Peripheral nerve stimulation in a whole-body echo-planar imaging system

Area of Science:

• Radiology
• Medical Physics
• Neuroimaging

Background:

• Echo-planar imaging (EPI) utilizes rapidly oscillating gradients, posing a risk of peripheral nerve stimulation (PNS).
• Understanding the incidence and characteristics of EPI-induced PNS is crucial for patient safety in MRI.

Purpose of the Study:

• To evaluate the incidence, type, and location of peripheral nerve stimulation during echo-planar imaging in a clinical MRI scanner.
• To investigate the influence of various EPI sequence parameters on the occurrence and nature of PNS.

Main Methods:

• Two groups were studied: 173 patients undergoing routine EPI scans (Group A) and 7 subjects undergoing 36 specific EPI sequences (Group B).
• Group B subjects reported PNS after each sequence to assess parameter effects.
• Stimulation incidence, type, and location were recorded for both groups.

Main Results:

• Only 5% of Group A reported PNS, whereas all subjects in Group B experienced stimulation.
• PNS was primarily dependent on the oscillating gradient's direction and the body's position within the gradient coil.
• Maximum stimulation occurred near the isocenter (30-40 cm), correlating with peak dB/dt.
• Y-gradients typically induced truncal stimulation, while X-gradients caused head stimulation.
• Hand clasping over the abdomen occasionally resulted in hand tingling.

Conclusions:

• EPI sequences frequently cause peripheral nerve stimulation, particularly under specific gradient conditions and body placements.
• Patient positioning and awareness of gradient effects are important for managing EPI-induced PNS.
• Recommendations include patient instruction to keep hands separated during scanning to potentially reduce stimulation.