Experimental evaluation of four-dimensional Magnetic Resonance Imaging for radiotherapy planning of lung cancer

Abstract

Radiotherapy planning for lung cancer typically requires both 3D and 4D Computed Tomography (CT) to account for respiratory related movement. 4D Magnetic Resonance Imaging (MRI) with self-navigation offers a potential alternative with greater reliability in patients with irregular breathing patterns and improved soft tissue contrast. In this study 4D-CT and a 4D-MRI Radial Volumetric Interpolated Breath-hold Examination (VIBE) sequence was evaluated with a 4D phantom and 13 patient respiratory patterns, simulating tumour motion. Quantification of motion related tumour displacement in 4D-MRI and 4D-CT found no statistically significant difference in mean motion range. The results demonstrated the potential viability of 4D-MRI for lung cancer treatment planning.

Statistical evaluation of the effectiveness of dual amplitude-gated stereotactic body radiotherapy using fiducial markers and lung volume

“…The slight differences in positional coordinates between the lung tumor and fiducial markers were likely caused by complicated respiratory movements, including linear movement and looping and hysteresis curves [6] . Therefore, determining each patient’s optimal fiducial marker is important for accurately tracking the lung tumor and maximizing treatment quality using pretreatment 4DCT and 4D magnetic resonance imaging [9] , [14] .…”

Optimization of a protocol for contrast-enhanced four-dimensional computed tomography imaging of thoracic tumors using minimal contrast agent

“…Although 4D-CT is currently standard in radiotherapy to assess patient-specific respiratory motion, it is not without limitations, e.g., motion artefacts caused by irregular breathing patterns, high radiation dose to the patient due to increased scan time, and poor soft-tissue contrast. Therefore, respiratory-correlated 4D-MRI has gained interest as an alternative to 4D-CT with excellent soft-tissue contrast, no radiation exposure, and relatively insensitivity to target motion [33][34][35][36][37][38][39][40]. Compared to 4D-CT, the potential of 4D-MRI-based contouring will be better at identifying hilar solid tumors, mediastinal lymph nodes, and mediastinal/ chest wall invasion, and better consistency in delineating K organs at risk (OARs) such as the lungs, esophagus, heart, spinal cord, major vessels, and chest wall.…”

Accelerating 4D image reconstruction for magnetic resonance-guided radiotherapy

“…In online adaptive radiotherapy, images acquired on the MR-Linac directly before the treatment are used to adapt the radiotherapy plan to the daily anatomy and target motion. For abdominal tumours affected by respiration, treatment margins can be derived from a prior 4D computed tomography, but confidence could be improved if margins were based on 4D-MRI acquired online [18] , [19] , [20] . In this setting, the MRI reconstruction time is critical and needs to be kept within two minutes [21] , [22] .…”