The intravoxel incoherent motion MRI of lateral pterygoid muscle: a quantitative analysis in patients with temporomandibular joint disorders.
OBJECTIVE
To quantitatively evaluate diffusion and perfusion status of lateral pterygoid muscle (LPM) in patients with temporomandibular joint disorder (TMD) by intravoxel incoherent motion (IVIM) imaging and to correlate with findings on temporomandibular joints (TMJs) by conventional MRI.


METHODS
42 patients with TMD underwent MRI. To assess IVIM parameters, diffusion-weighted imaging was obtained by spin-echo-based single-shot echoplanar imaging. Regions of interest were created on all diffusion-weighted images of the superior belly of the lateral pterygoid (SLP) and inferior belly of the lateral pterygoid (ILP) at b-values 0-500 s mm-2. Then, IVIM parameters, diffusion (D) and perfusion (f) were calculated using biexponential fittings. The correlation of these values with conventional MRI findings on TMJs was investigated.


RESULTS
For SLP, the f parameter in TMJs with anterior disc displacement without reduction was significantly higher than that in normal ones (p = 0.015). It was also significantly higher in TMJs with joint effusion than in those without (p = 0.016). On the other hand, for both SLP and ILP, the D parameter significantly increased in TMJs with osteoarthritis compared with those without (p = 0.015 and p = 0.022, respectively).


CONCLUSIONS
Pathological changes of LPM in patients with TMD may be quantitatively evaluated by IVIM parameters.
1 Oral and Maxillofacial Radiology Department, Graduate School, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.|2 Oral and Maxillofacial Radiology Department, Faculty of Dentistry, Mahidol University, Bangkok, Thailand.
Supak
S
Ngamsom
1 Oral and Maxillofacial Radiology Department, Graduate School, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
Shin
S
Nakamura
1 Oral and Maxillofacial Radiology Department, Graduate School, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
Junichiro
J
Sakamoto
1 Oral and Maxillofacial Radiology Department, Graduate School, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
Shinya
S
Kotaki
1 Oral and Maxillofacial Radiology Department, Graduate School, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
Akemi
A
Tetsumura
1 Oral and Maxillofacial Radiology Department, Graduate School, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
Tohru
T
Kurabayashi
D000328:Adult; D038524:Diffusion Magnetic Resonance Imaging; D017352:Echo-Planar Imaging; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011626:Pterygoid Muscles / Q000000981:diagnostic imaging* / Q000473:pathology; D013705:Temporomandibular Joint Disorders / Q000000981:diagnostic imaging* / Q000473:pathology
diagnostic imaging; diffusion-weighted MRI; masticatory muscles; pterygoid muscle; temporomandibular joint disorders