FIGURE 2. Diuretic renography was performed on 2.5-mo-old boy in whom grade 2 hydronephrosis on left side was diagnosed during pregnancy and confirmed after birth. (A) One-minute posterior views at diagnosis show parenchymal thinning of left kidney and no response to furosemide, whereas right kidney appears normal. (B) Same views obtained at follow-up show persistent left parenchymal thinning and improvement in left urinary flow under furosemide. (C) Background-corrected renal curves (left kidney, dark line; right kidney, dotted line) at diagnosis show decreased tracer uptake by left kidney (AI, 6.50 %ID) and typical obstructive curve pattern (EI, 0.66). Contralateral kidney was normal (AI, 8.94 %ID; EI, 4.35). (D) After surgery, left kidney improved in function and drainage (AI, 9.43 %ID; EI, 2.15) and right kidney remained normal (AI, 9.40 %ID; EI, 6.43).