The Preliminary Study About All Kinds Of Parotid Region Masses In CT Perfusion And Correlation Between CT Perfusion Parameters And Microvessel Densities

Objective:to explore CT perfusion characteristics of the masses in parotid region and to study the relationships between 4 perfusion parameters (include:blood flow BF; blood volume,BV;mean transit time,MTT;and capillary permeability surface product, PS) and the microvessel density (MVD) in the evaluation of 3 parotid tumors (pleomorphic adenomas, Warthin tumors, malignant tumors).Methods:CT perfusion was performed in 84 patients presenting as a mass or masses in the parotid region using 16 multi-slice spiral computed tomography ((LightSpeed; GE Medical Systems) in our Hospital From May 2008 to March 2010, but only 82 patients were successfully obtained, which included 20 pleomorphic adenomas,16 Warthin tumors,6 basal cell adenomas,16 inflammatory masses and 17 malignant tumors.In addition, Technical failure and artifacts was experienced in 2 patients.82 patients (37 men and 41 women, mean age:53.1±16.6 years, range from 20 to 82 years) underwent surgical resection or follow-up to make the final diagnosis after CT perfusion.A noncontrast CT parotid study was done to localize the region of interest (ROI) before obtaining a perfusion scan.50 milliliters of nonionic contrast (Ultravist300) was injected at 4 mL/s. The perfusion data were transferred to a workstation (Advantage Windows 4.2; GE Medical Systems),running a commercial software package based on a deconvolution-based technique (Perfusion 3; GE Medical Systems). Postprocessing-generated maps showed time-density curve (TDC) and 4 perfusion parametrics (BF,BV,MTT,PS). Make sure the ROI at which the parotid masses cross-section was largest on their functional part.3 different regions of interest (ROI) were manually placed through the parotid masses and were calculated by averaging ROI of 4 perfusion parameters. Special care was taken not to include visible vessels and to avoid obviously pathologic zones such as necrosis or cysts in the choice of the ROI.The size of the ROI should be at least 50 pixels to minimize the effect of photon noise and with a sufficient margin to avoid partial volume effects. all the perfusion date were postprocessed by 2 radiologists experienced in perfusion imaging separately,who was blinded to clinical date and histological results and recorded the TDC types, the 3 parameter values of the TDC characteristics (include:the time to peak, peak heigh,peak value) and the 4 perfusion parameters. In addition,Afer surgical resection,intratumoral MVD of 30 parotid tumors(10 pleomorphic adenomas,10 Warthin tumors and 10 malignant tumors) were determined by using immunohisto-chemistry by mouse antihuman CD34 antibody staining. Make ensure that histologic assessment of the MVD of the three parotid tumors,which the surgical specimens obtained and perfusion CT performed were at the same level. The result of MVD of three parotid tumors were assessed by 2 pathologists experienced in histologic techniques. The mean number of stained microvessels from 3 high-power fields(x400) per specimen was record by camera.then counting the numer of the stained microvessels of the pictures using Image-Pro Plus 6.0.Statistical analysis was performed using the SPSS 17.0 statistical package. The comparison of the 4 perfusion parameters among all the kinds of parotid masses was analyzed using the variance test, while the variance comparison between any two kinds of parotid masses. Spearman rank correlation analysis was performed to assess the relationships between 4 CT perfusion parameters and the MVD of the three parotid tumors. Statistical significance was assigned at the 5% level.Results:1. the TDC types and the 3 parameter values of the TDC characteristics (include:the time to peak, peak heigh,peak value) in the parotid masses:The TDC of pleomorphic adenomas mainly showed type I (a slowly ascending curve without flat and descending). The TDC of Warthin tumors showed mainly showed type II(a fast ascending and fast descending curve without flat). The TDC of basal cell adenomas mainly showed III(a fast ascending and slowly descending curve with a flat). The TDC of inflammatory tumors and malignant tumaos show different shapes,some of them were similar,but the TDC of malignant tumors mainly showed type IV(a fast ascending and with astable flat).2. the 3 parameter values of the TDC characteristics in the parotid masses:①the time to peak:the Warthin tumors, basal cell adenomas, malignant tumors< inflammatory masses< pleomorphic adenomas.②peak value:pleomorphic adenomas, inflammatory masses< the Warthin tumors, malignant tumors< basal cell adenomas.③peak heigh:pleomorphic adenomas< the Warthin tumors, malignant tumors< basal cell adenomas; inflammatory masses< basal cell adenomas.3. The 4 perfusion parameters were statistically significant different in the parotid masses:The patient s with pleomorphic adenomas had lower BF, BV and the longer MTT,they were poor in blood supplying;but the Warthin tumors and basal cell adenomas had higher BV and BF,so they were rich in blood supplying. The patient s with basal cell adenomas had the highest PS than other parotid masses; and the perfusion parameters characteristics were not obvious in the patients who has inflammatory masses and malignant tumors, No differences appeared between the two groups diseases in all the perfusion parameters.the perfusion parameters were difficulty to disagnosis them,we can have follow-up examination at regular intervals, their TDC type, the 3 parameter values of the TDC characteristics and clinical record to make different.4. correlation between CT perfusion parameters and microvessel densities in the three parotid masses:All the30 patients with parotid tumor showed strong positive relations between BV and their MVD(P< 0.01). All the30 patients (the three parotid tumor) showed negative relations between MTT and their MVD,but no statistically significant.the patients with pleomorphic adenomas and malignant tumors showed positive relations between BF,PS and their MVD, but the positive relations of PS(p<0.01) were stronger than BF(P< 0.05).Conclusion:1. CT perfusion has an important clinical value for diagnosing parotid masses.but it was very important to choose the fuctional vessel.2. CT perfusion of parotid masses is feasible and may differentiate the kinds of masses.the TDC types, the 3 parameter values of the TDC characteristics and perfusion parameters can improve accurancy in diagnosising most of the parotid masses all together,but the the TDC types, the 3 parameter values has the better clinical value than perfusion parameters in making differentences between parotid masses. 3. Strong positive relations significant correlation was observed between MVD and BV in the three parotid tumors,and there was negative relations correlation between MTT and MVD in the three parotid tumors,but there was no statistically significant.4. CT perfusion has advantage over counting MVD in evaluating angiogenesis.