Non-obstructive hydronephrosis Normal Obstructive hydronephrosis Mean 3.84 9.72 24.48 Standard Deviation(SD) 3.08 1.15 1.27 Range 0.7–7 8.57–11 11>

Table 2: Time to half-maximum activity clearance (T½) readings of the left kidney using technetium-99m-mercaptoacetyltriglycine.