Author: Soon N. Huh, Perry B. Johnson, Jiyeon Park, Ryan Stevens 👨🔬
Affiliation: University of Florida Health Proton Therapy Institute, UF Health Proton Therapy Institute, UFHPTI 🌍
Purpose:
MRI images with minimal artefacts to scan spine with Titanium instrumentation (screws, stabilizing rods, and spacer) are acquired by optimizing scanning parameters of pulse sequences (mainly B-FFE 3D) of 0.23T MRI Panorama MR Scanner and 1.5T MR Philips Ingenia MR Scanner to visualize spinal cord, spinal canal, recurrent/residual tumors, and anatomical changes, such as fluid accumulations.
Methods:
A house-made phantom, consisting of a boney ox tail, titanium screws, and bolus submerged in a water container was used to optimize various pulse sequences of 0.23T and 1.5T MRI. (1) For 0.23T: The balanced fast field echo 3D (b-FFE 3D in Philips MR scanner, Panorama MR scanner was mainly used for photon and proton planning, (2) for 1.5T MRI, two pulses sequences were optimized with another house-made phantom to acquire MRI Images with minimal artifacts.
Results:
(1) For 0.23T MRI, the B-FFE 3D pulse sequences are used to scan 3 orthogonal planes. It has been used to acquire MR images for spinal cord, canal, recurrent/residual tumors, fluid accumulation around surgical regions, and previously irradiated treatment region if Re-RT is used are visible as MR-based dosimetry.
(2) For 1.5T, MRI with minimal artifacts were acquired with the optimized pulse sequences such as VAT, and SEMAC using a house made phantom, and artifact-free MR images were acquired.
Conclusion:
Over the last decade, 0.23T MRI and CT Myelogram are compared side-by-side to delineate cord/canal, and also can be used to monitor tumor progression as MR-based surveillance throughout treatment. MRI has been used to define contours of targets, such as sarcoma, chordoma, spinal mets, and OARs, when diagnostic MRI is not clinically useful.