Matsugasumi T., Baco E., Palmer S., Aron M., Sato Y., Fukuda N., Süer E., Bernhard J.-C., Nakagawa H., Azhar R.A., Gill I.S., Ukimura O.
Journal of Urology 2015
Purpose: Multiparametric MR often underestimates or overestimates pathological cancer volume. We developed what is to our knowledge a novel method to estimate prostate cancer volume using MR/US fusion, biopsy proven cancer core length. Materials and Methods: We retrospectively analyzed the records of 81 consecutive patients with MR/US fusion, targeted biopsy proven, clinically localized prostate cancer who underwent subsequent radical prostatectomy. As 7 patients each had 2 visible lesions on MRI, 88 lesions were analyzed. The dimensions and estimated volume of visible lesions were calculated using apparent diffusion coefficient maps. The modified formula to estimate cancer volume was defined asthe formula of vertical stretching in the anteroposterior dimension of the MRbased 3-dimensional model, in which the imaging estimated lesion anteroposterior dimension was replaced by MR/US targeted, biopsy proven cancer core length. Agreement of pathological cancer volume with MR estimatedvolume or the novel modified volume was assessed using a Bland-Altman plot. Results: MR/US fusion, biopsy proven cancer core length was a stronger predictor of the actual pathological cancer anteroposterior dimension than MR estimated lesion anteroposterior dimension (r = 0.824 vs 0.607, each p <0.001). MR/US targeted, biopsy proven cancer core length correlated with pathological cancer volume (r = 0.773, p <0.001). The modified formula to estimate cancer volume demonstrated a stronger correlation with pathological cancer volume than with MR estimated volume (r = 0.824 vs 0.724, each p <0.001). Agreement of modified volume with pathological cancer volume was improved over that of MR estimated volume on Bland-Altman plot analysis. Predictability was more enhanced in the subset of lesions with a volume of 2 ml or less (ie if spherical, the lesion was approximately 16 mm in diameter). Conclusions: Combining MR estimated cancer volume with MR/US fusion, biopsy proven cancer core length improved cancer volume predictability.