Hiroaki Shimamoto DDS, PhD, Presenter: Nothing to Disclose

Naoya Kakimoto DDS, PhD, Abstract Co-Author: Nothing to Disclose

Kouichi Fujino, Abstract Co-Author: Nothing to Disclose

Shumei Murakami DDS, Abstract Co-Author: Nothing to Disclose

Souhei Furukawa DDS, PhD, Abstract Co-Author: Nothing to Disclose

Jun Hatazawa MD, PhD, Abstract Co-Author: Nothing to Disclose

Eku Shimosegawa, Abstract Co-Author: Nothing to Disclose

Seiki Hamada MD, PhD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

The purpose of this study was to investigate an influence of the metallic artifact of CT caused by dental metal prostheses on PET images of oral cavity.

The dental arch cast was fixed in a cylinder water-bath phantom. A sphere phantom at a vicinity of dental arch cast was set, as the imitation of a tumor. Simulating tumor image conditions, the ratio of 18F-FDG radioactivity concentration of a sphere phantom to that of a water-bath phantom was set to 2.5:1. The position of the tumor model was set in three sites, where white artifact area on the CT images (site A), slightly remote area from white artifact (site B), and black artifact area (site C), respectively. The PET/CT scan was acquired with and without the metal bridge at each tumor sites, and the artifactual influence was evaluated on the axial attenuation-corrected PET images, which a tumor visually showed the strongest accumulation. Measurements were performed on two PET/CT scanners (scanner 1: Gemini GLX 16; Philips Medical Systems, Markham, Ontario, Canada, and scanner 2: Discovery ST Elite; GE Medical Systems, Waukesha, Wis., USA). All PET/CT scans were performed similarly a clinical scan parameters in our hospital. The influence of the metal bridge on the attenuation-corrected PET images was evaluated by a change rate of SUVmean, with and without the metal bridge at each tumor site.

As for the site A, the change rate of SUVmean on the analyzed PET images, which were acquired by both PET/CT scanners showed the overestimation (scanner 1; +8.2 %, and scanner 2; +3.3 %, respectively). As for the site B, the change rate of SUVmean also showed the overestimation (scanner 1; +3.5 %, and scanner 2; +4.1 %, respectively). However, as for the site C, the change rate of SUVmean showed the underestimation (scanner 1; -25.8 %, and scanner 2; -29.5 %, respectively).

The black artifacts of the CT caused by metallic dental prostheses may cause false negative finding of FDG-PET in detecting oral cavity tumor. A careful image interpretation was needed in the metallic black artifactual area caused by the dental metal prostheses on the oral cavity.

The black artifacts of the CT caused by metallic dental prostheses may cause false negative finding of FDG-PET in detecting oral cavity tumor.

Shimamoto, H, Kakimoto, N, Fujino, K, Murakami, S, Furukawa, S, Hatazawa, J, Shimosegawa, E, Hamada, S, et al, , Metallic Artifacts of CT Caused by Dental Metal Prostheses on the Oral Cavity: A PET/CT Phantom Study.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6009720.html