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

Abstract

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 ± 6.2 mg/mL and WC = 345.1 ± 87.1 mg/mL) and mGGO (IC = 23.8 ± 8.3 mg/mL and WC = 606.8 ± 124.5 mg/mL) in the AP were significantly higher than those of the contralateral normal lung tissues (IC = 15.0 ± 4.9 mg/mL and WC = 156.4 ± 36.8 mg/mL; IC = 16.2 ± 5.7 mg/mL and WC = 169.4 ± 41.0 mg/mL) and ipsilateral normal lung tissues (IC = 15.1 ± 6.2 mg/mL and WC = 156.3 ± 38.8 mg/mL; IC = 15.9 ± 6.0 mg/mL and WC = 174.7 ± 39.2 mg/mL; all p < 0.001). After normalizing the data according to the values of the artery, pGGO (NIC = 0.1 and WC = 345.1 ± 87.1 mg/mL) and mGGO (NIC = 0.2 and WC = 606.8 ± 124.5 mg/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 ± 96.1 mg/mL) and IA (550.1 ± 158.2 mg/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.

Keywords: Blood supply; Dual-energy; Ground-glass nodule; Lung adenocarcinoma; Multidetector computed tomography; Spectral CT.

Fig. 1. Comparison of IC between GGO lesions and normal lung tissue.

A. Comparison of IC between pGGO lesions and normal lung tissue in AP. B. Comparison of IC between mGGO lesions and normal lung tissue in AP. AP = arterial phase, IC = iodine concentration, mGGO = mixed ground-glass opacity, pGGO = pure ground-glass opacity

Fig. 2. Difference of NIC between pGGO group and mGGO group in AP.

NIC = normalized iodine concentration

Fig. 3. Difference of WC between pGGO and mGOO (or precancerous lesions + MIA) groups and invasive adenocarcinoma group.

MIA = minimally invasive adenocarcinoma, WC = water content

Fig. 4. Dual-energy spectral CT scan of 64-year-old female patient with pathologically verified highly differentiated adenocarcinoma.

A. HRCT image manifested as pGGO in right lower lung (arrow). B. Thin dual-energy spectral CT plain scan (lung window). C. IC image of dual-energy spectral CT in AP. IC of lesion (15.5 mg/mL) was higher than that of contralateral and ipsilateral normal lung tissuse (13.3 mg/mL, 5.40 mg/mL). D. WC image of dual-energy spectral CT in AP. WC of lesion (301.8 mg/mL) was higher than that of contralateral and ipsilateral normal lung tissues (167.0 mg/mL, 125.1 mg/mL). HRCT = high-resolution computed tomography

Fig. 5. Dual-energy spectral CT study of 56-year-old female patient with pathologically verified highly differentiated adenocarcinoma.

A. HRCT image manifested as mGGO in frontal segment of right upper lobe (arrow). B. Thin dual-energy spectral CT plain scan (lung window). C. IC image of dual-energy spectral CT in AP. IC of lesion (20.7 mg/mL) was higher than that of contralateral and ipsilateral normal lung tissues (17.6 mg/mL, 18.9 mg/mL). D. WC image of dual-energy spectral CT in AP. WC of lesion (567.7 mg/mL) was higher than that of contralateral and ipsilateral normal lung tissues (146.9 mg/mL, 183.3 mg/mL).