An Implementation of Gastrointestinal Tract Motility in a 4D Imaging Phantom of Human Anatomy
E Subashi1*, P Segars2, H Veeraraghavan3, J Deasy4, N Tyagi5, (1) Memorial Sloan Kettering Cancer Center, New York, NY, (2) Duke University Medical Center, Durham, NC, (3) Memorial Sloan Kettering Cancer Center, New York, NY, (4) Memorial Sloan Kettering Cancer Center, New York, NY, (5) Memorial Sloan-Kettering Cancer Center, New York, NY
Presentations
TU-GH-BRB-7 (Tuesday, 7/12/2022) 1:45 PM - 3:45 PM [Eastern Time (GMT-4)]
Ballroom B
Purpose: To implement gastrointestinal (GI) tract motility in the 4D extended cardiac-torso (XCAT) digital phantom of human anatomy.
Methods: Motility modes that exhibit large amplitude changes in the diameter of the GI tract, and may persist over timescales comparable to intrafraction motion, were identified based on literature research. Search criteria included amplitude changes larger than planning risk volume (PRV) expansions and durations of the order of tens of minutes. The following modes were identified: peristalsis, rhythmic segmentation, high amplitude propagating contractions (HAPC), and tonic contractions. The motility patterns were modeled by a combination of travelling or standing sinusoidal and Gaussian waves. Wave dispersion in the temporal and spatial domain was implemented by exponential functions. Modeling functions were applied to the control points of the nonuniform rational B-spline (NURBS) surfaces defined in the reference XCAT library. GI motility was combined with the cardiac and respiratory motion available in the standard 4D-XCAT phantom. Initial model parameters were estimated based on the analysis of cine MRI acquisitions in 50 fractions from 10 patients treated in a 1.5T MR-linac.
Results: Gastrointestinal motility was routinely observed when examining intrafraction cine MRI acquisitions. Peristalsis was the most common pattern while tonic contractions could not be identified. GI motion was observed in the stomach, small intestine, and colon. Default parameters estimated from cine MRI data or from literature (if not observed in our measurements) are used as initial values for simulation experiments. Time-resolved 4D MRI images that simulate four modes of GI motility combined with cardiac and respiratory motion were generated based on population model parameters.
Conclusion: We demonstrate the ability to generate realistic 4D MRI images that simulate four modes of GI motility combined with cardiac and respiratory motion. The digital phantom provides realistic models to aid in multimodality imaging research.
Funding Support, Disclosures, and Conflict of Interest: MSKCC has a Master Research Agreement with Philips and Elekta Healthcare
Keywords
Not Applicable / None Entered.
Taxonomy
IM/TH- MRI in Radiation Therapy: General (most aspects)
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