Dynamic contrast-enhanced magnetic resonance imaging of masticatory muscles in patients with idiopathic condylar resorption

Abstract

Background/purpose: Idiopathic condylar resorption (ICR), a subset of temporomandibular disorders (TMDs), presents an unclear relationship between structural changes in the mandibular condyle and alterations in masticatory muscle perfusion. This study aimed to investigate the correlation between mandibular condyle structural changes and masticatory muscle perfusion in patients with ICR using dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI).

Materials and methods: From July 2018 to August 2022, patients with ICR from hospital-based TMD clinics underwent conventional and DCE MRI examinations. The patients were categorized on the basis of the degree of temporomandibular joint (TMJ) condylar resorption into grade 0 (normal), grade 1 (mild to moderate), and grade 2 (severe). DCE MRI parameters of masticatory muscles responsible for mouth closing (masseter [MA] and medial pterygoid [MP]) and opening (lateral pterygoid [LP]) were examined.

Results: Among 79 patients (158 TMJs), 41 % were assigned to the grade 0 group, 29 % were assigned to the grade 1 group, and 30 % were assigned to the grade 2 group. No significant differences in demographic or physical parameters were observed between the groups. In cases of severe condylar resorption (grade 2), the LP muscle exhibited a marked increase in plasma volume; none of the other muscles exhibited significant variations in plasma volume.

Conclusion: Increased plasma volume perfusion of the LP muscle is correlated with the severity of TMJ condylar resorption, indicating a specific correlation between muscle function and ICR severity. DCE MRI is useful for exploring muscular adaptation in patients with ICR and TMDs.

Keywords: Dynamic contrast enhanced magnetic resonance imaging; Idiopathic condylar resorption; Mandibular condyle; Masticatory muscles; Temporomandibular joint disorders.

Figure 1

Patient selection criteria.

Figure 2

Grading of osseous deformities in mandibular condyle on sagittal MRI images. Upper series (a–c) depicts sagittal T1–weighted MRI scans, and lower series (d–f) depicts gradient echo T2–weighted MRI scans. Osseous changes in mandibular condyle are categorized as grade 0 for normal (a, d), grade 1 for mild-to-moderate (b, e), and grade 2 for severe (c, f).

Figure 3

Selection of images and manual tracing of ROIs in three masticatory muscle pairs on DCE MRI images. Upper series (a–c) depicts coronal T1–weighted MRI scans after contrast administration, and lower series (d–f) depicts corresponding color-coded DCE MRI images (K_trans). ROIs are demarcated in MA (a, d), MP (b, e), and LP (c, f) muscle pairs. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Figure 4

Medians of blood plasma per unit volume of tissue (v_p) with DCE MRI values across different condyle grades in LP muscle. Pairwise comparisons with Kruskal–Wallis test adjusted using Bonferroni's correction: condyle grade 0 versus grade 1 (P = 1.000), condyle grade 0 versus grade 2 (P = 0.031), and condyle grade 1 versus grade 2 (P = 0.213).