Comparison of rectal cancer tumor volume parameters measured by MRI sequences and CT with those by pathological specimen / 中国肿瘤临床

ABSTRACT

Objective:This study aimed to compare rectal cancer tumor volume parameters measured by MRI sequences (T1WI, T2WI, and DWI) and/or CT with those by pathological specimen. Methods:Twenty-two patients with rectal cancer were prospectively enrolled. MRI sequences including T1WI, T2WI, and DWI, and/or CT of the pelvis were performed before operation. Volume parameters, such as tumor length along the rectal axis, maximum tumor width perpendicular to rectal axis, and tumor actual area in that perpendicular plane, were measured on T1WI, T2WI, DWI, and CT, respectively, for each patient. The respective pathological parameters were further measured in surgical specimen after total mesorectal excision. The two kinds of parameter values measured in imaging and pathology were statistically compared and accuracy appraisal was performed. Results:The mean Lpath-L was 4.06±1.14 cm. The mean LT1-L, LT2-L, LDWI-L, and LCT-L were 3.91± 1.51, 4.62±1.41, 3.39±1.05, and 3.94±1.23 cm, respectively. Correlation coefficients were 0.688, 0.635, 0.688, and 0.720 (P<0.05). An average 6 mm overestimation was found in T2WI, and 1 to 6 mm underestimation in T1WI, DWI, and CT in length values compared with those measured in surgical specimen. The mean Lpath-W was 2.56 ±0.94 cm. The mean LT1-W, LT2-W, LDWI-W, and LCT-W were 3.62±0.99, 3.66±0.76, 3.23±0.58, and 3.64±1.04 cm, respectively. The magnitude of mean overestimation ranged from 5.1 to 11.1 mm. The Apath was 4.30 ±2.83 cm2. AT1, AT2, ADWI, and ACT were 8.98±3.90, 8.99±3.43, 8.41±3.09, and 9.63±4.40 cm2, respectively, which double overestimated the tumor area in the perpendicular rectal plane. Conclusion:The difference in longitudinal length between MRI sequences/CT and pathological specimen was in the range of?6 mm to 6 mm. The mean maximum tumor width and areas in the maximum tumor perpendicular plane were overestimated. This study indicated that gross tumor volume delineation based on CT or MRI for rectal cancer irradiation should be conservative in the axial images of rectum, and meticulous consideration is required along the rectum.