P09.14.a Optimizing Mri Coil Setups for Enhanced Dti in Radiotherapy With Immobilization Devices: Towards Clinical Integration of White Matter Tracts

BACKGROUND Sparing of white matter tracts (WMT) is a promising strategy in brain tumor radiotherapy (RT), but requires advanced imaging, such as Diffusion Tensor Imaging (DTI), which presents several challenges in clinical implementation, such as acquiring high-quality DTI within RT immobilization setups and complex pre- and post-processing to generate WMTs compatible with treatment planning systems (TPS). First, this study evaluated MRI coil configurations under RT constraints to determine the optimal setup based on signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) metrics. Then, once the best setup was found, it describes a fully automated python and bash scripted pipeline designed to seamlessly integrate WMT into TPS to enhance tract sparing RT. MATERIAL AND METHODS Experiments were conducted using a 3T MRI scanner (MAGNETOM Vida, Siemens Healthineers, Erlangen, Germany). Five coil configurations were tested on five healthy subjects: •Reference (Diagnostic-like image quality): 20-channel head coil without RT immobilization. •Tests with thermoplastic mask: 1.Two 18-channel UltraFlex (18UFL) coils around the head. 2.One 18UFL coil atop the head. 3.One 4-channel small Flex (4FS) coil behind and one 18-channel Body coil (18BC) atop the head. 4.One 4FS coil behind and one 18UFL atop the head. DTI images were acquired in axial plane, Field Of View = 230 mm x 230 mm x 140 mm; Matrix= 184 x 184 x 56; Voxel= 1.25 mm x 1.25 mm; Slice thickness= 2.5 mm; TR/TE= 4100/76 ms; Flip Angle= 90°; b-values= 0 and 1000 s/mm2, 64 diffusion directions, acceleration factor of 4, and with anterior-posterior phase encoding direction. Preprocessing of raw data included Marchenko-Pastur PCA denoising, correction of susceptibility-induced distortion and eddy current artifacts (Topup and Eddy FSL(PMID: 15501092)). Synthesized b0 for diffusion distortion correction was used (Synb0-DISCO (PMID: 31075422)) as reverse phase-encoding scans were omitted to reduce acquisition time. SNR (for b0 images) and CNR (for b1000 images) were calculated with PreQal pipeline (PMID: 33533094).The optimal configuration was further tested with REadout Segmentation Of Long Variable Echo-trains (RESOLVE)(PMID: 19449372) DTI to assess reduced artifacts and improved resolution. RESULTS SNR and CNR values were: •Reference: SNR 20.69, CNR 0.84 •Setup 1: SNR 8.77, CNR 0.22 •Setup 2: SNR 18.09, CNR 0.61 •Setup 3: SNR 18.89, CNR 0.72. •Setup 4: SNR 22.00, CNR 0.74 With RESOLVE, Setup 4 achieved the best quality: SNR 33.94, CNR 1.32, outperforming the reference setup. CONCLUSION This study identifies an optimized MRI coil configuration (Setup 4) for achieving high-quality DTI acquisition under RT constraints in healthy volunteers. These findings demonstrate the feasibility of integrating advanced DTI imaging into RT workflows, paving the way for routine application in brain tumor patients.