title: A novel approach to evaluate spatial resolution of MRI clinical images for optimization and standardization of breast screening protocols.
abstract: OBJECTIVE
  Stringent quality assurance is required in MRI breast screening to ensure that different scanners and imaging protocols reach similar diagnostic performance. The authors propose a methodology, based on power spectrum analysis (PSA), to evaluate spatial resolution in clinical images. To demonstrate this approach, the authors have retrospectively compared two MRI sequences commonly employed in breast screening.
  
  
  METHODS
  In a novel approach to PSA, spatial frequency response curves (SFRCs) were extracted from the images. The SFRC characterizes spatial resolution describing the spatial frequency content of an image over a range of frequencies. Verification of the SFRCs was performed on MRI images of Eurospin agarose gel tubes acquired with different resolution settings. SFRCs of volunteer and patient images obtained with two clinical MRI sequences were then compared. The two sequences differed primarily in k-space coverage pattern, which was either radial (RAD) or linear (LIN).
  
  
  RESULTS
  The computed SFRCs were able to demonstrate the differences between RAD and LIN sequences in relatively small groups of subjects. The curves showed a similar pattern of decay in both volunteer and patient images, indicating that the spatial frequency response is mainly determined by the imaging protocol and not by intersubject anatomical differences. The LIN protocol produced images with increased sharpness; this was reflected in the corresponding SFRCs, which showed a higher content of spatial frequencies associated with image details.
  
  
  CONCLUSIONS
  The SFRC can provide an objective assessment of the presence of spatial details in the image and represent a useful quality assurance tool in the evaluation of different breast screening protocols. With a reference image, a comparative analysis of the SFRCs could ensure that equivalent image quality is achieved across different scanners and sites.
authors.affiliation: CR-UK Cancer Imaging Centre, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, London SM2 5PT, United Kingdom.
authors.forename: Marco
authors.initials: M
authors.lastname: Borri
authors.affiliation: Department of Radiology, The Royal Marsden NHS Foundation Trust, London SM2 5PT, United Kingdom.
authors.forename: Erica D
authors.initials: ED
authors.lastname: Scurr
authors.affiliation: Department of Radiology, The Royal Marsden NHS Foundation Trust, London SM2 5PT, United Kingdom.
authors.forename: Cheryl
authors.initials: C
authors.lastname: Richardson
authors.affiliation: Department of Radiology, The Royal Marsden NHS Foundation Trust, London SM2 5PT, United Kingdom.
authors.forename: Marianne
authors.initials: M
authors.lastname: Usher
authors.affiliation: CR-UK Cancer Imaging Centre, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, London SM2 5PT, United Kingdom.
authors.forename: Martin O
authors.initials: MO
authors.lastname: Leach
authors.affiliation: CR-UK Cancer Imaging Centre, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, London SM2 5PT, United Kingdom.
authors.forename: Maria A
authors.initials: MA
authors.lastname: Schmidt
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000592:standards*; D008403:Mass Screening / Q000592:standards*; D008875:Middle Aged; D059629:Signal-To-Noise Ratio