Novel SNR determination method in parallel MRI

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

doi:10.1117/12.653482

Novel SNR determination method in parallel MRI

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

MED - Health Sciences

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

2 Citations (Scopus)

Abstract

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 language	English
Title of host publication	Medical Imaging 2006
Subtitle of host publication	Physics of Medical Imaging
DOIs	https://doi.org/10.1117/12.653482
Publication status	Published - 2006
Event	Medical Imaging 2006: Physics of Medical Imaging - San Diego, CA, United States Duration: 2006 Feb 12 → 2006 Feb 16

Publication series

Name	Progress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume	6142 III
ISSN (Print)	1605-7422

Other

Other	Medical Imaging 2006: Physics of Medical Imaging
Country	United States
City	San Diego, CA
Period	06/2/12 → 06/2/16

Keywords

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
Biomaterials
Atomic and Molecular Physics, and Optics
Radiology Nuclear Medicine and imaging

Access to Document

10.1117/12.653482

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Novel SNR determination method in parallel MRI. / Miyati, Tosiaki; Imai, Hiroshi; Ogura, Akio; Doi, Tsukasa; Tsuchihashi, Toshio; Machida, Yoshio.

Medical Imaging 2006: Physics of Medical Imaging. 2006. 61423O (Progress in Biomedical Optics and Imaging - Proceedings of SPIE; Vol. 6142 III).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Miyati, T, Imai, H, Ogura, A, Doi, T, Tsuchihashi, T & Machida, Y 2006, Novel SNR determination method in parallel MRI. in Medical Imaging 2006: Physics of Medical Imaging., 61423O, Progress in Biomedical Optics and Imaging - Proceedings of SPIE, vol. 6142 III, Medical Imaging 2006: Physics of Medical Imaging, San Diego, CA, United States, 06/2/12. https://doi.org/10.1117/12.653482

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abstract = "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.",

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AU - Machida, Yoshio

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N2 - 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.

AB - 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.

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KW - Sensitivity encoding (SENSE)

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