title: Comparison of RigiScan and sleep laboratory nocturnal penile tumescence in the diagnosis of organic impotence.
abstract: OBJECTIVE
  We evaluated the relative use of RigiScan measurement of radial rigidity compared to sleep laboratory measurement of axial rigidity and trained observer determination of erectile function in the diagnosis of organic impotence.
  
  
  METHODS
  A total of 28 patients underwent simultaneous 2-night formal sleep laboratory nocturnal penile tumescence and RigiScan monitoring. Standard normal values for radial rigidity and axial rigidity were tested for accuracy in predicting normal nocturnal penile tumescence compared to trained observer determination of the adequacy of an erection for penetration.
  
  
  RESULTS
  RigiScan tip measurements correlated poorly with buckling pressure, while base measurements strongly correlated (p = 0.0005). Observer determination of a functional erection was strongly associated with tip (p = 0.002), base (p = 0.0005) and buckling pressure measurements (p = 0.0005). Using observer determination as the gold standard receiver operating curves were generated to select RigiScan base and buckling pressure measurements that predicted functional erections with the highest sensitivity and specificity.
  
  
  CONCLUSIONS
  RigiScan is a useful tool for measuring nocturnal penile tumescence. However, base measurements are more accurate than tip measurements for evaluating erectile function. The currently accepted level of rigidity used to define a normal erection (70% or greater) overestimates organic erectile dysfunction.
authors.affiliation: Department of Urology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Licht
authors.forename: R W
authors.initials: RW
authors.lastname: Lewis
authors.forename: P C
authors.initials: PC
authors.lastname: Wollan
authors.forename: C D
authors.initials: CD
authors.lastname: Harris
mesh_terms: D000328:Adult; D000368:Aged; D007172:Erectile Dysfunction / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010410:Penile Erection; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D012890:Sleep