Interest of Magnetic Resonance Imaging in the Diagnosis of Upper Urinary Tract Invasive Tumours

Urothelial tumours are the 6th most common cause of cancer in developed countries and occur throughout the urinary tract (urethra, bladder, ureter and pelvic cavities). Upper urinary tract tumours account for 5-10% of urothelial carcinomas. Nearly 60% of patients with upper urinary tract tumours are diagnosed as invasive (≥ T2). 90% of computed tomography lesions are tumour lesions. Currently, the diagnosis of upper urinary tract tumours is based on computed tomography with injection of nephrotoxic iodinated contrast medium (uro-computed tomography) and biopsies taken during ureteroscopy under general anaesthesia. Invasive tumours have a poor prognosis and patients with infiltrating tumours may benefit from neoadjuvant chemotherapy prior to nephroureterectomy (which may impair renal function). Uro-computed tomography cannot differentiate between invasive and non-invasive tumours and biopsies taken in the operating theatre during ureteroscopy under general anaesthesia are unreliable for staging and frequently underestimate the disease. The diagnosis of infiltrating tumours is most often made on nephro-ureterectomy specimens, making neoadjuvant treatment impossible. Recently, functional magnetic resonance imaging sequences (diffusion weighted imaging, apparent diffusion coefficient) highlighted the biophysical properties of the tissues such as cellular organisation, density and microcirculation and have thus made it possible to differentiate benign from malignant lesions by identifying the level of tissue involvement. Magnetic resonance imaging has become a real tool in the diagnosis of bladder tumours and can differentiate between infiltrating and non-infiltrating lesions.

The aim of this study is to make magnetic resonance imaging for each patient and compare results to pathological analysis (nephro-ureterectomy pathologic analysis or biopsy with 3 months Uro-computed tomography) to evaluate magnetic resonance imaging diagnosis capability for invasive tumour.