Percent improvement in renal pelvis antero-posterior diameter (PI-APD): prospective validation and further exploration of cut-off values that predict success after pediatric pyeloplasty supporting safe monitoring with ultrasound alone - Rickard, M; Braga, L H; Oliveria, J-P; Romao, R; Demaria, J; Lorenzo, A J (J Pediatr Urol, 2016)