title: Determination of Single-Kidney Glomerular Filtration Rate in Human Subjects by Using CT.
abstract: OBJECTIVE
  To test the hypothesis that computed tomography (CT)-derived measurements of single-kidney glomerular filtration rate (GFR) obtained in human subjects with 64-section CT agree with those obtained with iothalamate clearance, a rigorous reference standard.
  
  
  METHODS
  The institutional review board approved this HIPAA-compliant study, and written informed consent was obtained. Ninety-six patients (age range, 51-73 years; 46 men, 50 women) with essential (n = 56) or renovascular (n = 40) hypertension were prospectively studied in controlled conditions (involving sodium intake and renin-angiotensin blockade). Single-kidney perfusion, volume, and GFR were measured by using multidetector CT time-attenuation curves and were compared with GFR measured by using iothalamate clearance, as assigned to the right and left kidney according to relative volumes. The reproducibility of CT GFR over a 3-month period (n = 21) was assessed in patients with renal artery stenosis who were undergoing stable medical treatment. Statistical analysis included the t test, Wilcoxon signed rank test, linear regression, and Bland-Altman analysis.
  
  
  RESULTS
  CT GFR values were similar to those of iothalamate clearance (mean ± standard deviation, 38.2 mL/min ± 18 vs 41.6 mL/min ± 17; P = .062). Stenotic kidney CT GFR in patients with renal artery stenosis was lower than contralateral kidney GFR or essential hypertension single-kidney GFR (mean, 23.1 mL/min ± 13 vs 36.9 mL/min ± 17 [P = .0008] and 45.2 mL/min ± 16 [P = .019], respectively), as was iothalamate clearance (mean, 26.9 mL/min ± 14 vs 38.5 mL/min ± 15 [P = .0004] and 49.0 mL/min ± 14 [P = .001], respectively). CT GFR correlated well with iothalamate GFR (linear regression, CT GFR = 0.88*iothalamate GFR, r(2) = 0.89, P < .0001), and Bland-Altman analysis was used to confirm the agreement. CT GFR was also moderately reproducible in medically treated patients with renal artery stenosis (concordance coefficient correlation, 0.835) but was unaffected by revascularization (mean, 25.3 mL/min ± 15.2 vs 30.3 mL/min ± 18.5; P = .097).
  
