ABSTRACT
Objective To study the value of lung window and soft tissue window in measuring colon diseases with experimental CTVC examination.Methods Twenty-four artificial polypoid diseases were placed with glue in a thoroughly cleaned porcine colon(overall length,150 era)that was distented with air and submerged in a water phantom and scanned 10 times on a 64-MSCT(GE Light speed)with identical scanning parameters.The data were reconstructed every 0.625 mm and reviewed using 2D images, navigation,MPR and 3D volume-rendered images on a GE AW 4.2 workstation.The maximum diameters of the artificial polypoids were measured by two radiologists with more than 10 years working experience in lung window(W = 1000,L =-700)and soft tissue window(W =400,L =40),respectively.The average value of maximum diameters of the artificial polypoids were measured for 10 times and were compared with the actual diameter.Results Twenty-four artificial polypoid diseases and their shape,size,loeation and relation of diseases with bowel wall were all showed excellently.The maximum diameter measured was close to the actual diameter.The average value was mostly less than actual diameter and a few of them more than the actual diameter.The maximum diameter measured in lung window was close to the actual diameter,and there was no difference between the two data sets(t =0.431,P =0.669).There was difference between the maximum diameter measured in soft tissue window and the virtual diameter(t = 2.691,P = 0.010). Conclusion In screening the colon diseases,CTVC is a good method of choice with no insult or less insult, and higher repeatability.The lung window should be chosen in measuring colon diseases in CTVC examination.
ABSTRACT
Objective To explore the main influence factors(heart rate,rotation speed,and reconstruction algorithm)on the image quality of coronary artery with 40 mm VCT(64-detector row helical CT)using a pulsating cardiac phantom.Methods An adjustable pulsating cardiac phantom(GE) containing predetermined simulated coronary arteries was scanned using a 40 mm VCT(GE LightSpeed CT) with cardiac pulsating rates of 40,45,50,55,60,65,70,75,80,85,90,95,100,105,110,and 115 beats per minute(bpm).The variable rotation speeds technique of 0.35 s,0.40 s,and 0.45 s were used, respectively.The raw data were reconstructed using both one-sector and multi-sector reconstruction algorithm at optimal window of the R-R interval.The image quality score(IQS)was evaluated by two radiologists according to the same evaluation standard of reformated image.The correlation between heart rate(HR), roation speed,reconstruction algorithm,and IQS were analyzed.The IQS as independent variable and the HR,rotation speed,reconstruction algorithm as dependent variables were analyzed by multiple linear regression analysis.Restllts The heart rate and the reconstruction algorithm had significant influence on IQS.The rotation speed(0.35s,0.40s,and 0.45s)didn't have significant influence on IQS.There was linear regression relationship between heart rate,reconstruction algorithm and IQS(P