The value of dual energy spectral CT in the differential diagnosis of mass type colorectal adenocarcinoma from colorectal adenoma / 中华放射学杂志

ABSTRACT

Objective To assess the value of spectral CT imaging in distinguishing mass type colorectal adenocarcinoma from colorectal adenoma. Methods Forty patients underwent preoperative abdominal dual energy spectral CT scan were analyzed restrospectively, including 17 with colorectal adenomas and 23 with mass type colorectal adenocarcinomas proven by endoscopic and surgical pathology. All patients underwent plain and three-phase enhanced CT scanning. The conventional polychromatic CT value and its pre- and postcontrast CT values, monochromatic CT value of 40 to 100 keV, the slope of spectral curve and iodine(water) concentration were measured, and the maximum diameter of the lesion was recorded. The maximum diameters of the lesions and imaging parameter differences between the adenomas and adenocarcinomas in plain and three-phase enhanced scan were analyzed with independent sample t tests. The data of the parameters with significant differences were further analyzed by ROC curves. Results The maximum diameters of the adenomas and mass type adenocarcinomas were (1.97 ± 0.54), (2.32±0.53) cm respectively, and there was no statistically significant difference (t=-2.011, P=0.051). There was no statistically differences of the conventional polychromatic CT value and its pre-and postcontrast CT values between the two groups in 4 phases (P>0.05). However, in the arterial phase, the CT values of adenomas were significantly lower than those of adenocarcinomas at low (40, 50 keV) energy (P0.05). The slope of spectral curve and the iodine(water) concentration both showed significant differences in the arterial phase between the two groups (P0.05).The largest area under the ROC curve of the iodine(water) concentration in the arterial phase was 0.757 in differentiating adenomas and mass type adenocarcinomas, with sensitivity of 73.9%and specificity of 82.4%at the cut-off of 21.02 mg/cm3. Conclusion Spectral CT imaging is valuable in differentiating colorectal adenoma from mass type colorectal adenocarcinoma with the parameters of the arterial phase.