Investigating the Feasibility of Rapid MRI for Image-Guided Motion Management in Lung Cancer Radiotherapy

Abstract

Cycle-to-cycle variations in respiratory motion can cause significant geometric and dosimetric errors in the administration of lung cancer radiation therapy. A common limitation of the current strategies for motion management is that they assume a constant, reproducible respiratory cycle. In this work, we investigate the feasibility of using rapid MRI for providing long-term imaging of the thorax in order to better capture cycle-to-cycle variations. Two nonsmall-cell lung cancer patients were imaged (free-breathing, no extrinsic contrast, and 1.5 T scanner). A balanced steady-state-free-precession (b-SSFP) sequence was used to acquire cine-2D and cine-3D (4D) images. In the case of Patient 1 (right midlobe lesion, ~40 mm diameter), tumor motion was well correlated with diaphragmatic motion. In the case of Patient 2, (left upper-lobe lesion, ~60 mm diameter), tumor motion was poorly correlated with diaphragmatic motion. Furthermore, the motion of the tumor centroid was poorly correlated with the motion of individual points on the tumor boundary, indicating significant rotation and/or deformation. These studies indicate that image quality and acquisition speed of cine-2D MRI were adequate for motion monitoring. However, significant improvements are required to achieve comparable speeds for truly 4D MRI. Despite several challenges, rapid MRI offers a feasible and attractive tool for noninvasive, long-term motion monitoring.

4D respiratory motion‐compensated image reconstruction of free‐breathing radial MR data with very high undersampling

“…For instance, 4D MRI might be used to reduce motion blurring in abdominal imaging and for the assessment of lung function in pulmonary imaging (49)(50)(51). In the context of radiation oncology, it might be applied for patient-specific definition of safety margins or motionadapted radiotherapy planning (52)(53)(54)(55). Furthermore, high-fidelity MVFs are obtained during the 4D joint MoCo-HDTV reconstruction, which might be employed for motion-compensated positron emission tomography (PET) reconstruction in simultaneous PET/MR imaging (56)(57)(58)(59)(60)(61).…”

Lung Cancer

“…In addition, another study demonstrated that this technique was considered as a promising tool to analyze complex breathing patterns in patients with lung tumors and to use in planning of radiotherapy to account for individual tumor motion ). Therefore, in the last decades, many investigators have assessed the influence of respiratory motion to radiation therapy as well as PET/MRI by 4D MR imaging as well as different motion correction methods (Dikaios et al 2012, Tryggestad et al 2013, Sawant et al 2014, Dutta et al 2015, Fayad et al 2015, Stanescu and Jaffray 2016. Therefore, this part would be better to be more and more important for future lung MR imaging, especially oncologic fields.…”

Feasibility study on 3D image reconstruction from 2D orthogonal cine‐MRI for MRI‐guided radiotherapy

“…For this purpose, in‐room image guidance is increasingly utilized for motion management . Due to its exquisite soft tissue contrast, the ability to select arbitrary imaging planes, and the absence of imaging dose, Magnetic Resonance Imaging (MRI) is an ideal imaging modality to study organ motion, motivating several groups to develop integrated MRI‐radiotherapy systems …”