Abstract Details

Title A comparison of FLAIR and T1 maps from MP2RAGE at 7T for quantifying lesion volume and its correlation to disability in multiple sclerosis

Topic Multiple Sclerosis

Presentation(s) P5 - Poster Session 5 (5:30 PM-6:30 PM)

Poster/Presentation
Number 15-026

Objective

To investigate if MP2RAGE, which has advantages of inherent field inhomogeneity correction and excellent gray-white contrast, could be a better modality than FLAIR for robust lesion volume measurement and disability correlations.

Background Use of FLAIR scans to quantify multiple sclerosis (MS) lesion volume on 7T MRI has many downsides, including poor image homogeneity and artifacts that make it difficult for automated software to segment brain lesions. There is little data about the relative benefit of alternative modalities for identifying lesion volumes.

Design/Methods Forty-seven participants with MS underwent annual MRI on a 7T MRI scanner for a total of 80 scans (median 2 (range 1 – 3) per subject). Magnetization-prepared (MP)FLAIR and MP2RAGE images were acquired at 0.7mm³ resolution. White matter lesion masks were manually constructed from MPFLAIR and T1 maps (from MP2RAGE). Lesion volumes (normalized to intracranial volume) were compared to clinical characteristics and disability scales scores by Pearson or Spearman correlation, as appropriate. Relative correlation strength was compared by Fisher r to z transformation.

Results Lesion volumes between MPFLAIR and T1 maps were highly correlated (rho = 0.89, p<<0.05). However, normalized lesion volume was greater in MPFLAIR masks (mean 0.00659 (SD 0.00593)) than from T1 maps (mean 0.00430 (SD 0.00403)). Correlations for MPFLAIR lesion masks and most data points were slightly stronger than for T1 map lesion masks. For example, rho = 0.257 (p = 0.002) for MPFLAIR and EDSS, rho = 0.252 (p = 0.024) for T1 map. However, none of these differences was significant.

Conclusions 7T MPFLAIR and T1 map-based lesion volumes both correlate with disability, and thus either may be utilized for lesion masking. These results show that neither methodology is superior and further work is necessary to determine if T1 maps underestimate lesion volume or if MPFLAIR overestimates lesion volume.

Authors/Disclosures
Margaret Spini (University of Maryland School of Medicine) PRESENTER	No disclosure on file
	No disclosure on file
Daniel M. Harrison, MD, FAAN (University of Maryland School of Medicine)	Dr. Harrison has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Horizon Therapeutics. Dr. Harrison has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for American College of Physicians. The institution of Dr. Harrison has received research support from Roche-Genentech. Dr. Harrison has received publishing royalties from a publication relating to health care.

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