4D-MRI analysis of lung tumor motion in patients with hemidiaphragmatic paralysis

Purpose: To investigate the complex breathing patterns in patients with hemidiaphragmatic paralysis due to malignant infiltration using four-dimensional magnetic resonance imaging (4D-MRI). Patients and methods: Seven patients with bronchial carcinoma infiltrating the phrenic nerve were examined using 1.5 T MRI. The motion of the tumor and of both hemi-diaphragms were measured on dynamic 2D TrueFISP and 4D FLASH MRI sequences. Results: For each patient, 3-6 breathing cycles were recorded. The respiratory-induced mean cranio-caudal displacement of the tumor was 6.6 mm (+/- 2.8 SD). The mean displacement anterior-posterior was 7.4 mm (+/- 2.6), while right-left movement was about 7.4 mm (+/- 4.5). The mediastinum moved sidewards during inspiration, realizing a mediastinal shift. The paralyzed hemidiaphragm and the tumor Showed a paradox motion during respiration in five patients. In two patients, the affected hemidiaphragm had a regular, however minimal and asynchronous motion during respiration. Respiratory variability of both tumor and diaphragm motions was about 20% although patients were instructed to breath normally. The findings showed significant differences Compared to breathing patterns of patients without diaphragm dysfunction. Conclusion: 4D-MRI is a promising tool to analyze complex breathing patterns in patients with lung tumors. It should be considered for use in planning Of radiotherapy to account for individual tumor motion. (C) 2009 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 91 (2009) 449-454