Variational U-Net with Local Alignment for Joint Tumor Extraction and Registration (VALOR-Net) of Breast MRI Data Acquired at Two Different Field Strengths
Journal:
arXiv
Published Date:
Jan 23, 2025
Abstract
Background: Multiparametric breast MRI data might improve tumor diagnostics,
characterization, and treatment planning. Accurate alignment and delineation of
images acquired at different field strengths such as 3T and 7T, remain
challenging research tasks. Purpose: To address alignment challenges and enable
consistent tumor segmentation across different MRI field strengths. Study type:
Retrospective. Subjects: Nine female subjects with breast tumors were involved:
six histologically proven invasive ductal carcinomas (IDC) and three
fibroadenomas. Field strength/sequence: Imaging was performed at 3T and 7T
scanners using post-contrast T1-weighted three-dimensional time-resolved
angiography with stochastic trajectories (TWIST) sequence. Assessments: The
method's performance for joint image registration and tumor segmentation was
evaluated using several quantitative metrics, including signal-to-noise ratio
(PSNR), structural similarity index (SSIM), normalized cross-correlation (NCC),
Dice coefficient, F1 score, and relative sum of squared differences (rel SSD).
Statistical tests: The Pearson correlation coefficient was used to test the
relationship between the registration and segmentation metrics. Results: When
calculated for each subject individually, the PSNR was in a range from 27.5 to
34.5 dB, and the SSIM was from 82.6 to 92.8%. The model achieved an NCC from
96.4 to 99.3% and a Dice coefficient of 62.9 to 95.3%. The F1 score was between
55.4 and 93.2% and the rel SSD was in the range of 2.0 and 7.5%. The
segmentation metrics Dice and F1 Score are highly correlated (0.995), while a
moderate correlation between NCC and SSIM (0.681) was found for registration.
Data conclusion: Initial results demonstrate that the proposed method may be
feasible in providing joint tumor segmentation and registration of MRI data
acquired at different field strengths.