  
  CONCLUSIONS
  CT assessments of single-kidney GFR are reproducible and agree well with a reference standard. CT can be useful to obtain minimally invasive estimates of bilateral single-kidney function in human subjects.
authors.affiliation: From the Division of Nephrology and Hypertension, Mayo Clinic, 200 First St SW, Rochester, MN 55905 (S.H.K., A.S., S.M.H., S.C.T., L.O.L.) and Division of Nephrology, Soonchunhyang University Hospital, Seoul, South Korea (S.H.K.).
authors.forename: Soon Hyo
authors.initials: SH
authors.lastname: Kwon
authors.affiliation: From the Division of Nephrology and Hypertension, Mayo Clinic, 200 First St SW, Rochester, MN 55905 (S.H.K., A.S., S.M.H., S.C.T., L.O.L.) and Division of Nephrology, Soonchunhyang University Hospital, Seoul, South Korea (S.H.K.).
authors.forename: Ahmed
authors.initials: A
authors.lastname: Saad
authors.affiliation: From the Division of Nephrology and Hypertension, Mayo Clinic, 200 First St SW, Rochester, MN 55905 (S.H.K., A.S., S.M.H., S.C.T., L.O.L.) and Division of Nephrology, Soonchunhyang University Hospital, Seoul, South Korea (S.H.K.).
authors.forename: Sandra M
authors.initials: SM
authors.lastname: Herrmann
authors.affiliation: From the Division of Nephrology and Hypertension, Mayo Clinic, 200 First St SW, Rochester, MN 55905 (S.H.K., A.S., S.M.H., S.C.T., L.O.L.) and Division of Nephrology, Soonchunhyang University Hospital, Seoul, South Korea (S.H.K.).
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Textor
authors.affiliation: From the Division of Nephrology and Hypertension, Mayo Clinic, 200 First St SW, Rochester, MN 55905 (S.H.K., A.S., S.M.H., S.C.T., L.O.L.) and Division of Nephrology, Soonchunhyang University Hospital, Seoul, South Korea (S.H.K.).
authors.forename: Lilach O
authors.initials: LO
authors.lastname: Lerman
mesh_terms: D000368:Aged; D003287:Contrast Media / Q000378:metabolism; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007483:Iothalamic Acid / Q000378:metabolism; D007677:Kidney Function Tests / Q000379:methods; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D003287:Contrast Media; D007483:Iothalamic Acid
references.citation: Nephrol Dial Transplant. 2007 Feb;22(2):417-23
references.pmid: 17053082
references.citation: Radiology. 2007 Feb;242(2):417-24
references.pmid: 17255413
references.citation: Eur J Radiol. 2007 Feb;61(2):303-9
references.pmid: 17011152
references.citation: Ann Intern Med. 1999 Mar 16;130(6):461-70
references.pmid: 10075613
references.citation: Am J Kidney Dis. 1997 Nov;30(5):646-52
references.pmid: 9370179
references.citation: Kidney Int. 1996 Mar;49(3):846-54
references.pmid: 8648929
references.citation: Acta Radiol. 1995 Jul;36(4):410-7
references.pmid: 7619622
references.citation: Am J Hypertens. 1994 Sep;7(9 Pt 1):829-37
references.pmid: 7811442
references.citation: J Am Soc Nephrol. 1993 Nov;4(5):1159-71
references.pmid: 8305642
references.citation: Invest Radiol. 1993 Nov;28 Suppl 5:S79-84; discussion S85-6
references.pmid: 8282509
references.citation: Am J Kidney Dis. 1990 Sep;16(3):224-35
references.pmid: 2205098
references.citation: J Cereb Blood Flow Metab. 1985 Dec;5(4):584-90
references.pmid: 4055928
references.citation: Kidney Int. 1979 Aug;16(2):179-86
references.pmid: 390219
references.citation: Mayo Clin Proc. 1975 Nov;50(11):664-8
references.pmid: 1186298
references.citation: Circulation. 2002 Aug 27;106(9):1165-71
references.pmid: 12196346
references.citation: Eur Radiol. 2001;11(11):2270-7
references.pmid: 11702172
references.citation: Eur J Radiol. 2001 Sep;39(3):201-8
references.pmid: 11566250
references.citation: Am J Physiol Renal Physiol. 2001 Oct;281(4):F630-8
references.pmid: 11553509
references.citation: J Urol. 2001 Feb;165(2):382-5
references.pmid: 11176378
references.citation: N Engl J Med. 2014 Jan 2;370(1):13-22
references.pmid: 24245566
references.citation: Acta Radiol. 2004 Jul;45(4):474-80
references.pmid: 15323404
references.citation: Ann Nucl Med. 2003 Oct;17(7):561-5
references.pmid: 14651355
references.citation: AJR Am J Roentgenol. 2003 Jul;181(1):147-56
references.pmid: 12818847
references.citation: Circ Cardiovasc Interv. 2013 Aug;6(4):428-35
references.pmid: 23899868
references.citation: Eur Heart J. 2013 Feb;34(7):540-548a
references.pmid: 22771675
references.citation: Radiology. 2012 Aug;264(2):567-80
references.pmid: 22692035
references.citation: Radiology. 2007 May;243(2):405-12
references.pmid: 17456868
references.citation: AJR Am J Roentgenol. 2008 Nov;191(5):1552-8
references.pmid: 18941100
references.citation: J Am Soc Nephrol. 2009 Nov;20(11):2305-13
references.pmid: 19833901
references.citation: N Engl J Med. 2009 Nov 12;361(20):1953-62
references.pmid: 19907042
references.citation: Am J Kidney Dis. 2010 Jul;56(1):39-49
references.pmid: 20537455
references.citation: Am J Physiol Renal Physiol. 2011 Jun;300(6):F1394-401
references.pmid: 21367913
references.citation: Radiology. 2011 Aug;260(2):414-20
references.pmid: 21673226
references.citation: Hypertension. 2011 Dec;58(6):1066-72
references.pmid: 22042812