title: Endoscopic laser ablation of the prostate (ELAP): changes in magnetic resonance imaging and clinical outcome at 1 year.
abstract: OBJECTIVE
  To assess the ability of magnetic resonance imaging (MRI) to detect tissue changes immediately after laser ablation of the prostate and to correlate these changes with clinical outcome by detecting changes that may improve the outcome by allowing the laser dosimetry to be adjusted during therapy by monitoring effects on gland morphology.
  
  
  METHODS
  Eight men with proven bladder outlet obstruction had a standard four-quadrant laser ablation of the prostate with a side-firing non-contact fibre. MRI scans were performed before, during and immediately after treatment and again after one week, 3 months and one year.
  
  
  RESULTS
  The clinical outcome was a decrease in the American Urological Association (AUA)-7 symptom score from a pre-operative mean of 21.3-12.0 1 year after treatment and a corresponding increase in peak urinary flow rates from a mean of 8.9 mL/s to 12.3 mL/s. Immediately after treatment, MRI showed marked swelling of the gland (mean increase in volume 34%, range 12-75) with the loss of internal architecture. A low-signal thin periurethral band was present in six of the eight patients after 1 week and was replaced by a wider periurethral ring at 3 months in four of the six patients. No patient had evidence of prostatic cavitation after treatment or a significant reduction in prostate volume at 1 year.
  
  
  CONCLUSIONS
  MRI can detect tissue changes after laser ablation of the prostate. The marked swelling seen on MRI immediately after laser prostatectomy may explain the delayed improvement in symptoms. The periurethral ring may indicate the depth to which laser energy has an effect on the tissue and could delineate an area of necrosis. The lack of cavitation at one year questions the durability of the effect of laser treatment delivered in this way.
authors.affiliation: Department of Surgery, Hammersmith Hospital NHS Trust, London, UK.
authors.forename: R J
authors.initials: RJ
authors.lastname: Flynn
authors.forename: N M
authors.initials: NM
authors.lastname: de Souza
authors.forename: R
authors.initials: R
authors.lastname: Puni
authors.forename: G
authors.initials: G
authors.lastname: Williams
authors.forename: E A
authors.initials: EA
authors.lastname: Kiely
mesh_terms: D000368:Aged; D004724:Endoscopy / Q000379:methods; D006801:Humans; D053685:Laser Therapy / Q000379:methods*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011469:Prostatic Diseases / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome; D016055:Urinary Retention / Q000503:physiopathology / Q000601:surgery*; D014554:Urination / Q000502:physiology