title: Image noise reduction algorithm for digital subtraction angiography: clinical results.
abstract: OBJECTIVE
  To test the hypothesis that an image noise reduction algorithm designed for digital subtraction angiography (DSA) in interventional neuroradiology enables a reduction in the patient entrance dose by a factor of 4 while maintaining image quality.
  
  
  METHODS
  This clinical prospective study was approved by the local ethics committee, and all 20 adult patients provided informed consent. DSA was performed with the default reference DSA program, a quarter-dose DSA program with modified acquisition parameters (to reduce patient radiation dose exposure), and a real-time noise-reduction algorithm. Two consecutive biplane DSA data sets were acquired in each patient. The dose-area product (DAP) was calculated for each image and compared. A randomized, blinded, offline reading study was conducted to show noninferiority of the quarter-dose image sets. Overall, 40 samples per treatment group were necessary to acquire 80% power, which was calculated by using a one-sided α level of 2.5%.
  
  
  RESULTS
  The mean DAP with the quarter-dose program was 25.3% ± 0.8 of that with the reference program. The median overall image quality scores with the reference program were 9, 13, and 12 for readers 1, 2, and 3, respectively. These scores increased slightly to 12, 15, and 12, respectively, with the quarter-dose program imaging chain.
  
  
  CONCLUSIONS
  In DSA, a change in technique factors combined with a real-time noise-reduction algorithm will reduce the patient entrance dose by 75%, without a loss of image quality.
authors.affiliation: Department of Clinical Neuroscience, Karolinska Institutet and Department of Neuroradiology, Karolinska University Hospital, Stockholm 17176, Sweden; Department of Hospital Physics, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Michael
authors.initials: M
authors.lastname: Söderman
authors.forename: Staffan
authors.initials: S
authors.lastname: Holmin
authors.forename: Tommy
authors.initials: T
authors.lastname: Andersson
authors.forename: Charlotta
authors.initials: C
authors.lastname: Palmgren
authors.forename: Draženko
authors.initials: D
authors.lastname: Babic
authors.forename: Bart
authors.initials: B
authors.lastname: Hoornaert
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D015901:Angiography, Digital Subtraction / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging / Q000379:methods*; D011446:Prospective Studies; D011829:Radiation Dosage