The new 3 Tesla magnetic resonance imaging (MRI) machine, recently installed at Muelmed Mediclinic, Pretoria, contributes in establishing a world class imaging facility for ear conditions (otology) and neurotology. It is my opinion the Muelmed Mediclinic’s radiology group, De Beer De Jager Radiologists, has established themselves as one of the leading otology (ear) and neurotology imaging centers in South Africa, especially now after acquiring the 3 Tesla MRI Sigma Pioneer from General Electric Healthcare.
In addition to conventional computed tomography (CT), cone beam CT and the 1,5 Tesla MRI of the radiology practice, the 3 Tesla MRI adds to the diagnostic imaging options available to investigate most ear conditions. The in-house radiologists, with Dr André Burger and Dr Ilse Serfontein spearheading the team, show a keen interest in the temporal bone and it’s pathology.
Besides performing diagnostic investigations, they also perform basic diagnostic imaging of cochlear implant (CI) candidates for several surgeons in Gauteng. The radiologists are trained in MED-EL OTOPLAN and BONEBRIDGE (BB) fast view software in order to help with the pre-operative planning of the optimal CI electrode design and the ideal BONEBRIDGE placement site. The radiologists know how to combine all the imaging modalities in order to obtain the most accurate information.
Dr Burger makes it clear that the new 3 Tesla MRI does not replace the 1.5 Tesla MRI in all its applications. Whilst the stronger 3 Tesla magnet is complimentary to the standard 1,5 Tesla machine in many instances, it has shown to be superior in some.
It is extremely helpful in studies of the cochlear ducts, demonstrating with great accuracy cochlear bleeding due to the breakdown of the blood labyrinthine barrier. Clinically this study is indicated in sudden sensory neural hearing loss (SSNHL).
Another example of an imaging benefit with the new 3 Tesla MRI machine is seen in otosclerosis, a bony disorder of the otic capsule of the inner ear causing hearing loss. When utilizing the 3D-FLAIR (fluid attenuated inversion recovery) sequence retro cochlear, otosclerosis which represents the more advanced stage of the disease, can be seen as a hyper intense signal in the basal images. This is important in deciding for instance on whether a CI should rather be considered to treat the hearing loss.
Berrettini and co-workers showed that different patterns with the 3D-FLAIR sequence are related to different stages of cochlear otosclerosis. In pure fenestral otosclerosis no signal enhancement was seen but when sensorineural involvement was present, a hyper intense signal was found in the basal images resulting from increased protein concentration in the endolabyrinthine fluids. In some cases, post gadolinium enhancement, deriving from increased permeability or rupture of vessels, may corresponded to an advanced stage of otosclerosis.