Applications of quantitative and semi-quantitative dynamic contrast enhanced magnetic resonance imaging analysis in T-staging and N-staging of preoperative rectal cancer

Abstract

Objective To explore diagnostic values of the semi-quantitative and quantitative dynamic contrast enhanced magnetic resonance imaging(DCE-MRI) analysis in the T-stage and N-stage preoperative assessment of rectal cancer. Methods Twenty-seven patients with colonoscopy pathologically proven rectal cancer in Shanxi Province Tumor Hospital from July 2014 to Nov. 2014 were retrospectively analyzed. Among those, there were 18 men and 9 women, ages ranged from 45 to 73 years, and no prior surgeries were performed. The patients underwent DCE-MRI examinations before the surgery, with several semiquantitative and quantitative parameters including transfer constant(Ktrans), rate constant of bacKflux(Kep) , extravascular extracellular volume fraction(Ve), Time To Peak(TTP), Max Concentration, Area Under Curve(ADC) and Max Slope measured and statistically analyzed using Omni-Kinetics software. Differences of the quantitative and semiquantitative parameters between normal tissue and lesions were compared using the paired t test. Mann-whitney U tests were utilized to examine the differences of the quantitive and semiquantitative parameters between different T-stage or N-stage lesions to determine their diagnostic values. Receiver operating characteristic (ROC) curve analyses were performed to determine the cut-off values to quantitatively distinguish different T stages and N stages. Results There were significant differences of Ktrans, Kep, Max Conc and AUC between normal tissue and lesions (t=-6.270, -11.359, -2.487, -2.803, all P values<0.05). In T-staging, Ktrans and Kep values were statistically significant between T1-2 group and T3-4 group (Z=-4.077, -2.281, all P values<0.05). In N-staging, the Ktrans, Ve and TTP in no lymph node metastasis group was significantly lower than those in lymph node metastasis group (Z=-2.433, -2.832, -2.496, all P values<0.05). Conclusions The quantitative and semi-quantitative DCE-MRI parameters showed high correlations with pathology in differentiation of normal rectal wall and lesions, and in preoperative rectal cancer T-staging and N-staging, which demonstrated reference values in diagnosis. The cut-off value of Ktrans and Ve values provided high sensitivity and specificity in differentiation between T staging and N staging. Key words: Rectal neoplasms; Magnetic resonance imaging; Perfusion imaging; Dynamic contrast enhanced magnetic resonance imaging; Neoplasm staging