The Primary Study Of Multi-slice Dynamic CT Perfusion For NPC

objective To study the perfusion parameters and the time-densitycurves ( TDC ) features of local different structures ofpre-radiotherapy and post-radiotherapy nasopharyngeal carcinoma (NPC)cases, and stress to investigate their values in differential diagnosisof NPC local recur patients from local radiofibrosis patients.Materials and Methods Fifty-one patients related with nasopharyngealcarcinoma (15 nasopharyngeal carcinoma, 14 local relapse, 22radiofibrosis) and 20 without nasopharyngeal disease were included inthe study. The 20 control subjects without nasopharyngeal disease (tenwomen, ten men; age range, 20-60 years; mean age, 50years) underwentCT examination of the nasopharynx for an unrelated cause. Fifteenpatients (seven women, eight men; age range, 20-75 years; mean age,49years) had nasopharyngeal carcinoma without therapy. Fourteenpatients (five women, nine men; age range, 18-80 years; mean age, 52years) had local relapse. Twenty-two patients (seven women, fifteenmen; age range, 25-78 years; mean age, 51.8years) had radiofibrosisafter therapy. On transverse scout images of the nasopharynx, a levelwas determined at which the aorta, and vein were clearly visualized.The CT perfusionprotocol comprised 340 scans that were obtained at thissingle level with the following parameters: 80 kVp, 80 mA, 512 x 512matrix, 5-mm slice thickness, 0.65-sec scan time. A nonionic iodinatedcontrast agent containing 50ml was administered IV through a 16-or18-gauge catheter at the start of the CT perfusion study. Fifteenmilliliters of the contrast agent was injected with a power injectorat a rate of 4.5mL/sec via an antecubital vein. The patients keptswallowing quietly during the perfusion study. To avoid motionartifacts, patients were clearly informed of a possible flushingsensation during contrast agent injection. The images were transferredto GE AW4.2 workstation for data analysis. Three large regions ofinterest (ROIs) were drawn in the aorta, the vein, and the objectivesby two independent observers. The results of the four perfusionparameters (blood flow, blood volume, permeability surface, and meantransit time) in the four groups were compared using the one-wayanalysis of variance. This was followed, in case of significantheterogeneity, by two-by-two comparisons using theStudent-Newman-Kelus test. Data are givenas mean ±standard deviation.All statistical tests are two-tailed. Statistical significance wasdefined as a p value of less than 0.05.Results Significantdifferences in BF ,BV ,PS ,MTT existed among four groups,respectively(p<0.01). Apart from both control group and radiofibrosisgroup in PS had only statistically difference(p<0.05), significantdifferences in BF and PS were found by two-by-two comparisons in fourgroup(p<0.01),; except for both control group and fibrosisgroup(p>0.05), significant differences in BV were found by two-by-twocomparisons in four group(p<0.01); control group versus local relapsegroup, radiofibrosis group, pro-cure NPC group in MTT were higherstatistically(p<0.01), but among local relapse group, fibrosis group,pro-cure NPC group were not statistically diferences(p>0.05).Conclusions The TDC and perfusion parameters of localdifferent structures of pre-radiotherapy and post-radiotherapy NPC haddifferent characteristics, which were helpful for the differentialdiagnosis of post-radiotherapy local recur patients and localradiofibrosis patients.