Magnetic resonance imaging

Magnetic resonance imaging (MRI) provides excellent anatomic detail and soft tissue contrast for the evaluation of patients with renal disease. MRI needs longer scan time than computed tomography (CT); however, no radiation is involved. Gadolinium-based contrast agents (GBCAs) are used to help provide additional image contrast during MRI. MRI is indicated for characterization of renal mass, staging of malignant renal neoplasms, and determination of vena cava involvement by the renal tumour. Magnetic resonance (MR) angiography is widely accepted as a non-invasive imaging work-up of renal artery stenosis. MR urography is an alternative to CT urography to assess the upper urinary tract but does not identify urinary calculi. Diffusion-weighted imaging is a functional MR technique being used to characterize parenchymal renal disease and renal tumours. Nephrogenic systemic fibrosis is a rare but debilitating and potentially life-threatening condition which has been linked to exposure of GBCAs in patients with severe renal insufficiency. The risk versus benefit must be assessed before proceeding.