title: Tumor target volume for focal therapy of prostate cancer-does multiparametric magnetic resonance imaging allow for a reliable estimation?
abstract: OBJECTIVE
  We determined whether endorectal multiparametric magnetic resonance imaging at 1.5 Tesla could predict tumor target volume in the perspective of focal therapy of prostate cancer.
  
  
  METHODS
  A total of 84 consecutive patients underwent multiparametric magnetic resonance imaging before radical prostatectomy. The volume of each suspicious area detected on magnetic resonance imaging and of all surgical histological foci was determined by planimetry. We first used each magnetic resonance imaging sequence (T2-weighted, diffusion weighted and dynamic contrast enhanced) and then the sequence showing the largest tumor area (multiparametric volume). Finally, the largest area of any sequence was used to calculate a target volume according to the volume of a cylinder. Agreement between magnetic resonance imaging and pathological findings was assessed by linear regression and residual analysis.
  
  
  RESULTS
  Histology revealed 99 significant tumors with a volume of greater than 0.2 cc and/or a Gleason score of greater than 6. Of the tumors 16 (16.2%) were undetected by multiparametric magnetic resonance imaging. Linear regression analysis showed that tumor volume estimated by T2-weighted or diffusion weighted imaging correlated significantly with pathological volume (r(2) = 0.82 and 0.83, respectively). Residuals from diffusion weighted imaging volume estimations did not significantly differ from 0. Nevertheless, diffusion weighted imaging underestimated pathological volume in 43 of 87 cases (49%) by a mean of 0.56 cc (range 0.005 to 2.84). Multiparametric and target volumes significantly overestimated pathological volume by a mean of 16% and 44% with underestimation in 28 (32%) and 15 cases (17%), respectively. Volume underestimation was significantly higher for tumor foci less than 0.5 cc. The percent of Gleason grade 4 did not influence tumor volume estimation.
  
  
  CONCLUSIONS
  Magnetic resonance imaging can detect most significant tumors. However, delineating a target volume may require further adjustment before planning magnetic resonance imaging targeted focal treatment.
authors: Department of Radiology, Hôpital Cochin, Paris Descartes University, Sorbonne Paris Cité, Paris, France. Electronic address: frcornud@imagerie-tourville.com.
authors: F
authors: F
authors: Cornud
authors: Department of Radiology, Hôpital Cochin, Paris Descartes University, Sorbonne Paris Cité, Paris, France.
authors: Gaby
authors: G
authors: Khoury
authors: Department of Clinical Research, Assistance Publique-Hôpitaux de Paris, Tarnier Hospital, Paris Descartes University, Sorbonne Paris Cité, Paris, France.
authors: Naim
authors: N
authors: Bouazza
authors: Department of Pathology, Hôpital Cochin, Paris Descartes University, Sorbonne Paris Cité, Paris, France.
authors: Frederic
authors: F
authors: Beuvon
authors: Department of Urology, Hôpital Cochin, Paris Descartes University, Sorbonne Paris Cité, Paris, France.
authors: Michael
authors: M
authors: Peyromaure
authors: Department of Urology, Hôpital Cochin, Paris Descartes University, Sorbonne Paris Cité, Paris, France.
authors: Thierry
authors: T
authors: Flam
authors: Department of Urology, Hôpital Cochin, Paris Descartes University, Sorbonne Paris Cité, Paris, France.
authors: Marc
authors: M
authors: Zerbib
authors: Department of Radiology, Hôpital Cochin, Paris Descartes University, Sorbonne Paris Cité, Paris, France.
authors: Paul
authors: P
authors: Legmann
authors: Department of Urology, Hôpital Cochin, Paris Descartes University, Sorbonne Paris Cité, Paris, France.
authors: Nicolas B
authors: NB
authors: Delongchamps
mesh_terms: D000368:Aged; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000601:surgery; D015203:Reproducibility of Results; D012189:Retrospective Studies; D047368:Tumor Burden
keywords: diagnostic imaging; magnetic resonance imaging; prostate; prostatectomy; prostatic neoplasms