MSCT Imaging In Colorectal Cancer And Polyps Of The Colon Application

Objective: To evaluate the diagnostic values of different 16 slices CT colonographies(CTC) in colorectal tumors.Materials and Methods: Forty-two patients with colorectal tumors underwent transverse scan using 16 slices spiral CT. The length, the circumferential extension and the pathologic patterns of tumors were compared among the images shown by different techniques including the original transverse images, the images of the multiplanar reformation(MPR), shaded surface display(SSD), Raysum, CT virtual colonoscopy(CTVC), Wall View and virtual dissection(VD) obtained from the postprocessing in the workstation. All the tumors were confirmed by the conventional colonography(CC) and/or histology.Results: For evaluation of tumors'length, the correction rate of Wall View,SSD and Raysum(97.6%,95.2%,95.2%) were higher than CTVC(78.6%) and original transverse images (73.8%). For evaluation of the circumferential extension of colorectal tumors, the correction rate of VD(100%) was higher than CTVC,SSD,Raysum and original transverse images (85.7%,80.9%,80.9%,78.6%). For evaluation of the pathologic pattern, the correction rate of CTVC(90.5%) was higher than SSD,Raysum and VD(71.4%,71.4%,61.9%); Wall View(88.1%)was higher than VD(61.9%).Conclusion: There are advantages and disadvantages among seven different display methods of CT colonography for the colorectal tumors'diagnosis. Properly choosing display methods and using the combination ways can improve the diagnosis accuracy. Objective: To investigate the value of CT virtual colonoscopy (CTVC) in colorectal polyps diagnosis by using different density thresholds.Materials and Methods: 41 patients underwent l6-slice spiral CT scan. Original data were reconstructed by CTVC software in the work station(AW4.3). Polyps were classified into 3 groups by size. Using -800～-600Hu,-599～-400 Hu and -399～-200 Hu as density ranges of CTVC. Under each density range, the detection rate of each group was analysized respectively. All polyps were confirmed by colonoscopy and /or pathology.Result: For polyps 5mm or less in size, detection rate of CTVC under density range(-399～-200 Hu) was 61.3% ,which was higher than 29.0%(under -800～-600 Hu)and 35.5%(under -599～-400 Hu);polyps sized 6～9mm ,or 10mm or more, detection rate under different density ranges kept no significance .Conclusion: The density threshold of CTVC have a substantial influence on colorectal polyps screening;Properly increasing the density threshold of CTVC is helpful for the diagnosis of small-size colorectal polyp.