ESTRO 2024 - Abstract Book

S3889

Physics - Image acquisition and processing

ESTRO 2024

In this study we have demonstrated the impact of an ICD on quantitative T1 mapping techniques on an MR-linac in both phantom and a volunteer. The results show that in the presence of an ICD, common for patients undergoing radioablation for cardiac arrhythmia, bSSFP sequences may not be suitable due to artefacts resulting from magnetic field inhomogeneities. Spoiled GE sequences minimise the appearance of the artefacts but are inherently lower in SNR, which in turn may impact the accuracy of T1 measurement. The variability in T1 observed in this study is larger than previously reported differences between scar and normal myocardium. While quantitative T1 mapping is feasible on MR-linac, careful optimisation and sequence selection is needed to provide the necessary sensitivity for identifying myocardial scar.

Keywords: MR-linac, Quantitative MRI, Cardiac Imaging

References:

[1] Muser, D., Nucifora, G., Castro, S. A., Enriquez, A., Chahal, C. A. A., Magnani, S., ... & Santangeli, P. (2021). Myocardial substrate characterization by CMR T1 mapping in patients with NICM and no LGE undergoing catheter ablation of VT. Clinical Electrophysiology, 7(7), 831-840. [2] Messroghli, D. R., Walters, K., Plein, S., Sparrow, P., Friedrich, M. G., Ridgway, J. P., & Sivananthan, M. U. (2007). Myocardial T1 mapping: application to patients with acute and chronic myocardial infarction. Magnetic Resonance in Medicine: An Official Journal of the International Society for Magnetic Resonance in Medicine, 58(1), 34-40. [3] Akdag, O., Mandija, S., van Lier, A. L., Borman, P. T., Schakel, T., Alberts, E., ... & Fast, M. F. (2022). Feasibility of cardiac-synchronized quantitative T1 and T2 mapping on a hybrid 1.5 Tesla magnetic resonance imaging and linear accelerator system. Physics and Imaging in Radiation Oncology, 21, 153-159.

2119

Digital Poster

Comparative Evaluation of 4DCT and 3D T1/T2w MRI in Delineation of Moving Target: A Phantom Study

Bin Yang 1 , Mei Yan Tse 1 , Jie Rong Wang 1 , Jing Yuan 2 , Shu Ting Hung 1 , Wing Ki Chan 1 , Yeung Sum Wong 1 , Kin Yin Cheung 1 , Siu Ki Yu 1 1 Hong Kong Sanatorium & Hospital, Medical Physics Department, Hong Kong, Hong Kong. 2 Hong Kong Sanatorium & Hospital, Research Department, Hong Kong, Hong Kong

Purpose/Objective:

4-dimensional computed tomography (4DCT) has been widely used in treatment planning for moving targets [1-3]. The feasibility of 4-dimensional magnetic resonance imaging (4DMRI) in evaluating the target motion has also been studied in some literature [4-6]. However, there are few reports of quantitative evaluations on the commonly used 3D T1-weighted (T1w) fast-field-echo (FFE) and T2-weighted (T2w) turbo-spin-echo (TSE) sequences in MR-guided