Preoperative imaging protocol for cochlear implant candidates.

Objective: To formulate and test a CT imaging protocol for preoperative scanning of the temporal bone in cochlear implant candidates.

Material And Methods: A human head was scanned in three CT planes: axial, axiopetrosal and semilongitudinal. Multiplanar reformats (MPRs), based on axial slices, were created and compared with the corresponding images obtained by direct scanning in the respective planes.

MRI versus CT in assessment of cochlear patency in cochlear implant candidates.

Objective: To investigate how cochlear patency as seen on preoperative CT and MRI scans correlates with findings at surgery in cochlear implant patients.

Material And Methods: CT and MRI scans of 25 patients were reviewed by 3 independent observers. The reviewers classified the cochlear patency and recorded the location of any suspected decrease in patency.

Semilongitudinal and axial CT planes in assessing cochlear patency in cochlear implant candidates.

Objective: To investigate how cochlear patency as seen on computed tomography (CT), using axial plus semilongitudinal planes, is correlated with findings at surgery in cochlear implant patients.

Methods: Pre-operative CT scans of 45 patients were reviewed by three, independent observers. They classified the cochlear patency and recorded the location of any suspected decreased patency.

Cochlear orientation and dimensions of the facial recess in cochlear implantation.

Objective: To study the dimensions of the facial recess and the spatial relationship between the facial recess and the cochlea, using CT scanning in cochlear implantees.

Method: In 29 cochlear implantees, preoperative CT scans of the temporal bone were compared with findings done at surgery. The dimensions of the facial recess and the relationship between the facial recess and the cochlea were both measured on a viewing station and classified on printed films by 3 blinded and independent reviewers.

Electrode insertion depth in cochlear implantees estimated during surgery, on plain film radiographs and with electrode function testing.

Three methods of determining electrode insertion depth in cochlear implantees are studied: intraoperative counting of inserted electrodes, plain film radiography using Stenvers projection and postoperative electrode function testing. In 16 cases the number of electrodes inserted in the cochlea were counted both by the surgeon at surgery and by two independent observers on plain film radiographs using Stenvers projections. The electrode function was tested postoperatively.