title: Measurement of the ratio of glomerular filtration rate to plasma volume from the technetium-99m diethylene triamine pentaacetic acid renogram: comparison with glomerular filtration rate in relation to extracellular fluid volume.
abstract: Individual kidney glomerular filtration rate (IKGFR) can be measured from the renogram from the rate of uptake of technetium-99m diethylene triamine penta-acetic acid (99mTc-DTPA). A blood sample is required to derive IKGFR in millilitres per minute, which is then usually normalised to body surface area. We describe a technique which does not require a blood sample, is already normalised for plasma volume and uses the robust Patlak plot for measuring renal uptake. The rate of kidney uptake, dR(t)/dt, at time = 0, as a fraction of the injected dose, is equal to the fraction of the plasma volume (PV) filtered per minute, i.e. IKGFR/PV. The gradient dR(0)/dt cannot be accurately measured directly but is equal to [alpha .LV(0)], where alpha is the renal uptake constant (proportional to IKGFR) and LV is the count rate over a left ventricular ROI. LV(0) was obtained by extrapolation of LV(t), while alpha is the slope of the Patlak plot up to 3 min. GFR/PV (i.e. right plus left kidneys) in patients with normal renal function was about 0.04 min-1, as would be expected from normal values of GFR (120 ml/min) and plasma volume (3 l). GFR/PV correlated significantly with the ratio of GFR to extracellular fluid volume (ECV), measured from the terminal exponential of the plasma clearance curve (GFR/PV = 3.2.GFR/ECV + 5.3 ml/min/l [r = 0.82, n = 82]). GFR/PV (r = 0.74) and GFR/ECV (r = 0.82) both correlated inversely and non-linearly with plasma creatinine in 43 studies where the measurement was made within 1 week of the 99mTe-DTPA study.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Diagnostic Radiology, Hammersmith Hospital, London UK.
authors.forename: A M
authors.initials: AM
authors.lastname: Peters
authors.forename: H
authors.initials: H
authors.lastname: Allison
authors.lastname: Ussov WYu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D016572:Cyclosporine / Q000627:therapeutic use; D003882:Dermatomyositis / Q000000981:diagnostic imaging / Q000188:drug therapy; D005110:Extracellular Space / Q000502:physiology; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007674:Kidney Diseases / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008875:Middle Aged; D010953:Plasma Volume / Q000502:physiology; D011866:Radioisotope Renography; D012189:Retrospective Studies; D016284:Technetium Tc 99m Pentetate
chemical_list: D016572:Cyclosporine; D016284:Technetium Tc 99m Pentetate