Comparison of four dimensional computed tomography and magnetic resonance imaging in abdominal radiotherapy planning. (July 2018)

• Record Type: Journal Article
• Authors: Oar, Andrew; Liney, Gary; Rai, Robba; Deshpande, Shrikant; Pan, Li; Johnston, Meredith; Jameson, Michael; Kumar, Shivani; Lee, Mark
• Is Part Of: Physics and imaging in radiation oncology. Volume 7(2018)
• Page Start: 70
• Page End: 75
• Publication Date: 2018-07
• Subjects: MRI -- Motion management -- 4D-MRI, abdominal radiotherapy -- Four dimensional magnetic resonance imaging; Radiotherapy -- Periodicals; Radiation dosimetry -- Periodicals; Cancer -- Imaging -- Periodicals; Oncology -- Periodicals; 615.842
• DOI: 10.1016/j.phro.2018.09.004
• Languages: English
• ISSNs: 2405-6316

Abstract

Abstract: Background and Purpose: Four-dimensional (4D) computed tomography (CT) is widely used in radiotherapy (RT) planning and remains the current standard for motion evaluation. We assess a 4D magnetic resonance imaging (MRI) sequence in terms of motion and image quality in a phantom, healthy volunteers and patients undergoing RT. Materials and Methods: The 4D-MRI sequence is a prototype T1-weighted 3D gradient echo with radial acquisition with self-gating. The accuracy of the 4D-MRI respiratory sorting based method was assessed using a MRI-CT compatible respiratory simulation phantom. In volunteers, abdominal viscera were evaluated for artefact, noise, structure delineation and overall image quality using a previously published four-point scoring system. In patients undergoing abdominal RT, the tumour (or a surrogate) was utilized to assess the range of motion on both 4D-CT and 4D-MRI. Furthermore, imaging quality was evaluated for both 4D-CT and 4D-MRI. Results: In phantom studies 4D-MRI demonstrated amplitude of motion error of less than 0.2 mm for five, seven and ten bins. 4D-MRI provided excellent image quality for liver, kidney and pancreas. In patients, the median amplitude of motion seen on 4D-CT and 4D-MRI was 11.2 mm (range 2.8–20.3 mm) and 10.1 mm (range 0.7–20.7 mm) respectively. The median difference in amplitude between 4D-CT and 4D-MRI was −0.6 mm (range −3.4–5.2 mm). 4D-MRI demonstrated superior edge detection (median score 3 versus 1) and overall image quality (median score 2 versus 1) compared to 4D-CT. Conclusions: The prototype 4D-MRI sequence demonstrated promising results and may be used in abdominal targeting, motion gating, and towards implementing MRI-based adaptive RT.