title: Longer time to peak flow predicts better arterial flow parameters on penile Doppler ultrasound.
abstract: OBJECTIVE
  To review the associations between measured variables in Penile Doppler ultrasound procedures. Penile Doppler ultrasound is useful in the evaluation of erectile dysfunction, but there is no uniform standard of performing the procedure. It is generally believed that a peak systolic velocity > 30 cm/s, minimal venous leak, and resistive index > 0.8 are essential for adequate erection. While the arterial parameters are well studied, data on the predictive value of time to peak flow are lacking.
  
  
  METHODS
  Penile duplex Doppler ultrasounds performed for either erectile dysfunction or Peyronie's disease evaluation were reviewed. Clinical records, International Index of Erectile Function scores, and ultrasound variables were examined. "Fast" responders reached maximal peak systolic velocity (PSV) < or = 10 minutes, whereas "slow" responders reached maximal PSV between 15 and 25 minutes.
  
  
  RESULTS
  Of 146 total patients, 36 (25%) were fast responders and 110 (75%), slow responders. No preprocedural characteristics, including the Erectile Function domain score of the International Index of Erectile Function, predicted time to peak flow. Compared with the fast responders, slow responders had higher mean PSV (left: 33.9 +/- 19.5 vs 25.0 +/- 11.7 cm/s, P = .01; and right: 36.4 +/- 21.3 vs 25.0 +/- 13.3 cm/s, P = .002). There was also a higher percentage of patients with average PSV > 30 cm/s in slow responders (58% vs 36%, P = .02).
  
  
  CONCLUSIONS
  There were no significant differences in baseline characteristics between slow and fast responders. However, slow responders did seem to have significantly better arterial flow parameters, although penile dimensions, cavernosal artery diameter, Erectile Function domain scores, and subjective rigidity were similar.
authors.affiliation: Department of Urology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors.forename: Wayland
authors.initials: W
authors.lastname: Hsiao
authors.forename: Adam B
authors.initials: AB
authors.lastname: Shrewsberry
authors.forename: Kelvin A
authors.initials: KA
authors.lastname: Moses
authors.forename: Donald
authors.initials: D
authors.lastname: Pham
authors.forename: Chad W M
authors.initials: CW
authors.lastname: Ritenour
mesh_terms: D007172:Erectile Dysfunction / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010413:Penis / Q000098:blood supply* / Q000000981:diagnostic imaging*; D012039:Regional Blood Flow; D012189:Retrospective Studies; D013997:Time Factors; D018608:Ultrasonography, Doppler