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 agent 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 analysed in 10 participants to compare the coefficient of variation of mean versus maximum Q-PSI values (Q-PSImean versus Q-PSImax ). Second, dynamic PCE was evaluated in 10 subjects to optimize the time interval between contrast agent application and image acquisition. Finally, 50 participants (age groups: 20-29, 30-39, 40-49, 50-59 and 60-69 years) were examined to analyse age, gender, tooth types and maxilla versus 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 with Q-PSImean , with median values of 0.17 versus 0.21 (p = .002). Analysis of dynamic PCE revealed an optimal timing interval for image acquisition 4 min after contrast media application. No significant differences in PCE were observed by comparing age groups, female versus male participants and maxillary versus mandibular teeth (p > .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 < .05), except for the comparison of canines versus premolars (p = .80). CONCLUSIONS: PCE in dMRI was 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 pathosis. 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.

Determination of the palatal masticatory mucosa thickness by dental MRI: a prospective study analysing age and gender effects.

OBJECTIVES: The aim of this prospective study was to evaluate age and gender effects on the palatal masticatory mucosa thickness by using non-invasive and non-ionizing MRI. METHODS: 40 periodontally healthy participants of five gender-balanced age groups (20-29, 30-39, 40-49, 50-59 and 60-69 years, respectively) underwent dental MRI at 3 Tesla using a contrast-enhanced, high-resolution 3D-sequence. The palatal masticatory mucosa was measured at 40 standard measurement points by two independent observers. Statistical analysis was performed by using intraclass correlation coefficient (ICC), Shapiro-Wilk test, two-way analysis of variance and post-hoc Tukey HSD test. RESULTS: Measurements of the palatal masticatory mucosa thickness were highly reliable with a mean intraobserver ICC of 0.989 and a mean interobserver ICC of 0.987. Mean palatal masticatory mucosa thickness increased with the distance from the gingival margin in all tooth regions. Molars showed a considerably lower average palatal masticatory mucosa thickness at intermediate heights in comparison to canines and premolars. Average palatal masticatory mucosa thickness continuously increased with age and significantly differed between age groups (p < 0.01). A significant increase was observed between the age groups of 30-39 years and 40-49 years (p = 0.04). Gender had no significant effect on average palatal mucosa thickness (p = 0.19). However, there was a tendency towards thicker mucosa in males (mean ± SD, 3.36 mm ± 0.47) compared to females (3.23 mm ± 0.44). CONCLUSIONS: In the present study, dental MRI allowed for a highly reliable determination of the palatal masticatory mucosa thickness. Considerable intra- and interindividual variations in palatal masticatory mucosa thickness were observed. Average palatal masticatory mucosa thickness was dependent on age but not on gender.