Assessing Blood Supply Status Of Focal Ground-glass Opacity In Lung Using Spectral CT And Material Decomposition Analysis

Objective: To investigate the potential of using material decomposition analysis in spectral CT for the evaluation of blood supply status of ground-glass-opacity(GGO) in lungs and the differences of blood supply among different types of GGO or different subtypes of adenocarcinoma.Materials and Methods: 48 patients with lung adenocarcinoma, underwent contrast-enhanced spectral CT scan before treatment, with complete clinical data and clear pathologic diagnosis, were retrospectively analyzed(53 GGOs in total), including9 precancerous lesions, 9 minimally invasive lesions and 35 invasive carcinomas(among these, including 10 lepidic predominant adenocarcinoma, 22 acinar predominant adenocarcinoma,2 papillary predominant adenocarcinoma, 1 without new pathologic diagnosis). Iodine concentration(IC) and water content(WC) of GGO, the contralateral and ipsilateral normal lung tissue were measured in the arterial phase(AP);and their differences were analyzed using the SPSS 17.0 statistical software. IC values of GGO were further normalized to that of aorta. Repeated measurements were completed by the same radiologist after one month. Intraclass correlation coefficient(ICC) of IC and WC of GGO, the contralateral and ipsilateral normal lung tissue in the arterial phase was also calculated. IC, normalized IC and WC values were compared between p GGO and m GGO, and between the(preinvasive lesions + MIA) group and invasive adenocarcinoma group. To compare the difference of IC 、 normalized IC and WC valuesin the arterial phase between the lepidic predominant adenocarcinoma GGO group and acinar predominant adenocarcinoma GGO group. The correlation between GGO diameter and IC, normalized IC, WC values in arterial phase was also studied using Pearson rank correlation analysis.Results:1. The ICC value of IC in the arterial phase of the GGO lesion and the ipsilateral and contralateral normal pulmonary parenchyma was 0.956, 0.881, 0.910, respectively. The ICC value of WC in the arterial phase of the GGO lesion and the ipsilateral and contralateral normal pulmonary parenchyma was 0.948, 0.781, 0.640, respectively. The value of IC in the arterial phase had better consistency(all>0.881). The ICC value of IC and WC in the arterial phase for the GGO lesion also had better consistency(all>0.948).2. Differences of material decomposition between GGO and ipsilateral and contralateral normal pulmonary2.1 The IC of GGO in arterial phase(22.490±7.449mg/ml) was significantly higher than that of the ipsilateral and contralateral normal lung tissues(15.657±5.354,15.522±6.026mg/ml)(p=0.000, p=0.000). There was not significantly difference for IC in the arterial phase between ipsilateral and contralateral normal lung tissues(p=0.773).WC of GGO in arterial phase(488.333±170.284mg/ml) was significantly higher than that of the ipsilateral and contralateral normal lung tissues(163.522±39.376,166.376±39.700mg/ml)(p=0.000, p=0.000). There was not significantly difference for WC between ipsilateral and contralateral normal lung tissues(p=0.837).2.2 IC of p GGO in arterial phase(20.947±6.152mg/ml) was significantly higher than that of the ipsilateral and contralateral normal lung tissues(14.988±4.931, 15.074±6.163mg/ml)(p=0.000, p=0.000). There was not significantly difference for IC between ipsilateral and contralateral normal lung tissues(p=0.958).WC of p GGO in arterial phase(345.148±87.093mg/ml) was significantly higher than that of the ipsilateral and contralateral normal lung tissues(156.351±36.839,156.324±38.786mg/ml)(p=0.000, p=0.000). There was not significantly difference of WC between ipsilateral and contralateral normal lung tissues(p=0.998).2.3 IC of m GGO in arterial phase(23.767±8.260mg/ml) was significantly higher than that of the ipsilateral and contralateral normal lung tissues(16.211±5.707,15.893±5.994mg/ml)(p=0.000, p=0.000). There was not significantly difference for IC between ipsilateral and contralateral normal lung tissues(p=0.567).WC of m GGO in arterial phase(606.831±124.514 mg/ml) was significantly higher than that of the ipsilateral and contralateral normal lung tissues(169.457±41.037,174.694±39.154mg/ml)(p=0.000, p=0.000). There was not significantly difference for WC between ipsilateral and contralateral normal lung tissues(p=0.621).3. Differences of material decompositionbetween different types of GGO There was significantly difference for normalized IC(0.158, 0.132) and WC in the arterial phase between the p GGO group and m GGO group(p=0.049, 0.000). No significantly difference for IC was found between the p GGO group and m GGO group(p=0.161).4. Differences of material decomposition between different histology No significantly difference for IC(21.321±5.571 mg/ml, 23.093±8.012 mg/ml),normalized IC(0.130, 0.155) was found between the(preinvasive and MIA) group and invasive adenocarcinoma group(p=0.447, p=0.058). But there was some tendency for normalized IC. WC of invasive adenocarcinoma group(553.210±162.068 mg/ml) is significantly higher than(Preinvasive and MIA) group(362.183±103.189 mg/ml)(p=0.000).5. Differences of material decomposition between different subtypes of adenocarcinoma In total GGO cases, the normalized IC of acinar group(0.167) was significantly higher than lepidic group(0.124)(p=0.013). In m GGO cases, the normalized IC of acinar group(0.183) was significantly higher than lepidic group(0.131)(p=0.003). In p GGO cases, no significantly difference for normalized IC was found between the acinar group and lepidic group(p=0.606), but average normalized IC in acinar group(0.130) was higher than lepidic group(0.103).No significantly difference for IC and WC in total GGO cases, m GGO cases and p GGO cases was found between the acinar group and lepidic group(p=0.111, p=0.716;p=0.548,p= 0.905; p=0.124, p=0.877).6. Correlation between material decomposition of GGO and diameter There was a negative correlation between IC values in arterial phase and diameters in p GGO cases(p=0.019, r=-4.75). There was no correlation between normalized IC or WC values and diameters in p GGO cases(p=0.070, p=0.553). There was no correlation between IC, normalized IC, WC values and diameters in m GGO cases(p=0.496,p=0.678, p=0.119).Conclusion:1. We firstly put forward spectral CT and quantitatively material decomposition analysis could be indicative of the blood supply status in the GGO and used to different diagnosis among different types of GGO. This methods could also provide a new way and idea for future research of GGO cases.2. We firstly put forward spectral CT and quantitatively material decomposition analysis couldbe indicative of the difference of blood supply status among subtypes of lung adenocarcinoma, which could be helpful to prognosis and further study of GGO cases.