title: Three-Dimensional Renal Parenchymal Volume as a Surrogate for Renal Function Estimation in Obstructed Kidneys Undergoing Surgical Repair.
abstract: OBJECTIVE
  To investigate the relationship between renal parenchymal volume (RPV) and renal function in obstructed kidneys using a novel three-dimensional (3D) volume-rendering technique.
  
  
  METHODS
  Forty-seven consecutive patients who underwent pyeloplasty, ureteroureterostomy, or ureteroneocystostomy at a single institution between 2007 and 2013 were reviewed. Patients with preoperative CT scan and split differential functional (SDF) assessment by diuretic renography were included. Those with solitary kidneys and bilateral obstruction were excluded. Baseline serum creatinine (Cr) and estimated glomerular filtration rate (eGFR) as calculated by the modification of diet in renal disease equation were determined. Percent of total RPV for the obstructed kidney was determined using 3D reconstruction software by drawing regions of interest around the borders of the kidney on CT. The renal pelvis, hilar vessels, and hilar fat were excluded. Percent of total RPV was then correlated with SDF.
  
  
  RESULTS
  Nineteen patients with both preoperative CT and diuretic renal scans were included. Two underwent ureteroneocystostomy, 1 underwent ureteroureterostomy, and 16 underwent pyeloplasty. Mean serum Cr was 1.07±0.26 mg/dL with a mean eGFR of 69.43±18.90 mL/minute. Mean SDF was 37.32%±11.66% in the obstructed kidneys. There was a statistically significant correlation between percent of total RPV and SDF (R(2)=0.28, p=0.02).
  
  
  CONCLUSIONS
  There is a significant correlation between percent total RPV determined by 3D reconstruction of CT scan images and SDF as determined by diuretic renography in obstructed kidneys. CT-based percent RPV has potential as a functional assessment tool in obstructed kidneys. With further validation, it may be used to counsel patients considering surgical repair of ureteral or ureteropelvic junction obstruction.
authors.affiliation: Department of Urology, Loyola University Medical Center , Maywood, Illinois.
authors.forename: Humberto J
authors.initials: HJ
authors.lastname: Martinez-Suarez
authors.affiliation: Department of Urology, Loyola University Medical Center , Maywood, Illinois.
authors.forename: Timothy
authors.initials: T
authors.lastname: Durso
authors.affiliation: Department of Urology, Loyola University Medical Center , Maywood, Illinois.
authors.forename: Adam O
authors.initials: AO
authors.lastname: Kadlec
authors.affiliation: Department of Urology, Loyola University Medical Center , Maywood, Illinois.
authors.forename: Gopal N
authors.initials: GN
authors.lastname: Gupta
authors.affiliation: Department of Urology, Loyola University Medical Center , Maywood, Illinois.
authors.forename: Ahmer V
authors.initials: AV
authors.lastname: Farooq
authors.affiliation: Department of Urology, Loyola University Medical Center , Maywood, Illinois.
authors.forename: Thomas
authors.initials: T
authors.lastname: Turk
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007677:Kidney Function Tests / Q000379:methods*; D007682:Kidney Pelvis / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011866:Radioisotope Renography / Q000379:methods*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D014517:Ureteral Obstruction / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D055815:Young Adult