Tomoko Maekawa1,2, Masaaki Hori3, Katsutoshi Murata4, Thorsten Feiweier5, Issei Fukunaga3, Christina Andica3, Akifumi Hagiwara3,6, Koji Kamagata3, Saori Koshino3,6, Osamu Abe6, Shigeki Aoki3. 1. Department of Radiology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan. t-maekawa@juntendo.ac.jp. 2. Department of Radiology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. t-maekawa@juntendo.ac.jp. 3. Department of Radiology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan. 4. Siemens Healthcare Japan KK, Gate City Osaki West Tower, 11-1 Osaka 1-Chome, Shinagawa-ku, Tokyo, 141-8644, Japan. 5. Siemens Healthcare GmbH, Henkestrasse 127, 91052, Erlangen, Germany. 6. Department of Radiology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
Abstract
PURPOSE: Compared with the conventional pulsed gradient spin-echo (PGSE) sequence, diffusion-weighted imaging (DWI) with the oscillating gradient spin-echo (OGSE) sequence can shorten the diffusion time by changing the frequency. The purpose was to investigate whether n-alkanes are suitable as isotropic phantoms for estimating the diffusion coefficient with the OGSE sequence. MATERIALS AND METHODS: We investigated changes in the apparent diffusion coefficient (ADC) due to differences in the viscosities of nine n-alkane phantoms with different numbers of carbon atoms from C8H18 to C16H34 using OGSE and PGSE sequences at 21 °C. Effective diffusion times of 4.3, 5.1, 6.5, 9.3, 20, 40, and 60 ms were used. The T2 relaxation times of each n-alkane phantom were measured using quantitative synthetic magnetic resonance imaging (MRI). Circular regions of interest were placed manually within the alkane phantoms on ADC and T2 maps. RESULTS: In each alkane phantom, changes in mean ADC values were almost constant with changes in diffusion times. Viscosities and ADC values showed inverse proportionality, as expected theoretically. CONCLUSION: The ADC values of alkanes do not depend on diffusion times. The n-alkanes can be useful phantoms for assessing the accuracy of clinical protocols of DWI with the OGSE sequence.
PURPOSE: Compared with the conventional pulsed gradient spin-echo (PGSE) sequence, diffusion-weighted imaging (DWI) with the oscillating gradient spin-echo (OGSE) sequence can shorten the diffusion time by changing the frequency. The purpose was to investigate whether n-alkanes are suitable as isotropic phantoms for estimating the diffusion coefficient with the OGSE sequence. MATERIALS AND METHODS: We investigated changes in the apparent diffusion coefficient (ADC) due to differences in the viscosities of nine n-alkane phantoms with different numbers of carbon atoms from C8H18 to C16H34 using OGSE and PGSE sequences at 21 °C. Effective diffusion times of 4.3, 5.1, 6.5, 9.3, 20, 40, and 60 ms were used. The T2 relaxation times of each n-alkane phantom were measured using quantitative synthetic magnetic resonance imaging (MRI). Circular regions of interest were placed manually within the alkane phantoms on ADC and T2 maps. RESULTS: In each alkane phantom, changes in mean ADC values were almost constant with changes in diffusion times. Viscosities and ADC values showed inverse proportionality, as expected theoretically. CONCLUSION: The ADC values of alkanes do not depend on diffusion times. The n-alkanes can be useful phantoms for assessing the accuracy of clinical protocols of DWI with the OGSE sequence.
Authors: M E Moseley; Y Cohen; J Mintorovitch; L Chileuitt; H Shimizu; J Kucharczyk; M F Wendland; P R Weinstein Journal: Magn Reson Med Date: 1990-05 Impact factor: 4.668
Authors: Jacobus F A Jansen; M Eline Kooi; Alfons G H Kessels; Klaas Nicolay; Walter H Backes Journal: Invest Radiol Date: 2007-06 Impact factor: 6.016
Authors: P S Tofts; D Lloyd; C A Clark; G J Barker; G J Parker; P McConville; C Baldock; J M Pope Journal: Magn Reson Med Date: 2000-03 Impact factor: 4.668
Authors: Christian Vollmar; Jonathan O'Muircheartaigh; Gareth J Barker; Mark R Symms; Pamela Thompson; Veena Kumari; John S Duncan; Mark P Richardson; Matthias J Koepp Journal: Neuroimage Date: 2010-03-23 Impact factor: 6.556