MR urography today.

Magnetic resonance (MR) urography is performed by pursuing two different imaging strategies. On the one hand, heavily T2-weighted turbo spin-echo sequences are employed for obtaining unenhanced static-water images of the urinary tract. On the other, the T(1)-weighted MR urographic technique imitates conventional intravenous pyelography and is, therefore, referred to as excretory MR urography. For this reason, a gadolinium contrast agent is injected intravenously and, after its renal excretion, the gadolinium-enhanced urine is imaged with fast T1-weighted gradient-echo sequences. Both MR urographic techniques can be combined for a comprehensive examination of the upper urinary tract. This article reviews the current technical principles, imaging capabilities, and clinical applications of T2- and T1-weighted MR urography in adult and pediatric patients.