ObjectivesEdema and necrosis of the temporomandibular joint (TMJ) have been described in terms of bone marrow signal abnormalities in magnetic resonance imaging (MRI). However, painful joints often show no such signaling abnormalities, making the diagnosis of TMJ disorders difficult in the clinical setting. An association has been suggested between TMJ bone marrow change and TMJ pain, but even when such change results in slight pain, it may be too slight to be visually apparent on MR images. We hypothesized that fluid-attenuated inversion recovery (FLAIR) can be used to detect such minimal changes. The purpose of this study was to determine whether there is an association between signal intensity on FLAIR images and pain in the TMJ.MethodsThe study included 85 TMJs in 45 patients referred to our department for MRI. The signal intensity on FLAIR images was measured. Pain was evaluated based on the visual analog scale. An unpaired t test and Pearson’s product-moment correlation coefficient were used for the statistical analysis. A p value of <0.05 was considered statistically significant.ResultsSignal intensity on the FLAIR images was significantly higher in painful than in nonpainful TMJs, although a significant correlation was not observed between the signal intensity and the pain score.ConclusionsThe results of this study suggest an association between abnormalities in the marrow of the mandibular condyle and pain. They also indicate that FLAIR imaging is a useful tool in the clinical diagnosis of painful TMJs.

On images, a dermoid cyst is often described as resembling a "sack of marbles" or "marbles in a bag". Typically, it comprises an inhomogeneity filled with multiple nodules in a fluid matrix on both computed tomography and magnetic resonance imaging (MRI). How it appears, however, will vary depending on its histological contents, which may cause confusion in arriving at a diagnosis. This report describes a dermoid cyst in the floor of the mouth of a 55 year-old woman that showed an atypical internal appearance on MRI. Most of the lesion showed homogeneous high signal intensity on T1 - and T2-weighted images, suggesting that it was derived from fat. A small area within the mass, however, showed moderate signal intensity almost equal to that of muscle on T1-weighted images and high signal intensity on fat-suppressed T2-weighted images. Given the location of the lesion, a dermoid cyst was one possible diagnosis. A lipoma or lipoma variants were also considered, however, based on signal intensity. Histopathological section of the excised specimen revealed a dermoid cyst with sebaceous glands in its walls and keratin in its cavity. Dermoid cysts show variation in their internal structures and contents. Since MRI can reflect such histological variation, signal intensity requires careful interpretation.

Objective. The purpose of this study was to determine the potential of fluid attenuated inversion recovery (FLAIR) sequence images in the identification of joint effusion (JE) in comparison with T2-weighted images.Study design. A total of 31 joints (28 patients) with JE were investigated by magnetic resonance imaging. Regions of interest were placed over JE, cerebrospinal fluid (CSF) and gray matter (GM) on T2-weighted and FLAIR images and their signal intensities compared. The signal intensity ratios (SIRs) of JE and CSF were calculated used GM as the reference point. The Pearson product-moment correlation coefficient was used for the statistical analysis.Result. The SIR of JE showed a strong correlation between T2-weighted and FLAIR images. However, no correlation was observed for CSF. The average suppression ratio for JE was lower than that for CSF. According to the inclusion and exclusion criteria (Table I), 201 joints were excluded from this study. A total of 31 joints of 28 patients were studied. A total of 31 joints of 28 patients were studied. There were 4 males and 24 females. The mean age of the patients was 39.9 years with an age range of 13 to 76 years. ConclusionAll images were obtained with the 1. The signal intensity ratio (SIR)s of JE and CSF were calculated as follows: SIR = the signal intensity of JE or CSF/the signal intensity of GM. In the FLAIR sequence images, the patients were divided into Group A (TE, 122 ms) and Group B (TE, 168 ms) for the statistical analysis. The Pearson product-moment correlation coefficient was used to assess the correlation between the SIRs on the T2-weighted and FLAIR images of both JE and CSF. A probability of less than 0.05 was considered statistically significant. The suppression ratios of the signal intensities in FLAIR imaging were also compared according to the following equation: (SIR of T2-weighted imagesSIR of FLAIR images)/SIR of T2-weighted images × 100 (Figure 3). 6 ResultsThe SIRs obtained for JE and CSF on T2-weighted and FLAIR images are shown in Table III. The average SIR of JE was higher than that of CSF on both T2-weighted and FLAIR images in both Groups A and B.A strong correlation between T2-weighted images and FLAIR images was obtained for JE in both groups. The correlation coefficient was 0.81 in Group A and 0.94 in Group B (Figures 4 and 5). On the other hand, no correlation was found between the two sets of images for CSF (0.09 in Group A、-0.33 in Group B).The average suppression ratio for the signal intensity of JE by FLAIR imaging was 36.9% in Group A and 16.3% in Group B. The ratio for CSF was 75.6% in Group A and 71.7% in Group B (Table IV). The signal intensity of CSF was suppressed more markedly than that of JE.7 DiscussionJoint effusion is considered to be a pathological collection of joint fluid that can only be observed on T2-weighted images. Hitherto, the only way to determine the presence of JE has been by amount of fluid present in the joint. We hypothesized that the FLAIR technique would provide additional inform...

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We report herein a case of squamous cell carcinoma presumed to have arisen from the right Stensen's duct. The patient, a 62-year-old man, was referred to our hospital with swelling in the right cheek.

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We report herein a case of a luminal and intramural unicystic ameloblastoma (UA) with a marked fluid-fluid level. The validity of imaging findings in diagnosing UA in the present case is discussed in reference to the literature. The patient was a 50-year-old woman who presented with swelling of the gingiva in the region of the left mandibular third molar and numbness in the lower lip. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed a large mass lesion with a unilocular appearance and a biphasic aspect, suggesting liquid content. Contrast-enhanced MRI (CE-MRI) and dynamic contrast-enhanced MRI (DCE-MRI) demonstrated that the biphasic aspect indicated a fluid-fluid level with no blood pooling/flow; it also revealed a thick rim-enhanced margin with mural protrusion. Postoperatively, the lesion was histopathologically diagnosed as a luminal and intramural UA. In conclusion, extensive imaging including both standard CT and MRI together with CE-MRI and DCE-MRI allowed mural protrusions or nodules on a thick cystic wall and liquid content to be correctly identified. This suggests that such imaging can play an important role in diagnosing a UA, even though the results were at first misleading due to the marked fluid-fluid level.

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