Cranial fixation plates in cerebral magnetic resonance imaging: a 3 and 7 Tesla in vivo image quality study

Abstract

Image quality after CFP implantation was not significantly impaired in 7 T MRI, and artifacts were comparable to those in 3 T MRI.

In vitro and in silico assessment of RF‐induced heating around intracranial aneurysm clips at 7 Tesla

“…UHF sites tend to be cautious with respect to the higher resonance frequency, the various transmit radiofrequency (RF) coils, and the fact that 7T MRI currently is not medically indicated. Nevertheless, some UHF sites already have performed dedicated safety tests for passive implants (25)(26)(27)(28)(29)(30)(31)(32)(33) or have included carefully selected subjects with implants (34,35). Because manufacturers only have verified MRI of patients with implanted aneurysm clips to be conditional for some clips in an MR environment up to 3T, a detailed compliance test for 7T is a prerequisite before any examination.…”

7T: Physics, safety, and potential clinical applications

“…An important feature of these safety assessments is the formulation of a generalized approach, which then can ideally be applied to arbitrary RF coil and transmission scenarios, which is the practical reality at UHF MR sites. So far only one clinical follow‐up study has been published that investigates potential impairment of postoperative MRI at 7T after cranial fixation plate implantation for neurosurgical bone flap fixation . Here, following the conditional labeling of the implants for 7T use, image quality was not significantly impaired in 7T MRI, and artifacts were comparable to those in 3T images (Fig.…”

Doppler ultrasound triggering for cardiac MRI at 7T

“…In addition, in both setups (cranial fixation plates and head coil; and DUS trigger and body coil), identical RF coil elements made of meander strip‐line coils were used, and both devices were placed similarly with respect to underlying body tissue. Hence, results from the intensive numerical simulations and experiences were assumed to be valid for the present setup, too. However, potential additional effects arising from the connected transmission line, particularly common mode currents, had to be taken into account.…”

“…For safety compliance testing, distortions of the transmit RF field from the transducer and/or transmission line had to be taken into account. The piezoelectric element had comparable geometry as the previously 7T approved cranial fixation plates . In addition, in both setups (cranial fixation plates and head coil; and DUS trigger and body coil), identical RF coil elements made of meander strip‐line coils were used, and both devices were placed similarly with respect to underlying body tissue.…”