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Quantitative assessment of contrast-enhancement patterns of the healthy dental pulp by magnetic resonance imaging - A prospective in vivo study.

AIM
This prospective in vivo study aimed to optimize the assessment of pulpal contrast-enhancement (PCE) on dental magnetic resonance imaging (dMRI) and investigate physiological PCE-patterns.


METHODOLOGY
In 70 study participants, 1585 healthy teeth were examined using 3-Tesla dMRI before and after contrast administration. For all teeth, the quotient of post- and pre-contrast pulp signal intensity (Q-PSI) was calculated to quantify PCE. First, pulp chambers were analyzed in 10 participants to compare the coefficient of variation of mean vs. maximum Q-PSI-values (Q-PSImean vs. Q-PSImax ). Second, dynamic pulpal contrast-enhancement was evaluated in 10 subjects to optimize the time interval between contrast application and image acquisition. Finally, 50 participants (age groups: 20-29, 30-39, 40-49, 50-59, and 60-69 years) were examined to analyze age, gender, tooth types and maxilla vs. mandible as independent factors of PCE. Statistical analysis was performed using Wilcoxon signed rank test and linear mixed models.


RESULTS
PCE-assessment based on Q-PSImax was associated with a significantly smaller coefficient of variation compared Q-PSImean , with median values of 0.17 vs. 0.21 (p=0.002). Analysis of dynamic PCE revealed an optimal timing interval for image acquisition 4 minutes after contrast media application. No significant differences in PCE were observed by comparing age groups, female vs. male participants and maxillary vs. mandibular teeth (p>0.05). Differences between tooth types were small (median Q-PSImax values of 2.52 / 2.32 / 2.30 / 2.20 for molars / premolars / canines / incisors), but significant (p<0.05), except for the comparison of canines vs. premolars (p=0.80).


CONCLUSIONS
PCE in dMRI is a stable intra-individual marker with only minor differences between different tooth types, thus forming an important basis for intra-individual controls when assessing teeth with suspected endodontic pathology. Furthermore, it was demonstrated that PCE is independent of age, gender and jaw type. These findings indicate that dMRI-based PCE analysis could be a valuable diagnostic tool for the identification of various pulp diseases in future patient studies.