gms | German Medical Science

Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants

Medical University of Hannover

01.06. bis 04.06.2005, Hannover

PET and cochlear implant patients: the impact on selection of candidates difficult to assess: the impact on selection of candidates difficult to assess

Meeting Abstract

  • corresponding author G. Berding - Department of Nuclear Medicine, University School of Medicine, Hannover
  • K.H. Matzke - Department of Nuclear Medicine, University School of Medicine, Hannover
  • T. Brunkhorst - Department of Nuclear Medicine, University School of Medicine, Hannover
  • W.H. Knapp - Department of Nuclear Medicine, University School of Medicine, Hannover
  • T. Lenarz - Department of Otolaryngology, University School of Medicine, Hannover
  • A. Lesinski-Schiedat - Department of Otolaryngology, University School of Medicine, Hannover

Medical University of Hannover, Department of Otolaryngology. Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants. Hannover, 01.-04.06.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc05omci067

Die elektronische Version dieses Artikels ist vollständig und ist verfügbar unter: http://www.egms.de/de/meetings/omci2005/05omci067.shtml

Veröffentlicht: 31. Mai 2005

© 2005 Berding et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielf&aauml;ltigt, verbreitet und &oauml;ffentlich zug&aauml;nglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Introduction

The intactness of the retrocochlear pathway is a prerequisite for successful outcome after cochlear implant (CI) surgery. However, objective measures to assess the intactness preoperatively are not widely established. Positron emission tomography (PET) is one potential tool in this respect, but the acquisition and evaluation of PET data is a complex issue. The aim of the present study was to optimize O-15-water PET activations studies to help answer the above question in clinically inclusive cases.

Materials and Methods

Six patients (4 female, mean age 42) were inclued. PET scans were obtained in 3D-mode after injection of 370 MBq O-15-water at a time. Uptake was acquired for 90-s at rest or during stimulation via a transtympanic needle electrode on the promontorium (p-test). In group A (3 patients) with 4 positive p-tests, 3 scans were obtained per condition (rest, stimulation with pulses on left or right side). In group B (3 other patients) with also 4 positive p-tests, 6 scans were obtained per condition (see above, but stimulation was performed with bursts). All together 27 scans at rest were available. Data was analyzed using statistical parametric mapping (SPM99, Wellcome Department of Cognitive Neurology, London, UK). The "compare populations" model was applied after spatial transformation of all scans to the stereotatic anatomical space according to NMI. An uncorrected p-value ≤ 0.001 at voxel level was considered as significant. We compared for evaluation of Group A: 3 scans during activation vs. 27 resting scans and for Group B: 6 scans during activation vs. 6 scans of the respective patient during rest - and vs. 27 "pooled" resting scans from all patients.

Results

In group A no significant activation of the auditory cortex could be detected. For group B comparisons to the respective patients resting scans revealed a bilateral activation in one patient and comparisons to the "pooled" resting scans showed 3 ipsilateral activations (with a corrected p-value on voxel level lower than 0.05). If results from both comparisons performed for group B are considered together, in all 4 positive p-tests corresponding activations of the auditory cortex could be demonstrated with PET.

Conclusions

O-15-water PET is capable to display activations of the auditory cortex that correspond to positive impression of hearing in p-tests (both advocating for intactness of the central auditory pathway). However, optimised PET methodology is mandatory - e.g. with respect to the stimulation signal (bursts) and a sufficient number of scans (at least 6) per condition - to obtain reliable results.