In a retrospective study by Juang et al, all fetal MRI scans performed at Phoenix Children’s Hospital between January 1, 2020 and August 1, 2022 were reviewed to find those with sufficient quality to reconstruct a 3D SVR image. First, a medical student reader examined unprocessed fetal brain MRI—from either balanced turbo-field-echo or T2-weighted single-shot fast spin echo (T2 SSFSE) sequences—attempting FOP measurements whenever possible.
Next, 3D SVR reconstructions of the fetal brain images were performed using at least six T2 SSFSE imaging sequences. Two pediatric neuroradiologists with nearly a decade of experience read all FOP measurements, with the same reader recording the reconstructed imaging and FOP measurements. Nomograms were generated accordingly to assess the relationship between normal fetal FOP measurements and gestational age.
Finally, of the 70 fetal MRI scans selected for this ARRS Annual Meeting’s Summa Cum Laude Online Poster, FOP was visualized in 9 cases on unprocessed fetal MRIs compared to 55 cases on 3D SVR images. Furthermore, among 55 3D SVR cases, prechiasmatic optic nerve width was successfully measured bilaterally in 53 cases, optic chiasm width in all 56 cases, and optic tract width bilaterally in 30 cases.
Specifically, a linear regression fit estimated the relationship between optic chiasm width (OCW) in millimeters and gestational age (GA) in weeks in normal fetuses as OCW = 0.11 × GA + 2.0 (R ^ 2 = 0.30); similarly, the relationship between pre-chiasmatic (PC) optic nerve width and GA was estimated as PC = 0.04 × GA +0.24 (R^2 = 0.34).