Non-obstructive hydronephrosis Normal Obstructive hydronephrosis Mean 3.1 10.03 10.03 SD 2.51 0.89 0.89 Range 0.59–5.61 9.14–10.92 < 10.03

Table 1: Time to half-maximum activity clearance (T½) readings of the right kidney using technetium-99m-mercaptoacetyltriglycine