Use of a PET scan to quantify disease activity in patients with hearing loss due to otosclerosis.

N/A

Otosclerosis is an isolated ear disorder which can cause hearing and balance impairment. The cause of these symptoms is a disturbed bone metabolism confined to the area of the otic pit, the embryologic predecessor of the inner ear. Most patients present with fenestral otosclerosis, in which there is otosclerosis in the area around the oval window (causing fixation of the stapes foot plate and therefore conductive hearing loss). If otosclerosis advances it can progress to the inner ear (cochlear otosclerosis), causing sensorineural hearing loss and balance problems.
The result of the disturbed bone metabolism causes otospongiosis, which can be visualised on computed tomography (CT). The aim of this study is to assess the degree of disease activity (as a derivative of bone metabolism) with 18F-fluoride PET. 18F-fluoride is a tracer used uniquely for bone imaging purposes.

The hypothesis is that patients with otosclerosis have a higher uptake of 18F-fluoride in the area of interest than control patients. Control patients underwent a 18F-fluoride PET/CT for various other, mainly orthopaedic, reasons.

Otosclerosis is a disorder with a very indolent course (years). This is the reason that the PET scan and the high resolution CT scan (for regular medical treatment) are not necessarily performed on the same date.



Different specific areas can be affected by otosclerosis:

1. Fenestral area (oval window area, close to stapes);

2. Bone adjacent to medial aspect of the cochlea;

3. Bone adjacent to lateral aspect of the cochlea;

4. Bone adjacent to apex of the cochlea;

5. Anterior wall of the internal auditory canal;

6. Posterior wall of the internal auditory canal;

7. Bone adjacent to lateral aspect of the semicircular canals.



Assessment of the PET scans: Standard Uptake Values (SUV) at different areas in the inner ear.



Assessment of the CT scans: Bone density measurements (Hounsfield Units) of the same areas.



Assessment of the audiometric data:

1. (Progression of the ) conductive hearing loss;

2. (Progression of the) sensorineural hearing loss.

30 otosclerosis patients: 18F-fluoride PET scan of the head and neck with a low-dose CT scan for attenuation. Apart from that patients will undergo, or may already have undergone, a high-resolution CT scan as part of their regular medical treatment.



10 patients with fenestral otosclerosis, 10 patients with moderate cochlear otosclerosis, 10 patients with severe cochlear otosclerosis.



10 control patients: 18F-fluoride PET/CT scan (for other, mainly orthopaedic indications) in which the head and neck area is included.



Control patients are not specifically appointed to the study but will be selected retrospectively. The scanning protocol is the same for both control patients and otosclerosis patients.