Potential and limitations of diffusion-weighted magnetic resonance imaging in kidney, prostate, and bladder cancer including pelvic lymph node staging: a critical analysis of the literature

Context: Diagnosis, staging, and treatment monitoring are still suboptimal for most genitourinary tumours. Diffusion-weighted magnetic resonance imaging (DW-MRI) has already shown promise as a noninvasive imaging modality in the early detection of microstructural and functional changes in several pathologies of various organs.

Objective: To assess the potential and limitations of DW-MRI in the management of patients with kidney, prostate, and bladder cancer.

Evidence acquisition: A nonsystematic literature search using the Medline/PubMed and Embase databases for full-length papers reporting on DW-MRI for kidney, prostate, and bladder cancer was performed up to August 1, 2011. Only those articles with complete data reporting on DW-MRI applications with potential implications in solving commonly encountered clinical challenges relating to tumour detection, staging, and treatment monitoring were finally examined.

Evidence synthesis: For kidney tumours DW-MRI is a reasonable alternative to conventional cross-sectional imaging to detect and characterise focal renal lesions, especially in patients with impaired renal function. For prostate cancer, DW-MRI applied in addition to conventional T2-weighted and contrast-enhanced magnetic resonance imaging (MRI) improves tumour detection and localisation. In addition, it has shown promise for the assessment of tumour aggressiveness and for treatment monitoring during active surveillance, radiation therapy, and focal therapy. For bladder cancer, DW-MRI may improve the performance of conventional T2-weighted and contrast-enhanced MRI in the work-up of bladder cancer, helping to differentiate non-muscle-invasive from muscle-invasive tumours. For pelvic lymph nodes, initial results showed the potential to improve nodal staging of prostate and bladder cancer compared with conventional cross-sectional imaging.

Conclusions: DW-MRI holds promise to ameliorate the management of patients with kidney, prostate, and bladder cancer including pelvic lymph node staging. Current limitations include the lack of standardisation of the technique across multiple centres and the still limited expertise.