title: Accurate prostate tumour detection with multiparametric magnetic resonance imaging: dependence on histological properties.
abstract: BACKGROUND
  To benefit most of focal treatment of prostate tumours, detection with high precision of all tumour voxels is needed. Although diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) have good diagnostic performance, perfect tumour detection is challenging. In this study, we investigated the variation in prostate tissue characteristics Gleason score (GS), cell density (CD) and microvessel density (MVD) to explain the limitations in tumour voxel detection with a MRI-based logistic regression model.
  
  
  METHODS
  Twelve radical prostatectomy patients underwent a pre-operative 3.0T DWI and DCE-MRI exam. The MRI scans were used to calculate voxel-wise tumour probability with a logistic regression model for the peripheral zone (PZ) of the prostate. Tumour probability maps were correlated and validated with whole-mount histology. Additionally, from the whole-mount histological sections CD, MVD and GS were retrieved for every single voxel. GS, CD and MVD of true- and false-positive voxels and of true- and false-negative voxels were compared using Mann-Whitney U-tests.
  
  
  RESULTS
  False-negative tumour voxels had significantly lower CD and MVD (p < 0.0001) and were similar to non-tumour PZ. True-positive detected tumour voxels had high CDs and MVDs (p < 0.0001). In addition, tumour voxels with higher GS showed a trend towards more frequent detection (p = 0.06). Tumour voxels with GS ≥ 3 + 4 showed higher CD and MVD compared to tumour voxels with GS 3 + 3 (p < 0.0001).
  
  
  CONCLUSIONS
  Tumour voxels with low CD and MVD resemble healthy tissue and are limiting tumour voxel detection using DWI and DCE-MRI. Nevertheless, the most aggressive tumour voxels, containing high CD, MVD and GS, are more likely to be detected and can therefore be treated with high dose using focal therapy or focal boosting.
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht , The Netherlands.
authors.forename: Alie
authors.initials: A
authors.lastname: Borren
authors.forename: Greetje
authors.initials: G
authors.lastname: Groenendaal
authors.forename: Maaike R
authors.initials: MR
authors.lastname: Moman
authors.forename: Arto E
authors.initials: AE
authors.lastname: Boeken Kruger
authors.forename: Paul J
authors.initials: PJ
authors.lastname: van Diest
authors.forename: Marco
authors.initials: M
authors.lastname: van Vulpen
authors.forename: Marielle E P
authors.initials: ME
authors.lastname: Philippens
authors.forename: Uulke A
authors.initials: UA
authors.lastname: van der Heide
mesh_terms: D000368:Aged; D003287:Contrast Media; D006801:Humans; D016015:Logistic Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011379:Prognosis; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000601:surgery
chemical_list: D003287:Contrast Media