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Evaluating the image quality and brain microstructural exploration of mean apparent propagator-MRI-a pilot study
Qinglei Shi1,2, Yuchen Gu1, Diwei Shi3,4
1Chinese University of Hong Kong (Shenzhen) School of Medicine, No. 2001, Longxiang Avenue, Longgang District, Shenzhen, 518172, People's Republic of China.
Background:
To investigate the impact of positivity constraints and Laplacian regularization on Mean Apparent Propagator (MAP)-MRI image quality and effectiveness in analyzing brain microstructural changes, validated using an Intermittent Exotropia (IXT) cohort.
Methods:
A total of 31 patients with IXT (16 males, 15 females; mean age 10.94 ± 1.69 years) and 37 age- and sex-matched healthy controls (23 males, 14 females; mean age 11.14 ± 2.06 years) underwent MRI scans. Imaging protocols included simultaneous multi-slice echo planar imaging (SMS-EPI) for q-space sampling and 3D magnetization-prepared rapid acquisition gradient echo (MP-RAGE) sequences. Three MAP-MRI-based reconstruction algorithms were evaluated: MAPL (with Laplacian regularization), CMAP (positivity-constrained), and CMAPL (combining both constraints). Image quality was assessed objectively using wavelet-based signal-to-noise ratio (WSNR), and subjectively by two radiologists using a 5-point scale rating signal uniformity, contrast, noise level, and anatomical completeness. Statistical analyses included one-way ANOVA, Kruskal-Wallis tests, and Cohen's κ for inter-rater agreement. Diagnostic performance was evaluated using voxel-wise t-tests with Gaussian Random Field (GRF) correction at P = 0.01.
Results:
MAPL outperformed CMAP and CMAPL in both objective and subjective image quality, particularly in RTOP, RTAP, MSD, and QIV maps (all P < 0.05). It also provided a more comprehensive visualization of changes in the bilateral dorsal visual pathways, including BA17, BA18, BA19, BA39, BA40, BA8, BA6, and the supplementary motor area (SMA). Moreover, MAPL demonstrated superior sensitivity in detecting alterations in brain regions associated with language, emotion, and decision-making (BA10, BA11, BA22, BA37, and BA47), which may reflect secondary changes induced by visual impairment.
Conclusions:
MAPL surpasses CMAP and CMAPL in both image quality and the ability to display brain microstructural changes, establishing it as the superior method for exploring brain structural alterations.
Clinical Trial Information:
It was registered on July 18, 2021 (ChiCTR2100048852) at www.chictr.org.cn and commenced on September 1, 2021.
Insights
The MAPL algorithm offers superior Mean Apparent Propagator (MAP)-MRI image quality and brain microstructural change analysis compared to CMAP and CMAPL methods. This technique enhances visualization of visual pathway alterations and associated brain region changes.
Area of Science:
- Neuroimaging
- Medical Physics
- Radiology
Background:
- Investigating the impact of positivity constraints and Laplacian regularization on Mean Apparent Propagator (MAP)-MRI.
- Assessing image quality and effectiveness in analyzing brain microstructural changes using a cohort with Intermittent Exotropia (IXT).
Purpose of the Study:
- To compare the performance of three MAP-MRI reconstruction algorithms: MAPL, CMAP, and CMAPL.
- To evaluate their effectiveness in detecting microstructural brain alterations in IXT patients.
Main Methods:
- 31 IXT patients and 37 healthy controls underwent MRI scans using SMS-EPI and MP-RAGE sequences.
- MAP-MRI reconstruction algorithms (MAPL, CMAP, CMAPL) were evaluated.
- Image quality assessed objectively (WSNR) and subjectively by radiologists; diagnostic performance analyzed using voxel-wise t-tests with GRF correction.
Main Results:
- MAPL demonstrated superior objective and subjective image quality compared to CMAP and CMAPL (P < 0.05).
- MAPL provided better visualization of changes in dorsal visual pathways and related brain regions.
- MAPL showed higher sensitivity in detecting alterations in brain regions linked to language, emotion, and decision-making.
Conclusions:
- The MAPL algorithm surpasses CMAP and CMAPL in both image quality and the ability to display brain microstructural changes.
- MAPL is established as the superior method for exploring brain structural alterations in conditions like IXT.
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