Evaluation Of Virtual Coloscopy With 64-slice Helical CT: Clinical And Experimental Study

Objective: To study the value of lung window and soft tissue window in measuring colon diseases with experiment in CTVC examination.Materials and Methods: Twenty-four artificial polypoid diseases were placed with glue in a thoroughly cleaned porcine colon(overall length,150 cm) that was distented with air and submerged in a water phantom and scanned 10 times on a 64-MDCT of GE LIGHT SPEED in identical scanning parameter. The datas were reconstructioned every 0.625mm and reviewed using 2D images, navigation, MPR and 3D volume-rendered images on GE AW4.2 workstation. The artificial polypoid diseases'max-diameter were measured by two radiologists with more than 10 years work experience in lung window (W=1000,L=-700)and soft tissue window(W=400,L=40), respectively. Working out the average value of the artificial polypoid diseases'max-diameter after measuring 10 times and comparing with the actual diameter.Results: Twenty-four artificial polypoid diseases and their shape, size, location and relation of diseases with bowels wall were all be showed excellently. The max-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 max-diameter measured in lung window were close to the actual diameter, there were no difference between two sets datas (t=0.431,P=0.669).There were difference between the max-diameter measured in soft tissue window and the virtual diameter(t=2.691,P=0.010).Conclusion: In screening colon diseases ,CTVC is a good choice of non insult or less insult, higher repeatability. We shalled choose the lung window in measuring colon diseases in CTVC examination. Objective: To assess the accuracy of the 360°virtual dissection in measuring the distance between rectal cancer and anus with experiment.Methods: Ten artificial rectal tumor-like lesions were placed with glue in a thoroughly cleaned porcine colon(overall length,20 cm) that was distented with air and submerged in a water phantom and scanned on a 64-MDCT of GE LIGHT SPEED. The datas were reconstructioned every 0.625mm and reviewed on GE AW4.2 workstation.To measure the lesions'distance to the starting point on the 360°virtual dissection. Working out the average value after measuring 10 times and comparing with the actual distance.Results: On 360°virtual dissection,10 lesions'distance wered measured exactly and the most results were close to the actual distance ,only a few exceed the actual distance slightly.The actual distance was 145 mm～10mm, mean value was 77.5mm;the result measured on 360°virtual dissection and the mean value were 142.4 mm～9.6 mm and 76.5mm, respectively . There were no difference between two sets datas(t=0.049,P=0.961).Conclusion: The 360°virtual dissection of 64-MDCT could measure the distance between the rectal cancer and anus and provide important information for surgery. Objective: To study the value of 2D plane view, 360°virtual dissection and 3D intracavity view of computed tomography virtual colonoscopy in display colon depressed(diameter≤3mm)lesions with experiment.Materials and Methods : A thoroughly cleaned porcine colon(overall length,20cm),after turnovering it and to count the number of the lesion and measure each diameter, put it(was distented with air) into a water phantom turnovering it again and scanned on a 64-MDCT of GE LIGHT SPEED. The data were reconstructed every 0.625mm and reviewed using 2D plane view, 360°virtual dissection and 3D volume-rendered images on GE AW4.2 workstation.Results : In 41 depressed lesions,3D volume-rendered images, 360°virtual dissection and 2D plane view showing the number of lesions was 39,32 and 20,respectively.The sensitivity was 95%,78% and 49%,respectively.Conclusion: The 3D volume-rendered images was optimization in showing the colon depressed lesions. If want to gain a good value, 2D plane view must combine 3D volume-rendered images and 360°virtual dissection . Objective:To evaluate the techniques and applications of 64 multislice helical CT colonography in colonic lesions.Methods:Thirty-eight patients (including 12 colorectal carcinomas,10 polypi, 9 colon multiple scrobiculus, 2 multiple diverticula, 2 negative, 1 congenital bowel malrotaion,1 ulcerative colitis and tunica mucosa glandular organ hyperplasy,1 colocolic anastomosis of terminal ileum and sigmoid colon) underwent volume scanning using 64 multislice helical CT after cleaning colon. Six types of reconstruction included computed tomography virtual colonoscopy, volume rendering, multiple planar reconstruction, 360°sectional view, RaySum,and navigation.CTVC appearances were compared with fiberoptic colonoscopy.Results : In 12 colorectal carcinomas and 10 polypi,the lesions'morphology,number,size, were satisfactorily shown by CTVC. The lesions'location,range,and 1 intestinal canal obviously stenosis were also exactly shown by RaySum.The relationship between tumor and environment, 3 liver or retroperitoneal lymph node metastasis were satisfactorily shown by MPR and 2D transection image. In 360°sectional view,the distance between tumor and anus was exactly measured and the result was conformity with CC. Of the CTVC appearances,1 sigmoid colon carcinoma and 1 transverse colon polyp was unconformity with fiberoptic colonoscopy;1 ulcerative colitis and decending colon carcinoma was diagnosed ulcerative colitis and tunica mucosa glandular organ hyperplasy by pathology. Conclusion: Sixty-four multislice helical CT is a valuable imaging technique for detecting colon diseases. CTVC can obtain more clinical information than conventional colonoscopy combining MPR,raysum,VR,...