T1/T2 ratio: A quantitative sensitive marker of brain tissue integrity in multiple sclerosis

Abstract

Background and Purpose The aim of this study is to determine whether cerebral white matter (WM) microstructural damage, defined by decreased fractional anisotropy (FA) and increased axial (AD) and radial (RD) diffusivities, could be detected as accurately by measuring the T1/T2 ratio, in relapsing‐remitting multiple sclerosis (RRMS) patients compared to healthy control (HC) subjects. Methods Twenty‐eight RRMS patients and 24 HC subjects were included in this study. Region‐based analysis based on the ICBM‐81 diffusion tensor imaging (DTI) atlas WM labels was performed to compare T1/T2 ratio to DTI values in normal‐appearing WM (NAWM) regions of interest. Lesions segmentation was also performed and compared to the HC global WM. Results A significant 19.65% decrease of T1/T2 ratio values was observed in NAWM regions of RRMS patients compared to HC. A significant 6.30% decrease of FA, as well as significant 4.76% and 10.27% increases of AD and RD, respectively, were observed in RRMS compared to the HC group in various NAWM regions. Compared to the global WM HC mask, lesions have significantly decreased T1/T2 ratio and FA and increased AD and RD (p < . 001). Conclusions Results showed significant differences between RRMS and HC in both DTI and T1/T2 ratio measurements. T1/T2 ratio even demonstrated extensive WM abnormalities when compared to DTI, thereby highlighting the ratio's sensitivity to subtle differences in cerebral WM structural integrity using only conventional MRI sequences.

Intensity scaling of conventional brain magnetic resonance images avoiding cerebral reference regions: A systematic review

“…No congruent results were observed with radial diffusivity (RD) as correlations were reported to be statistically significant [ 25 ] or insignificant [ 29 ], [ 33 ] in WM regions; in MS WM lesions correlations were statistically significant (Spearman rho = -0.58, p<0.001) [ 29 ]; in subcortical GM, no statistically significant correlations were observed [ 33 ]. Correlations with DWI fractional anisotropy (FA) were also inconsistent since they were statistically significant [ 25 ] or insignificant [ 33 ] in WM, and statistically significant correlations were found in GM [ 14 , 33 ]. Likewise, correlations with axial diffusivity (AD) were statistically significant in subcortical GM (R 2 = 0.12, p<0.000001 Bonferroni corrected) [ 33 ] but, in WM, statistically insignificant, negative, or positive [ 25 , 33 ].…”

Myelin damage and cortical atrophy in watershed regions in patients with moyamoya angiopathy

“…However, compared to all these methods, T1w/T2w mapping is faster and offers much more simple data acquisition and postprocessing, which is why it is more likely to be used in routine clinical practice. As demonstrated in multiple sclerosis patients, it is not inferior to diffusion tensor imaging or magnetization transfer ratio for measuring demyelination ( Pareto et al, 2020 ; Hannoun et al, 2022 ). As far as we can tell, it is the first attempt to assess myelin integration in patients with MMA using the T1w/T2w mapping technique.…”

“…Therefore, the T1w to T2w signal intensity ratio should semi-quantitatively reflects the structural white matter integrity, especially after the recently proposed postprocessing algorithm (Ganzetti et al, 2014). This method has been shown to be useful in patients with other neurologic disorders, associated with myelin damage, particularly in multiple sclerosis; also, it is not inferior to the diffusion tensor imaging or magnetization transfer ratio for demyelination measurement (Pareto et al, 2020;Hannoun et al, 2022). The advantages of the T1w/T2w mapping include its simplicity and no increase in the total time of magnetic resonance imaging (MRI) acquisition; also, this method is plausible for retrospective analysis.…”

Networks of microstructural damage predict disability in multiple sclerosis

“…Overall a reduction in T1/T2 seems to be a proxy for pathological changes in MS. 10,11,13 However, it is important to note that T1/T2 is a not a purely quantitative measures, and in MS similar to other neurodegenerative disorders, it can change as a result of many different processes that may change as T1/T2 changes in different directions. These changes may be due to myelin, neurite density, and iron deposition.…”

“…Advanced MRI sequences are not routinely obtained in clinical practice or in large clinical trials. T1/T2 ratio measures are a promising marker of microstructural damage 10,11 because they can be estimated from MRI sequences routinely acquired in clinical practice and trials. 12 The pathological substrates of the T1/T2 ratio are still debated and it is not yet clear whether this measure reflects demyelination, axonal or dendrites loss.…”