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Session: MR-Linac [Return to Session]

Assessing Artefacts of Cardiac Pacemakers and Leads at a 1.5T Elekta Unity MR-Linac

D Lee1, M Trombetta1, G Shaw1, S Oh1, M Hwang1, D Pavord1*, J Sohn1, (1) Allegheny Health Network, Pittsburgh, PA


SU-H330-IePD-F6-2 (Sunday, 7/10/2022) 3:30 PM - 4:00 PM [Eastern Time (GMT-4)]

Exhibit Hall | Forum 6

Purpose: This study assessed artefacts of cardiac pacemakers and leads at a 1.5 Elekta Unity MR-linac. Artifacts from implanted pacemakers (PM) and metal leads have been investigated for diagnostic and cardiac MRI, however it can be scanner-specific and its magnitude is unknow for Unity MR-Linac.

Methods: This study tested three MR conditional PMs (PM1, PM2 and PM3), and three leads (Lead1, Lead2 and Lead3). Each lead was attached to a plastic bottle and cut out the area of the plastic bottle where the lead tip touches. Three bottles, leads upward, were placed in a water tank and a 3.5cm thick steak covered the leads, and then PMs were placed at the top of the steak with a 5cm distance each other. An MR scan was performed using T1, T2 and ultra-short-echo-time (UTE, TE=1ms). All MR image sets were transferred to MiM software (v7.0.6, MIM Software Inc, Cleveland, OH) and the area of artefacts (i.e., signal void or attenuation) were contoured to measure the size of artefacts.

Results: Artefacts of PM2 were the most and followed by PM1 and PM3. The size of artefacts on PM(s) was up to 8.3cm (UTE), 8.6cm (T1) and 9.0cm (T2) along left-right and superior-inferior directions, and they were up to 2.8cm (UTE), 4.0cm (T2) and 4.5cm (T1) in depth. Artefacts of Lead1 was the most and followed by Lead2 and Lead3. The size artefacts on leads was up to 0.5 cm (UTE), 0.7 cm (T2) and 1.2cm (T1).

Conclusion: This study is the first that measured artefacts of pacemakers and leads using a 1.5T Elekta Unity MR-Linac. We found that the artefacts considerably varied across pacemakers and MR sequences but were able to measure the range and magnitude. These data can be used to determine if a pacemaker should be relocated for accurate target visualization.


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