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Updated: Oct 11, 2026
Diffusion Tensor Magnetic Resonance Imaging in the Analysis of Neurodegenerative Diseases
Published on: July 28, 2013
Variations in T1 and T2 relaxation times of normal appearing white matter and lesions in multiple sclerosis
V L Stevenson1, G J Parker, G J Barker
1NMR Research Unit, Institute of Neurology, Queen Square, WC1N 3BG, London, UK.
Objective:
To investigate the variation in T1 and T2 relaxation times of normal appearing white matter (NAWM) and lesions in multiple sclerosis (MS) throughout the brain.
Background:
The magnetic resonance imaging (MRI) sequence fast FLAIR (fluid attenuated inversion recovery) has demonstrated overall increased lesion detection when compared to conventional or fast spin echo (FSE) but fewer lesions in the posterior fossa and spinal cord. The reasons for this are unknown, but may be due to variations in the T1 and T2 relaxation times within NAWM and MS lesions.
Method:
Ten patients and 10 controls underwent MRI of the brain which involved FSE, fast FLAIR and the measurement of T1 and T2 relaxation times.
Results:
Of 151 lesions analysed (22 infra-tentorial, 129 supra-tentorial), eight were missed by the fast FLAIR sequence. T1 and T2 relaxation times in normal controls were longer in the infra-tentorial, than supra-tentorial, region. Patient NAWM relaxation times were prolonged compared with control values in both regions. Lesions demonstrated longer relaxation times than either control white matter or patient NAWM in both regions, however this difference was less marked infra-tentorially. The eight posterior fossa lesions not visible on the fast FLAIR sequence were characterised by short T1 and T2 relaxation times which overlapped with the patient NAWM for both T1 and T2 and with control values for T2 relaxation times.
Conclusion:
Both lesion and NAWM relaxation time characteristics vary throughout the brain. The T1 and T2 relaxation times of infra-tentorial lesions are closer to the relaxation times of local NAWM than supra-tentorial lesions, resulting in reduced contrast between posterior fossa lesions and the background NAWM. Consequently the characteristics of some lesions overlap with those of NAWM resulting in reduced conspicuity. By utilising this information, it may be possible to optimise fast FLAIR sequences to improve infra-tentorial lesion detection.
Insights
Multiple sclerosis (MS) lesions and normal appearing white matter (NAWM) exhibit varying T1 and T2 relaxation times across the brain. Posterior fossa lesions show reduced contrast, impacting detection by fast FLAIR MRI.
Area of Science:
- Neuroimaging
- Radiology
- Biophysics
Background:
- Fast fluid attenuated inversion recovery (FLAIR) MRI enhances lesion detection in multiple sclerosis (MS) compared to conventional sequences.
- However, fast FLAIR shows reduced sensitivity for posterior fossa and spinal cord lesions.
- Variations in T1 and T2 relaxation times of normal appearing white matter (NAWM) and MS lesions may explain these detection differences.
Purpose of the Study:
- To investigate regional variations in T1 and T2 relaxation times of NAWM and MS lesions.
- To understand how these variations affect lesion conspicuity on fast FLAIR MRI, particularly in the posterior fossa.
Main Methods:
- Brain MRI was performed on 10 MS patients and 10 healthy controls.
- Imaging included fast spin echo (FSE) and fast FLAIR sequences.
- T1 and T2 relaxation times were measured in normal appearing white matter (NAWM) and MS lesions.
Main Results:
- T1 and T2 relaxation times were longer in the infra-tentorial region compared to the supra-tentorial region in controls.
- Patient NAWM relaxation times were prolonged compared to controls in both regions.
- MS lesions showed longer T1 and T2 relaxation times than control white matter and patient NAWM, with less difference observed infra-tentorially. Eight posterior fossa lesions missed by fast FLAIR had T1 and T2 relaxation times overlapping with NAWM.
Conclusions:
- T1 and T2 relaxation time characteristics of MS lesions and NAWM vary regionally within the brain.
- Infra-tentorial MS lesions exhibit T1 and T2 relaxation times closer to local NAWM, reducing contrast and conspicuity.
- Optimizing fast FLAIR sequences based on these relaxation time properties may improve infra-tentorial lesion detection in MS.
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