title: Breath-hold signal-loss sequence for the qualitative assessment of flow disturbances in cardiovascular MR.
abstract: OBJECTIVE
  To develop a breath-hold segmented sequence which generates similar patterns of signal loss to a non-breath-hold, relatively long echo time, conventional gradient echo sequence for the qualitative assessment of valvular heart disease.
  
  
  METHODS
  Both velocity-sensitized and acceleration-sensitized segmented sequences were developed. The sensitivities were empirically adjusted to give similar degrees of signal loss to a conventional sequence. These sequences were compared with a conventional sequence in eight patients with flow disturbances and in four healthy subjects.
  
  
  RESULTS
  There was no significant difference in the extent of signal loss observed when using the breath-hold velocity- and acceleration-sensitized sequences developed and the conventional sequence (1862 mm(2), 1831 mm(2), and 1782 mm(2), respectively; P = ns). However, the image quality obtained was significantly better with the breath-hold sequences (both P < 0.01). Furthermore, the image quality achieved with the acceleration-sensitized sequence was significantly better than that achieved with the velocity-sensitized sequence (P < 0.01) where artifacts from beat-to-beat variations in blood-flow velocities were a frequent problem.
  
  
  CONCLUSIONS
  Signal loss in complex flow is best demonstrated using the breath-hold acceleration-sensitized sequence where the signal from both stationary and constant velocity material is rephased at the echo time.
mesh_terms: D000328:Adult; D016477:Artifacts; D006349:Heart Valve Diseases / Q000175:diagnosis*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D019047:Phantoms, Imaging; D012119:Respiration