Étude de corrélation radio-anatomopathologique sur pièces de prostatectomie radicale des facteurs d agressivité du cancer de la prostate (score de Gleason et volume tumoral) en IRM 1.5 Tesla avec antenne de surface : quel est l apport de la séquence de diffusion ?

Abstract

Cette étude a pour but de corréler le score de Gleason et le coefficient de diffusion apparent (ADC) dans les foyers de cancer prouvés sur pièce de prostatectomie, et d établir laquelle des 3 séquences de routine permet la mesure du volume la mieux corrélée au volume anatomo-pathologique. 45 patients (78 foyers tumoraux) ont bénéficié d une IRM, incluant les séquences T2, T1 de contraste dynamique et diffusion. La mesure du volume et de l ADC des foyers en IRM a été effectuée après repérage et comparaison sur les coupes histologiques. L ADC est négativement corrélé au score de Gleason (p<0.001), pour les 3 grades de cancer : bas, intermédiaire et haut grade. La séquence de contraste dynamique est la mieux corrélée au volume tumoral mesuré en pathologie comparativement aux séquences T2 et diffusion. L ADC est négativement corrélé au score de Gleason. Nous préconisons de mesurer le foyer tumoral sur la séquence T1 de contraste dynamique.To access the relationship between apparent diffusion coefficient (ADC) value on 1.5 Tesla magnetic resonance imaging (MRI) and Gleason 's score in prostate cancer, obtained from whole mount specimens after radical prostatectomy (RP), and to determine which MRI sequence used for prostate cancer evaluation allows a better estimation of tumor's volume. 45 men with 78 foci of prostate cancer who underwent MR imaging, including a single-shot EPI diffusion weighted MRI (b=0 & b=600 mm /sec), T2 weighted MRI and dynamic contrast enhanced T1-weighted MRI, with a 12-channel pelvic phased-array body coil, within 2 months before RP, were included. After the RP, the prostate was whole-mounted and cancer foci were drawn on whole mounts pathologic slides. Two radiologists in consensus estimated the cancer volume in each of the 3 sequences, and measured the ADC value in the cancer zone. Comparison of mean ROI ADC value and tumor's Gleason grade was performed with a Scheffe's test and correlation between tumor's volumes was calculated for each sequence by using concordance correlation coefficients (CCCs). ADC value was found to be related to the Gleason grade (p<0.001); for low, intermediate and high grade tumor (p<0.005). Dynamic contrast enhanced T1-weighted imaging was statistically better to estimate the tumor volume than the two others (p<0.005). Mean ADC value was found to be negatively correlated to Gleason grade in prostate cancer proved on whole mount prostatectomy specimens. Dynamic contrast enhanced T1-weighted imaging was the most accurate sequence to measure tumor volume in prostate cancer at 1.5 Tesla using a phased-array coil.ST QUENTIN EN YVELINES-BU (782972101) / SudocSudocFranceF