Percent of Tracer Clearance at 40 Minutes in MAG3 Renal Scans Is More Sensitive Than T1/2 for Symptomatic Ureteropelvic Junction Obstruction

P40 markedly increases the sensitivity of a renal scan for diagnosing symptomatic UPJO and may be another valuable marker in addition to T1/2 to document functional improvement in drainage after pyeloplasty.