrospective study included 48 patients with lung adenocarcinoma, who underwent a contrast-enhanced dual-energy spectral CT scan before treatment (53 GGOs in total). The iodine concentration (IC) and water content (WC) of the GGO, the contralateral and ipsilateral normal lung tissues were measured in the arterial phase (AP) and their differences were analyzed. IC, normalized IC (NIC), and WC values were compared between the pure ground-glass opacity (pGGO) and the mixed ground-glass opacity (mGGO), and between the group of preinvasive lesions and the minimally invasive adenocarcinoma (MIA) and invasive adenocarcinoma (IA) groups. Results: The values of pGGO ($IC=20.9{\pm}6.2mg/mL$ and $WC=345.1{\pm}87.1mg/mL$) and mGGO ($IC=23.8{\pm}8.3mg/mL$ and $WC=606.8{\pm}124.5mg/mL$) in the AP were significantly higher than those of the contralateral normal lung tissues ($IC=15.0{\pm}4.9mg/mL$ and $WC=156.4{\pm}36.8mg/mL$; $IC=16.2{\pm}5.7mg/mL$ and $WC=169.4{\pm}41.0mg/mL$) and ipsilateral normal lung tissues ($IC=15.1{\pm}6.2mg/mL$ and $WC=156.3{\pm}38.8mg/mL$; $IC=15.9{\pm}6.0mg/mL$ and $WC=174.7{\pm}39.2mg/mL$; all p < 0.001). After normalizing the data according to the values of the artery, pGGO (NIC = 0.1 and $WC=345.1{\pm}87.1mg/mL$) and mGGO (NIC = 0.2 and $WC=606.8{\pm}124.5mg/mL$) were statistically different (p = 0.049 and p < 0.001, respectively), but not for the IC value (p = 0.161). The WC values of the group with preinvasive lesions and MIA ($345.4{\pm}96.1mg/mL$) and IA ($550.1{\pm}158.2mg/mL$) were statistically different (p < 0.001). Conclusion: Using dual-energy spectral CT and material decomposition analysis, the IC in GGO can be quantitatively measured which can be an indicator of the blood supply status in the GGO.