Thin imaging and multiplanar reconstruction in 64-slice CT for preoperative T staging on different parts and various pathological staging of colorectal cancer / 中国医学影像技术

ABSTRACT

Objective To explore the diagnostic value of thin image and multiplanar reconstruction (MPR) for preoperative T staging on different regions and various pathological staging of colorectal cancer. Methods A total of 163 colorectal cancer patients underwent 64-slice CT examination, then cross section image with thickness of 5 mm (5 mm interval) and 0.5 mm (0.4 mm interval) were reconstructed. The lesions were evaluated and T staged with 5 mm, 0.5 mm and MPR image, respectively. Patients were divided according to the region of lesions groupⅠ the anterior wall of lower rectal or near dentate line; groupⅡ the posterior or lateral wall of lower rectal; group Ⅲ upper middle rectal or clone. Patients in group Ⅲ were divided into 4 subgroups according to postoperative pathological staging group A Tis and T1; group B T2 (B1 T2a; B2 T2b); group C T3; group D T4. The accurate diagnostic rates of different regions, different imaging techniques and different pathological staging were analyzed compared with postoperative pathological results. Results CT accurate T staging diagnostic rate for group Ⅰ, Ⅱ, Ⅲ was 44.44%, 61.54% and 66.67% respectively with 5 mm; 51.85%, 61.54% and 69.92% respectively with 0.5 mm; 51.85%, 76.92% and 78.86% with MPR. There was significant difference of CT accurate diagnostic rates only between group Ⅰ and group Ⅲ (5 mm P=0.031, MPR P=0.004). MRP was better then 5 mm and 0.5 mm only in group Ⅲ (P=0.008, P=0.019). The sensibility of diagnostic T staging of A, B, C and D subgroup in group Ⅲ was as follows 53.85%, 30.00%(B1 57.14%, B2 6.25%), 84.00% and 60.00% with 5 mm; 76.92%, 33.33%(B1 76.92%, B2 18.75%),84.00% and 60.00% with 0.5 mm; 92.31%, 53.33%(B1 78.57%, B2 31.25%), 86.67% and 80.00% with MPR. CT accurate T staging diagnostic rate of subgroup B2 was significantly lower than those of other groups, and most of the errors were over valuated. Conclusion CT has good sensitivity, specificity and accuracy for diagnostic T staging for early colorectal cancer. MPR can raise the accurate diagnostic rate of upper middle rectal and colon tumor. CT diagnostic value for T staging of lesions at the anterior wall of lower rectal or near dentate line tumor is limited, and the primary cause is over diagnosis of T2b lesions.