One-step TNM staging of high-risk prostate cancer using magnetic resonance imaging (MRI): toward an upfront simplified "all-in-one" imaging approach?

Abstract

Background: Multiparametric magnetic resonance imaging (mpMRI) is the standard for local prostate cancer (PCa) staging. Whole-body MRI (wbMRI) has shown capabilities for metastatic screening. This study assesses the feasibility and value of an all-in-one AJCC TNM staging of PCa during a unique MRI session combining mpMRI and wbMRI.

Methods: Thirty consecutive patients with "high-risk" PCa prospectively underwent mpMRI of the prostate and wbMRI, in addition to (99m) Tc bone scan (BS), completed with standard X-rays (±TXR) and contrast enhanced CT for distant staging. For the statistical analysis, a "best valuable comparator" (BVC) combining a panel review of all available baseline and follow-up imaging, biological, and clinical data was used to adjudicate lymph node and bone metastatic status.

Results: Prostate mpMRI was analyzed using ESUR guidelines. Sensitivity of BS ± TXR combined with CT and of wbMRI for detecting metastases (bones or nodes) was 85% and 100%, respectively, and specificity was 88% and 100%, respectively. For the overall staging of the patients as being either N0M0 or having disease extension beyond the prostate, wbMRI was superior to the combination of BS and CT (improvement in all ROC characteristics and of AUC by 13.6% (95% CI: +0.7% to +26.5%, P = 0.039)). The main limitation is the limited number of patients.

Conclusions: AJCC M and N staging using wbMRI is feasible during the same imaging session as mpMRI performed for T staging, in less then one hour. wbMRI outperforms BS ± TXR and abdomino-pelvic CT work up for discriminating subsets of patients with or without distant spread of the cancer.

Keywords: bone metastases; lymph nodes; magnetic resonance imaging; prostate cancer.