Dataset Information

Reproducibility and Reliability of Quantitative and Weighted T₁ and T₂^? Mapping for Myelin-Based Cortical Parcellation at 7 Tesla.

ABSTRACT: Different magnetic resonance (MR) parameters, such as R₁ (=1/T₁) or T₂^?, have been used to visualize non-invasively the myelin distribution across the cortical sheet. Myelin contrast is consistently enhanced in the primary sensory and some higher order cortical areas (such as MT or the cingulate cortex), which renders it suitable for subject-specific anatomical cortical parcellation. However, no systematic comparison has been performed between the previously proposed MR parameters, i.e., the longitudinal and transversal relaxation values (or their ratios), for myelin mapping at 7 Tesla. In addition, usually these MR parameters are acquired in a non-quantitative manner ("weighted" parameters). Here, we evaluated the differences in 'parcellability,' contrast-to-noise ratio (CNR) and inter- and intra-subject variability and reproducibility, respectively, between high-resolution cortical surface maps based on these weighted MR parameters and their quantitative counterparts in ten healthy subjects. All parameters were obtained in a similar acquisition time and possible transmit- or receive-biases were removed during post-processing. It was found that CNR per unit time and parcellability were lower for the transversal compared to the longitudinal relaxation parameters. Further, quantitative R₁ was characterized by the lowest inter- and intra-subject coefficient of variation (5.53 and 1.63%, respectively), making R₁ a better parameter to map the myelin distribution compared to the other parameters. Moreover, quantitative MRI approaches offer the advantage of absolute rather than relative characterization of the underlying biochemical composition of the tissue, allowing more reliable comparison within subjects and between healthy subjects and patients. Finally, we explored two parcellation methods (thresholding the MR parameter values vs. surface gradients of these values) to determine areal borders based on the cortical surface pattern. It is shown that both methods are partially observer-dependent, needing manual interaction (i.e., choice of threshold or connecting high gradient values) to provide unambiguous borders.

SUBMITTER: Haast RA

PROVIDER: S-EPMC5114304 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Publications

Reproducibility and Reliability of Quantitative and Weighted T1 and T2∗ Mapping for Myelin-Based Cortical Parcellation at 7 Tesla.

Haast Roy A M RA Ivanov Dimo D Formisano Elia E Uludaǧ Kâmil K

Frontiers in neuroanatomy 20161118

Different magnetic resonance (MR) parameters, such as R1 (=1/T1) or T2∗, have been used to visualize non-invasively the myelin distribution across the cortical sheet. Myelin contrast is consistently enhanced in the primary sensory and some higher order cortical areas (such as MT or the cingulate cortex), which renders it suitable for subject-specific anatomical cortical parcellation. However, no systematic comparison has been performed between the prev ...[more]

PMID: 27917112

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Project description:BackgroundT2-weighted (T2w) intracranial vessel wall imaging (IVWI) provides good contrast to differentiate intracranial vasculopathies and discriminate various important plaque components. However, the strong cerebrospinal fluid (CSF) signal in T2w images interferes with depicting the intracranial vessel wall. In this study, we propose a T2-prepared sequence for whole-brain IVWI at 3T with CSF suppression.MethodsA preparation module that combines T2 preparation and inversion recovery (T2IR) was used to suppress the CSF signal and was incorporated into the commercial three-dimensional (3D) turbo spin echo sequence-Sampling Perfection with Application optimized Contrast using different flip angle Evolution (SPACE). This new technique (hereafter called T2IR-SPACE) was evaluated on nine healthy volunteers and compared with two other commonly used 3D T2-weighted sequences: T2w-SPACE and FLAIR-SPACE (FLAIR: fluid-attenuated inversion recovery). The signal-to-noise ratios (SNRs) of the vessel wall (VW) and CSF and contrast-to-noise ratios (CNRs) between them were measured and compared among these three T2-weighted sequences. Subjective wall visualization of the three T2-weighted sequences was scored blindly and independently by two radiologists using a four-point scale followed by inter-rater reproducibility analysis. A pilot study of four stroke patients was performed to preliminarily evaluate the diagnostic value of this new sequence, which was compared with two conventional T2-weighted sequences.ResultsT2IR-SPACE had the highest CNR (11.01 ± 6.75) compared with FLAIR-SPACE (4.49 ± 3.15; p < 0.001) and T2w-SPACE (-56.16 ± 18.58; p < 0.001). The subjective wall visualization score of T2IR-SPACE was higher than those of FLAIR-SPACE and T2w-SPACE (T2IR-SPACE: 2.35 ± 0.59; FLAIR-SPACE: 0.52 ± 0.54; T2w-SPACE: 1.67 ± 0.58); the two radiologists' scores showed excellent agreement (ICC = 0.883).ConclusionThe T2IR preparation module markedly suppressed the CSF signal without much SNR loss of the other tissues (i.e., vessel wall, white matter, and gray matter) compared with the IR pulse. Our results suggest that T2IR-SPACE is a potential alternative T2-weighted sequence for assessing intracranial vascular diseases.

Dataset Information

Reproducibility and Reliability of Quantitative and Weighted T₁ and T₂^? Mapping for Myelin-Based Cortical Parcellation at 7 Tesla.

Publications

Reproducibility and Reliability of Quantitative and Weighted T<sub>1</sub> and T<sub>2</sub><sup>∗</sup> Mapping for Myelin-Based Cortical Parcellation at 7 Tesla.

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Dataset Information

Reproducibility and Reliability of Quantitative and Weighted T1 and T2? Mapping for Myelin-Based Cortical Parcellation at 7 Tesla.

Publications

Reproducibility and Reliability of Quantitative and Weighted T<sub>1</sub> and T<sub>2</sub><sup>∗</sup> Mapping for Myelin-Based Cortical Parcellation at 7 Tesla.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Reproducibility and Reliability of Quantitative and Weighted T₁ and T₂^? Mapping for Myelin-Based Cortical Parcellation at 7 Tesla.