Medtronic SYNCHROMED EL serie Gebrauchsanweisung Seite 19

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10 Precautions
Static Magnetic Field
For magnetic fields up to 1.5 T, the magnetic force and torque on the
SynchroMed EL pump will be less than the force and torque due to gravity. For
magnetic fields of 2.0 T, the patient may experience a slight tugging sensation at
the pump implant site. An elastic garment or wrap will prevent the pump from
moving and reduce the sensation the patient may experience. SynchroMed EL
pump performance has not been established in >2.0 T MR scanners and it is
not recommended that patients have MRI using these scanners.
Image Distortion
The SynchroMed EL pump contains ferromagnetic components that will cause
image distortion and image dropout in areas around the pump. The severity of
image artifact is dependent on the MR pulse sequence used. For spin echo pulse
sequences the area of significant image artifact may be 20-25 cm across. Images
of the head or lower extremities should be largely unaffected.
Minimizing Image Distortion: MR image artifact may be minimized by careful
choice of pulse sequence parameters and location of the angle and location of
the imaging plane. However, the reduction in image distortion obtained by
adjustment of pulse sequence parameters will usually be at a cost in signal to
noise ratio. The following general principles should be followed:
1. Use imaging sequences with stronger gradients for both slice and read
encoding directions. Employ higher bandwidth for both RF pulse and data
sampling.
2. Choose an orientation for read-out axis that minimizes the appearance of in-
plane distortion.
3. Use spin echo (SE) or gradient echo (GE) MR imaging sequences with a
relatively high data sampling bandwidth.
4. Use shorter echo time (TE) for gradient echo technique, whenever possible.
5. Be aware that the actual imaging slice shape can be curved in space due to
the presence of the field disturbance of the pump (as stated above).
6. Identify the location of the implant in the patient and when possible, orient
all imaging slices away from the implanted pump.
Medtronic - Kerkrade / PARTNUMBER : 198076-036 SHEETNR. :