Correction of dental artifacts within the anatomical surface in PET/MRI using active shape models and k-nearest-neighbors

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

Claes N. Ladefoged, Flemming L. Andersen, Sune H. Keller, Thomas Beyer, Liselotte Højgaard, Francois Bernard Lauze

n combined PET/MR, attenuation correction (AC) is performed indirectly based on the available MR image information. Metal implant-induced susceptibility artifacts and subsequent signal voids challenge MR-based AC. Several papers acknowledge the problem in PET attenuation correction when dental artifacts are ignored, but none of them attempts to solve the problem. We propose a clinically feasible correction method which combines Active Shape Models (ASM) and k- Nearest-Neighbors (kNN) into a simple approach which finds and corrects the dental artifacts within the surface boundaries of the patient anatomy. ASM is used to locate a number of landmarks in the T1-weighted MR-image of a new patient. We calculate a vector of offsets from each voxel within a signal void to each of the landmarks. We then use kNN to classify each voxel as belonging to an artifact or an actual signal void using this offset vector, and fill the artifact voxels with a value representing soft tissue. We tested the method using fourteen patients without artifacts, and eighteen patients with dental artifacts of varying sizes within the anatomical surface of the head/neck region. Though the method wrongly filled a small volume in the bottom part of a maxillary sinus in two patients without any artifacts, due to their abnormal location, it succeeded in filling all dental artifact regions in all patients. In conclusion, we propose a method, which combines ASM and kNN into a simple approach which, as the results show, succeeds to find and correct the dental artifacts within the anatomical surface.
Original languageEnglish
Title of host publicationProceedings of SPIE Medical Imaging 2014 : Image processing
EditorsSebastien Ourselin, Martin A. Styner
Number of pages7
PublisherSPIE - International Society for Optical Engineering
Publication date2014
Article number90341M
ISBN (Print)9780819498274
DOIs
Publication statusPublished - 2014
EventMedical Imaging 2014: Image Processing - San Diego, United States
Duration: 15 Feb 2014 → …

Conference

ConferenceMedical Imaging 2014
LandUnited States
BySan Diego
Periode15/02/2014 → …
SeriesProceedings of S P I E - International Society for Optical Engineering
Volume9034
ISSN0277-786X
SeriesProgress in Biomedical Optics and Imaging
Number35
Volume15
ISSN1605-7422

ID: 128599792