Prostate tumour volumes: evaluation of the agreement between magnetic resonance imaging and histology using novel co-registration software
Menée sur 37 patients atteints d'un cancer de la prostate, cette étude évalue, du point de vue du volume tumoral, la concordance des résultats d'une IRM multiparamétrique et d'une analyse histologique
Objective : To evaluate the agreement between prostate tumour volume determined using multiparametric magnetic resonance imaging (MRI) and that determined by histological assessment, using detailed software-assisted co-registration.
Materials and Methods : A total of 37 patients who underwent 3T multiparametric MRI (T2-weighted imaging [T2WI], diffusion-weighted imaging [DWI]/apparent diffusion coefficient [ADC], dynamic contrast-enhanced [DCE] imaging) were included. A radiologist traced the borders of suspicious lesions on T2WI and ADC and assigned a suspicion score of between 2 and 5, while a uropathologist traced the borders of tumours on histopathological photographs. Software was used to co-register MRI and three-dimensional digital reconstructions of radical prostatectomy specimens and to compute imaging and histopathological volumes. Agreement in volumes between MRI and histology was assessed using Bland–Altman plots and stratified by tumour characteristics.
Results : Among 50 tumours, the mean differences (95% limits of agreement) in MRI relative to histology were −32% (−128 to +65%) on T2WI and −47% (−143 to +49%) on ADC. For all tumour subsets, volume underestimation was more marked on ADC maps (mean difference ranging from −57 to −16%) than on T2WI (mean difference ranging from −45 to +2%). The 95% limits of agreement were wide for all comparisons, with the lower 95% limit ranging between −77 and −143% across assessments. Volume underestimation was more marked for tumours with a Gleason score ≥7 or a MRI suspicion score 4 or 5.
Conclusion : Volume estimates of prostate cancer using MRI tended to substantially underestimate histopathological volumes, with a wide variability in extent of underestimation across cases. These findings have implications for efforts to use MRI to guide risk assessment.
BJU International , résumé, 2013