Novel SNR determination method in parallel MRI

Tosiaki Miyati, Hiroshi Imai, Akio Ogura, Tsukasa Doi, Toshio Tsuchihashi, Yoshio Machida

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)


We devised two kinds of new methods for accurate measurement of the image signal-to-noise ratio (SNR) in parallel magnetic resonance imaging (MRI) because image noise of the parallel MRI was not spatially constant. Using the first (Consecutive) method, more than fifty consecutive scans of the uniform phantom were obtained with identical scan parameters. Then the SNRs in each pixel were calculated from the ratio of mean signal intensity to the standard deviation of the time domain on a pixel-by-pixel. With the second (Remove) method, the phantom was removed after the first scan, and the second scan was done with identical parameters and the RF coil loading device. The SNRs in each pixel were then obtained from the ratio of the signal intensity of the first scan to the second scan (w/o phantom) image which was multiplied by the square root of 2/pi and filtered by the running mean (7 by 7 pixels). Moreover, actual geometry factors were calculated from image SNRs of parallel and no parallel MRI. The image SNR and actual geometry factor of parallel MRI with the Consecutive method agreed with that of the Remove method. The SNRs of the no parallel MRI with the above two methods conformed with that of the conventional SNR method (NEMA standard). Both new methods make it possible to obtain a more detailed determination of SNR in parallel MRI, and to calculate the actual geometry factor.

Original languageEnglish
Title of host publicationMedical Imaging 2006
Subtitle of host publicationPhysics of Medical Imaging
Publication statusPublished - 2006
Externally publishedYes
EventMedical Imaging 2006: Physics of Medical Imaging - San Diego, CA, United States
Duration: 2006 Feb 122006 Feb 16

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume6142 III
ISSN (Print)1605-7422


OtherMedical Imaging 2006: Physics of Medical Imaging
Country/TerritoryUnited States
CitySan Diego, CA


  • Image noise
  • Image quality
  • METR
  • Magnetic resonance imaging (MRI)
  • OT
  • Parallel MRI
  • Sensitivity encoding (SENSE)
  • Signal intensity
  • Signal-to-noise ratio (SNR)

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Biomaterials
  • Radiology Nuclear Medicine and imaging


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