title: Optimized Fast Dynamic Contrast-Enhanced Magnetic Resonance Imaging of the Prostate: Effect of Sampling Duration on Pharmacokinetic Parameters.
abstract: OBJECTIVE
  The aim of this study was to evaluate the effect of sampling duration on pharmacokinetic parameters from dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) and their diagnostic accuracy regarding the detection of potentially malignant prostate lesions.
  
  
  METHODS
  Sixty-six consecutive male patients (mean [SD] age, 65.4 [10.8] years) with clinically suspected prostate cancer were included. All patients underwent multiparametric MRI of the prostate (T2-weighted imaging, diffusion-weighted imaging, and DCE-MRI) on a 3 T MRI scanner. Patients were divided into 2 groups depending on the prostate imaging reporting and data system (PI-RADS) score of the detected lesions (group A: PI-RADS ≤3, n = 32; group B: PI-RADS >3, n = 34). In all patients, DCE-MRI was performed using a CAIPIRINHA-Dixon-TWIST volume interpolated breath-hold examination sequence (spatial resolution, 3 × 1.2 × 1.2 mm; temporal resolution, 5 seconds; total sampling duration, 4:10 minutes [250 seconds]) with body weight-adapted administration of contrast agent (gadobutrol, Bayer Healthcare, Berlin, Germany). Five DCE-MRI series with different acquisition durations ranging from 50 to 250 seconds were retrospectively generated from the original data sets. Pharmacokinetic parameters (ie, Ktrans, Kep, Ve, and iAUC60) were calculated for the different sampling durations using the Tofts model. Both lesion groups and all 5 DCE-MRI series were compared regarding pharmacokinetic parameters. Diagnostic accuracy for the detection of potentially malignant lesions was calculated for all 5 series using receiver operating characteristic analysis.
  
  
  RESULTS
  For all 5 series, Ktrans, Kep, and iAUC60 in patient group B were significantly higher than the respective parameters in patient group A (all P ≤ 0.008). In both groups, Ktrans, Kep, and iAUC60 remained constant at 200 and 150 seconds acquisition duration and did not significantly differ from parameters estimated from the original data sets (250 seconds; all P ≥ 0.310). Ve did not differ significantly between the 2 groups (P ≥ 0.337) and acquisition time did not have a significant effect on this parameter (P ≥ 0.275). Receiver operating characteristic analyses showed consistent diagnostic accuracy for the different series; only diagnostic accuracy of Kep decreased with lowered sampling duration, showing lowest accuracy for the 50-second series (0.682; 95% confidence interval, 0.553-0.811).
  
  
  CONCLUSIONS
  Using fast optimized DCE-MRI of the prostate, a minimum sampling duration of 150 seconds is required for sufficient pharmacokinetic parameter estimates, providing a high diagnostic accuracy regarding the discrimination between benign and potentially malignant lesions.
authors.affiliation: From the Departments of *Diagnostic and Interventional Radiology and †Urology, University Hospital Tübingen, Eberhard Karls University Tübingen, Tübingen; and ‡Siemens Healthcare GmbH, Erlangen, Germany.
authors.forename: Ahmed E
authors.initials: AE
authors.lastname: Othman
authors.forename: Florian
authors.initials: F
authors.lastname: Falkner
authors.forename: Petros
authors.initials: P
authors.lastname: Martirosian
authors.forename: Christina
authors.initials: C
authors.lastname: Schraml
authors.forename: Christian
authors.initials: C
authors.lastname: Schwentner
authors.forename: Dominik
authors.initials: D
authors.lastname: Nickel
authors.forename: Konstantin
authors.initials: K
authors.lastname: Nikolaou
authors.forename: Mike
authors.initials: M
authors.lastname: Notohamiprodjo
mesh_terms: D000368:Aged; D003198:Computer Simulation; D003287:Contrast Media / Q000493:pharmacokinetics; D003627:Data Interpretation, Statistical; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007700:Kinetics; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008657:Metabolic Clearance Rate; D008954:Models, Biological; D009942:Organometallic Compounds / Q000493:pharmacokinetics*; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology*; D015203:Reproducibility of Results; D018401:Sample Size; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C090600:gadobutrol