Sains Malaysiana 49(4)(2020): 793-800

http://dx.doi.org/10.17576/jsm-2020-4904-08

Relationship between Volume of Leukoaraiosis Spot and Degree of Tissue Damage: A Quantitative Diffusion Tensor Imaging Study

(Hubungan antara Isi Padu Tompok Leukoaraiosis dengan Darjah Kerosakan Tisu: Satu Kajian Kuantitatif Pengimejan Tensor Difusi)

NUR HARTINI MOHD TAIB^1*, WAN AHMAD KAMIL WAN ABDULLAH¹, IBRAHIM LUTFI SHUAIB², MUHAMMAD NUR SALIHIN YUSOFF³, ENRICO MAGOSSO², SUZANA MAT ISA² & AHMAD HADIF ZAIDIN SAMSUDIN¹

¹Department of Radiology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan Darul Naim, Malaysia

²Advanced Medical and Dental Institute, Universiti Sains Malaysia, 13200 Kepala Batas, Penang, Malaysia

³Medical Radiation Programme, School of Health Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan Darul Ehsan, Malaysia

Received: 13 February 2019/Accepted: 20 December 2019

ABSTRACT

Diffusion tensor imaging (DTI) offers parameter indices, namely, mean diffusivity (MD) and fractional anisotropy (FA). Leukoaraiosis is a brain white matter hyperintensity as observed on fluid-attenuated inversion recovery (FLAIR) images. In this study, we attempt to assess leukoaraiosis at its specific spot using a new parameter, namely, lesion-to-normal appearing white matter ratio (LNR). LNR was then used to investigate the relationship between the volume of leukoaraiosis spot and the degree of tissue damage. This study involved 49 leukoaraiosis subjects who altogether contributed to 274 leukoaraiosis spots. The MD, FA, and volume were measured at each spot. LNR was calculated by comparing the MD values of the spot with those of the surrounding normal-appearing white matter (NAWM). The correlation between MD, FA, and LNR with leukoaraiosis volume was then analysed. The leukoaraiosis tissues generally exhibited higher MD (103.97 ± 12.32 × 10^-5 mm²/s) and lower FA (0.31 ± 0.08) values than the NAWM tissues (79.30 ± 4.76 × 10^-5 mm²/s and 0.41 ± 0.09, respectively). LNR values were found to range from 0.04 to 1.63. The results showed an insignificant association between the leukoaraiosis volume and LNR [r = −.055, p = .368], whereas a very weak association was shown with MD [r = −.196, p = .001] and FA [r = .268, p < .001]. The volume of the leukoaraiosis spot does not necessarily indicate the degree of tissue damage. By using LNR instead of MD, an accurate analysis was performed since the variability of MD for NAWM surrounding the lesion is taken into account.

Keywords: Brain imaging; diffusion tensor imaging; leukoaraiosis; neuroimaging; white matter

ABSTRAK

Pengimejan tensor difusi menawarkan indeks parameter seperti difusi min (MD) dan anisotropi pecahan (FA). Leukoaraiosis adalah hiperkeamatan jirim putih otak melalui pemerhatian pada imej pemulihan penyongsangan pelemahan cecair (FLAIR). Dalam kajian ini, kami cuba menilai leukoaraiosis pada tompok khususnya menggunakan parameter baru iaitu nisbah lesi-jirim putih yang kelihatan normal (LNR). LNR kemudiannya digunakan untuk mengkaji hubungan antara isi padu tompok leukoaraiosis dan tahap kerosakan tisu. Kajian ini melibatkan 49 subjek leukoaraiosis yang kesemuanya menyumbang kepada 274 tompok leukoaraiosis. MD, FA dan isi padu diukur di setiap tompok. LNR dihitung dengan membandingkan nilai-nilai MD bagi tompok tersebut dengan jirim putih yang kelihatan normal (NAWM) di sekitarnya. Hubungan antara MD, FA dan LNR dengan isi padu leukoaraiosis kemudiannya dianalisa. Tisu leukoaraiosis umumnya menunjukkan nilai-nilai MD yang lebih tinggi (103.97 ± 12.32 × 10^-5 mm²/s) dan FA lebih rendah (0.31 ± 0.08) berbanding NAWM (masing-masing 79.30 ± 4.76 × 10^-5 mm²/s dan 0.41 ± 0.09). Nilai LNR didapati dalam julat 0.04 hingga 1.63. Keputusan menunjukkan perkaitan yang tidak signifikan antara isi padu leukoaraiosis dan LNR [r = −.055, p = .368] manakala perkaitan yang sangat lemah dengan MD [r = −.196, p = .001] dan FA [r = .268, p < .001] telah ditunjukkan. Isi padu tompok leukoaraiosis tidak semestinya menunjukkan tahap kerosakan tisu. Dengan menggunakan LNR berbanding MD, analisis yang tepat telah dilakukan kerana kebolehubahan MD bagi NAWM yang mengelilingi lesi telah diambil kira.

Kata kunci: Jirim putih; leukoaraiosis; pengimejan neuro; pengimejan otak; pengimejan tensor difusi

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*Corresponding author; email: nhartini@usm.my