Variations of MRI-assessed peristaltic motions during radiation therapy

• Published in: PloS one 2018-10, Vol.13 (10), p.e0205917-e0205917
• Main Authors: Mostafaei, Farshad, Tai, An, Omari, Eenas, Song, Yingqiu, Christian, James, Paulson, Eric, Hall, William, Erickson, Beth, Li, X Allen
• Format: Article
• Language: English
• Subjects: Abdomen; Abdominal cancer; Biology and Life Sciences; Breathing; Cancer therapies; CAT scans; Computed tomography; Computer and Information Sciences; Diagnosis; Gallbladder; Gating; Health physics; Image acquisition; Liver; Liver cancer; Magnetic resonance imaging; Medical imaging; Medicine and Health Sciences; NMR; Nuclear magnetic resonance; Oncology; Organs; Pancreas; Pancreatic cancer; Patients; Peristalsis; Physics; Radiation; Radiation therapy; Radiotherapy; Research and Analysis Methods; Respiration; Risk factors; Simulation; Studies; Tumors; Ultrasonic imaging
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0205917

Understanding complex abdominal organ motion is essential for motion management in radiation therapy (RT) of abdominal tumors. This study investigates abdominal motion induced by respiration and peristalsis, during various time durations relevant to RT, using various CT and MRI techniques acquired under free breathing (FB) and breath hold (BH). A series of CT and MRI images acquired with various techniques under free breathing and/or breath hold from 37 randomly-selected pancreatic or liver cancer patients were analyzed to assess the motion in various time frames. These data include FB 4DCT from 15 patients (for motion in time duration of 5 sec), FB 2D cine-MRI from 4 patients (time duration of 1.7 min, 1 second acquisition time per slice), FB cine-MRI acquired using MR-Linac from 6 patients in various fractions (acquisition time is less than 0.6 seconds per slice), FB 4DMRI from 2 patients (time duration of 2 min), respiration-gated T2 with gating at the end expiration (time duration of 3-5 min), and BH T1 with multiphase dynamic contrast in acquisition times of 17 seconds for each of five phases (pre-contrast, arterial, venous, portal venous and delayed post-contrast) from 10 patients. Motions of various organs including gallbladder (GB) and liver were measured based on these MRI data. The GB motion includes both respiration and peristalsis, while liver motion is primarily respiration. By subtracting liver motion (respiration) from GB motion (respiration and peristalsis), the peristaltic motion, along with small residual motion, was obtained. From cine-MRI, the residual motion beyond the respiratory motion was found to be up to 0.6 cm in superior-inferior (SI) and 0.55 cm in anterior-posterior (AP) directions. From 2D cine-MRI acquired by the MR-Linac, different peristaltic motions were found from different fractions for each patient. The peristaltic motion was found to vary between 0.3-1 cm. From BH T1 phase images, the average motions that were primarily due to peristalsis movements were found to be 1.2 cm in SI, 0.7 cm in AP, and 0.9 cm in left-right (LR) directions. The average motions assessed from 4DCT were 1.0 cm in SI and 0.3 cm in AP directions, which were generally smaller than the motions assessed from cine-MRI, i.e., 1.8 cm in SI and 0.6 cm in AP directions, for the same patients. However, average motions from 4DMRI, which are coming from respiratory were measured to be 1.5, 0.5, and 0.4 cm in SI, AP, and LR directions, respectively. The abdo