Siemens Symphony: strong artifact on images
What happened
Severe noise-like artifact on the images; calibration of the RF chain did not improve image quality.
What was checked
- RF chain calibration was repeated, reported in the case as ineffective.
- LED room lamps were replaced with halogen ones to rule out lighting as an interference source — no change.
- Visual inspection and step-by-step localization of the interference source; the engineers found the helium line poorly secured to the filter box housing after a recent cold head replacement.
Cause
After the cold head replacement the helium line had not been clamped back onto the filter box. The poor contact with the housing let the line pick up and carry RF noise across the shielding, so it acted like an antenna and distorted the images.
What was done
The engineers re-clamped and properly secured the helium line to the filter box housing, restoring solid contact; the artifact disappeared and the scanner returned to normal imaging.
Safety
The magnet field is always on — use only non-magnetic tools near the bore, protect hands against cryogenic burns when handling the helium line, and never leave any penetration of the RF enclosure open or poorly sealed.
Lesson: Before chasing complex RF faults, recheck everything touched by recent service — a single unsecured conductor crossing the shield can be the whole problem.
Covered in the course: MRI Service — Level 2: Fault-Finding →
Written from an anonymised case shared by service engineers. It is not a manufacturer instruction and grants no authorisation. Independent note; names are trademarks of their owners.