Characterizing electronic noise interference from the external laser positioning system on a radiation therapy MRI...

Area of Science:

• Medical Imaging
• Radiation Oncology
• Medical Physics

Background:

• Magnetic Resonance Imaging (MRI) simulation is crucial for radiation therapy planning, utilizing external laser positioning systems (ELPS) for patient setup.
• ELPS, if active during MRI scans, can introduce electronic noise, potentially degrading image quality.

Purpose of the Study:

• To investigate the impact of MRI simulation lasers on general image quality.
• To assess the effect of these lasers on quantitative imaging accuracy in various MRI sequences.

Main Methods:

• Cine acquisition visualized real-time signal-to-noise ratio (SNR) changes with ELPS activation/deactivation.
• SNR was measured using the American College of Radiology (ACR) protocol across multiple MRI coils and phantoms.
• Quantitative MRI scans assessed T1, T2, ADC, PDFF, and R2* values with and without ELPS activation.

Main Results:

• Visible electronic noise and a two-fold SNR decrease occurred with the integrated body coil when ELPS was active.
• No significant SNR drop was observed with other tested coils.
• Image intensity uniformity, ghosting, and low contrast detectability degraded with the Head/Neck coil; geometric distortion was unaffected.
• Quantitative MRI values showed concordance, but ADC vials had increased standard deviation with ELPS activation.

Conclusions:

• Activation of ELPS during MRI imaging should be avoided to prevent unnecessary image noise.
• This is critical for quality assurance testing, particularly with the integrated body coil, which is highly susceptible to ELPS-induced noise.
• Clinical guidelines are needed to inform staff about ELPS-induced noise interference during MRI procedures.