Treatment Planning in Implant Dentistry: New MRI Sequence for Bone Visualization Compared with Dental CT in Axial and Reformated Images

Treatment Planning in Implant Dentistry: New MRI Sequence for Bone Visualization Compared with Dental CT in Axial and Reformated Images
K. DULA, L. REMONDA, T. H??BNER, C. KIEFER, G. SCHROTH, and D. BUSER, University of Berne, Switzerland
2003
IADR
Objective: To find new MR-sequences for bone visualisation and compare with images from Dental CT for treatment planning in implant dentistry.
Methods: A special water phantom with built in air-water transitions was used to study different MR sequences. The aqcuired magnitude and phase images were grouped according to the degree of the field distortions. Thus, a new sequence to delineate bone could be found which is based on a 3D FLASH sequence (64 axial partitions each 1mm thick, 12,3-msec TR, 6-msec TE, 10¨? flip angle, 192-mm FOV, 256x256 matrix). With this new MRI sequence and additionally with a 1 mm turbo spin-echo (TSE) and a normal T1- and T2-weighted turbo spin-echo sequence, a total of 25 patients with bone defects in the maxilla or mandible were examined on a 1.5 Tesla imaging system. Then, multislice axial CT-Scans were performed. The scans were reformatted as panoramic and cross-sectional views using a self developed software package for the MR images and a commercially available software package for the CT scans. Anatomical landmarks and the bone volume at the defect site were rated in all axial slices and reformatted images from two observers. T-test and Chi-Quadrat Test were used to compare the results.
Results: The agreement in detecting the anatomical landmarks was extremely high with correlation coefficient values ranging from 0.986 to 0.996 (99.6% agreement). The paired differences test showed mean values ranging from 0.0583 to 0.1625. The correlation of metric measurements between Dental CT-Scans and "Dental MR" for bone volume determination was strong and statistically significant (P< .001).
Conclusions: The accuracy of "Dental MR" images in determining anatomy and extent of bone defects by metric measurements is comparable to that of Dental CT-Scans.
Acknowledgments: This study was supported by the ITI-Foundation for Dental Research and Education (Grant no. 193/2000), Waldenburg, Switzerland.