title: Pulse sequence programming in a dynamic visual environment: SequenceTree.
abstract: OBJECTIVE
  To describe SequenceTree, an open source, integrated software environment for implementing MRI pulse sequences and, ideally, exporting them to actual MRI scanners. The software is a user-friendly alternative to vendor-supplied pulse sequence design and editing tools and is suited for programmers and nonprogrammers alike.
  
  
  METHODS
  The integrated user interface was programmed using the Qt4/C++ toolkit. As parameters and code are modified, the pulse sequence diagram is automatically updated within the user interface. Several aspects of pulse programming are handled automatically, allowing users to focus on higher-level aspects of sequence design. Sequences can be simulated using a built-in Bloch equation solver and then exported for use on a Siemens MRI scanner. Ideally, other types of scanners will be supported in the future.
  
  
  RESULTS
  SequenceTree has been used for 8 years in our laboratory and elsewhere and has contributed to more than 50 peer-reviewed publications in areas such as cardiovascular imaging, solid state and nonproton NMR, MR elastography, and high-resolution structural imaging.
  
  
  CONCLUSIONS
  SequenceTree is an innovative, open source, visual pulse sequence environment for MRI combining simplicity with flexibility and is ideal both for advanced users and users with limited programming experience.
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
authors.forename: Jeremy F
authors.initials: JF
authors.lastname: Magland
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
authors.forename: Cheng
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Langham
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
authors.forename: Felix W
authors.initials: FW
authors.lastname: Wehrli
mesh_terms: D000465:Algorithms; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D011381:Programming Languages; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D012984:Software; D012985:Software Design; D018511:Systems Integration
keywords: MRI simulation; graphical user interface; pulse sequence; software