title: Pulse sequence considerations for simulation and postimplant dosimetry of prostate brachytherapy.
abstract: OBJECTIVE
  The purpose of this work is to present a brief review of MRI physics principles pertinent to prostate brachytherapy, and a summary of our experience in optimizing protocols for prostate brachytherapy applications.
  
  
  METHODS
  We summarized essential MR imaging characteristics and their interplays that need to be considered for prostate brachytherapy applications. These include spatial resolution, signal-to-noise ratio, image contrast, artifacts, geometric distortion, specific absorption rate, and total scan time. We further described the optimization of the protocols for three pulse sequences: three-dimensional (3D) fast-spoiled gradient echo sequence for T1-weighted imaging, 3D fast-spin echo sequence for T2-weighted imaging, and 3D fast imaging in steady-state precession sequence for combined T1 and T2-weighed imaging. The utilization of an endorectal coil was also described.
  
  
  RESULTS
  Using the optimized protocols, we acquired high-quality images of the entire prostate within 3-5 minutes for each sequence. These images display the desired image contrasts and a spatial resolution that is equal to or better than 0.59 mm × 0.73 mm × 1.2 mm. While 3D fast-spoiled gradient echo sequence and 3D fast-spin echo sequence depict radioactive seed markers and anatomic structures separately, 3D fast imaging in steady-state precession sequence demonstrates great promise for imaging both seed markers and prostate anatomy simultaneously in a single acquisition.
  
  
  CONCLUSIONS
  We have optimized current MRI protocols and demonstrated that the anatomic structures and positive contrast radioactive seed markers for prostate post-implant dosimetry can be adequately imaged either separately or simultaneously using different pulse sequences within a total scan time of 3-5 minutes each.
authors.affiliation: Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX. Electronic address: jma@mdanderson.org.
authors.forename: Jingfei
authors.initials: J
authors.lastname: Ma
authors.affiliation: Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Marinus A
authors.initials: MA
authors.lastname: Moerland
authors.affiliation: Department of Diagnostic Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Aradhana M
authors.initials: AM
authors.lastname: Venkatesan
authors.affiliation: Department of Diagnostic Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Tharakeswara K
authors.initials: TK
authors.lastname: Bathala
authors.affiliation: Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Rajat J
authors.initials: RJ
authors.lastname: Kudchadker
authors.affiliation: Department of Radiation Oncology, University of Michigan, Ann Arbor, MI.
authors.forename: Kristy K
authors.initials: KK
authors.lastname: Brock
authors.affiliation: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Frank
keywords: MRI protocols; Prostate brachytherapy; Pulse sequences; Radioactive seeds