Fig. 4.

Four-year-old with history of horseshoe kidney who has previously undergone left pyeloplasty but has persistent hydronephrosis and ureteral dilation and clinical concern for obstruction. a Axial T2-weighted fat suppressed image shows renal parenchyma crossing the midline anterior to the spine (blue arrow) consistent with a horseshoe kidney. There is moderate pelvocaliectasis of the left moiety (red arrow). b Coronal T2-weighted image shows abrupt narrowing of the distal left ureter (red arrow). At surgery, the stricture was found to be related to scar tissue from prior pyeloplasty