Application Of Perfusion And Spectral Imaging In Distinguishing Central Lung Cancer And Atelectasis

Objective:Identification of central lung cancer and obstructive atelectasis by perfusion imaging,and to explore the best distinguishing time interval between perfusion scan to distinguish between mass and atelectasis.Identification of central lung cancer and obstructive atelectasis by spectral imaging.Studying the ability of substance quantification and separation technology and Effective-Z to distinguish mass and atelectasis,and the correlation between Effective-Z and iodine(water)concentration.Method:Perfusion scan:Perfusion scan of 20 patients with central lung cancer complicated with atelectasis.Injecting iodine contrast agent into the right elbow vein using a German Olic high pressure syringe.Injection rate 5.0ml/s,total injection volume is 60ml.The patient was placed in the supine position,and the whole lung was scanned first to determine the extent of the perfusion scan.Infusion scan procedure 5s after injection of contrast agent.Each scan was performed for 2 s,23 scans in total,and the scan was completed in 44 s.Perfusion analysis with GE AW4.7 workstation.Measuring the perfusion parameters of the mass and atelectasis,BF、BV、PS、MTT、TTP;secondly,the CT value of the tumor and atelectasis was measured,grouped from the 7th scan,divided into 5 groups.(7,11,15,19,23 times,change the number of scans into time groups:17s、25s、33s、41s、49s).The CT values of 5 groups of tumors and atelectasis were measured,and the difference of CT values between the masses and atelectasis was calculated.Subjective scores were obtained for the 5 groups.Spectral scan:Dual-energy CT for single-stage enhanced scanning of 20 patients with central lung cancer and atelectasis.Injecting iodine contrast agent into the right elbow vein using a German Olic high pressure syringe.Injection rate 3.5ml/s,total injection volume is 60ml.Patient taking supine position.After the contrast agent was injected for40 seconds,the spectral scanning procedure was started,and the scanning range was from the tip of the lung to the diaphragm.Spectral analysis using GE AW4.7 workstation.Using optimized CNR technology to find the best single energy diagram for distinguishing between masses and atelectasis.ROI of tumor and atelectasis on the basis of the best single energy map.Measuring of iodine(water)concentration and Effective-Z of tumor and atelectasis.Results:1.The average BF of the mass and atelectasis is:77.26 ml/100 g/min、177.4ml/100g/min,the average BV is:3.83 ml/100g、9.21 ml/100g,the BF and BV of atelectasis are significantly higher than the mass(P<0.05);the average PS of the mass and atelectasis is:20.37 ml/100 g/min、26.33 ml/100 g/min,the atelectasis PS is slightly higher than the mass(P>0.05);the mean MTT of the mass and atelectasis is:24.03s、21.30s,the atelectasis has slightly less MTT than the mass(P>0.05);the average TTP is:5.50s、5.75s,the mass has slightly less TTP than the atelectasis(P>0.05).2.5 groups(17s、25s、33s、41s、49s).The difference in mean CT values between atelectasis and mass is:21.14Hu、35.32Hu、37.92Hu、33.11Hu、31.00Hu.The difference in CT value of 17s is significantly smaller than the other 4 groups(P<0.05).The ability of the remaining 4 groups to distinguish between masses and atelectasis is better than that of the 17s group.3.5 groups(17s、25s、33s、41s、49s).The average subjective score for distinguishing between lumps and atelectasis is:2.47、3.27、3.44、3.53、3.47.The subjective score of 17s is significantly lower than the other 4 groups(P<0.05).The ability of the 17s group to distinguish between mass and atelectasis is inferior to the other4 groups.4.The average iodine(water)concentration of the tumor and atelectasis was 13.45100ug/cm~3,17.90 100ug/cm~3,the iodine(water)concentration of the tumor was significantly lower than the atelectasis,the difference was statistically significant.The mean water(iodine)concentrations of the tumor and atelectasis were:1030.00 mg/cm~3and 1032.00 mg/cm~3,respectively.There was no significant difference in the concentration of water(iodine)between the mass and the atelectasis.The average Eff-Z of the mass and atelectasis were 8.41 and 8.65,respectively.The Eff-Z of the mass was significantly lower than that of atelectasis.The difference was statistically significant.5.The average iodine(water)concentration of the tumor and atelectasis was 13.45100ug/cm~3,17.90 100ug/cm~3,respectively.The average Eff-Z was 8.41 and 8.65,and there was a positive correlation between iodine(water)concentration and effective atomic number.Conclusion:1.Perfusion imaging can distinguish between tumor and obstructive atelectasis,which can provide a basis for accurate delineation of stereotactic radiotherapy targets.2.In order to reduce the patient’s scanning dose,it can be seen that after the contrast agent is injected for 25s,the perfusion scan is performed,or a single-phase enhanced scan is performed within 25s-49s.3.Best single energy image,material quantification and separation techniques,and Eff-Z can be used as effective methods to distinguish solid lung mass from obstructive atelectasis4.The positive correlation between the Effective-Z and the iodine(water)concentration can broaden the effective atomic number in clinical applications.