“…T 1/2 is dependent on age, type of radiopharmaceutical, time of furosemide injection, hydration status, placement of a urinary catheter, furosemide dose, interval of measurement, and the method of calculation of T 1/2 33,45,47 . The most commonly used method is the time from furosemide administration until renal activity declined to 50% of its original value 48 . Using this method, T 1/2 <10 min is normal, 10< T 1/2 <20 min is equivocal and T 1/2 >20 min is consistent with obstruction.…”