Koff curve
A standardized curve used to interpret drainage patterns on diuretic renography, particularly for diagnosing ureteropelvic junction obstruction.
Full Definition
The Koff curve is a drainage curve analysis method used in nuclear medicine renography, particularly MAG3 scans, to evaluate the washout characteristics of radiopharmaceutical from the renal collecting system following diuretic administration. Developed by Dr. Stephen Koff, this analysis helps differentiate between true obstruction and functional delay in urine drainage from the renal pelvis. A T1/2 (half-time) of less than 10 minutes suggests unobstructed drainage, 10-20 minutes indicates indeterminate drainage, and greater than 20 minutes suggests obstruction requiring further evaluation or intervention.
Usage
Usage note: Capitalize 'Koff' as an eponym; T1/2 values should be expressed in minutes.
In Context
- "The MAG3 renogram showed a flattened Koff curve suggestive of left UPJ obstruction." — Nuclear medicine report
- "Koff curve analysis revealed a T1/2 of 25 minutes, indicating significant obstruction." — Diagnostic imaging interpretation