Liuhong Zhu1, Zhongping Zhang2, Qihua Cheng1, Phillip Zhe Sun3, and Gang Guo1
1Radiology, Xiamen Second Hospital, Xiamen, China, People's Republic of, 2MR Research China, GE Healthcare, Beijing, China, People's Republic of, 3Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States
Synopsis
One hundred and thirteen
patients with acute ischemic stroke underwent DKI sequence scanning. 131 lesions
were outlined and divided into six groups. The changed percentages of DKI
indices (FA%, MD%, Da%, Dr%, MK%, Ka%, Kr%) relative to normal contra-lateral
ROI were computed. The statistical analysis results illustrated that there was
a trend that when the acute ischemic stroke affected tissue mostly contained
white matter, the complexity of micro-structure changes of the tissue was much
higher than other affected locations. Also, the kurtosis-derived parameters presented
to have greater potential in distinguishing each group.Background and Purpose
Diffusion kurtosis imaging (DKI) has been
developed to probe non-Gaussian properties of water diffusion in brain tissues recently[1-4]. The aim of this study was to explore the value of DKI
technology in the analysis of micro-structural change complexity of brain tissue
affected by acute ischemic stroke.
Material and Methods
One hundred and thirteen
patients ((66.62±14.88) Y, 42 women, 71 men) with acute ischemic stroke underwent
routine MR scanning with additional DKI sequence scanning (b=0, 1000, 2000s/mm
2,
15 directions) from February 2014 to August 2015. 131 lesions in common
affected locations (Periventricular white matter area (PWM): 35 lesions;
corpuscallosum area (CC): 6 lesions; cerebellum area (CB): 17 lesions; basal
ganglia area (BG): 11 lesions; brain stem area (BS): 17 lesions; lobes mixed
with grey and white matter (LGW): 45 lesions) were outlined. Normal contra-lateral
region of interest (ROI), which was the mirror region of each lesion, was also
outlined. The values of DKI-derived indices, such as fraction anisotropy (FA),
mean diffusion (MD), axial diffusion (Da), radial diffusion (Dr), mean kurtosis
(MK), axial kurtosis (Ka) and radial kurtosis (Kr), were calculated. The
changed percentages of all index (FA%, MD%, Da%, Dr%, MK%, Ka%, Kr%) relative to
normal contra-lateral ROI were also computed. Statistical analysis about multiple
comparisons using Kolmogorov-Smirnov test among groups were performed.
Results
Diffusivity-derived indices (FA, MD, Da and Dr) decreased
and kurtosis-derived parameters (MK, Ka and Kr) increased in all lesion groups
(Table1). The upper 3 lines in figure1 performed larger fluctuation
than the lower 4 lines among groups. Table2 showed the Kolmogorov-Smirnov test of DKI metrics between
every two groups. It showed that there was significant difference (p<0.05) of
MK% between almost all of the two groups (except BG vs. BS; BG vs. LGW; BS vs.
LGW) (p<0.05), and Ka% performs nearly the same as MK%. While there was no significant
difference of MD% and Da% between almost all of the two groups (except PWM vs.
CB; PWM vs. BG; PWM vs. BS) (p>0.05). Dr% illustrated no statistical significance
among all groups (p>0.05). FA% was significantly lower in PWM group and CC
group than BG group (p=0.002 and 0.009 respectively). The change percentage of
kurtosis-derived parameters in descending order was as following: CC > PWM
> BS > LGW > BG > CB.
Discussions
Tissues locating at CC
area and PWM area mainly contained bunches of white matter, while contained
grey matter nucleus at BG area. The results illustrated that there was a trend
that when the acute ischemic stroke affected tissue mostly contained white
matter, the complexity of micro-structure changes of the tissue was much higher
than other affected locations. Also, the kurtosis-derived parameters performed larger fluctuation
among groups, which meant that they had greater potential in distinguishing
each group.
Conclusion
DKI technology could reveal the different complexity
of micro-structure changes among various locations affected by acute ischemic
stroke, and kurtosis-derived parameters perform better than diffusivity-derived
parameters among groups.
Acknowledgements
We are grateful
for the support from Na Xu, Yehua Song and Ruiqiang Peng from the department of
internal neurology of Xiamen Second Hospital during patient recruitment and data
acquisition. This work was supported by Joint project for Xiamen key diseases (Grant
No. 3502Z20149032) and Planned Project Grant (Grant No. 3502Z20154065) from
Xiamen Science and Technology Bureau.References
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