PURPOSE: As calculated from a (99m)technetium (Tc)-mercaptoacetyltriglycine (MAG3) renogram, differential renal function is an important parameter affecting the clinical treatment of children with prenatal unilateral hydronephrosis. We determined whether value is potentially added by calculating a functional image from MAG3 renograms that represents proximal tubule ability to clear tracer from the blood, that is the MAG3 clearance image. MATERIALS AND METHODS: MAG3 clearance image findings and differential renal function at presentation and followup in 59 nonsurgically and 42 surgically treated children with prenatally diagnosed unilateral hydronephrosis were retrospectively reviewed. All patients underwent at least 3 99mTc-MAG3 renograms. RESULTS: In the surgical and nonsurgical groups there was no significant difference in followup (p = 0.11), age at presentation (p = 0.98) or age at last visit (p = 0.97), whereas differential renal function was significantly different (p = 0.01). A large affected kidney with focal defects was the most frequent finding in each group, including kidneys with a normal differential renal function of 45% to 55%. In the nonsurgical group the most common observation was improvement in the MAG3 clearance image in 26 of 59 cases (44%) and stabilized differential renal function in 41 (70%). Postoperatively the MAG3 clearance image improved in 31 of 42 cases (74%) and differential renal function remained stable in 25 (60%), while no significant increase in differential renal function was noted at the last visit (p = 0.74). CONCLUSIONS: This study shows that it is possible to assess regional parenchymal function using the MAG3 clearance image in children with unilateral hydronephrosis. This information is available in addition to 99mTc-MAG3 information on the whole kidney, that is differential renal function. The majority of affected kidneys with normal differential renal function showed parenchymal defects, suggesting regional renal dysfunction. However, functional improvement on a regional basis occurred in each group of children during followup.
PURPOSE: As calculated from a (99m)technetium (Tc)-mercaptoacetyltriglycine (MAG3) renogram, differential renal function is an important parameter affecting the clinical treatment of children with prenatal unilateral hydronephrosis. We determined whether value is potentially added by calculating a functional image from MAG3 renograms that represents proximal tubule ability to clear tracer from the blood, that is the MAG3 clearance image. MATERIALS AND METHODS:MAG3 clearance image findings and differential renal function at presentation and followup in 59 nonsurgically and 42 surgically treated children with prenatally diagnosed unilateral hydronephrosis were retrospectively reviewed. All patients underwent at least 3 99mTc-MAG3 renograms. RESULTS: In the surgical and nonsurgical groups there was no significant difference in followup (p = 0.11), age at presentation (p = 0.98) or age at last visit (p = 0.97), whereas differential renal function was significantly different (p = 0.01). A large affected kidney with focal defects was the most frequent finding in each group, including kidneys with a normal differential renal function of 45% to 55%. In the nonsurgical group the most common observation was improvement in the MAG3 clearance image in 26 of 59 cases (44%) and stabilized differential renal function in 41 (70%). Postoperatively the MAG3 clearance image improved in 31 of 42 cases (74%) and differential renal function remained stable in 25 (60%), while no significant increase in differential renal function was noted at the last visit (p = 0.74). CONCLUSIONS: This study shows that it is possible to assess regional parenchymal function using the MAG3 clearance image in children with unilateral hydronephrosis. This information is available in addition to 99mTc-MAG3 information on the whole kidney, that is differential renal function. The majority of affected kidneys with normal differential renal function showed parenchymal defects, suggesting regional renal dysfunction. However, functional improvement on a regional basis occurred in each group of children during followup.