glomerular filtration rate index multiregional glomerular filtration rate index multi-regional GFR clinical_measurement_ontology PMID:14561850 VT:0002847 CMO:0003631 slaulede multi-regional K(cl) 2021-01-07T18:35:31Z The concentration of a contrast agent in the cortex (predominantly blood signal) from multiple areas of both kidneys is compared to the concentration in multiple areas of the medulla (predominantly urine) of both kidneys to obtain the first order rate constant, k(cl). The clearance of the contrast agent can serve as a marker for the glomerular filtration rate.