[Differences of Energy Spectrum CT Findings between Small Cell Lung Cancer with Mediastinal Lymph Node Metastasis and Mediastinal Sarcoidosis].

Objective To compare the differences of energy spectrum CT between small cell lung cancer(SCLC)with mediastinal lymph node metastasis and mediastinal sarcoidosis.Methods Twenty-five SCLC patients with mediastinal lymph node metastasis(SCLC group)and 26 patients with mediastinal sarcoidosis(sarcoidosis group)confirmed by bronchoscopy and biopsy in Tangshan People's Hospital from January 2018 to June 2019 were selected as the research objects.The CT value,iodine concentration,water concentration and energy spectrum curve slope under different single energy levels were compared between SCLC group and sarcoidosis group.Results The single-energy CT values of 40-80 keV segments in the arterial phase of the SCLC group were significantly higher than those in the sarcoidosis group(all P <0.05).The single-energy CT values of 90-140 keV segments were not significantly different from those in the sarcoidosis group(all P >0.05).The single-energy CT values of 40-90 keV segments in venous phase of the SCLC group were significantly higher than those of the sarcoidosis group(all P <0.05),and the single-energy CT values of 100-140 keV segments were not significantly different from those of the sarcoidosis group(all P >0.05).The concentrations of iodine in the arterial phase and venous phase of the SCLC group were(11.56±4.06)µg/cm 3 and(13.39±0.87)µg/cm 3,respectively,which were significantly higher than those [(4.43±3.85)µg/cm 3,t=11.564,P=0.026;(7.23±2.71)µg/cm 3,t=13.653,P=0.021] in the sarcoidosis group.The concentrations of water in the arterial and venous phases of the SCLC group were(1040.67±5.62)mg/cm 3 and(1035.23±8.57)mg/cm 3,respectively,which showed no statistically significant difference compared with those [(1028.87±6.94)mg/cm 3,t=3.155,P=1.861;(1021.53±4.68)mg/cm 3,t=3.265,P=1.687] in the sarcoidosis group.The slopes of energy spectrum curve at 40-70 keV,70-100 keV and 100-140 keV in venous phase of the SCLC group were significantly higher than those of the sarcoidosis group(all P <0.05),whereas they showed no significant difference between the two groups in arterial phase(all P >0.05).Conclusion The differences between SCLC with mediastinal lymph node metastasis and mediastinal sarcoidosis can be shown on the single-energy CT values of 40-80 keV in arterial phase and 40-90 keV in venous phase,iodine concentrations in arterial phase and venous phase,and the slope of energy spectrum curve in venous phase.

[Different Energy Spectrum CT Findings between Anterior Mediastinal Lymphoma and Thymic Carcinoma].

Objective To investigate the differences in energy spectrum CT findings between anterior mediastinal lymphoma and thymic carcinoma. Methods Twenty-two cases of anterior mediastinal lymphoma and 28 cases of thymic carcinoma confirmed by biopsy in Tangshan People's Hospital were selected.The CT values and changes of iodine content and water content in lesion sites were measured by energy spectrum analysis software.The differences between anterior mediastinal lymphoma and thymic carcinoma were compared. Results The single-energy CT value of 40-80 keV in thymus carcinoma was higher than that in anterior mediastinal lymphoma(P=0.001,P=0.037,P=0.042,P=0.034,P=0.002;P=0.016,P=0.013,P=0.018,P=0.024,P=0.012).The difference in the single-energy CT value of 90-110 keV between anterior mediastinal lymphoma and thymic carcinoma showed no statistical significance(all P>0.05).The concentrations of water in the arterial and venous stages of thymic carcinoma were significantly lower than those in the anterior mediastinal lymphoma(P=0.030,P=0.037),whereas the iodine concentrations were significantly higher(P=0.026,P=0.000). Conclusion Anterior mediastinal lymphoma and thymic carcinoma have remarkably different 40-80 keV single energy CT value and iodine concentration in arterial and venous phases,which may be helpful for the differential diagnosis of these two malignancies.

Evaluation of high-pitch flash scan for pulmonary venous CTA on a 128-slice dual source CT: compared with prospective ECG-triggered sequence scan.

To compare the image quality (IQ) and radiation dose of high-pitch scan and prospective ECG-triggered sequence scan on a 128-slice DSCT system for patients with atrial fibrillation (AF). Pulmonary venous (PV) CTA was performed with two protocols, including high-pitch scan and prospective ECG-triggered sequence scan. For each protocol, 20 sex, age and body-mass-index (mean 24.2 kg/m(2)) matched patients were identified. Two experienced radiologists, who were blinded to the scan protocols, independently graded the CT images of the two groups by a 5-point scale for subjective IQ assessment. Measured CT attenuation (Hounsfield units ± standard deviation), signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) at various anatomic locations were also recorded for objective IQ evaluation. Radiation exposure parameters [dose length product (DLP) and effective radiation dose (ERD)] were compared. Twenty-three patients (57.5 %) showed an ECG pattern of AF in total. Subjective IQ was rated excellent in 100 % for the high-pitch scan group, while minor step artifacts were observed in two patients (10 %) with arrhythmia for the prospective ECG-triggered sequence group. There was no significant difference on IQ, neither by subjective, nor by objective measures (SNR, CNR) between the two groups. The ERD of high-pitch flash scan and prospective ECG-triggered sequence scan were 0.9 (± 0.25) and 2.9 (± 0.69) mSv, respectively. Significantly lower radiation was achieved by using high-pitch flash scan (P < 0.05). High-pitch flash scan can provide similar subjective and objective IQ compared with prospective ECG-triggered sequence scan for PV CTA, while radiation exposure was significantly reduced.