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T(2) Distribution in the Forearm Muscles and the T(2) Threshold for Defining Activated Muscle
PURPOSE: In order to detect exercised muscles by the increase in T(2), we have defined a Gaussian T(2) distribution and reference values (T(2r) and SD(r)) in resting state muscles, and a threshold for detecting exercised muscles. METHODS: The subjects were healthy adult volunteers (14 males and 12 f...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Japanese Society for Magnetic Resonance in Medicine
2018
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6630056/ https://www.ncbi.nlm.nih.gov/pubmed/30449822 http://dx.doi.org/10.2463/mrms.mp.2018-0059 |
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author | Takamori, Masayoshi Akiyama, Sumikazu Yoshida, Kazuya Wakashin, Hidefumi Seo, Yoshiteru |
author_facet | Takamori, Masayoshi Akiyama, Sumikazu Yoshida, Kazuya Wakashin, Hidefumi Seo, Yoshiteru |
author_sort | Takamori, Masayoshi |
collection | PubMed |
description | PURPOSE: In order to detect exercised muscles by the increase in T(2), we have defined a Gaussian T(2) distribution and reference values (T(2r) and SD(r)) in resting state muscles, and a threshold for detecting exercised muscles. METHODS: The subjects were healthy adult volunteers (14 males and 12 females). Multiple-spin-echo (MSE) MR images were obtained with 10 TE values from 10 to 100 ms using a 0.2T MRI system. T(2) values for 10 forearm muscles were obtained in the resting state and after isometric wrist flexion exercise with 5%, 15%, and 25% of the maximum voluntary contraction (MVC). Z values were obtained by (T(2e) − T(2r))/SD(r), where T(2e) was T(2) after exercise. Based on sample size calculations, three thresholds (Z(T) = 1.00, 2.56, and 3.07) were applied to agonist and antagonist muscles. RESULTS: A normal distribution of T(2) was detected in resting muscles at 34 ± 3 ms (mean ± standard deviation [SD]) in 26 subjects using the Kolmogorov–Smirnov test, the Shapiro–Wilk test, and the Jarque–Bera test (P > 0.05). No gender differences were shown between the T(2) or SD, and a similar result was obtained in 12 measurements on a single subject (P < 0.01). The T(2r) and SD(r) were used for reference values. The threshold Z(T) = 1.00 showed the highest sensitivity (0.86) even with 5% MVC, but it showed a lower specificity (0.85) than the other thresholds. Z(T) = 3.07 showed the highest specificity (1.0), but it showed a lower sensitivity (0.36) with the 5% MVC, compared with Z(T) = 2.56 (0.50). The receiver operating characteristics analysis also supported these results. CONCLUSION: We found that the T(2) distribution in muscles was Gaussian, suggesting that a one-sample t-test can be applied, and that Z(T) = 2.56 could cover low-intensity exercise with high specificity and a low false-positive rate. |
format | Online Article Text |
id | pubmed-6630056 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | Japanese Society for Magnetic Resonance in Medicine |
record_format | MEDLINE/PubMed |
spelling | pubmed-66300562019-07-23 T(2) Distribution in the Forearm Muscles and the T(2) Threshold for Defining Activated Muscle Takamori, Masayoshi Akiyama, Sumikazu Yoshida, Kazuya Wakashin, Hidefumi Seo, Yoshiteru Magn Reson Med Sci Major Paper PURPOSE: In order to detect exercised muscles by the increase in T(2), we have defined a Gaussian T(2) distribution and reference values (T(2r) and SD(r)) in resting state muscles, and a threshold for detecting exercised muscles. METHODS: The subjects were healthy adult volunteers (14 males and 12 females). Multiple-spin-echo (MSE) MR images were obtained with 10 TE values from 10 to 100 ms using a 0.2T MRI system. T(2) values for 10 forearm muscles were obtained in the resting state and after isometric wrist flexion exercise with 5%, 15%, and 25% of the maximum voluntary contraction (MVC). Z values were obtained by (T(2e) − T(2r))/SD(r), where T(2e) was T(2) after exercise. Based on sample size calculations, three thresholds (Z(T) = 1.00, 2.56, and 3.07) were applied to agonist and antagonist muscles. RESULTS: A normal distribution of T(2) was detected in resting muscles at 34 ± 3 ms (mean ± standard deviation [SD]) in 26 subjects using the Kolmogorov–Smirnov test, the Shapiro–Wilk test, and the Jarque–Bera test (P > 0.05). No gender differences were shown between the T(2) or SD, and a similar result was obtained in 12 measurements on a single subject (P < 0.01). The T(2r) and SD(r) were used for reference values. The threshold Z(T) = 1.00 showed the highest sensitivity (0.86) even with 5% MVC, but it showed a lower specificity (0.85) than the other thresholds. Z(T) = 3.07 showed the highest specificity (1.0), but it showed a lower sensitivity (0.36) with the 5% MVC, compared with Z(T) = 2.56 (0.50). The receiver operating characteristics analysis also supported these results. CONCLUSION: We found that the T(2) distribution in muscles was Gaussian, suggesting that a one-sample t-test can be applied, and that Z(T) = 2.56 could cover low-intensity exercise with high specificity and a low false-positive rate. Japanese Society for Magnetic Resonance in Medicine 2018-11-19 /pmc/articles/PMC6630056/ /pubmed/30449822 http://dx.doi.org/10.2463/mrms.mp.2018-0059 Text en © 2018 The Japan Neurosurgical Society This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/4.0/ |
spellingShingle | Major Paper Takamori, Masayoshi Akiyama, Sumikazu Yoshida, Kazuya Wakashin, Hidefumi Seo, Yoshiteru T(2) Distribution in the Forearm Muscles and the T(2) Threshold for Defining Activated Muscle |
title | T(2) Distribution in the Forearm Muscles and the T(2) Threshold for Defining Activated Muscle |
title_full | T(2) Distribution in the Forearm Muscles and the T(2) Threshold for Defining Activated Muscle |
title_fullStr | T(2) Distribution in the Forearm Muscles and the T(2) Threshold for Defining Activated Muscle |
title_full_unstemmed | T(2) Distribution in the Forearm Muscles and the T(2) Threshold for Defining Activated Muscle |
title_short | T(2) Distribution in the Forearm Muscles and the T(2) Threshold for Defining Activated Muscle |
title_sort | t(2) distribution in the forearm muscles and the t(2) threshold for defining activated muscle |
topic | Major Paper |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6630056/ https://www.ncbi.nlm.nih.gov/pubmed/30449822 http://dx.doi.org/10.2463/mrms.mp.2018-0059 |
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