Correlation Between MRI Findings And The Level Of Tumor-Infiltrating Lymphocytes In Patients With Breast Cancer

Objective:Studies confirmed that increased tumor-infiltrating lymphocytes（TILs）levels in patients with breast cancer positively correlating with the better prognosis and increased pathologic complete response rate.To investigate associations between MRI findings and the TIL levels,we whether indirectly predict TIL levels by the MRI features,in order to provide evidence for evaluating prognosis from imagings.Methods:From June 2015 to December 2016,138 patients with invasive ductal carcinoma（140 lesions）confirmed by pathology whose breast MRI showed masses were randomly selected,their clinicopathology and imaging findings were retrospectively analyzed.By use of the Breast Imaging Reporting and Data System（BI-RADS）lexicon,an analysis of the shape,margin,signal intensity and homogeneity in the fat-suppressed T₂WI,internal enhancement,the pattern of time-signal intensity curve（TIC）,the size,early enhancement rate and ADC values.All lesions according to the level of TILs were divided into two groups:those with a TIL level<30%were included in the low-TIL group,and those with a TIL level≥30%were included in the high-TIL group.Associations between TIL levels and imaging features were evaluated.The parameters including the shape,margin,signal intensity and homogeneity in the fat-suppressed T₂WI,internal enhancement and the pattern of TIC were compared withχ2 test,P<0.05 were considered statistically significant.The size,early enhancement rate and ADC values were indicated with mean±standard deviation（x±s）,the differences were compared with independent sample t-test,P<0.05 were considered statistically significant.Results:The low-TIL group included 97 lesions,and the high-TIL group included 43lesions.15.5%（15/97）of cases in the low-TIL group and 37.2%（16/43）of cases in the high-TIL group had a round or oval shape,there was a significant difference between the two groups（P=0.004）.12.4%（12/97）of cases in the low-TIL group and37.2%（16/43）of cases in the high-TIL group had a circumscribed margin,there was a significant difference between the two groups（P=0.001）.25.8%（25/97）of cases in the low-TIL group and 67.4%（29/43）of cases in the high-TIL group showed homogeneous signal on fat-suppressed T₂WI,there was a significant difference between the two groups（P<0.001）.21.6%（21/97）of cases in the low-TIL group and39.5%（17/43）of cases in the high-TIL group showed homogeneous internal enhancement,there was a significant difference between the two groups（P=0.029）.The average maximum diameters of cases in the low-TIL group and high-TIL group were（2.09±0.70）cm and（2.23±0.71）cm respectively,there was no significant difference between the two groups（P=0.267）.In the low-TIL group,29.9%（29/97）of cases showed equal signals on fat-suppressed T₂WI,61.9%（60/97）of cases showed mildly high signals,8.2%（8/97）of cases showed high signals,in the high-TIL group,18.6%（8/43）of cases showed equal signals,65.1%（28/43）of cases showed mildly high signals,and 16.3%（7/43）of cases showed high signals,there was no significant difference between them（P=0.608）.In the low-TIL group,TIC were typeⅠin 4.1%（4/97）of cases,typeⅡin 8.2%（8/97）and typeⅢin 87.6%（85/97）of cases,in the high-TIL group,TIC were typeⅡin 16.3%（7/43）and typeⅢin83.7%（36/43）of cases,there was no significant difference between them（P=0.078）.The mean early enhancement rates of cases in the low-TIL group and high-TIL group were（180±58）%and（162±50）%respectively,there was no significant difference between the two groups（P=0.080）.When b value is equal to 500s/mm²,the mean ADC values of the low-TIL group and high-TIL group were（1.04±0.17）×10^-33 mm²/s and（1.03±0.21）×10^-33 mm²/s respectively,there was no significant difference between them（P=0.681）;when b value is equal to 1000 s/mm²,the mean ADC values of the two groups were（0.90±0.13）×10^-3mm²/s and（0.89±0.18）×10^-3mm²/s respectively,there was no significant difference between them（P=0.681）.Conclusion:A part of MRI features of breast cancer had certain correlations with TILs.The features including homogeneous signal on fat-suppressed T₂WI,a regular shape,a circumscribed margin,and homogeneous enhancement,are a major pattern of breast cancer with high TIL levels.By the MRI characteristic findings of breast cancer,we can indirectly predict the level of TILs,which helps to evaluate prognosis and provide a certain evidence for clinical to choose the appropriate treatment.