Effect of diffusion time on liver DWI: An experimental study of normal and fibrotic livers

Purpose To investigate whether diffusion time (Δ) affects the diffusion measurements in liver and their sensitivity in detecting fibrosis. Methods Liver fibrosis was induced in Sprague‐Dawley rats (n = 12) by carbon tetrachloride (CCl4) injections. Diffusion‐weighted MRI was performed longitudinally...

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Published in:Magnetic resonance in medicine 2014-11, Vol.72 (5), p.1389-1396
Main Authors: Zhou, Iris Y., Gao, Darwin S., Chow, April M., Fan, Shujuan, Cheung, Matthew M., Ling, Changchun, Liu, Xiaobing, Cao, Peng, Guo, Hua, Man, Kwan, Wu, Ed X.
Format: Article
Language:English
Subjects:
Animals
b-value
Diffusion Magnetic Resonance Imaging - methods
diffusion time
Disease Models, Animal
Echo-Planar Imaging
Liver Cirrhosis - pathology
liver fibrosis
rat
Rats
Rats, Sprague-Dawley
restricted diffusion
Sensitivity and Specificity
Time Factors
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Summary:Purpose To investigate whether diffusion time (Δ) affects the diffusion measurements in liver and their sensitivity in detecting fibrosis. Methods Liver fibrosis was induced in Sprague‐Dawley rats (n = 12) by carbon tetrachloride (CCl4) injections. Diffusion‐weighted MRI was performed longitudinally during 8‐week CCl4 administration at 7 Tesla (T) using single‐shot stimulated‐echo EPI with five b‐values (0 to 1000 s/mm2) and three Δs. Apparent diffusion coefficient (ADC) and true diffusion coefficient (Dtrue) were calculated by using all five b‐values and large b‐values, respectively. Results ADC and Dtrue decreased with Δ for both normal and fibrotic liver at each time point. ADC and Dtrue also generally decreased with the time after CCl4 insult. The reductions in Dtrue between 2‐week and 4‐week CCl4 insult were larger than the ADC reductions at all Δs. At each time point, Dtrue measured with long Δ (200 ms) detected the largest changes among the 3 Δs examined. Histology revealed gradual collagen deposition and presence of intracellular fat vacuoles after CCl4 insult. Conclusion Our results demonstrated the Δ dependent diffusion measurements, indicating restricted diffusion in both normal and fibrotic liver. Dtrue measured with long Δ acted as a more sensitive index of the pathological alterations in liver microstructure during fibrogenesis. Magn Reson Med 72:1389–1396, 2014. © 2013 Wiley Periodicals, Inc.
ISSN:0740-3194
1522-2594
DOI:10.1002/mrm.25035