title: Motion corrected DWI with integrated T2-mapping for simultaneous estimation of ADC, T2-relaxation and perfusion in prostate cancer.
abstract: Multiparametric magnetic resonance imaging (MRI) and PI-RADS (Prostate Imaging - Reporting and Data System) has become the standard to determine a probability score for a lesion being a clinically significant prostate cancer. T2-weighted and diffusion-weighted imaging (DWI) are essential in PI-RADS, depending partly on visual assessment of signal intensity, while dynamic-contrast enhanced imaging is less important. To decrease inter-rater variability and further standardize image evaluation, complementary objective measures are in need.
  
  
  
  We here demonstrate a sequence enabling simultaneous quantification of apparent diffusion coefficient (ADC) and T2-relaxation, as well as calculation of the perfusion fraction f from low b-value intravoxel incoherent motion data. Expandable wait pulses were added to a FOCUS DW SE-EPI sequence, allowing the effective echo time to change at run time. To calculate both ADC and f, b-values 200s/mm2and 600s/mm2were chosen, and for T2-estimation 6 echo times between 64.9ms and 114.9ms were used.
  
  
  
  Three patients with prostate cancer were examined and all had significantly decreased ADC and T2-values, while f was significantly increased in 2 of 3 tumors. T2 maps obtained in phantom measurements and in a healthy volunteer were compared to T2 maps from a SE sequence with consecutive scans, showing good agreement. In addition, a motion correction procedure was implemented to reduce the effects of prostate motion, which improved T2-estimation.
  
  
  
  This sequence could potentially enable more objective tumor grading, and decrease the inter-rater variability in the PI-RADS classification.
authors.affiliation: Department of Radiation Sciences, Umeå University, Umeå, Sweden; Department of Radiology, Uppsala University Hospital, Uppsala, Sweden. Electronic address: mikael.skorpil@umu.se.
authors.forename: M
authors.initials: M
authors.lastname: Skorpil
authors.affiliation: Department of Radiation Sciences, Umeå University, Umeå, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Brynolfsson
authors.affiliation: Applied Science Laboratory, GE Healthcare, Uppsala, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Engström
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media / Q000737:chemistry*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D064368:Healthy Volunteers; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009038:Motion; D060787:Neoplasm Grading; D010477:Perfusion; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography; D011336:Probability; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D015203:Reproducibility of Results
chemical_list: D003287:Contrast Media
keywords: Apparent diffusion coefficient; Diffusion weighted imaging; Magnetic resonance imaging; Perfusion; Prostate cancer; T2-relaxation