MP7-17 DIFFERENTIAL DETECTION OF LESIONS ON MULTI-PARAMETRIC PROSTATE MRI WITH OR WITHOUT USE OF AN ENDORECTAL COIL BASED ON QUANTITATIVE MEASURES OF OBESITY

Abstract

INTRODUCTION AND OBJECTIVES: Multiparametric 3T MRI (MP-MRI) with the use of an endorectal coil (ERC) provides improved signal to noise ratio for evaluation of prostatic lesions suspicious for prostate cancer. Herein, we aim to determine the degree of lesion identification lost by eliminating the use of an ERC based upon measures of obesity. METHODS: Prospectively collected data on 20 patients on an active surveillance protocol at the National Cancer Institute who have undergone non-ERC MP-MRI in 2013 following a prior ERC MP-MRI were analyzed. MP-MRI prostatic lesions suspicious for prostate cancer were identified and recorded on both ERC and non-ERC studies for each patient. Patient demographics including age, PSA, BMI, abdominal girth, waist circumference, and the drop distance from the anterior abdominal wall to the anterior aspect of the prostate were recorded. Quantitative measures of obesity were measured on T2-weighted MRI sequences. These parameters were analyzed using univariate and multivariable linear regression models individually with age and PSA to assess for significance in the decrease in number of lesions identified on followup studies without ERC use. RESULTS: The average number of lesions identified on ERC MP-MRI and followup non-ERC MP-MRI was 1.4 0.9 and 0.5 0.7, respectively. On univariate analysis, age and PSA were not significantly associated with a decrease in the number of lesions identified when the ERC was not used on followup MP-MRI. Of the quantitative parameters of obesity, on univariate analysis, greater BMI (p1⁄40.01) and abdominal girth (p1⁄40.0097) were significantly associated with a larger differential in the number of lesions identified. On multivariable linear regression models incorporating each of the measures of obesity with age and PSA, BMI (p1⁄40.026) and abdominal girth (p1⁄40.019) remained significant independent predictors of the difference in numbers of lesions identified between ERC and non-ERC studies. CONCLUSIONS: Typically more intraprostatic lesions are identified by MP-MRI performed with ERC due to the optimized signal to noise ratio. This difference is more dramatic in obese patients where the distance between body and surface coils and the prostate gland are increased. BMI and abdominal girth are predictors of significantly lower lesion identification when ERC is eliminated from the MP-MRI study. Since obesity has a negative impact on the detection of prostate cancer with non-ERC MRI, ERC use may be most important in this patient population.