Program Information
Comparison of MRI Image Distortion of Different Sequences Used for Gamma Knife Stereotactic Radiosurgery Treatment Planning
C Lin1*, Y Feng2 , W Jiang2 , Z Huang3 , (1) Department of Physics, East Carolina University, Greenville, NC, (2) East Carolina University, Greenville, NC, (3) Department of Radiation Oncology, Methodist University Hospital, Germantown, TN
Presentations
SU-I-GPD-J-98 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: Gamma Knife (GK) stereotactic radiosurgery (SRS) treatment requires high dosimetric accuracy and geometric precision and it is crucial to minimize the geometric distortion in magnetic resonance imaging (MRI) acquisition for high geometrical accuracy. The goal of this work is to evaluate and compare the distortion in clinical practice with different scanners and sequences.
Methods: MODUS QUASARTM GRID3D Phantom was scanned on 1.5 Tesla GE Signa (with T1-FSPGR and T2-FGRE) and Siemens Aera (with T1-FLASH and T2-CISS) units with 3D distortion correction applied and QUASARTMGRID3D Image Distortion Analysis Software was used for analysis and comparative study of MRI image distortion. The geometric accuracy was quantified with x, y, z, and r (radial) deviations through comparing 2002 vertices of expected 3D spatial position for MRI scanners from different manufactures. The tolerance limit of distortion is within 1 mm.
Results: T1 and T2 sequences for both GE and Siemens units showed that maximum deviations of all x, y and z distortions were less than 1 mm which were acceptable while radial distortion yielded the highest and x distortion had the lowest deviations. Mean absolute deviation of x, y, z and r directions were less than 0.6 mm except that one was 1.2 mm in radial direction in T1 images acquired from the GE machine. GE MRI scanner showed larger maximum deviation for T1 sequence with smaller maximum deviation for T2 sequence than Siemens MRI scanner for x, y, z and r deviations.
Conclusion: The quantitative analysis of MRI sequence using Modus Grid3D phantom allows the evaluation of MRI image distortion in x, y, z, and r directions for QA purpose. Reducing MRI distortion could improve the target and normal tissue delineation, thus, ensuring more accurate GK radiation treatment. Furthermore, GE Signa and Siemens Aera units presented similar results.
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