title: Renal parenchyma thickness: a rapid estimation of renal function on computed tomography.
abstract: OBJECTIVE
  To define the relationship between renal parenchyma thickness (RPT) on computed tomography and renal function on nuclear renography in chronically obstructed renal units (ORUs) and to define a minimal thickness ratio associated with adequate function.
  
  
  METHODS
  Twenty-eight consecutive patients undergoing both nuclear renography and CT during a six-month period between 2004 and 2006 were included. All patients that had a diagnosis of unilateral obstruction were included for analysis. RPT was measured in the following manner: The parenchyma thickness at three discrete levels of each kidney was measured using calipers on a CT workstation. The mean of these three measurements was defined as RPT. The renal parenchyma thickness ratio of the ORUs and non-obstructed renal unit (NORUs) was calculated and this was compared to the observed function on Mag-3 lasix Renogram.
  
  
  RESULTS
  A total of 28 patients were evaluated. Mean parenchyma thickness was 1.82 cm and 2.25 cm in the ORUs and NORUs, respectively. The mean relative renal function of ORUs was 39%. Linear regression analysis comparing renogram function to RPT ratio revealed a correlation coefficient of 0.48 (p < 0.001). The linear regression equation was computed as Renal Function = 0.48 + 0.80 * RPT ratio. A thickness ratio of 0.68 correlated with 20% renal function.
  
  
  CONCLUSIONS
  RPT on computed tomography appears to be a powerful predictor of relative renal function in ORUs. Assessment of RPT is a useful and readily available clinical tool for surgical decision making (renal salvage therapy versus nephrectomy) in patients with ORUs.
authors.affiliation: Department of Surgery, Division of Urology, Section of Minimally Invasive Urologic Surgery, The Warren Alpert School of Medicine of Brown University, Providence, Rhode Island, USA. kaplonda@gmail.com
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Kaplon
authors.forename: Michael S
authors.initials: MS
authors.lastname: Lasser
authors.forename: Mark
authors.initials: M
authors.lastname: Sigman
authors.forename: George E
authors.initials: GE
authors.lastname: Haleblian
authors.forename: Gyan
authors.initials: G
authors.lastname: Pareek
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002908:Chronic Disease; D005665:Furosemide; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging* / Q000503:physiopathology; D008875:Middle Aged; D011866:Radioisotope Renography / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000379:methods; D014517:Ureteral Obstruction / Q000000981:diagnostic imaging* / Q000473:pathology; D055815:Young Adult
chemical_list: D005665:Furosemide