320-detector Row CT Three-phase Enhanced Technique And Its Diagnostic Efficacy Of SPLs

Objective To explore the best enhanced three-phase technique of320-detectorCT, and evaluate its clinical diagnostic performance of solitary pulmonary lesions(SPL).Methods From February2013to April2014, successfully collected one hundredcases solitary pulmonary lesions(55malignant,23benign or chronic inflammation,22active inflammation) which met with the admitting criterion. The diameter of thelesions range from0.6centimeter to4.6centimeter, the average diameter is（2.41±0.88）cm. Additionally40normal were collected as controls. All cases wereconfirmed by surgery、pathohistology and clinical follow-up. Firstly scan the lungroutinely applying the320-detector row CT(320-DCT) before contrast mediuminjected,50ml contrast medium with an iodine concentration of370mg I/ml wasinjected at a flow rate of5ml/s,0second or4seconds after the start of bolusinjection,20intermittent low-dose volume acquisitions were made with2s intervals,the total acquisition time is38s, repeat one acquisition in3min. Volume perfusiondata transferred to the320-DCT Vice operating table automatically, Post-processingwas performed using perfusion software(dual-input single department mode) andproduce the time density curve. Record the peak enhancement time of pulmonaryartery(PA-TTP)、 left atrium(LA-TTP)、 thoracic artery(AO-TTP) andSPNs(SPL-TTP).The CT value was measured at the following time point：pre-contrast(0s)、PA-TTP、LA-TTP、AO-TTP、SPL-TTP and delayed3min, and thenet enhancement(NE) was calculated. The differences of CT value and NE in allgroup SPL at every phase were analyzed，and the diagnostic performance of the NE between different phases was compared. Analyze the characteristics of TDC curvesand strengthening alteration in different phase of different type solitary pulmonarylesions. The difference of CT value and net enhancement were compared betweendifferent types of SPLs. Apply the AUC of Receiver operating characteristiccurves(ROC) to compare the diagnostic performance of net enhancement of eachphase, and employ multiphase net enhancement and combined several diagnosticstandard to diagnose malignant SPLs.Result There were no statistical significant differences in PA-TTP、LA-TTP、AO-TTP among the four group(all P＜0.5). Statistically significant differenceswere found in peak enhancement time among the three group lesion（F=52.163,P＜0.001）,peak enhancement time of group C is much earlier than that of group Band C; in group C no difference was found between SPL-TTP and LA-TTP（t=1.434,P=0.159）; and there was no significant difference in SPL-TTP betweengroup A and B（t=0.907,P=0.367）. Group C enhanced significantly in phasePA-TTP and LA-TTP, and up to peak enhancement at18s; of group C, both the CTvalue and NE have no significant differences between LA-TTP and SPL-TTP（t=1.693,P=0.098；t=0.226,P=0.072）；C group almost have no enhancement in3min. Group A and B almost not enhanced in PA-TTP and LA-TTP phase, the twogroup have peak enhancement nearly at the same time(28s). At3min, significantdifferences were found in CT value and net enhancement among the three group（F=31.577,P＜0.001；F=9.42,P＜0.001），the NE of groupAshowed significantlyhigher than group B and C. All the SPLs displayed six types of TDC; the TDC ofmalignant SPL was mainly manifested as typeⅡ, Ⅴ, Ⅵ, the three type TDCaccounted about92.7%; the TDC of group B mainly displayed as type Ⅲ、Ⅳ, thetwo type accounted about73.9%; while active inflammatory lesions mostly showedas typeⅠ（90.9%）. Take type（Ⅱ+Ⅴ+Ⅵ）as the diagnostic criteria of malignant,the sensitivity, specificity, positive predictive value, negative predictive value,diagnostic accuracy were92.7%、82.2%、86.4%、90.2%、88.0%respectively. In28s phase, the tumor vessel has the highest displaying rate (41%), mainly the malignant SPL shown tumor vessel, accounting for90.2%. Tumor vascularidentifying the malignant demonstrated the sensitivity, specificity, positivepredictive value, negative predictive value, diagnostic accuracy were67.3%、91.1%、90.2%、69.5%、78%respectively. We observed107cases of lung cancer(29cases of central lung cancer,78cases of peripheral lung cancer), dilatedbronchial arteries and stretch into lesion was visible in27cases of central lungcancer; only nine cases of peripheral lung cancer have dilated bronchial arteries, nodefinite bronchial arteries can be seen stretching into.45cases of benign lesionswere observed and15cases have dilated bronchial arteries. When applying the NEof each phase to diagnostic SPLs, the NE at the peak enhancement time of Agroup(28s) has the greatest diagnostic efficacy(AUC=0.872); cutoff value is25.5HU and indicating a sensitivity of92.7%，specificity of82.2%, positivepredictive value of86.2%， negative predictive value of88.1%, diagnosticaccuracy of87.0%for identifying lung cancer; the NE at the peak enhancementtime of C group(18s) has the greatest diagnostic efficacy(AUC=0.985); cutoffvalue is37.5HU and indicating a sensitivity of81.8%，specificity of87.2%,positive predictive value of64.3%, negative predictive value of94.4%, diagnosticaccuracy of86.0%for identifying acute inflammation. Combining netenhancement of28s and3min phase the diagnostic accuracy in diagnosing acuteinflammatory and malignant respectively increased by2.0%、8.0%, applyingmultiple enhanced features identifying malignant SPLs produced the maximumdiagnostic performance（AUC=0.922）.Conclusion The enhanced three-phase technique which take the18s、28s、3min as the scan phase has the largest diagnostic and differential diagnosisperformance in SPLs, it is the optimal lung three-phase technique of the320-detectorCT.