T2 relaxation time analysis in patients with multiple sclerosis: correlation with magnetization transfer ratio

Abstract

The aim of the current study was to perform T2 relaxation time measurements in multiple sclerosis (MS) patients and correlate them with magnetization transfer ratio (MTR) measurements, in order to investigate in more detail the various histopathological changes that occur in lesions and normal-appearing white matter (NAWM). A total number of 291 measurements of MTR and T2 relaxation times were performed in 13 MS patients and 10 age-matched healthy volunteers. Measurements concerned MS plaques (105), NAWM (80), and "dirty" white matter (DWM; 30), evenly divided between the MS patients, and normal white matter (NWM; 76) in the healthy volunteers. Biexponential T2 relaxation-time analysis was performed, and also possible linearity between MTR and mean T2 relaxation times was evaluated using linear regression analysis in all subgroups. Biexponential relaxation was more pronounced in "black-hole" lesions (16.6%) and homogeneous enhancing plaques (10%), whereas DWM, NAWM, and mildly hypointense lesions presented biexponential behavior with a lower frequency(6.6, 5, and 3.1%, respectively). Non-enhancing isointense lesions and normal white matter did not reveal any biexponential behavior. Linear regression analysis between monoexponential T2 relaxation time and MTR measurements demonstrated excellent correlation for DWM( r=-0.78, p<0.0001), very good correlation for black-hole lesions( r=-0.71, p=0.002), good correlation for isointense lesions( r=-0.60, p=0.005), moderate correlation for mildly hypointense lesions( r=-0.34, p=0.007), and non-significant correlation for homogeneous enhancing plaques, NAWM, and NWM. Biexponential T2 relaxation-time behavior is seen in only very few lesions (mainly on plaques with high degree of demyelination and axonal loss). A strong correlation between MTR and monoexponential T2 values was found in regions where either inflammation or demyelination predominates; however, when both pathological conditions coexist, this linear relationship is lost.

Quantitative MRI for Analysis of Active Multiple Sclerosis Lesions without Gadolinium-Based Contrast Agent

“…10-12. We found that enhancing lesions had shorter T2 than nonenhancing lesions but longer T2 than NAWM. This finding is consistent with those in other studies, 11,19 whereas some early studies on relaxation times in MS lesions showed a longer T2 in acute than in chronic lesions. 20 However, looking at the original studies, Larsson et al 21 did not find a difference in T1 and T2 measurements between acute and chronic plaques, but a tendency toward a slight increase in T1 and T2 in the acute plaques and a very high T2 value in the center of the plaque at a later stage.…”

Evaluation of Delayed Neuronal and Axonal Damage Secondary to Moderate and Severe Traumatic Brain Injury Using Quantitative MR Imaging Techniques

“…The main etiologies of increased water concentration in central nervous parenchyma are inflammatory processes, edema, demyelination, gliosis, or neuronal loss. [10][11][12] A higher mean value of T2 relaxation time was observed in the NAWM and CC of the test group in our study, compared with the control group, demonstrating higher water concentration in these regions. The cause of this increased water concentration is thought to be axonal loss (with concomitant myelin sheath loss) and gliosis, secondary to TBI.…”

Clinical Applications of Synthetic MRI of the Brain

“…[16,92] Previous reports of relaxation measurements in MS lesions have shown variable result. Some findings are in line with our study, with shorter T2 in enhancing lesions and longer T2 in non-enhancing lesions [93], and longer T2 in enhancing lesions compared to NAWM [94]. An early study reported a decrease in T1 and T2 over time in acute brain stem lesions.…”