title: 68Ga-EDTA PET/CT imaging and plasma clearance for glomerular filtration rate quantification: comparison to conventional 51Cr-EDTA.
abstract: Glomerular filtration rate (GFR) can accurately be determined using (51)Cr-ethylenediaminetetraacetic acid (EDTA) plasma clearance counting but is time-consuming and requires technical skills and equipment not always available in imaging departments. (68)Ga-EDTA can be readily available using an onsite generator, and PET/CT enables both imaging of renal function and accurate camera-based quantitation of clearance of activity from blood and its appearance in the urine. This study aimed to assess agreement between (68)Ga-EDTA GFR ((68)Ga-GFR) and (51)Cr-EDTA GFR ((51)Cr-GFR), using serial plasma sampling and PET imaging.
  
  
  METHODS
  (68)Ga-EDTA and (51)Cr-EDTA were injected concurrently in 31 patients. Dynamic PET/CT encompassing the kidneys was acquired for 10 min followed by 3 sequential 3-min multibed step acquisitions from kidneys to bladder. PET quantification was performed using renal activity at 1-2 min (PETinitial), renal excretion at 2-10 min (PETearly), and, subsequently, urinary excretion into the collecting system and bladder (PETlate). Plasma sampling at 2, 3, and 4 h was performed, with (68)Ga followed by (51)Cr counting after positron decay. The level of agreement for GFR determination was calculated using a Bland-Altman plot and Pearson correlation coefficient (PCC).
  
  
  RESULTS
  (51)Cr-GFR ranged from 10 to 220 mL/min (mean, 85 mL/min). There was good agreement between (68)Ga-GFR and (51)Cr-GFR using serial plasma sampling, with a Bland-Altman bias of -14 ± 20 mL/min and a PCC of 0.94 (95% confidence interval, 0.88-0.97). Of the 3 methods used for camera-based quantification, the strongest correlation was for plasma sampling-derived GFR with PETlate (PCC of 0.90; 95% confidence interval, 0.80-0.95).
  
  
  CONCLUSIONS
  (68)Ga-GFR agreed well with (51)Cr-GFR for estimation of GFR using serial plasma counting. PET dynamic imaging provides a method to estimate GFR without plasma sampling, with the additional advantage of enabling renal imaging in a single study. Additional validation in a larger cohort is warranted to further assess utility.
authors: Centre for Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Australia Department of Medicine, University of Melbourne, Melbourne, Australia michael.hofman@petermac.org.
authors: Michael
authors: M
authors: Hofman
authors: Centre for Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Australia.
authors: David
authors: D
authors: Binns
authors: Centre for Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Australia.
authors: Val
authors: V
authors: Johnston
authors: Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Melbourne, Australia; and.
authors: Shankar
authors: S
authors: Siva
authors: Centre for Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Australia.
authors: Mick
authors: M
authors: Thompson
authors: Centre for Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Australia.
authors: Peter
authors: P
authors: Eu
authors: Department of Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, Melbourne, Melbourne, Australia.
authors: Marnie
authors: M
authors: Collins
authors: Centre for Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Australia Department of Medicine, University of Melbourne, Melbourne, Australia.
authors: Rodney J
authors: RJ
authors: Hicks
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002860:Chromium Radioisotopes / Q000737:chemistry; D003404:Creatinine / Q000097:blood; D004492:Edetic Acid / Q000737:chemistry*; D005260:Female; D005710:Gallium Radioisotopes; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D001743:Urinary Bladder / Q000000981:diagnostic imaging
chemical_list: D002860:Chromium Radioisotopes; D005710:Gallium Radioisotopes; D019275:Radiopharmaceuticals; D004492:Edetic Acid; D003404:Creatinine
keywords: 51Cr EDTA; 68Ga; EDTA; GFR; glomerular filtration rate