On precise localization of boundaries between extended uniform objects in MRI: tooth imaging as an example.
OBJECTIVE
The purpose of this study was to investigate the achievable precision of localization of boundaries between extended uniform objects in MRI and to study the effect of zero-filling on reaching it.


METHODS
A theoretical model of an object boundary in the presence of noise was introduced, and the error of localization was derived. The effect of zero-filling on reaching the achievable precision was assessed by computer simulations and experimentally on an extracted tooth in a signal-giving medium.


RESULTS
With the help of the theoretical model, the achievable precision of localization of boundaries between two uniform extended objects was shown to surpass the nominal resolution by a factor equal to the contrast-to-noise ratio. In the simulations and phantom experiments, zero-filling followed by image segmentation allowed for approaching the theoretical value. As an application example, an MRI-based dental impression was performed in vivo, and a bridge was produced and permanently fixed to the volunteer's teeth.


CONCLUSIONS
This work demonstrates that in an MRI experiment, the achievable precision of localization of object boundaries is not limited to the nominal resolution and can surpass it by an order of magnitude. Zero-filling is a simple and effective method of reaching it.
Tymofiyeva
Olga
O
Department of Experimental Physics 5, University of Wuerzburg, Am Hubland, 97074 Wuerzburg, Germany. oltymofi@physik.uni-wuerzburg.de
Schmid
Florian
F
von Kienlin
Markus
M
Breuer
Felix A
FA
Rottner
Kurt
K
Boldt
Julian
J
Richter
Ernst-Juergen
EJ
Jakob
Peter M
PM
D003198:Computer Simulation; D003814:Dentistry, Operative; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008954:Models, Biological; D019047:Phantoms, Imaging; D012680:Sensitivity and Specificity; D014070:Tooth / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D014081:Tooth Extraction