The glomerular filtration rate determined with ⁹⁹³Tc-DTPA and a portable cadmium telluride detector

Abstract

In twenty-two patients with ⁵¹Cr-EDTA renal clearance (glomerular filtration rate) values of 36-141 ml/min, the final plasma disappearance rate constant of i.v. injected ^99mTc-DTPA (Sn) was found to be very close to that of ⁵¹Cr-EDTA determined from 180 to 300 min after injection. The disappearance of i.v. injected ^99mTc-DTPA (Sn) was also recorded from the body surface by means of a low weight cadmium telluride detector (CRN, Strasbourg, France) and commercially available stationary or portable tape recorders. The disappearance rate constant of ^99mTc-DTPA as determined externally from 30 min was comparable to that in plasma determined from 180-300 min. The external rate constant could be converted to plasma clearance by means of one plasma ^99mTc-activity determination 180 min after injection. The calculated values agreed with the conventionally determined ⁵¹Cr-EDTA clearance values. The portability of the detector system allows it to be used to estimate alterations in GFR during the measurement due to changes in physical conditions such as posture, exercise, etc.

Key Words:

• cadmium telluride detector
• external detector
• glomerular filtration rate
• ^99mTc-DTPA