Objective To investigate the clinical value of chest low-dose CT (LDCT) combined with computer-aided detection (CAD) system for lung cancer screening in high risk population. Methods Two hundred and nineteen healthy candidates underwent 64-slice LDCT scan. All images were reviewed in consensus by two radiologists with 15 years of thoracic CT diagnosis experience. Then the image data were analyzed with CAD alone. Finally images were reviewed by two radiologists with 5 years of CT diagnosis experience with and without CT Viewer software. The sensitivity, false positive rate of CAD for pulmonary nodule detection were calculated. SPSS 11.5 software and Chi-square test were used for the statistics. Results Of 219 candidates ,104(47.5% )were detected with lung nodules. There were 366 true nodules confirmed by the senior radiologists. The CAD system detected 271 (74.0%)true nodules and 424 false-positive nodules. The false-positive rate was 1.94/per case. The two junior radiologists indenfifid 292(79.8%), 286(78.1%) nodules without CAD and 336 (91.8%), 333 (91.0%) nodules with CAD respectively. There were significant differences for radiologists in indentifying nodules with or without CAD system (P<0.01). Conclusions CAD is more sensitive than radiologists for indentifying the nodules in the central area or in the hilar region of the lung. While radiologists are more sensitive for the peripheral and sub-pleural nodules,or ground glass opacity nodules, or nodules smaller than 4 mm. CAD can not be used alone. The detection rate can be improved with the combination of radiologist and CAD in LDCT screen.

Objective:To explore the clinical application value of the dual-layer detector spectral CTA in evaluation of brain perfusion impairment in patients with acute ischemic stroke.Methods:Clinical and imaging data of 35 patients with acute ischemic stroke in Weihai Central Hospital from March 2020 to October 2020 were reviewed retrospectively. All patients underwent head and neck spectral CTA examination and dynamic cerebral perfusion CT examination with dual-layer detector spectral CT. The iodine density map and effective atomic number map were reconstructed using CTA data, and the iodine density and effective atomic number, as well as the cerebral blood volume (CBV) and cerebral blood flow (CBF) values of the hypoperfusion area and the contralateral side were measured and compared; the areas of brain hypoperfusion regions were measured. Pearson′s correlation coefficient was used to analyze the correlation between iodine density values and CBV values, iodine density values and CBF values, effective atomic number values and CBV values, effective atomic number values and CBF values, as well as hypoperfusion area shown on CTA images and displayed on CTP-CBF map.Results:Of all the 35 patients, the iodine density value [(0.22±0.07) mg/ml], effective atomic number value (7.38±0.05), CBV value [(1.9±0.7) ml/100 g] and CBF value [(15.1±5.9) ml/(100 g·min)] of the hypoperfusion area were significantly lower than those of the healthy side [iodine density value (0.44±0.10) mg/ml, effective atomic number value (7.52±0.06), CBV value (3.4±0.7) ml/100 g, CBF value (57±27) ml/(100 g·min); t values were -14.7, -14.5, -11.2, -9.7, respectively, all P<0.001]. No significant difference was found between the hypoperfusion area shown on spectral CTA [(2 292±1 393) mm 2] and shown on CTP-CBF map [(2 290±1 359) mm 2] ( t=-0.076, P=0.944). There was a positive correlation between iodine density value and CBV (affected side: r=0.350, P=0.039, healthy side: r=0.551, P=0.001); a positive correlation was also found between effective atomic number value and CBV (affected side: r=0.488, P=0.003, healthy side: r=0.552, P=0.001); and there was a strong positive correlation between the hypoperfusion area on CTA and that on CTP-CBF ( r=0.993, P<0.001). Conclusion:Dual-layer detector spectral CTA can provide the “one-stop” assessement including head and neck vascular evaluation, as well as the hypoperfution area measument, which can be an alternative rapid method for evaluation of patients with acute ischemic stroke.